UBC Theses and Dissertations

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UBC Theses and Dissertations

Electroslag casting of valve bodies 1982

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E L E C T R O S L A G C A S T I N G OF V A L V E B O D I E S b y D E E P A K G U P T A B . T e c h . , I n d i a n I n s t i t u t e o f T e c h n o l o g y , K a n p u r , I n d i a , A T H E S I S S U B M I T T E D IN P A R T I A L F U L F I L M E N T OF T H E R E Q U I R E M E N T S FOR T H E D E G R E E OF M A S T E R OF A P P L I E D S C I E N C E i n T H E F A C U L T Y OF G R A D U A T E S T U D I E S D e p a r t m e n t o f M e t a l l u r g i c a l E n g i n e e r i n g We a c c e p t t h i s t h e s i s a s c o n f o r m i n g t o t h e r e q u i r e d s t a n d a r d T H E U N I V E R S I T Y OF B R I T I S H C O L U M B I A J a n u a r y 1 9 8 2 ( c ) D e e p a k G u p t a , 1 9 8 2 In presenting t h i s thesis i n p a r t i a l f u l f i l m e n t of the requirements for an advanced degree at the University of B r i t i s h Columbia, I agree that the Library s h a l l make i t f r e e l y a v a i l a b l e for reference and study. I further agree that permission for extensive copying of t h i s thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. I t i s understood that copying or p u b l i c a t i o n of t h i s thesis for f i n a n c i a l gain s h a l l not be allowed without my written permission. Department of The University of B r i t i s h Columbia 2075 Wesbrook Place Vancouver, Canada V6T 1W5 Da t e O O W - f8- , t̂ S2~- 3E-6 (2/79) i i A B S T R A C T T h e E l e c t r o s l a g C a s t i n g ( E S C ) p r o c e s s h a s b e e n w i d e l y u s e d i n t h e S o v i e t U n i o n f o r t h e p r o d u c t i o n o f h i g h q u a l i t y s t e e l c a s t i n g s . T h i s w o r k p r e s e n t s t h e r e s u l t s o f a n e x a m i n a - t i o n o f t h e E S C p r o c e s s f o r t h e p r o d u c t i o n o f s i m p l e s h a p e d v a l v e b o d i e s . S t a i n l e s s s t e e l ( A I S I 3 1 6 a n d A C I C F - 8 M ) a n d l o w a l l o y s t e e l ( A I S I 4 3 4 0 ) v a l v e b o d i e s w e r e m a d e a t U . B . C . a n d t e s t e d b y n o n - d e s t r u c t i v e a n d d e s t r u c t i v e m e t h o d s . I t i s c o n c l u d e d t h a t t h i s t e c h n i q u e o f f e r s d i s t i n c t q u a l i t y a n d p r o d u c t i o n a d v a n t a g e s a n d t h e p r o p e r t i e s e a s i l y m e e t t h e r e q u i r e d A S M E / A S T M s p e c i f i c a t i o n s . T h e r e f o r e t h e y a r e e q u i - v a l e n t t o o r b e t t e r t h a n t h e c o n v e n t i o n a l c a s t i n g s a n d f o r c - i n g s H o w e v e r , t h e r e may b e d i f f i c u l t i e s i n r e c o n c i l i n g t h e m e t h o d w i t h p r e s e n t c o d e q u a l i f i c a t i o n r e q u i r e m e n t s . TABLE OF CONTENTS A b s t r a c t T a b l e o f C o n t e n t s L i s t o f T a b l e s L i s t o f F i g u r e s — Acknow ledgements • C h a p t e r 1 INTRODUCTION 2 PROCESS DESCRIPTION AND CHARACTERISTICS 2.1 E l e c t r o s l a g R e m e l t i n g P r o c e s s C h a r a c t e r i s t i c s .. Wh ich A f f e c t t h e P r o p e r t i e s o f t h e M a t e r i a l s . . . 2 . 1 . 1 C h a r a c t e r i s t i c s R e l a t e d t o C h e m i c a l R e f i n i n g 2 . 1 . 2 C h a r a c t e r i s t i c s R e l a t e d t o S o l i d i f i c a t i o n s t r u c t u r e 3 PRESENT WORK 3.1 F u r n a c e D e s i g n 3 . 2 V a l v e Mo ld D e s i g n 3 . 3 M e l t i n g P r o c e d u r e 3 . 4 S e l e c t i o n o f S l a g s f o r ESC P r o c e s s 4 EVALUATION OF ESC VALVE CASTINGS A . STAINLESS STEEL VALVE CASTINGS 4 .1 R e m e l t i n g Log f o r S t a i n l e s s S t e e l ESC V a l v e s . . . 4 . 2 N o n - D e s t r u c t i v e T e s t i n g (NDT) 4 . 2 . 1 Dye P e n e t r a n t T e s t 4 . 2 . 2 U l t r a s o n i c T e s t 4 . 2 . , 3 R a d i o g r a p h y T e s t 4 . 3 D e s t r u c t i v e T e s t i n g (DT) 4 . 3 . 1 M a c r o s t r u c t u r e s 4 . 3 . 2 M i c r o s t r u c t u r e s 4 . 3 . 3 D e l t a F e r r i t e Measurements 4 . 3 . 4 I n t e r d e n d r i t i c M i c r o s e g r e g a t i o n 4 . 3 . 5 C o m p o s i t i o n A n a l y s i s and M a c r o s e g r e g a t i o n . . . 4 . 3 . 6 P r o b l e m s W i t h A l l o y i n g D u r i n g t h e ESC O p e r a t i o n 4 . 3 . 7 P r o b l e m s W i t h U s i n g C a s t E l e c t r o d e s i n ESC O p e r a t i o n 4 . 4 M e c h a n i c a l P r o p e r t i e s 4 . 4 . 1 T e n s i l e T e s t i n g B . LOW ALLOY STEEL VALVE CASTINGS 4 . 5 Remel . t ing Log f o r A I S I 4340 ESC V a l v e s 4 . 6 N o n - D e s t r u c t i v e T e s t i n g (NDT) 4 . 6 . 1 Dye P e n e t r a n t T e s t 4 . 6 . 2 U l t r a s o n i c T e s t 4 . 6 . 3 R a d i o g r a p h y T e s t 4 . 7 D e s t r u c t i v e T e s t i n g (DT) 4 . 7 . 1 M a c r o s t r u c t u r e s 4 . 7 . 2 S u l p h u r P r i n t s 4 . 7 . 3 I n t e r d e n d r i t i c M i c r o s e g r e g a t i o n 4 . 7 . 4 C o m p o s i t i o n A n a l y s i s and M a c r o s e g r e g a t i o n . . . 4 . 7 . 5 Hea t T r e a t m e n t and M i c r o s t r u c t u r e s 4 . 7 . 6 D i m e n s i o n a l Measurements 4 . 8 M e c h a n i c a l P r o p e r t i e s 4 . 8 . 1 T e n s i l e T e s t i n g 4 . 8 . 2 Impact T e s t i n g 5 OTHER TRIALS AND FUTURE WORK 6 SUMMARY AND CONCLUSIONS REFERENCES TABLES^ FIGURES APPENDIX 1 - ASME/ASTM S p e c i f i c a t i o n s V L IST OF TABLES T a b l e s Page I R e m e l t i n g Log f o r S t a i n l e s s S t e e l ESC V a l v e s 83 I I F e r r i t e Numbers o f S t a i n l e s s S t e e l C a s t i n g s 84 I I I A v e r a g e F e r r i t e Numbers o f S t a i n l e s s S t e e l C a s t i n g s D e t e r m i n e d by Magne-Gage and S c h o e f e r ' s D iag ram 85 IV I n t e r d e n d t i t i c M i c r o s e g r e g a t i o n R a t i o s o f CF-8M C a s t i n g s . . 86 V C h e m i c a l C o m p o s i t i o n o f V a l v e No . 5 (CF-8M) 87 VI C h e m i c a l C o m p o s i t i o n o f V a l v e No . 6 (316) 87 V I I C h e m i c a l C o m p o s i t i o n o f V a l v e No . 7 (316+Cr) 88 V I I I C h e m i c a l C o m p o s i t i o n o f V a l v e No . 9 (CF-8M) 88 IX C h e m i c a l C o m p o s i t i o n o f V a l v e No . 10 (316+Cr+Mo) 89 X C h e m i c a l C o m p o s i t i o n o f C o n v e n t i o n a l C a s t i n g (CF-8M) 89 XI P e r c e n t C o m p o s i t i o n o f C r and Mo i n A r e a s 1 and 2 and t h e P a r e n t V a l v e C a s t i n g No . 10 90 X I I T e n s i l e P r o p e r t i e s o f V a l v e N o s . 5 , 6 and 7 90 X I I I T e n s i l e P r o p e r t i e s o f V a l v e No . 9 , C o n v e n t i o n a l C a s t i n g and ASME/ASTM S t a n d a r d s f o r A I S I 316 and ACI CF-8M 91 XIV T e n s i l e P r o p e r t i e s o f l a r g e s p e c i m e n s f r om V a l v e N o s . 6 and 9 and s m a l l s p e c i m e n s f r om a l a r g e s p e c i m e n 92 XV R e m e l t i n g Log f o r A I S I 4340 ESC V a l v e s 93 XVI I n t e r d e n d r i t i c M i c r o s e g r e g a t i o n a t t h e C e n t r e o f A I S I 4340 ESC V a l v e s 94 XVI I C h e m i c a l C o m p o s i t i o n o f V a l v e N o . 3 (4340) 95 X V I I I C h e m i c a l C o m p o s i t i o n o f V a l v e No. 8 (4340) 96 XIX C h e m i c a l C o m p o s i t i o n o f V a l v e No. 13 (4340) 97 XX C h e m i c a l C o m p o s i t i o n o f V a l v e No. 14 (4340.) 9 7 T a b l e s v i Page XXI S u l p h u r C o n t e n t s o f t h e A I S I 4340 E l e c t r o d e and ESC V a l v e s . 98 X X I I D i m e n s i o n a l Measurements on V a l v e N o s . 1 1 , 12 and 13 98 X X I I I T e n s i l e P r o p e r t i e s o f A I S I 4340 E l e c t r o s l a g C a s t V a l v e s . . . 99 XXIV T e n s i l e P r o p e r t i e s o f C o n v e n t i o n a l A I S I 4340 Hot R o l l e d B a r 100 XXV T r a n s v e r s e T e n s i l e P r o p e r t i e s o f A i r - m e l t e d and V a c u u m - a r c M e l t e d A I S I 4340 S t e e l s 7 5 100 XXVI L o n g i t u d i n a l M e c h a n i c a l P r o p e r t i e s o f B a r S t o c k Made From R e m e l t e d A I S I 4340 S t e e l 7 5 100 XXVI I M e c h a n i c a l P r o p e r t i e s o f ESR 4340 M a t e r i a l i n t h e T r a n s - : i l v e r s e D i r e c t i o n Hea t T r e a t e d t o D i f f e r e n t S t r e n g t h L e v e l s ^ . . . 101 X X V I I I a T e n s i l e P r o p e r t i e s o f L a r g e Spec imens f r om ESC V a l v e N o . 8 ( A I S I 4340) 101 X X V I l i b T e n s i l e P r o p e r t i e s o f S m a l l Spec imens f r o m L a r g e Spec imen f r om ESC V a l v e No . 8 ( A I S I 4340) 101 XXIX FATT V a l u e s E s t i m a t e d f r om D u c t i l e - B r i t t l e - T r a n s i t i o n C h a r a c t e r i s t i c s o f t h e ESC and E l e c t r o d e M a t e r i a l 102 VI 1 L IST OF FIGURES F i g u r e Page 8 1 E l e c t r o s l a g c a s t p r o d u c t s 103 2 'YOZO' p r o c e s s o f M i t s u b i s h i Heavy I n d u s t r i e s L t d . 1 1 ' 1 2 . . . 104 3 . S c h e m a t i c o f t h e ESC p r o c e s s 105 4 F r a c t u r e t o u g h n e s s o f ESC A I S I 4340 s t e e l c o n t a i n i n g v a r y i n g amounts o f s u l p h u r ^ 106 5 E l e c t r o s l a g c a s t i n g i n s t a l l a t i o n a t U . B . C 107 108 109 6 O r t h o g o n a l v i e w s o f t h e v a l v e mo ld segments 7a P l a n v i e w s o f t h e v a l v e mo ld segments 7b S e c t i o n s t h r o u g h t h e v a l v e mo ld segments 110 8 A s s e m b l e d v a l v e mo ld I l l 9 S l a g m e l t i n g f u r n a c e H I 10 S o l i d i f i e d s l a g s k i n on t h e c a s t i n g 112 no I T P h a s e d i a g r a m f o r C a F ^ A j Z ^ - C a O s y s t e m 113 12 S t a i n l e s s s t e e l ESC v a l v e H 4 13 L o n g i t u d i n a l h o l e s i n t h e c a s t i n g s due t o m o i s t u r e H 5 14 S c h e m a t i c o f t h e s e c t i o n i n g p r o c e d u r e o f t h e v a l v e s H 6 15 M a c r o s t r u c t u r e o f V a l v e No . 5 (CF-8M) 16 M a c r o s t r u c t u r e o f V a l v e No. 6 (316) H 7 17 M a c r o s t r u c t u r e o f V a l v e No . 9 (CF-8M) 118 1.8 M a c r o s t r u c t u r e o f V a l v e No . 10 (316+Cr+Mo) 119 19 M a c r o s t r u c t u r e o f c o n v e n t i o n a l c a s t i n g (CF-8M) 120 20a M i i c r o s t r u c t u r e o f CF-8M ESC v a l v e s b e f o r e h e a t t r e a t - ment ( e t c h a n t - o x a l i c a c i d ) 121 20b M i c r o s t r u c t u r e o f CF-8M ESG v a l v e s a f t e r h e a t t r e a t - ments ( e t c h a n t - o x a l i c a c i d ) 21 M i c r o s t r u c t u r e o f a s - c a s t ESC V a l v e No. 5 , 6 and 7 ( e t c h a n t - o x a l i c a c i d ) 22 M i c r o s t r u c t u r e o f h e a t - t r e a t e d ESC V a l v e No . 5 , 6 and 7 ( e t c h a n t - o x a l i c a c i d ) 23 M i c r o s t r u c t u r e o f CF-8M s p e c i m e n h e a t e d t o 850°C ( e t c h a n t - KOH) 24 M i c r o s t r u c t u r e o f h e a t t r e a t e d CF-8M c o n v e n t i o n a l c a s t i n g ( e t c h a n t - KOH) 25 M i c r o s t r u c t u r e o f V a l v e No . 9 i n a s - c a s t c o n d i t i o n ( e c h a n t - KOH) 26 M i c r o s t r u c t u r e o f V a l v e No . 9 i n h e a t - t r e a t e d c o n d i t i o n ( e t c h a n t - KOH) 27 M i c r o h a r d n e s s i n d e n t a t i o n s on s i g m a and a u s t e n i t e p h a s e s . . 28 S c h o e f e r ' s d i a g r a m f o r d e t e r m i n a t i o n o f f e r r i t e numbers o f s t a i n l e s s s t e e l c a s t i n g s 6 6 29a V a r i a t i o n o f C r , Ni and:Mo a c r o s s t h e d e n d r i t i c . d i r e c t i o n i n V a l v e No. 9 a t t h e edge 29b V a r i a t i o n o f C r , Ni and Mo a c r o s s t he d e n d r i t i c ' ' , * ; d i r e c t i o n i n V a l v e No . 9 a t t h e c e n t r e . . 30a V a r i a t i o n o f Cr'v.;Nf and ;Mo a c r o s s t h e ' d e n d r i t i c : '"' v: ; d i r e c t i o n i n c o n v e n t i o n a l c a s t i n g a t t h e edge 30b V a r i a t i o n o f C r , N i , and Mo a c r o s s t h e d e n d r i t i c d i r e c t i o n i n c o n v e n t i n a l c a s t i n g a t t h e m i d - r a d i u s 30c V a r i a t i o n o f C r , N i , and Mo a c r o s s t h e d e n d r i t i c d i r e c t i o n i n c o n v e n t i o n a l c a s t i n g a t t h e c e n t r e . . 31 C o m p o s i t i o n v a r i a t i o n i n V a l v e No . 5 (CF-8M) 32 C o m p o s i t i o n v a r i a t i o n i n V a l v e No . 6 (316) 33 C o m p o s i t i o n v a r i a t i o n i n V a l v e No . 7 (316+Cr) F i g u r e 34 C o m p o s i t i o n v a r i a t i o n i n V a l v e No . 9 (CF-8M) 35 C o m p o s i t i o n v a r i a t i o n i n V a l v e No . 10 (316+Cr+Mo) 36 C o m p o s i t i o n v a r i a t i o n i n c o n v e n t i o n a l c a s t i n g ( C F - 8 M ) 37 SEM p h o t o g r a p h s o f a g g l o m e r a t e d f e r r o a l l o y powder i n a r e a 1 i n V a l v e No. 10 38 SEM p h o t o g r a p h s o f a g g l o m e r a t e d f e r r o a l l o y powder i n a r e a 2 i n V a l v e No . 10 39 EDXA p l o t s o f a g g l o m e r a t e d f e r r o a l l o y powder i n a r e a s 1 and 2 and t h e p a r e n t m e t a l ( V a l v e No . 10) 7. '. 40a EDXA p l o t s o f i n c l u s i o n s i n a r e a s 1 and 2 and F e - C r powder 40b EDXA p l o t s o f i n c l u s i o n s i n a r e a s 1 and 2 and F e - C r powder 40c EDXA p l o t s o f i n c l u s i o n s i n Fe-Mo powder 41 M a c r o p o r o s i t y i n t h e c e n t r e o f t h e CF-8M e l e c t r o d e 42 M a c r o s t r u c t u r e o f t h e e l e c t r o d e p i e c e t h a t d r o p p e d i n V a l v e No . 9 43 M a c r o s t r u c t u r e o f t h e CF-8M e l e c t r o d e d r o p p e d 44 I n c l u s i o n s i n t h e e l e c t r o d e p i e c e d r o p p e d i n V a l v e No . 9 and e l e c t r o d e t i p ( o p t i c a l p h o t o g r a p h s ) 45 I n c l u s i o n s i n t h e e l e c t r o d e p i e c e d r o p p e d i n V a l v e No . 9 , e l e c t r o d e t i p and t h e p a r e n t c a s t i n g ( V a l v e No . 9 ) 46a EDXA p l o t s o f i n c l u s i o n s i n t h e e l e c t r o d e p i e c e d r o p p e d i n V a l v e No . 9 and t h e e l e c t r o d e t i p 46b EDXA p l o t s o f i n c l u s i o n s i n t h e p a r e n t c a s t i n g ( V a l v e No . 9) 47 S c h e m a t i c t o e x p l a i n t h e p e c u l i a r poo l p r o f i l e o b s e r v e d i n V a l v e No . 9 48 M a c r o s t r u c t u r e o f t h e p e c u l i a r poo l p r o f i l e o b s e r v e d i n V a l v e No. 9 F i g u r e 49 S c h e m a t i c o f t h e t e n s i l e s p e c i m e n s used . . 50 V a r i a t i o n o f t e n s i l e p r o p e r t i e s w i t h f e r r i t e number o f s t a i n l e s s s t e e l c a s t i n g s 51 P h o t o g r a p h o f t h e de fo rmed and f r a c t u r e d a r e a s o f s m a l l t e n s i l e s p e c i m e n f r o m V a l v e No . 6 52 P h o t o g r a p h o f t h e de fo rmed and f r a c t u r e d a r e a s o f l a r g e t e n s i l e s p e c i m e n f r o m V a l v e No . 6 53 A I S I 4340 ESC v a l v e 54 C r a c k s i n V a l v e N o . 14 r e v e a l e d by d y e - p e n e t r a n t t e s t 55 R a d i o g r a p h s o f V a l v e No . 3 56 M a c r o s t r u c t u r e o f V a l v e No . 3 Top - HC£ e t c h Bo t tom ( N H 4 ) 2 S 0 4 e t c h 57 M a c r o s t r u c t u r e o f V a l v e No . 8 (HC£ e t c h ) 58 M a c r o s t r u c t u r e o f V a l v e No . 13 ( H C P . e t c h . ) ' - . , . 59 M a c r o s t r u c t u r e o f V a l v e No . 14 (HC£ e t c h ) ( t o p p a r t e t c h e d f o r a l o n g e r t i m e ) 60 M a c r o s t r u c t u r e o f t h e t r a n s v e r s e s e c t i o n o f a m i l d s t e e l ESC v a l v e (HC£ e t c h ) 61 D e n d r i t i c s t r u c t u r e o f V a l v e No . 3 62 S u l p h u r p r i n t s o f V a l v e No . 3 63 S u l p h u r p r i n t s o f V a l v e No . 8 64 V a r i a t i o n o f C r , N i , and Mo a c r o s s t h e d e n d r i t i c d i r e c t i o n i n V a l v e No . 8 65 V a r i a t i o n o f C r , N i and Mo a c r o s s t h e d e n d r i t i c d i r e c t i o n i n V a l v e No. 13 . — 66 V a r i a t i o n o f C r , Ni and Mo a c r o s s t h e d e n d r i t i c d i r e c t i o n i n V a l v e No. 14 67 C o m p o s i t i o n v a r i a t i o n i n V a l v e No . 3 F i g u r e 68 C o m p o s i t i o n v a r i a t i o n i n V a l v e No . 8 69 C o m p o s i t i o n v a r i a t i o n i n V a l v e No . 13 70 C o m p o s i t i o n v a r i a t i o n i n V a l v e No . 14 71 M a c h i n e d A I S I 4340 ESC v a l v e 72 S e p a r a t e d s u r f a c e s a l o n g a c r a c k i n V a l v e No . 14 73 H a r d n e s s v a r i a t i o n i n h e a t - t r e a t e d V a l v e No . 13 74 H a r d n e s s v a r i a t i o n i n h e a t - t r e a t e d V a l v e No . 14 75 M i c r o s t r u c t u r e s A I S I 4340 v a l v e i n a s - c a s t and h e a t - t r e a t e d c o n d i t i o n s ; e l e c t r o d e i n h e a t - t r e a t e d c o n d i t i o n 76 M i c r o s t r u c t u r e o f A I S I 4340 ESC V a l v e No . 13 i n h e a t - t r e a t e d c o n d i t i o n 77 F r a c t o g r a p h s o f l a r g e t e n s i l e s p e c i m e n s o f A I S I 4340 f r o m ESC v a l v e No . 8 78 O r i e n t a t i o n o f t h e c h a r p y s p e c i m e n s and t h e n o t c h i n V a l v e No . 8 , 79 D u c t i l e b r i t t l e t r a n s i t i o n c h a r a c t e r i s t i c s o f V a l v e No . 3 and t h e e l e c t r o d e 80 D u c t i l e b r i t t l e t r a n s i t i o n c h a r a c t e r i s t i c s o f V a l v e No . 8 81 D u c t i l e b r i t t l e t r a n s i t i o n c h a r a c t e r i s t i c s o f V a l v e N o . 1 3 82 O p t i c a l f r a c t o g r a p h s o f c h a r p y s p e c i m e n s f r o m v a l v e No . 8 t e s t e d a t d i f f e r e n t t e m p e r a t u r e s and o r i e n t a t i o n s a - TT b - TL c ~ E d - E . . . . . 83 O p t i c a l f r a c t o g r a p h s o f c h a r p y s p e c i m e n s f r o m t h e A I S I 4340 e l e c t r o d e 84 SEM f r a c t o g r a p h s o f c h a r p y s p e c i m e n a - r i d g e a r e a b - m i c r o - c r a c k s . . 85 SEM f r a c t o g r a p h s o f d i f f e r e n t r e g i o n s o f a c h a r p y spec imen x i i F i g u r e Page 86 S o v i e t e l e c t r o s l a g c a s t v a l v e 193 87 S c h e m a t i c o f t h e methods used f o r mak ing h o l l o w ESC v a l v e s 194 88 E l e c t r o s l a g c a s t i n g o f a f l a n g e f o r use i n v a l v e b o d i e s . . 195 89 ESC v a l v e w i t h t h e w e l d e d i n s e r t 1 9 5 90 M a c r o s t r u c t u r e o f t h e ESC v a l v e w i t h t h e w e l d e d i n s e r t . . . 196 A C K N O W L E D G E M E N T S x i i i I w o u l d l i k e t o t h a n k s i n c e r e l y my r e s e a r c h s u p e r v i s o r , P r o f e s s o r A l e c M i t c h e l l , f o r h i s f r i e n d l y a s s i s t a n c e a n d g u i d a n c e t h r o u g h o u t t h e c o u r s e o f t h i s r e s e a r c h p r o j e c t . T h a n k s a r e e x t e n d e d t o my f e l l o w g r a d u a t e s t u d e n t s o f t h e D e p a r t m e n t o f M e t a l l u r g y f o r t h e i r h e l p f u l s u g g e s t i o n s . T h e a s s i s t a n c e o f t h e t e c h n i c a l s t a f f o f t h i s d e p a r t m e n t , i n p a r t i c u l a r M r . G u s S i d l a , i s g r e a t l y a p p r e c i a t e d . A n d f i n a l l y , I am t h a n k f u l f o r t h e f i n a n c i a l a s s i s t a n c e o f t h e N a t u r a l S c i e n c e s a n d E n g i n e e r i n g R e s e a r c h C o u n c i l o f C a n a d a a n d o f t h e A m e r i c a n I r o n a n d S t e e l I n s t i t u t e . C h a p t e r 1 1 I N T R O D U C T I O N W i t h t h e g r o w t h a n d e x p a n s i o n o f t h e a e r o s p a c e a n d n u c l e a r i n d u s t r y , t h e d e m a n d f o r s p e c i a l t y ; m e t a l s w i t h e x - c e p t i o n a l l y h i g h s t a n d a r d s o f q u a l i t y a n d r e l i a b i l i t y h a s i n - c r e a s e d t r e m e n d o u s l y . T h e s p e c i f i c a t i o n s f o r t h e c o m p o n e n t s a r e b e c o m i n g m o r e a n d m o r e r i g i d . T h e r e s u l t i s , a s m i g h t b e e x p e c t e d , ^ . . - a h i g h r a t e o f r e j e c t i o n o f c o n v e n t i o n a l l y m a d e p r o d u c t s w h i c h f a i l t o p a s s r i g o r o u s t e s t i n g p r i o r t o i n s t a l - l a t i o n a n d f a i l w h e n i n s e r v i c e . A l t h o u g h t h e V a c u u m A r c R e m e l t i n g ( V A R ) p r o c e s s w a s c o n c e i v e d a s e a r l y a s t h e m i d - n i n e t e e n t h c e n t u r y , i t h a s o n l y b e e n u s e d e x t e n s i v e l y i n t h e l a s t t h i r t y y e a r s . E l e c t r o s l a g R e m e l t i n g ( E S R ) p r o c e s s , on . t h e o t h e r h a n d , i s r e l a t i v e l y n e w . O v e r t h e l a s t f i f t e e n y e a r s , E S R h a s b e e n e s t a b l i s h e d a s a n i n d u s t r i a l l y - v i a b l e p r o c e s s f o r t h e p r o d u c t i o n o f h i g h q u a l i t y m a t e r i a l . i n a w i d e c o m p o s i t i o n r a n g e . T h e c o m m o n o b j e c t i v e b e h i n d t h e d e v e l o p m e n t o f b o t h t h e s e r e m e l t i n g p r o c e s s e s w a s t h a t o f p r o d u c i n g h i g h q u a l i t y m a t e r i a l b y c h e m i c a l r e f i n i n g a n d c o n - t r o l l e d s o l i d i f i c a t i o n . T h e p o s s i b l e h i g h c o s t o f r e m e l t i n g i s o f f s e t b y t h e p r o c e s s e s ' a d v a n t a g e s o f i n c r e a s e d s e r v i c e l i f e o f t h e c o m p o n e n t s , v e r y l o w r e j e c t i o n r a t e s , a n d h i g h o v e r a l l y i e l d . 2 I n i t i a l l y , t h e E S R p r o c e s s w a s w i d e l y u s e d i n U . S . S . R . f o r u p g r a d i n g t h e a i r - m e l t e d q u a l i t y m a t e r i a l . T h e n t h e u s e o f E S R w a s e x t e n d e d t o f o r g i n g a p p l i c a t i o n s a n d t h e p r o c e s s g a i n e d p r o m i n e n c e i n o t h e r c o u n t r i e s ; a l s o . D u r i n g r e c e n t y e a r s i t b e c a m e e v i d e n t t h a t t h e c a s t E S R m a t e r i a l w a s e q u i - v a l e n t t o o r b e t t e r t h a n t h e c o n v e n t i o n a l c a s t i n g s a n d f o r g - i h g s . T h i s l e d t o s p e c u l a t i o n a s t o w h e t h e r o r n o t t h e E S R p r o c e s s c a n b e e x t e n d e d t o p r o d u c e s h a p e s v e r y c l o s e t o t h e f i n a l c a s t o r f o r g e d p r o d u c t ( n e a r n e t s h a p e s ) . T h e n e x t s t e p i n t h i s l o g i c a l s e q u e n c e w a s t h e e m e r g e n c e o f t h e E l e c t r o - s l a g C a s t i n g ( E S C ) p r o c e s s . G e n e r a l l y , t h e c o n v e n t i o n a l l y c a s t c o m p o n e n t s a r e a s s o c i - a t e d w i t h d e f e c t s s u c h a s s h r i n k a g e , p o r o s i t y , l a r g e n o n - m e t a l l i c i n c l u s i o n s , s e g r e g a t i o n a n d h e n c e h a v e p o o r a n d a n i s o t r o p i c m e c h a n i c a l p r o p e r t i e s . A l t h o u g h w i t h r e c e n t c a s t - i n g t e c h n i q u e s , s u c h a s s q u e e z e - c a s t i n g , i t i s p o s s i b l e t o p r o d u c e b e t t e r q u a l i t y c a s t i n g s , t h e s e a r e l i m i t e d t o a s m a l l s c a l e o n l y a n d i n v o l v e h e a v y c a p i t a l e x p e n s e . T h e h o t w o r k i n g p r o c e s s e s ( f o r g i m g : a n d r o l 1 i n g ) c a n b e a p p l i e d t o e l i m i n a t e t h e c a s t i n g d e f e c t s a n d p r o d u c e a b e t t e r q u a l i t y m a t e r i a l , b u t t h e i n c r e a s e i n a n i s o t r o p y o f t h e m e c h a n i c a l p r o p e r t i e s a n d e x t r a c o s t m a k e s t h i s s t e p u n a t t r a c t i v e . H o w e v e r , w i t h t h e E S C p r o c e s s i t i s n o t o n l y p o s s i b l e t o p r o d u c e l a r g e c a s t i n g s w i t h t h e s a m e e a s e a s t h e s m a l l o n e s , b u t t h e y a r e f r e e f r o m m o s t o f t h e d e f e c t s m e n t i o n e d a b o v e a n d a r e m a n u f a c t u r e d a t a c o m p a r a t i v e l y l o w c o s t . 3 T h e E . O . P a t o n I n s t i t u t e i n K i e v , U . S . S . R . h a s e x t e n s i v e l y u s e d t h e E S C p r o c e s s t o p r o d u c e c o m p o n e n t s f o r a w i d e v a r i e t y o f a p p l i c a t i o n s . T h e s e r a n g e f r o m d e n t u r e s w e i g h i n g a f e w g r a m s t o v e r y l a r g e v a l v e b o d i e s , r o l l s , p r e s s u r e v e s s e l s , 1 - 2 c r a n k s h a f t s : , ; g e a r s , e t c . w e i g h i n g s e v e r a l t o n n e s ( s e e F i g u r e 1 ) . N u m e r o u s e x a m p l e s o f t h e s e a r e p u b l i s h e d i n t h e 3 - 2 3 l i t e r a t u r e . T h e p r o d u c t i o n o f f u e l - h a n d ! i n g c o m p o n e n t s l i k e v a l v e s , p u m p s , a n d s t e a m f i t t i n g s f o r b o i l i n g w a t e r r e a c t o r n u c l e a r p o w e r p l a n t s a n d t h e p e t r o c h e m i c a l i n d u s t r y 3 - 9 h a s b e e n r e p o r t e d b y t h e S o v i e t s o n s e v e r a l o c c a s i o n s . E S C t u b e s a n d f i t t i n g s f o r t h e p e t r o c h e m i c a l i n d u s t r y h a v e b e e n m a n u f a c t u r e d b y t h e M i t s u b i s h i C o r p o r a t i o n o f J a p a n . 1 0 - 1 2 T h e y h a v e u s e d t h e E S C m e t h o d ( Y O Z O ) t o p r o d u c e r e f o r m e r t u b e s i n HK a l l o y s , ( s e e F i g u r e 2 ) . T u b e s w i t h v a r y i n g s e c t i o n , e l b o w s , o v a l s e c t i o n s , h e a d e r t u b e s a n d s o m e ' I ' b e a m s e c t i o n s h a v e b e e n p r o d u c e d . 1 1 A n o t h e r a r e a o f E S C a p p l i c a t i o n i s i n t h e m a n u f a c t u r e o f c r a n k s h a f t s , r o l l s a n d g e a r s . T h e p r o d u c t i o n o f d i e s e l e n g i n e c r a n k s h a f t s up t o 1 6 0 t o n n e s i n w e i g h t h a s 4 - 7 9 b e e n r e p o r t e d ' a n d t h e y a r e p r e s e n t l y i n u s e i n t h e S o v i e t U n i o n . H e a v y d u t y k i l n - r i n g g e a r s i n s i z e s up t o 1 5 0 t o n n e s 1 8 13 f o r 6 - 7 m e t e r d i a m e t e r k i l n s a r e r e p o r t e d t o be i n s e r v i c e . ' ' R a t o n a l s o r e p o r t s ' o f t h e m a n u f a c t u r e o f E S C r o l l s f o r u s e i n t h e r o l l i n g o f s t e e l . 5 _ 8 > 1 4 O t h e r r e p o r t e d E S C a p p l i c a t i o n s i n c l u d e d i e b l o c k s i n 4 a l l o y s s i m i l a r t o H l l a n d H 1 3 , c a s t c l o s e t o t h e f i n i s h e d s h a p e , ' h o b b i n g c u t t e r s m a d e f r o m T l a n d M2 t o o l s t e e l s 17 1 8 c a s t b y E S C t o t h e s e m i - f i n i s h e d s h a p e , g u n t u b e s , p r e - o c i s i o n d e n t u r e s i n a u s t e n i t i c s t a i n l e s s s t e e l , a n d n o z z l e s c a s t o n p r e s s u r e v e s s e l s . I t i s e v i d e n t f r o m t h e a b o v e l i s t t h a t E S C i n d e e d o f f e r s a p r o m i s i n g p r o s p e c t f o r p r o d u c i n g f i n i s h e d s h a p e c o m p o n e n t s w i t h o u t a n y h o t o r c o l d w o r k i n g o p e r a t i o n . I t i s a l s o o b v i o u s t h a t m o s t o f r e p o r t s a v a i l a b l e a r e o f S o v i e t o r i g i n a n d l i t t l e o r n o w o r k h a s b e e n d o n e i n t h i s f i e l d i n N o r t h A m e r i c a . H e n c e i t i s o f c o n s i d e r a b l e i m p o r t a n c e t o i n v e s t i g a t e t h i s p r o m i s i n g a s p e c t o f t h e E l e c t r o s l a g R e m e l t i n g p r o c e s s a n d t o d e t e r m i n e i f t h e p r o p e r t i e s o f t h e E S C p r o d u c t s q u a l i f y u n d e r t h e A S M E / A S T M c o d e s , g i v e n N o r t h A m e r i c a n e c o n o m i c m a n u f a c t u r - i n g c o n s t r a i n t s . C h a p t e r 2 5 P R O C E S S D E S C R I P T I O N AND C H A R A C T E R I S T I C S T h e e l e c t r o s l a g r e m e l t i n g p r o c e s s i s s i m i l a r t o t h e v a c u u m a r c r e m e l t i n g p r o c e s s i n t h a t b o t h p r o c e s s e s u s e a s o l i d c o n s u m a b l e e l e c t r o d e a n d m e l t i t t h r o u g h a h i g h - t e m p e r - a t u r e p r o c e s s r e g i o n i n t o a w a t e r - c o o l e d m o l d . H o w e v e r , t h e y d i f f e r i n t h e h e a t i n g m e c h a n i s m . U n l i k e W A R , w h e r e h e a t i n g i s t h r o u g h a n a r c , t h e E S R p r o c e s s u t i 1 i z e s r e s i s t a n c e h e a t i n g o f a l i q u i d s l a g b e t w e e n t h e e l e c t r o d e a n d t h e i n g o t s u r f a c e . D e t a i l e d a c c o u n t s o f t h e o p e r a t i o n o f t h e E S R p r o c e s s a r e a v a i l - 2 4 - 2 9 a b l e i n l i t e r a t u r e . T h e c o n c e p t o f t h e E S C p r o c e s s i s t h e s a m e a s t h e E S R p r o c e s s e x c e p t t h a t t h e E S C p r o c e s s u s e s a s h a p e d w a t e r - c o o l e d m o l d . T h i s i s i l l u s t r a t e d s c h e m a t i c a l l y i n F i g u r e 3 . A c o n s u m a b l e e l e c t r o d e o f d e s i r e d c o m p o s i t i o n i s m a d e a s o n e p o l e o f a h i g h c u r r e n t s o u r c e a n d a w a t e r - c o o l e d c o p p e r o r a l u m i n u m : - s h a p e d m o l d i s t h e o t h e r p o l e . T h e J o u l e h e a t g e n e r a t e d i n t h e s l a g p o o l m e l t s t h e e l e c t r o d e t i p a n d m o l t e n m e t a l d r o p s f a l l t h r o u g h t h e l i q u i d s l a g i n t o t h e m o l t e n m e t a l p o o l f r o m w h i c h t h e c a s t i n g s o l i d i f i e s i n t h e w a t e r - c o o l e d m o l d i n a d i r e c t i o n a l , p r o g r e s s i v e m a n n e r . E f - f e c t i v e r e f i n i n g o f t h e m e t a l w i t h r e s p e c t t o s u l p h u r , p h o s - p h o r u s a n d n o n - m e t a l l i c i n c l u s i o n s t a k e s p l a c e d u r i n g t h e f o r m a t i o n o f t h e m e t a l d r o p , a s i t t r a v e r s e s t h r o u g h t h e s l a g p o o l , a n d i n t h e l i q u i d m e t a l p o o l . A c o n t i n u o u s s h e l l o f 6 s o l i d s l a g f o r m s b e t w e e n t h e m o l d a n d t h e s o l i d i f y i n g c a s t i n g a n d t h i s p r o v i d e s s m o o t h s u r f a c e s t o t h e c a s t i n g . A s o u n d c a s t i n g ,i s b u i l t up p r o g r e s s i v e l y b y a n e a r l y v e r t i c a l s o l i d i - f i c a t i o n p a t t e r n . A l l t h i s e f f e c t i v e l y e l i m i n a t e s m a c r o s e g r e - g a t i o n ; b r i n g s m i e r o s e g r e g a t i o n t o a m i n i m u m ; a n d r e m o v e s p o r o - s i t y , s h r i n k a g e , h o t c r a c k s a n d o t h e r d e f e c t s r e l a t e d t o c o n - v e n t i o n a l c a s t i n g s . 2 . 1 E l e c t r o s l a g R e m e l t i n g P r o c e s s C h a r a c t e r i s t i c s W h i c h A f f e c t t h e P r o p e r t i e s o f t h e M a t e r i a l s A l m o s t a l l t h e e x i s t i n g 1 i t e r a t u r e o n E S R , h a s , a t o n e p o i n t o r a n o t h e r , e x t o l l e d t h e v i r t u e s o f t h e p r o c e s s . O f t h e s e t h e o n e s w h i c h a f f e c t t h e m e c h a n i c a l p r o p e r t i e s c a n b e b r o a d l y c l a s s i f i e d u n d e r t h e f o l l o w i n g t w o c a t e g o r i e s : t h o s e r e l a t e d t o c h e m i c a l r e f i n i n g . t h o s e r e l a t e d t o s o l i d i f i c a t i o n s t r u c t u r e . 2 . 1 . 1 C h a r a c t e r i s t i c s R e l a t e d t o C h e m i c a l R e f i n i n g T h e E S R p r o c e s s h a s e a r n e d i t s name f r o m t h e i n h e r e n t r e - f i n i n g c h a r a c t e r i s t i c s . T h e m o s t i m p o r t a n t i s t h e r e m o v a l o f l a r g e q u a n t i t i e s o f s u l p h u r , e v e n w h e n t h e l e v e l o f t h i s i s 3 0 31 l o w i n t h e s t a r t i n g m a t e r i a l . ' V e r y l o w s u l p h u r l e v e l s c a n b e o b t a i n e d b y u s i n g h i g h l y b a s i c s l a g s . I t i s w e l l e s t a - b l i s h e d t h a t o n e o f t h e m o s t e f f e c t i v e w a y s o f o b t a i n i n g g o o d a n d r e a s o n a b l y i s o t r o p i c m e c h a n i c a l p r o p e r t i e s i s t h r o u g h 7 3 2 - 3 5 s u l p h u r c o n t r o l . F i g u r e 4 s h o w s t h e f r a c t u r e t o u g h n e s s r e s u l t s o f a s e r i e s o f E S R 4 3 4 0 s t e e l s c o n t a i n i n g v a r y i n g a m o u n t s o f s u l p h u r . S i n c e s u l p h i d e s a r e i n i t i a t i o n s i t e s f o r f r a c t u r e i n m a n y c a s e s , c o n t r o l o f t h e i r s h a p e a n d s i z e r e - s u l t s i n u n i f o r m f r a c t u r e c h a r a c t e r i s t i c s i n t h r e e p r i m a r y d i r e c t i o n s . I t i s n o t e w o r t h y t h a t w i t h t h e r e c e n t a d v a n c e s i n l a d l e s t e e l m a k i n g t e c h n o l o g i e s , i t i s p o s s i b l e t o a c h i e v e l o w s u l p h u r l e v e l s a n d s u l p h i d e i n c l u s i o n s h a p e c o n t r o l . H e n c e s u l p h u r c o n t r o l i s n o l o n g e r c o n s i d e r e d t o b e a n i m p o r t a n t f a c t o r d e c i d i n g f o r o r a g a i n s t t h e E S R p r o c e s s . H o w e v e r , a l t h o u g h l o w e r i n g o f t h e o v e r a l l s u l p h u r l e v e l o f t h e s t e e l p r o v i d e s t h e m o s t s i g n i f i c a n t i m p r o v e m e n t , d e - s u l p h u r i s a t i o n i s o n l y t h e f i r s t s t e p . R e m o v a l o f o t h e r i n - c l u s i o n s a n d d e t r i m e n t a l r e s i d u a l i m p u r i t i e s , a n d c o n t r o l l i n g t h e s h a p e a n d d i s t r i b u t i o n o f s u l p h i d e i n c l u s i o n s a r e a l s o o f c o n s i d e r a b l e i m p o r t a n c e i n o b t a i n i n g t h e o p t i m u m m e c h a n i c a l p r o p e r t i e s . A l t h o u g h m a n y r e f e r e n c e s a r e a v a i l a b l e i n t h e l i t e r a t u r e w h i c h d e a l w i t h t h e t y p e , s i z e , c o n t e n t a n d d i s t r i - b u t i o n o f i n c l u s i o n s i n E S R m a t e r i a l , v e r y f e w r e f e r t o t h e a c t u a l m e c h a n i s m b y w h i c h t h e n o n - m e t a l l i c i n c l u s i o n s a r e r e m o v e d f r o m t h e m a t e r i a l d u r i n g e l e c t r o s l a g r e m e l t i n g . A s t h e c a s t i n g i s s o l i d i f i e d i n a w a t e r - c o o l e d m e t a l m o l d , t h e c h a n c e o f e x o g e n o u s i n c l u s i o n s b e i n g p r e s e n t i n t h e r e m e l t e d m a t e r i a l i s v e r y l o w . H o w e v e r , i n d i g e n o u s i n c l u s i o n s o f e i t h e r d e - o x i d a t i o n ( f o r m e d b y d i s s o l v e d o x y g e n a n d t h e d e o x i d a n t s ) 8 and/or s o l i d i f i c a t i o n (formed by p r e c i p i t a t i o n during s o l i d i f i - c a t i o n ) are present i n ESR m a t e r i a l . Some of the e a r l y work shows that the e l e c t r o d e i n c l u s i o n content a f f e c t s the i n - e l u s i o n content of the i n g o t , but i t i s well accepted now, 37 as M i t c h e l l p o i n t s out, that v i r t u a l l y no ingot i n c l u s i o n s are i d e n t i f i a b l e as unreacted e l e c t r o d e r e l i c s . ' In the l i q u i d metal pool there are few i n c l u s i o n s present, unless very high d e o x i d a t i o n r a t e s are used. The l i q u i d has only d i s s o l v e d oxygen and deoxidants i n near e q u i l i b r i u m with the s l a g . When the l i q u i d metal f r e e z e s , i n c l u s i o n s c h a r a c t e r i s t i c of the oxygen and deoxidant content of the l i q u i d are nucleated and O C O f ) O ~l grown in the ingot l i q u i d - s o l i d zone. ' ' This process gives r i s e to a f i n e background of s m a l l , g l o b u l a r and d i s - persed i n c l u s i o n s . The t o t a l volume f r a c t i o n in ESR i s much lower than the best a i r - m e l t i n g p r a c t i c e . G e n e r a l l y , i n c l u s i o n s have a gr e a t e r e f f e c t on non-uniform deformation (percent r e d u c t i o n in area) than upon uniform de- formation (percent e l o n g a t i o n ) . If the i n c l u s i o n s have an a n i s o t r o p i c shape (e.g. elongated s u l p h i d e i n c l u s i o n s in r o l - l e d m a t e r i a l ) , d u c t i l i t y w i l l be a n i s o t r o p i c . T h e r e f o r e , the no n - m e t a l l i c i n c l u s i o n content of remelted s t e e l s i s of prime importance i n determining t h e i r mechanical behaviour. 2 . 1 . 2 C h a r a c t e r i s t i c s Related to S o l i d i f i c a t i o n S t r u c t u r e Contrary to the conventional c a s t i n g processes i n which 9 m e l t i n g a n d c a s t i n g r e p r e s e n t t w o s e p a r a t e a n d d i f f e r e n t o p e r a - t i o n a l s t e p s , t h e E S R p r o c e s s i s c h a r a c t e r i z e d b y a d d i t i o n o f h e a t d u r i n g t h e s o l i d i f i c a t i o n s t e p . H e n c e t h e t e m p e r a t u r e g r a d i e n t s a n d t h e s o l i d i f i c a t i o n r a t e c a n b e c o n t r o l l e d t o e s t a - b l i s h a p r o g r e s s i v e a n d d i r e c t i o n a l s o l i d i f i c a t i o n c o n d i t i o n ( o b t a i n e d b y h i g h t h e r m a l g r a d i e n t s a n d l o w g r o w t h r a t e s ) . S u c h s l o w m e l t r a t e s a r e p o s s i b l e f i r s t l y d u e t o t h e i n s u l a t i n g c h a r a c t e r o f t h e s l a g p o o l w h i c h l e v e l s o f f t h e t h e r m a l g r a - d i e n t s a c r o s s t h e p o o l a n d s e c o n d l y d u e t o t h e f o r m a t i o n o f t h e t h i n s l a g s k i n b e t w e e n t h e m o l d w a l l a n d t h e m e t a l . T h e s e s o l i - d i f i c a t i o n c o n d i t i o n s l e a d t o a s t r u c t u r e w h i c h i s p r a c t i c a l l y f r e e o f p o r o s i t y , s h r i n k a g e , h o t - c r a c k s , e t c . T h i s a l s o e f - f e c t i v e l y e l i m i n a t e s m a c r o s c o p i c i n h o m o g e n i t i e s s u c h a s b a n d e d s t r u c t u r e o r f r e c k l e s , m a c r o s c o p i c s p o t s e g r e g a t i o n , a n d b r i n g s m i c r o s e g r e g a t i o n t o a m i n i m u m . A l t h o u g h l o w m e l t r a t e s l e a d t o a f i n e d e n d r i t i c s t r u c t u r e , m v c r o s e g r e g a t i o n i s p r o n o u n c e d a s t h e s y s t e m d e v i a t e s f r o m e q u i - l i b r i u m s o l i d i f i c a t i o n . A l s o v e r y h i g h m e l t r a t e s l e a d t o a n e q u i a x e d s t r u c t u r e w i t h i n c r e a s e d m i c r o s e g r e g a t i o n . A n o p t i m u m m e l t r a t e l e a d s t o l e a s t m i c r o s e g r e g a t i o n a n d h e n c e g o o d m e c h a n i - 3 8 c a l p r o p e r t i e s . I n c o n c l u s i o n , i t c a n b e s a i d t h a t t h e e n h a n c e d m e c h a n i c a l p r o p e r t i e s a n d i s o t r o p i c . , b e h a v i o u r o f t h e ESR m a t e r i a l a r e d u e t o g o o d c h e m i c a l r e f i n i n g a n d s o l i d i f i c a t i o n s t r u c t u r e . C h a p t e r . 3 10 P R E S E N T WORK I n t h e l a t t e r p a r t o f 1 9 7 4 , a p r o g r a m w a s i n i t i a t e d a m o n g D r . A l e c M i t c h e l l , P r o f e s s o r o f M e t a l l u r g y U . B . C , W e s t i n g h o u s e E l e c t r o - m e c h a n i c a l D i v i s i o n (WEMD) a n d D r . B o r i s M e d o v a r , D i r e c t o r o f E S R T e c h n i c a l D e v e l o p m e n t a t P a t o n I n s t i t u t e , K i e v , U . S . S . R . A 1 0 - i n c h E S C v a l v e b o d y w a s m a d e i n t h e U . S . S . R . a n d s e n t f o r e v a l u a t i o n a t U . B . C . a n d WEMD. E v a l u a t i o n s o f d e s t r u c - t i v e a n d n o n - d e s t r u c t i v e t e s t i n g o f t h e v a l v e b o d y a r e a v a i l - a b l e . 3 9 ' 4 0 T h e r e s u l t s i n d i c a t e t h a t t h e c a s t i n g q u a l i t y f a i l e d c h e m i c a l l y a n d m e c h a n i c a l l y t o m e e t A S M E r e q u i r e m e n t s a s o r i g i - n a l l y p r e d i c t e d b y t h e S o v i e t w o r k e r s . H e n c e t o s t u d y i n - d e p t h t h e p r o p e r t i e s a n d t h e p r o c e s s v i a b i l i t y o f E S C p r o d u c t s , a s i m p l e a n d i n e x p e n s i v e E S C f u r n a c e w a s i n s t a l l e d a t U . B . C . T h e f u r n a c e i s c a p a b l e o f m a k i n g c a s t - i n g s up t o o n e t o n n e . T h e f u r n a c e h a s m a d e v a l v e - b o d y c a s t i n g s i n a l l o y a n d s t a i n l e s s s t e e l s f r o m b o t h w r o u g h t a n d c a s t e l e c - t r o d e s . 3 . 1 h a s F u r n a c e D e s i g n D e t a i l e d a c c o u n t o f t h e d e s i g n b e e n r e p o r t e d p r e v i o u s l y . 4 1 a n d o p e r a t i o n o f t h i s f u r n a c e 11 T h e m e c h a n i c a l p a r t o f t h e d e s i g n c o n s i s t s o f a w a t e r - c o o l e d e l e c t r o d e h o l d e r c a r r i a g e w h i c h c a n m o v e v e r t i c a l l y u s i n g a l u m i n i u m r a i l g u i d e s . T h e s e g u i d e s a r e f i x e d t o t h e i n s i d e o f a v e r t i c a l I - b e a m f r a m e w o r k . T h e c a r r i a g e i s s u s p e n d e d f r o m a s i n g l e c h a i n d r i v e h a v i n g a v a r i a b l e s p e e d r e d u c t o r a n d t h i s i n c o n j u n c t i o n w i t h a s p e e d c o n t r o l l e r g i v e s a r a n g e o f e l e c t r o d e s p e e d s f r o m 0 - 1 6 3 m m / m i n ( s e e F i g u r e 5 ) . T h e e l e c t r i c a l p a r t c o n s i s t s o f t w o s t e p d o w n t r a n s f o r m e r s . T h e f i r s t o n e i s r a t e d a t 2 5 0 KVA w i t h 1 2 5 0 0 V i n p u t a n d 6 0 0 V o u t p u t . T h e s e c o n d t r a n s f o r m e r i s s i n g l e p h a s e d r y t y p e a n d i s a l s o r a t e d a t 2 5 0 KVA w i t h i n p u t v o l t a g e o f 6 0 0 V a n d o u t p u t v o l t a g e v a r i a b l e o v e r a r a n g e o f 2 5 V - 6 0 V i n s t e p s o f a b o u t 2 . 5 V . T h e o p e r a t i n g p a r a m e t e r s c a n b e m o n i t o r e d f r o m t h e c o n t r o l p a n e l w h i c h n o t o n l y s h o w s t h e p r i m a r y a n d s e c o n d a r y c u r r e n t a n d s e c o n d a r y v o l t a g e b u t a l s o h a s a d i g i t a l c o u n t e r t o m e a s u r e t h e e l e c t r o d e t r a v e l . A l s o , a m u l t i c h a n n e l t h e r m o m e t e r s h o w s t h e m o l d c o o l i n g w a t e r t e m p e r a t u r e s . 3 . 2 V a l v e M o l d D e s i g n S m o o t h s u r f a c e f i n i s h , f l a t t o p s a n d b o t t o m s , c o n t r o l l e d v e r t i c a l s o l i d i f i c a t i o n a n d s h a p e d p r o d u c t s a r e s o m e o f t h e d i s c u s s e d u n i q u e f e a t u r e s o f E S R i n g o t s . A l l o f t h e s e a r e d i r e c t l y a t t r i b u t a b l e t o o r a r e s t r o n g l y i n f l u e n c e d b y m o l d d e s i g n 12 a n d o p e r a t i n g p a r a m e t e r s . T h e o p t i m u m m o l d d e s i g n i s a s s o c i a - t e d w i t h t h e m a n n e r i n w h i c h t h e m o l d a s s e m b l y d i s s i p a t e s t h e h e a t p r i m a r i l y f r o m t h e s l a g l a y e r , m o l t e n p o o l a n d s o l i d i f i e d i n g o t c a s t i n g . E S R m o l d d e s i g n h a s b e e n d i s c u s s e d t o s o m e e x - 25 4 2 t e n t - . b y M i t c h e l 1 a n d C r e m e s i o e t a l . M o s t o f t h e E S R m o l d s u s e d a r e m a d e o u t o f c o p p e r b e c a u s e o f i t s h i g h t h e r m a l c o n d u c t i v i t y . T h i s a d d s s u b s t a n t i a l l y t o t h e o v e r a l l c o s t o f t h e p r o d u c t . F a b r i c a t i o n o f a c o p p e r m o l d a l s o p r e s e n t s a p r o b l e m a s t h e m e t a l h a s t o b e f o r m e d a n d w e l d e d i n t o t h e m o l d s h a p e . T h i s i s p a r t i c u l a r l y d i f f i c u l t f o r E S C m o l d s w i t h c o n t o u r e d s e c t i o n s . S i n c e t h e i n v e n t o r y c o s t s a n d f a b r i c a t i o n m a k e c o p p e r m o l d s u n a t t r a c t i v e , a c a s t - t o - s h a p e m o l d o f l e s s c o s t l y a l u m i n u m w a s c o n s i d e r e d t o b e a v i a b l e a l t e r n a t i v e . G e a r c a s t i n g s u s i n g a c a s t a l u m i n u m m o l d w e r e m a d e s u c c e s s - f u l l y i n U . B . C . T h e w a t e r c h a n n e l p o s i t i o n s a n d d i m e n s i o n s i n t h e g e a r m o l d w e r e r o u g h l y c a l c u l a t e d t o g i v e a m a x i m u m h o t - 4 3 f a c e t e m p e r a t u r e o f 3 0 0 ° C d u r i n g t h e E S C p r o c e s s . F o l l o w i n g t h i s , a n a l u m i n u m m o l d f o r c a s t i n g o f v a l v e b o d i e s w a s m a n u - f a c t u r e d . T h e v a l v e m o l d w a s c a s t o u t o f a l u m i n u m u s i n g a s t e e l p a t t e r n . T h e o r t h o g o n a l v i e w s o f t h e v a l v e b o d y a r e g i v e n i n F i g u r e 6 . A c c o r d i n g l y t h e c o m p l e t e v a l v e m o l d w a s d i v i d e d i n t o 13 f o u r s e g m e n t s - t w o p l a t e m o l d s f o r t h e f l a t s i d e s o f t h e v a l v e a n d t w o m o l d s w i t h c u p p e d d e p r e s s i o n s t o a c c o m m o d a t e t h e i n l e t / o u t l e t s e c t i o n s o f t h e v a l v e . T h e s e c t i o n a l d r a w - i n g s o f t h e s e s e g m e n t s a r e g i v e n i n F i g u r e 7 a - b . F i g u r e 8 s h o w s t h e a s s e m b l e d v a l v e m o l d . B e s i d e s t h i s , t w o r o u n d s e c t i o n m o l d s w e r e u s e d - o n e o n t o p a n d t h e o t h e r a t t h e b o t t o m o f t h e v a l v e m o l d . 3 . 3 M e l t i n g P r o c e d u r e T h e v a l v e m o l d i s p l a c e d b e t w e e n t w o r o u n d m o l d s a n d t h e w h o l e a s s e m b l y i s p l a c e d on a w a t e r - c o o l e d c o p p e r b a s e p l a t e . To p r e v e n t a n y d a m a g e t o t h e b a s e p l a t e d u e t o a r c i n g w i t h t h e e l e c t r o d e a t t h e i n i t i a t i o n o f t h e p r o c e s s , a s t a r t e r b l o c k i s u s e d . T h e r e a r e t w o d i f f e r e n t p r a c t i c e s e m p l o y e d t o i n i - t i a t e t h e p r o c e s s . One i s k n o w n a s ' m o l t e n - s l a g ' s t a r t a n d t h e o t h e r i s t h e ' d r y - s l a g ' s t a r t . B o t h t h e p r o c e s s e s w e r e t r i e d a n d t h e y w o r k e d e q u a l l y w e l l . I n t h e ' m o l t e n - s l a g ' s t a r t t h e m a i n s l a g c o m p o n e n t , i . e . C a F ^ , i s m e l t e d i n a s l a g m e l t i n g f u r n a c e ( s e e F i g u r e 9 ) . T h i s f u r n a c e h a s a g r a p h i t e c r u c i b l e a n d e m p l o y s a s i n g l e - p h a s e g r a p h i t e e l e c t r o d e s y s t e m . C a F 2 i s a d d e d t o t h e ' f u r n a c e a n d p o w e r i s a p p l i e d t o i n i t i a t e an a r c w h i c h f o r m s a s m a l l p o o l o f m o l t e n C a F 2 a n d t h e n t h e h e a t i n g i s t h r o u g h r e s i s t a n c e h e a t - i n g o f t h e s l a g . When a l l t h e s l a g ( C a F 2 ) h a s m e l t e d , i t i s p o u r e d i n t o t h e w a t e r - c o o l e d m o l d a n d t h e e l e c t r o s l a g f u r n a c e 14 i s e n e r g i z e d . A f t e r t h i s t h e r e m a i n i n g s l a g c o m p o n e n t s a r e a d d e d s l o w l y . I n t h e ' d r y - s l a g ' s t a r t , a b e d o f t u r n i n g s o f a m e t a l s i m i l a r t o t h e e l e c t r o d e i s p l a c e d b e t w e e n t h e s t a r t e r p l a t e a n d t h e e l e c t r o d e . A l t e r n a t i v e l y a p e l l e t o f c o m p r e s s e d m i x - t u r e o f C a F 2 a n d m e t a l t u r n i n g s c a n b e u s e d . E i t h e r o n e o f t h e s e i s u s e d a n d t h e e l e c t r o d e i s l o w e r e d s u c h t h a t i t p r e s - s e s t h e t u r n i n g s a g a i n s t t h e s t a r t e r p l a t e . T h e n t h e d r y C a F i s p o u r e d i n t o t h e s u r r o u n d i n g a n n u l u s b e t w e e n t h e e l e c t r o d e a n d t h e m o l d w a l l s . When t h e f u r n a c e i s e n e r g i z e d , p o w e r i s a p p l i e d a c r o s s t h e s h o r t - c i r c u i t c u r r e n t p a t h e s t a b l i s h e d b y t h e t u r n i n g s . u n d e r t h e e l e c t r o d e . T h i s c a u s e s m e l t i n g o f t h e s l a g a n d c o n t i n u e s t i l l a l a r g e e n o u g h v o l u m e o f m o l t e n s l a g i s g e n e r a t e d t o s u s t a i n r e s i s t a n c e h e a t i n g . A f t e r a l l t h e C a F 2 i s m e l t e d , t h e r e m a i n i n g s l a g c o m p o n e n t s ( C a O , Ai^O^* L ^ O . ^ e t c . ) a r e a d d e d . T h e e l e c t r o d e i s l o w e r e d a s i t m e l t s a n d t h e m o l d i s s l o w l y f i l l e d up w i t h r e s o l i d i f i e d m e t a l . A t t h e e n d o f t h e r u n , p o w e r i s t e r m i n a t e d a n d t h e e l e c t r o d e i s w i t h d r a w n f r o m t h e m o l d , t h e c a s t i n g b e i n g t a k e n o u t a f t e r a b o u t t h i r t y m i n - u t e s . T h e c a s t i n g s h a v e a s m o o t h s u r f a c e d u e t o a t h i n , c o n - t i n u o u s s h e l l o f s o l i d s l a g w h i c h f o r m s b e t w e e n t h e m o l d a n d t h e s o l i d i f y i n g m e t a l ( s e e F i g u r e 1 0 ) . 15 T h e m a i n o p e r a t i n g p a r a m e t e r s e s t a b l i s h e d d u r i n g t h e pro> d u c t i o n o f v a l v e c a s t i n g s w e r e a s f o l l o w s : o p e r a t i n g v o l t a g e 3 6 - 3 9 V p r i m a r y c u r r e n t 2 0 0 - 2 6 0 A s e c o n d a r y c u r r e n t 3 0 0 0 - 4 0 0 0 A - m e l t r a t e 0 . 8 - 1 . 0 k g / m i n . 3 . 4 S e l e c t i o n o f S l a g s f o r E S C P r o c e s s T h e s l a g p o o l i s p e r h a p s t h e m o s t i m p o r t a n t c o m p o n e n t i n t h e e l e c t r o s l a g r e m e l t i n g p r o c e s s . I t i s r e q u i r e d t o ' f i l l a n u m b e r o f s i m u l t a n e o u s f u n c t i o n s - i t m u s t a c t a s a h e a t s o u r c e , h e a t - t r a n s f e r m e d i u m , m e t a l c o n t a i n e r a n d m e t a l r e - 4 4 . . . f i n e r . ' T h e r e f o r e t h e c o r r e c t c h o i c e o f s l a g c o m p o s i t i o n i s o f p r i m e i m p o r t a n c e f o r s u c c e s s f u l E S R o p e r a t i o n . T h e c h o i c e r e s t s u p o n t h e f o l l o w i n g : a ) h e a t g e n e r a t i o n a n d t r a n s f e r c h a r a c t e r i s t i c s o f t h e s l a g - ( e l e c t r i c a l c o n d u c t i v i t y , t h e r m a l c a p a c i t y a n d t h e r m a l c o n d u c t i v i t y ) . b ) s l a g p h a s e p r o p e r t i e s - ( v a p o u r p r e s s u r e , l i q u i d u s t e m - p e r a t u r e , v i s c o s i t y , s u r f a c e t e n s i o n a n d d e n s i t y ) . c ) m e t a l r e f i n i n g c h a r a c t e r i s t i c s ( c h e m i c a l c o m p o s i t i o n ) . T h e m o r e i m p o r t a n t o f t h e a b o v e p o i n t s a r e d i s c u s s e d b e l o w w i t h r e f e r e n c e t o s l a g s e l e c t i o n . 16 T h e t e r n a r y C a F 2 - CaO - M^O^ s y s t e m i s t h e m o s t i m p o r - t a n t a n d u n i v e r s a l l y a p p l i c a b l e s l a g s y s t e m i n t h e f i e l d o f E S R . F l u o r i d e g e n e r a l l y d e c r e a s e s t h e s o l i d u s a n d l i q u i d u s t e m p e r a t u r e s a n d v i s c o s i t y , a n d i n c r e a s e s e l e c t r i c a l c o n d u c - t i v i t y o f C a F 2 + A « - 2 U 3 - I t h a s b e e n o b s e r v e d t h a t r e l a t i v e l y s m a l l a d d i t i o n s o f A ^ O g t o p u r e C a F 2 p r o d u c e s a s u b s t a n t i a l d e c r e a s e i n t h e c o n d u c t i v i t y o f t h e l i q u i d . T h e w o r k o f 4 5 M i t c h e l l a n d C a m e r o n s h o w e d t h a t t h i s o c c u r s b e c a u s e t h e f l u o r i d e i o n c o n t r i b u t i o n t o t h e t o t a l i o n i c m o b i l i t y i s r e - 3 - d u c e d b y c o m p l e x i n g i t i n A & O F , , a n d A £ 0 2 F 2 . T h i s w o u l d b e t h r o u g h t h e r e a c t i o n A * 2 . 0 3 + 4 F " > A £ 0 2 F 2 " + A £ 0 F ~ T h i s e f f e c t i s a l s o s e e n i n t h e a d d i t i o n o f s i l i c a t e s a n d o f r a r e e a r t h o x i d e s . H o w e v e r , a d d i t i o n o f CaO r e p l a c e s t h e f l u o r i d e p a r t o f t h e c o m p l e x i o n s b y o x i d e i o n s t h u s r e l e a s - i n g f l u o r i d e i o n s a s c h a r g e c a r r i e r s , e . g . , A £ 0 2 F 2 " + 0 2 ~ > AJIO3" + 2 F ~ a n d A £ 0 F ~ + 0 2 " > AJ>0~ + 2 F " T h i s p r o d u c e s a n i n c r e a s e i n e l e c t r i c a l c o n d u c t i v i t y b u t t h i s 4 4 i n c r e a s e i s n o t s u b s t a n t i a l . Low e l e c t r i c a l c o n d u c t i v i t y b y t h e a d d i t i o n o f A 2 - 2 0 3 l e a d s t o h i g h e r m e l t r a t e s a n d h i g h e r e f f i c i e n c y . 17 46 I t h a s a l s o b e e n n o t e d t h a t t h e r a t e o f d i s s o l u t i o n o f A j ^ O g i n C a F ^ i s h i g h e r i n t h e p r e s e n c e o f C a O . T h i s i s b e - c a u s e A £ 2 n 3 d i s s o l v e s e s s e n t i a l l y b y a n a c i d / b a s e r e a c t i o n : A £ 2 ° 3 + ° 2 ~ 2 A i O " a n d h e n c e i s d i s s o l v e d m u c h f a s t e r b y a s l a g c o n t a i n i n g CaO t h a n C a F ^ a l o n e . T h i s d e c r e a s e s t h e o v e r a l l m e l t i n g t i m e a n d t h u s a l s o i n c r e a s e s t h e e f f i c i e n c y . Due t o t h e h i g h t e m p e r a t u r e s a t t a i n e d d u r i n g t h e m e l t i n g , e x p e c i a l l y i n t h e r e g i o n d i r e c t l y b e l o w t h e e l e c t r o d e , t h e t h e r m a l s t a b i l i t y o f t h e . s l a g c o m p o n e n t s s h o u l d b e h i g h i . e . t h e s l a g c o m p o n e n t s s h o u l d h a v e a l o w v a p o u r p r e s s u r e . A l s o 44 i t h a s b e e n n o t e d t h a t p r o d u c t i o n o f CaO d u e t o v o l a t i l i t y o f C a F ^ t h r o u g h t h e r e a c t i o n A £ 2 0 3 + 3 C a F 2 = = 2 A £ F 3 + 3 C a O c a n c a u s e s i g n i f i c a n t s h i f t i n A J ^ O ^ / C a O r a t i o . P r e s e n c e o f S i 0 ^ a n d H 2 0 w i l l h a v e s i m i l a r e f f e c t s . A n e s s e n t i a l r e q u i r e m e n t f o r t h e s l a g t o b e a s u i t a b l e m e l t i n g m e d i u m i s t h a t i t m u s t h a v e a l i q u i d u s t e m p e r a t u r e a t l e a s t 1 0 0 ° C b e l o w t h a t o f t h e m e t a l , b u t m u s t a l s o f o r m a s o l i d p h a s e o n f r e e z i n g w h i c h h a s a m e l t i n g p o i n t h i g h e r t h a n t h a t o f t h e m e t a l . 4 4 ' 4 ' ' T h e s e c o n d i t i o n s l e a d t o g o o d s u r - f a c e q u a l i t y o f t h e c a s t i n g s . 18 T h e p h a s e d i a g r a m f o r C a F 2 - A £ 2 0 3 - C a O i s s h o w n i n F i g u r e 4 8 1 1 . F r o m t h i s i t c a n b e s e e n t h a t f o r l o w l i q u i d u s t e m p e r a - t u r e s o f t h e s l a g , a p p r o x i m a t e l y e q u a l p r o p o r t i o n s o f A & 2 0 3 a n d CaO s h o u l d b e p r e s e n t i n t h e t e r n a r y s l a g s y s t e m . T h e m e t a l r e f i n i n g c h a r a c t e r i s t i c s a r e a c o m p l e x f u n c t i o n o f t h e s l a g c o m p o s i t i o n , p o w e r mode ( a . c . o r d . c ) , m e l t i n g c o n d i t i o n s , d e o x i d a t i o n , a n d o f c o u r s e t h e m e t a l t h a t i s b e i n g r e f i n e d . CaO i s p r i m a r i l y u s e d a s a d e s u l p h u r i s i n g a g e n t . 4 4 I t h a s b e e n s u g g e s t e d t h a t a d d i t i o n o f a r a r e - e a r t h - o x i d e ( R E 2 0 3 ) t o t h e t e r n a r y s y s t e m o f C a F 2 + C a O + A & 2 0 3 l e a d s t o w i d e r e g i o n s i n t h e p h a s e d i a g r a m w h e r e t h e p h y s i c a l p r o p e r t i e s a r e c o m p a t i b l e w i t h E S R p r o c e s s i n g . B e s i d e s s t r o n g l y c o m p l e x i n g 2 - - 0 a n d F~ ( h e n c e i n c r e a s i n g t h e e l e c t r i c a l r e s i s t i v i t y ) , t h e p r e s e n c e o f ( R E - 0 - S ) n ~ c o m p l e x e s a l s o l e a d s t o a s t r o n g l y b a s i c b e h a v i o u r w i t h r e s p e c t t o s u l p h u r r e a c t i o n s . B o t h t h e s e c o n d i t i o n s a r e h i g h l y d e s i r a b l e f o r E S R . T a k i n g t h e a b o v e p o i n t s i n c o n s i d e r a t i o n , t w o d i f f e r e n t s l a g c o m p o s i t i o n s w e r e s e l e c t e d f o r s t a i n l e s s s t e e l a n d l o w a l l o y s t e e l c a s t i n g s . F o r s t a i n l e s s s t e e l we h a d 70% C a F 2 , 15% CaO , 15% A s ^ a n d f o r l o w a l l o y s t e e l ( A I S I 4 3 4 0 ) w h e r e a v e r y l o w s u l p h u r c o n t e n t i s r e q u i r e d we h a d 50% C a F 0 , 15% CaO , 15% A £ o 0 o , 20% L a 9 0 q 19 A s t h e s l a g s u s e d w e r e h i g h l y b a s i c a n d t h e f a c t t h a t t h e c a s t i n g s w e r e d e o x i d i s e d , c a r e f u l c o n t r o l o f r e s i d u a l h y d r o g e n c o n t e n t i n t h e c a s t i n g s w a s o f p r i m e i m p o r t a n c e . T h r e e m a i n s o u r c e s o f h y d r o g e n i n E S R a r e t h e h y g r o s c o p i c , b a s i c s l a g , t h e h u m i d i t y o f t h e a t m o s p h e r e f r o m w h i c h h y d r o g e n i s t r a n s p o r t e d t h r o u g h t h e s l a g i n t o t h e l i q u i d m e t a l p o o l , a n d t h e h y d r o g e n c o n t e n t o f t h e e l e c t r o d e . O f t h e s e t h e l a s t o n e i s n o t s o s e r i o u s a s t h e f i r s t t w o b e c a u s e s u f f i c i e n t l y l o w e l e c t r o d e h y d r o g e n c o n t e n t s c a n be o b t a i n e d b y t o d a y ' s s t e e l m e l t i n g p r a c t i c e . H i g h l y b a s i c s l a g s ( e . g . s l a g s c o n - t a i n i n g C a O ) h y d r a t e e a s i l y . A l s o h y d r o g e n p i c k - u p f r o m t h e a t m o s p h e r e i s i n c r e a s e d i f b a s i c s l a g s a r e u s e d b e c a u s e s u c h s l a g s p r o m o t e t h e f o r m a t i o n o f O H " i o n s - 0 2 ~ + H 2 0 ^ — 2 0 H " ( a t t h e s l a g s u r f a c e ) a n d t h i s i s s u b s e q u e n t l y t r a n s f e r r e d t o t h e m e t a l . 2 0 H " ^ = ^ - 0 2 " + [ 0 ] + [ 2 H ] ( a t t h e s l a g - m e t a l i n t e r f a c e ) A c c o r d i n g t o t h i s a l o w p a r t i a l p r e s s u r e o f 0 ^ i n F e ( a s i n t h e d e o x i d i s e d c o n d i t i o n ) w o u l d p r o m o t e t r a n s f e r o f h y d r o g e n t o t h e m e t a l C a r e f u l s t o r a g e , p r e h e a t i n g , p r e f u s i n g , a n d u s i n g t h e m o l t e n s l a g s t a r t t e c h n i q u e a r e a f e w w a y s t o a v o i d h y d r o g e n 20 i n t h e s l a g . H y d r o g e n f r o m t h e a t m o s p h e r e c a n be r e d u c e d b y c r e a t i n g a d r y a t m o s p h e r e b y s i m p l y p r o t e c t i n g t h e s u r f a c e o f t h e s l a g b y a s h i e l d i n g h o o d . A p p l i c a t i o n o f s u p e r i m p o s e d d . c . o n a . c . m e l t i n g h a s a l s o b e e n c l a i m e d t o r e d u c e t h e h y d r o g e n 4 9 5 0 c o n t e n t d u r i n g e l e c t r o s l a g r e m e l t i n g , ' b u t t h e s e w e r e a n a m b i g u o u s s e r i e s o f e x p e r i m e n t s . U t i l i z i n g t h e m o l t e n - s l a g s t a r t t e c h n i q u e , h y d r o g e n p r o b - l e m s w e r e n o t e n c o u n t e r e d i n t h e c a s t i n g s . H o w e v e r , w h e n t h e d r y s l a g - s t a r t t e c h n i q u e w a s u s e d , t h e p r o b l e m o f h y d r o g e n w a s s e v e r e e n o u g h t o c r e a t e s e v e r a l l o n g i t u d i n a l h o l e s i n t h e b o t t o m h a l f o f t h e c a s t i n g s . U s i n g p r e f u s e d o r e v e n d o u b l e p r e f u s e d s l a g i n d r y s t a r t d i d n o t s o l v e t h e p r o b l e m . T h e t e r n a r y d i a g r a m o f C a F 2 - A & 2 0 3 - C a 0 ( s h o w n i n F i g u r e 1 1 ) s h o w e d t h a t 7 0 % C a F 2 / 1 5 % C a 0 / 1 5 % c U 2 0 3 s l a g c o m p o s i t i o n c o u l d p r e c i p i - t a t e s o m e CaO w h e n s o l i d i f i e d a n d t h i s c o u l d e a s i l y r e h y d r a t e . T h e r e f o r e p r e f u s i n g t h e s l a g d i d n o t e l i m i n a t e h y d r o g e n i n t h e c a s t i n g . To a v o i d h y d r o g e n p r o b l e m s d u e t o m o i s t u r e i n t h e s l a g i n t h e d r y - s l a g s t a r t , t h e c o m p o n e n t s w e r e h e a t e d t o s u f - f i c i e n t l y h i g h t e m p e r a t u r e s . C a F 2 a n d A j ^ O ^ , w h i c h a r e n o t s o s u s c e p t i b l e t o m o i s t u r e , w e r e p r e h e a t e d t o 5 0 0 ° C w h i l e CaO w a s p r e h e a t e d a n d L a 2 ( C 0 3 ) 3 w a s c a l c i n e d a t 8 0 0 ° C . T h e s e w e r e u s e d d i r e c t l y i n t h e h o t c o n d i t i o n . No t r a c e s o f m o i s - t u r e r e l a t e d p o r o s i t y w e r e o b s e r v e d . 21 A l t h o u g h i t w a s a c l e a r i n d i c a t i o n t h a t t h e h o l e s i n t h e c a s t i n g s w e r e d u e t o t h e m o i s t u r e i n t h e s l a g , p r e c a u t i o n w a s t a k e n t o a v o i d h y d r o g e n f r o m t h e a t m o s p h e r e . A s h i e l d i n g h o o d m a d e o f s t a i n l e s s s t e e l a n d l i n e d w i t h s a f f i l ( A ^ O ^ > f i b r o u s s p o n g e ) w a s u s e d . T h i s h a d a h o l e i n t h e m i d d l e f o r t h e e l e c t r o d e a n d t w o m o r e s m a l l h o l e s a t t h e s i d e - o n e f o r a d d i - t i o n o f d e o x i d a n t a n d a l l o y i n g a d d i t i o n s a n d t h r o u g h t h e o t h e r h o l e , a r g o n w a s p a s s e d d u r i n g t h e m e l t i n g o p e r a t i o n . S e v e r a l v a l v e c a s t i n g s w e r e m a d e i n l o w a l l o y s t e e l ( A I S I 4 3 4 0 ) a n d c a s t s t a i n l e s s s t e e l ( C F - 8 M ) . A l l t h e v a l v e s w e r e s u b j e c t e d t o n o n - d e s t r u c t i v e t e s t i n g ( N D T ) , m a c r o e x a m i n a t i o n , m i c r o e x a m i n a t i o n a n d m e c h a n i c a l t e s t i n g . T h e n e x t s e c t i o n d e a l s w i t h t h e e v a l u a t i o n o f v a l v e c a s t - i n g s a n d h a s b e e n d i v i d e d i n t o t w o p a r t s . P a r t A d e a l s w i t h t h e s t a i n l e s s s t e e l v a l v e c a s t i n g s w h i l e p a r t B d e a l s w i t h l o w a l l o y s t e e l ( A I S I 4 3 4 0 ) v a l v e c a s t i n g s . 22 C h a p t e r 4 E V A L U A T I O N OF E S C V A L V E C A S T I N G S A . S T A I N L E S S S T E E L V A L V E C A S T I N G S F i v e s t a i n l e s s s t e e l v a l v e s w e r e m a d e . O u t o f t h e s e t w o w e r e m a d e f r o m C F - 8 M ( 0 . 0 8 % m a x . C , 1 . 5 % m a x . M n , 1 . 5 % m a x . S i , 0 . 0 4 % m a x . S , 0 . 0 4 % m a x . P , 1 8 . 0 - 2 1 . 0 % C r , 9 . 0 - 1 2 . 0 % N i , 2 . 0 - 3 . 0 % M o ) e l e c t r o d e , o n e f r o m 3 1 6 ( 0 . 0 8 % m a x . C , 2 . 0 % m a x . M n , 0 . 0 3 % m a x . S , 0 . 0 4 % m a x . P , 1 . 0 % m a x s i , ' 1 0 . 0 - 1 4 . 0 % N i , 1 6 . 0 - 1 8 . 0 % C r , 2 . 0 - 3 . 0 % M o ) r o l l e d b a r , o n e f r o m 3 1 6 r o l l e d b a r w i t h c o n t r o l l e d a d d i t i o n o f c h r o m i u m c h i p s a n d t h e l a s t o n e w i t h 3 1 6 r o l l e d b a r f r o m c o n t r o l l e d a d d i t i o n s o f f e r r o - c h r o m e a n d f e r r o - m o l y b d e n u m p o w d e r . T h e a l l o y i n g w a s d o n e t o c h a n g e t h e 3 1 6 b a r c h e m i s t r y t o C F - 8 M c o m p o s i t i o n . T h i s w a s d o n e k e e p i n g i n v i e w t h a t e v e n a m a n u - f a c t u r e r who d o e s n o t h a v e e l e c t r o d e c a s t i n g f a c i l i t y c a n p r o - d u c e C F - 8 M c a s t i n g s w i t h t h e r e a d i l y a v a i l a b l e 3 1 6 r o l l e d b a r c o m p o s i t i o n . B e s i d e s t h i s , a C F - 8 M b l o c k ( 1 2 " x 1 6 % " x 1 7 " ) w a s c o n - v e n t i o n a l l y c a s t a f t e r r e f i n i n g i n A 0 D . T h e h e a t t r e a t m e n t g i v e n w a s a d o u b l e q u e n c h i n g t r e a t m e n t f r o m 1 0 9 4 ° C ( 2 0 0 0 ° F ) . T h e p r o p e r t i e s o f t h i s c o n v e n t i o n a l c a s t i n g w e r e c o m p a r e d w i t h E S C v a l v e s . 23 A t y p i c a l e l e c t r o s l a g c a s t i n g o f a v a l v e b o d y m a d e i n s t a i n l e s s s t e e l i s s h o w n i n F i g u r e 1 2 . 4 . 1 R e m e l t i n g L o g f o r S t a i n l e s s S t e e l E S C V a l v e s T a b l e I g i v e s t h e m e l t i n g c o n d i t i o n s f o r 5 s t a i n l e s s s t e e l v a l v e s m a d e b y t h e E S C p r o c e s s . Some o f t h e s p e c i a l c h a r a c t e r - i s t i c s n o t i c e d d u r i n g t h e m e l t o r i n t h e c a s t i n g s a r e a s f o l - 1 o w s : - V a l v e N o . 5 - M e l t i n g h a d t o be i n t e r r u p t e d a b r u b t l y ( h e n c e no h o t t o p p i n g c y c l e ) b e c a u s e o f a m i n o r e x p l o s i o n h e a r d t o w a r d s t h e e n d o f i t s r u n . T h i s w i l l b e d i s c u s s e d i n s e c t i o n 4 . 3 . 7 . To a v o i d a n y p o r o s i t y d u e t o t h e m o i s t u r e i n t h e s l a g c o m p o n e n t s ( p a r t i c u l a r l y C a O ) , t h e s l a g w a s p r e f u s e d a n d c r u s h e d f o r u s e . H o w e v e r , w h e n t h e c a s t i n g w a s s e c t i o n e d , l a r g e h o l e s ( a b o u t t h e d i a m e t e r o f a p e n c i l ) r u n n i n g l o n g i - t u d i n a l l y f r o m t h e b o t t o m f o r a d i s t a n c e o f a b o u t 8 i n c h e s w e r e o b s e r v e d . ( s e e F i g u r e 1 .3 ) . A s t h e s l a g w a s p r e f u s e d , t h e c h a n c e s o f m o i s t u r e b e i n g r e s p o n s i b l e f o r t h e h o l e s w e r e l o w . T h e y c o u l d a l s o b e d u e t o c a r b o n m o n o x i d e e v o l u t i o n d u e t o i n - s u f f i c i e n t d e o x i d a t i o n . V a l v e N o . 6 - T h e c a s t i n g w a s i n c o m p l e t e b e c a u s e t h e e l e c t r o d e w a s n o t l o n g e n o u g h . E x t r a a l u m i n u m p o w d e r w a s a d d e d i n t h e b e g i n n i n g o f t h e r u n t o a v o i d CO e v o l u t i o n A l s o t h e m o l d w a s c o v e r e d f r o m t h e t o p a n d a r g o n w a s p a s s e d o v e r t h e s l a g . T h e ; s e c t i o n e d : c a s t i n g a g a i n s h o w e d 24 l o n g i t u d i n a l h o l e s . A t t h i s p o i n t i t w a s c e r t a i n t h a t t h e h o l e s w e r e d u e t o m o i s t u r e . V a l v e N o . 7 - E l e c t r o l y t i c c h r o m i u m c h i p s w e r e a d d e d t o i n c r e a s e t h e c h r o m i u m c o n t e n t o f t h e c a s t i n g . T h e s l a g w a s p r e f u s e d t w i c e t o a v o i d t h e m o i s t u r e p r o b l e m b u t a g a i n t h e r e w e r e s o m e h o l e s . H o w e v e r , t h e s i z e a n d d e n s i t y o f t h e s e h o l e s h a d d e c r e a s e d c o n s i d e r a b l y . A s m e n t i o n e d i n s e c t i o n 3 . 4 t h e h o l e s w e r e d u e t o r e h y d r a t i o n o f p r e c i p i t a t e d CaO i n t h e f u s e d s l a g . V a l v e N o . 9 - H e a t i n g t h e s l a g c o m p o n e n t s t o h i g h t e m p e r a t u r e ( m e n t i o n e d b e f o r e ) a v o i d e d t h e p r o b l e m o f m o i s t u r e i n t h e s l a g . No t r a c e o f m o i s t u r e r e l a t e d p o r o s i t y w a s o b s e r v e d . T h e c a s t i n g w a s s o u n d a n d c o m p l e t e . V a l v e N o . 1 0 - 70% F e - C r a n d 65% F e - M o p o w d e r w a s a d d e d t o i n c r e a s e t h e c h r o m i u m a n d m o l y b d e n u m c o n t e n t s o f t h e c a s t i n g . T h e f e e d i n g r a t e w a s u n e v e n b e c a u s e o f a n i n a d e q u a t e f e e d i n g a r r a n g e m e n t w h i c h p r o b a b l y r e s u l t e d i n c l u s t e r s o f f e r r o a l l o y p o w d e r s e g r e g a t e d i n p o c k e t s i n t h e c a s t i n g . No p o r o s i t y w a s o b s e r v e d i n t h i s c a s t i n g . 4 . 2 N o n - D e s t r u c t i v e T e s t i n g ( N D T ) A s U . B . C . d o e s n o t h a v e t h e f a c i l i t y f o r r a d i o g r a p h y a n d t h e a p p r o p r i a t e u l t r a s o n i c t e s t i n g f o r h e a v y s e c t i o n s , t w o 25 C F - 8 M v a l v e s w e r e e x t e r n a l l y e v a l u a t e d - o n e f o r r a d i o g r a p h y a n d o n e f o r u l t r a s o n i c t e s t i n g . 4 . 2 . 1 D y e P e n e t r a n t T e s t T h e s t a i n l e s s v a l v e s w e r e s e c t i o n e d l o n g i t u d i n a l l y a n d a c o n v e n t i o n a l d y e - p e n e t r a n t s y s t e m w a s u s e d . I t s h o w e d t h a t t h e i n t e r n a l s u r f a c e w a s s o u n d . 4 . 2 . 2 U l t r a s o n i c T e s t U l t r a s o n i c t e s t i n g w a s p e r f o r m e d o n a f u l l E S C v a l v e a n d t h e n o n a s e c t i o n e d h a l f c a s t i n g . T h e t e s t i n g w a s d o n e a c c o r d - i n g t o t h e A S M E S A - 3 8 8 ( A S T M A 3 8 8 - 7 1 ) s p e c i f i c a t i o n f o r h e a v y s e c t i o n s t e e l f o r g i n g s . T e s t r e s u l t s i n d i c a t e t h a t ' n o u s e a b l e u l t r a s o n i c r e s p p n s e w a s r e c e i v e d f r o m t h e a u s t e n i t i c ( C F - 8 M ) s t a i n l e s s s t e e l v a l v e c a s t i n g a t d e p t h s o f 7 - 3 / 4 i n c h e s . . . : ' T h e A S M E s p e c i f i c a t i o n s a l s o n o t e t h a t t h e ' h e a v y a u s t e n i t i c s t a i n l e s s s t e e l f o r g i n g s a r e m o r e d i f f i c u l t t o p e n e t r a t e u l t r a - s o n i c a l l y t h a n s i m i l a r c a r b o n o r l o w - a l l o y s t e e l f o r g i n g s . T h e d e g r e e o f a t t e n u a t i o n n o r m a l l y i n c r e a s e s w i t h s e c t i o n s i z e ; a n d t h e n o i s e l e v e l , g e n e r a l l y o r i n i s o l a t e d a r e a s , may b e - c o m e t o o g r e a t t o p e r m i t d e t e c t i o n o f d i s c r e t e i n d i c a t i o n s . I n m o s t i n s t a n c e s t h i s a t t e n t u a t i o n r e s u l t s f r o m i n h e r e n t c o a r s e g r a i n e d m i c r o s t r u c t u r e o f t h e s e a u s t e n i t i c a l l o y s : 1 F o l l o w i n g t h i s a t h r e e i n c h t h i c k s e c t i o n w i t h o n e m a c h i n e c u t s u r f a c e w a s t e s t e d w i t h t h e 1 M H , - 3 / 4 i n c h d i a m e t e r t r a n s d u c e r . T h e 26 p e n e t r a t i o n d i r e c t i o n w a s t r a n s v e r s e t o t h e g r a i n o r i e n t a t i o n . I t w a s s t i l l q u e s t i o n a b l e w h e t h e r o r n o t f i n e d e f e c t s c o u l d b e d e t e c t e d . A l t h o u g h a b e t t e r p e n e t r a t i o n c o u l d h a v e b e e n a c c o m p l i s h e d i n t h e d i r e c t i o n o f t h e g r a i n i n a t h r e e i n c h s e c t i o n , t h e s e r e s u l t s i n d i c a t e t h a t u l t r a s o n i c t e s t i n g i s n o t s u i t a b l e f o r a u s t e n i t i c s t a i n l e s s s t e e l E S C v a l v e s . 4 . 2 . 3 . . R a d i o g r a p h y T e s t R a d i o g r a p h y w a s p e r f o r m e d i n a c c o r d a n c e w i t h A S T M E 9 4 - 7 7 s p e c i f i c a t i o n u s i n g a c o b a l t - 6 ' 0 s o u r c e . No a p p a r e n t d e f e c t s c o u l d b e d e t e c t e d . 4 . 3 D e s t r u c t i v e T e s t i n g ( D T ) T h e c o n v e n t i o n a l a n d E S C v a l v e c a s t i n g s w e r e s e c t i o n e d l o n g i t u d i n a l l y t h r o u g h t h e m i d d l e a n d h a l f i n c h t h i c k p l a t e s w e r e c u t o u t ( s e e F i g u r e 1 4 ) f o r d e s t r u c t i v e t e s t s . 4 . 3 . 1 M a c r o s t r u c t u r e s T h e h a l f i n c h t h i c k p l a t e s w e r e s u r f a c e g r o u n d a n d m a c r o - e t c h e d v i n 1 a n a c i d s o l u t i o n ( 3 8 % H C £ , 12% H 2 S 0 4 , 50% H 2 0 ) a t a b o u t 6 5 - 7 0 ° C f o r 1 - 2 h o u r s . T h e m a c r o s t r u c t u r e s o b t a i n e d a r e s h o w n i n F i g u r e s 1 5 - 1 9 . T h e g r a i n s t r u c t u r e c l e a r l y s h o w s t h e c h i l l i n g e f f e c t o f t h e w a t e r - c o o l e d m o l d a n d a l m o s t 27 v e r t i c a l s o l i d i f i c a t i o n p a t t e r n . A l s o , t h e s t r u c t u r e s a r e e s s e n t i a l l y f r e e o f s o l i d i f i c a t i o n d e f e c t s. a l t h o u g h s o m e p e c u l i a r i . t i e s : ' d o e x i s t . F i g u r e 16 s h o w s a s l a g i n c l u s i o n a t t h e t o p o f t h e c a s t i n g . T h i s w a s d u e t o a n i n t e r r u p t e d h o t - t o p p i n g c y c l e a n d c a n b e c o r r e c t e d e a s i l y . F i g u r e 1 7 s h o w s a c h a n g e o f p o o l p r o f i l e i n t h e t o p r i g h t h a n d c o r n e r a n d a p e c u l i a r s t r u c t u r e i n t h e c e n t r e . . T h i s i s b e l i e v e d t o b e a p i e c e o f e l e c t r o d e w h i c h d r o p p e d d u r i n g t h e m e l t i n g o p e r a t i o n . F i g u r e 1 8 s h o w s s o m e b i g i n c l u s i o n s s c a t t e r e d i n t h e c a s t i n g . T h i s c a s t i n g w a s m a d e w i t h t h e a d d i t i o n o f f e r r o - c h r o m e a n d f e r r o - m o l y b d e n u m p o w d e r s d u r i n g t h e m e l t a n d t h e s e i n c l u s i o n s a r e b e l i e v e d t o b e d u e t o t h e f e r r o - a l l o y a d d i t i o n s . T h e s e t w o e a s e s w i l l b e i d e n t i f i e d a n d d i s c u s s e d s u b s e q u e n t l y . T h e m a c r o s t r u c t u r e o f t h e t o p q u a r t e r p a r t o f t h e l o n g i - t u d i n a l s e . c . t i i o n o f t h e c o n v e n t i o n a l C F - 8 M c a s t i n g i s g i v e n i n F i g u r e 1 9 . M o s t o f t h e a r e a i s c o v e r e d b y e q u i a x e d g r a i n s t h o u g h t h e r e i s s o m e c o l u m n a r s t r u c t u r e n e a r t h e e d g e o f t h e c a s t i n g . T h i s m a c r o s t r u c t u r e a l s o s h o w s a b a n d e d s t r u c t u r e b e t w e e n t h e c o l u m n a r a n d t h e e q u i a x e d z o n e s a n d a t a n a n g l e t o t h e t o p s u r f a c e . T h i s i s t h o u g h t t o b e d u e t o e i t h e r a f e e d e r o r a r i s e r p l a c e d a t t h i s p o s i t i o n . T h e m a c r o - e t c h e d p l a t e s w e r e t h e n c u t up f o r m i c r o - e x a m i n a t i o n a n d o t h e r t e s t s . 28 4 . 3 . 2 M i c r o s t r u c t u r e s T h e a u s t e n i t i c c a s t s t a i n l e s s s t e e l d e s i g n a t e d a s C F - 8 M b y A C I c l o s e l y c o r r e s p o n d s t o t h e w r o u g h t g r a d e A I S I t y p e 3 1 6 s t a i n l e s s s t e e l . T h e s i l i c o n a n d c h r o m i u m c o n t e n t s o f t h e c a s t a l l o y a r e h i g h e r a n d t h e n i c k e l c o n t e n t l o w e r t h a n i n t h e w r o u g h t a l l o y . T h e v a r i a t i o n s i n c h e m i s t r y may b e s m a l l b u t t h e y a r e n o t t r i v i a l - t h e y p r o v i d e f o r o p t i m u m f o r g e a b i l i t y a n d c o n s i d e r a b l e d u c t i l i t y f o r h o t a n d c o l d w o r k i n g o n o n e h a n d a n d o p t i m u m c a s t a b i l i t y o n t h e o t h e r . D e p e n d i n g p r i n c i p a l l y o n c o m p o s i t i o n , b u t a l s o o n t h e r m a l h i s t o r y t o a l e s s e r e x t e n t , m i c r o s t r u c t u r e s r a n g i n g f r o m n o n - m a g n e t i c ( f u l l y a u s t e n i t i c a s i n T y p e 3 1 6 ) t o p e r c e p t i b l y m a g n e t i c ( d u e t o s u b s t a n t i a l a m o u n t s o f f e r r i t e p h a s e p r e s e n t i n t h e a u s t e n i t i c m a t r i x , a s i n C F - 8 M ) c a n b e p r o d u c e d . B e s i d e s p r o d u c t i o n o f s o u n d c a s t i n g s , p r e s e n c e o f d e l t a - f e r r i t e i m p r o v e s w e l d a b i l i t y a n d i m p r o v e s t h e r e s i s t a n c e t o 51 h o t c r a c k i n g d u r i n g c a s t i n g o p e r a t i o n . I t a l s o i m p r o v e s r e s i s t a n c e t o c o r r o s i v e : m e d i a . s u c h a s • s u l p h u r o u s a n d a c e t i c 52 a c i d s , t o i n t e r g r a n u l a r a t t a c k , a n d t o c h l o r i d e s t r e s s 5 3 c o r r o s i o n c r a c k i n g . D e l t a f e r r i t e a l s o i n c r e a s e s t h e p r o o f s t r e s s a n d t e n s i l e s t r e n g t h v a l u e s b y a d i s p e r s i o n - s t r e n g t h e n - 54 i n g e f f e c t . ( t h i s w i l l b e d i s c u s s e d l a t e r ) . T h i s i s t h e r e a l r e a s o n f o r h i g h e r c h r o m i u m c o n t e n t i n C F - 8 M . F r o m t h e a b o v e we s e e t h a t p r e s e n c e o f d e l t a - f e r r i t e i n C F - 8 M c a s t i n g s i s e s s e n t i a l t o o b t a i n g o o d c o r r o s i o n 29 r e s i s t a n c e a n d m e c h a n i c a l p r o p e r t i e s . H o w e v e r , t h e p r e s e n c e o f d e l t a - f e r r i t e i n a u s t e n i t i c s t a i n l e s s s t e e l s h a s b e e n s h o w n 55 t o a c c e l e r a t e t h e f o r m a t i o n o f a n i n t e r m e t a l 1 i c s i g m a p h a s e . S i g m a p h a s e w a s f i r s t d e t e c t e d i n F e - C r - N i a l l o y s a n d r e p o r t e d 56 i n 1 9 2 7 . I t h a s b e e n i d e n t i f i e d a s a h a r d , b r i t t l e , n o n - m a g n e t i c , i n t e r m e d i a t e p h a s e w i t h a t e t r a g o n a l c r y s t a l s t r u c t u r e o c c u r r i n g i n m a n y b i n a r y a n d t e r n a r y a l l o y s o f t h e i t r a n s i t i o n 4 7 5 8 5 9 e l e m e n t s a n d h a s b e e n w e l l d o c u m e n t e d i n t h e l i t e r a t u r e . ' ' T h e f o r m a t i o n o f s i g m a p h a s e i s e n h a n c e d b y a d d i t i o n o f f e r - r i t e - s t a b i l i z e r s s u c h a s c h r o m i u m , m o l y b d e n u m a n d s i l i c o n . A l t h o u g h t h i s p h a s e f o r m s m o s t r e a d i l y f r o m f e r r i t e , i t c a n 6 0 a l s o f o r m f r o m a u s t e n i t e . S i g m a f o r m a t i o n i s t i m e - a n d t e m - p e r a t u r e - d e p e n d e n t a n d c a n b e d e s c r i b e d o n a t r a n s f o r m a t i o n 61 d i a g r a m b y a t y p i c a l ' C c u r v e . T h e t e m p e r a t u r e r a n g e o f s i g m a f o r m a t i o n i s r e g a r d e d a s a b o u t 6 0 0 ° C t o 9 5 0 ° C a n d i n a l l o y s o f t h e 1 8 - 8 t y p e w i t h 2 t o 3 p e r c e n t m o l y b d e n u m a n d r e t a i n e d d e l t a - f e r r i t e , t h e m a x i m u m r a t e o f f o r m a t i o n o c c u r s a t a b o u t 8 5 0 ° C w i t h f e r r i t e t r a n s f o r m i n g t o s i g m a a n d a u s t e n i t e i n l e s s t h a n o n e - h a l f h o u r . I t h a s b e e n r e p o r t e d ' t h a t d e l t a - f e r r i t e b e i n g a r e g i o n o f r e l a t i v e l y h i g h c h r o m i u m c o n t e n t , f o r m s s i g m a i n a c o m p a r a t i v e l y s h o r t t i m e b y a c o n c e n t r a t i o n o f c h r o m i u m t h r o u g h d i f f u s i o n f r o m a d j a c e n t c h r o m i u m - r i c h f e r r i t e t o a r e a s w h e r e s i g m a n u c l e a t e d . T h e d e p l e t i o n o f c h r o m i u m i n t h e s u r r o u n d i n g f e r r i t e e v e n t u a l l y r e s u l t s i n t h e f o r m a t i o n o f a u s t e n i t e . T h i s i s s h o w n i n F i g u r e 2 3 . 30 T h e e f f e c t s o f s i g m a o n t h e c o r r o s i o n b e h a v i o u r o f a u s t e n i - t i c s t a i n l e s s s t e e l s a r e m o s t s e r i o u s i n h i g h l y o x i d i s i n g e n - 59 v i r o n m e n t s s u c h a s n i t r i c a c i d . I n g e n e r a l s i g m a p h a s e i n - c r e a s e s t h e h a r d n e s s , y i e l d s t r e n g t h , a n d t e n s i l e s t r e n g t h , b u t d e c r e a s e s t h e i m p a c t s t r e n g t h , b o t h a t r o o m t e m p e r a t u r e a n d a t e l e v a t e d t e m p e r a t u r e s . L o s s o f l o w t e m p e r a t u r e d u c t i l i t y a n d c o r r o s i o n r e s i s t a n c e i s p a r t i c u l a r l y s e v e r e w h e n t h e s i g m a p h a s e f o r m s a n e a r l y c o n t i n u o u s n e t w o r k a r o u n d t h e a u s t e n i t e g r a i n s . ^ 2 I n c o n s e q u e n c e o f t h e a b o v e d i s c u s s i o n , i t i s i m p o r t a n t t o i d e n t i f y t h e f e r r i t e a n d s i g m a p h a s e s i n t h e s t a i n l e s s s t e e l v a l v e c a s t i n g s a n d t o e l i m i n a t e a n y s i g m a p h a s e p r e s e n t i n t h e a s - c a s t c o n d i t i o n b y a s u i t a b l e h e a t t r e a t m e n t . T h e C F - 8 t y p e c a s t a l l o y s a r e u s e d i n t h e s o l u t i o n t r e a t e d c o n - d i t i o n w h i c h i n v o l v e s h e a t i n g a t 1 1 0 0 t o 1 1 5 0 ° C a n d q u e n c h i n g i n w a t e r o r o i l . T h e h e a t t r e a t m e n t a d o p t e d w a s h e a t i n g t h e s p e c i m e n s t o 1 1 2 0 ° C f o r 1 - 2 h o u r s a n d q u e n c h i n g i n w a t e r . T h e m i c r o s t r u c t u r e a f t e r h e a t t r e a t m e n t w a s e s s e n t i a l l y a u s t e n - i t i c w i t h f e r r i t e d i s t r i b u t e d t h r o u g h o u t t h e m a t r i x i n d i s - c o n t i n u o u s p o o l s . S i g m a p h a s e w a s e l i m i n a t e d . M a n y t e c h n i q u e s h a v e b e e n c i t e d i n t h e l i t e r a t u r e t o i d e n t i f y a n d d i f f e r e n t i a t e s i g m a p h a s e f r o m o t h e r p h a s e s o c c u r - 6 3 6 5 r i n g i n a u s t e n i t i c s t a i n l e s s s t e e l s . ' Two d i f f e r e n t p o l i s h i n g a n d e t c h i n g p r o c e d u r e s w e r e u s e d t o i d e n t i f y t h e f e r r i t e a n d s i g m a p h a s e s i n E S C v a l v e s . 31 I n t h e f i r s t o n e , t h e s p e c i m e n s w e r e m e c h a n i c a l l y p o l i s h e d t o 5 m i c r o n s , t h e n e l e c t r o - p o l i s h e d i n c h r o m i c - a c e t i c s o l u t i o n ( 1 3 3 ml a c e t i c a c i d , 7 ml w a t e r , 25 gms C r 0 3 ) a t 2 8 - 3 0 V f o r 8 - 1 0 m i n u t e s . T h e n t h e y w e r e e l e c t r o - e t c h e d i n 10 w t . % o x a l i c a c i d s o l u t i o n a t 6 V f o r 2 0 - 3 0 s e c o n d s . T h i s p r o c e d u r e w a s f o u n d t o o u t l i n e t h e f e r r i t e p h a s e c l e a r l y a n d t h e o x a l i c a c i d e t c h a t t a c k s t h e s i g m a p h a s e v e r y r a p i d l y . F i g u r e 2 0 a - b s h o w s t h e m i c r o s t r u c t u r e o f a s p e c i m e n f r o m C F - 8 M v a l v e i n t h e a s - c a s t c o n d i t i o n . T h e f e r r i t e p h a s e s h o w s up i n r e l i e f a n d i t i s c l e a r l y o u t l i n e d a n d t h e s i g m a p h a s e w h i c h i s p r e d o m i n a n t l y p r e s e n t w i t h i n t h e f e r r i t e p h a s e i s a t t a c k e d s e v e r e l y . T h e h e a t t r e a t e d s p e c i m e n s s h o w t h a t t h e s i g m a p h a s e i s e l i m i n a t e d a n d o n l y f e r r i t e i s l e f t b e h i n d . S i m i l a r l y F i g u r e s 2.1 a n d 22 s h o w t h e m i c r o s t r u c t u r e s f r o m 3 d i f f e r e n t v a l v e s i n t h e a s - c a s t a n d h e a t - t r e a t e d c o n d i t i o n s r e s p e c t i v e l y . I n t h e s e c o n d p r o c e d u r e , t h e s p e c i m e n s w e r e p o l i s h e d t o 1 m i c r o n a n d e t c h e d i n a m i x e d a c i d s o l u t i o n ( H N O ^ a n d HC£ i n H 2 0 ) s e v e r a l t i m e s t o r e m o v e t h e d i s t u r b e d m e t a l . T h e n t h e y w e r e e t c h e d i n V i l e l l a ' s r e a g e n t ( 5 m £ H C £ , 1 gm p j i c r i c a c i d , 1 0 0 n u e t h a n o l ) t o o u t l i n e t h e s i g m a p h a s e . F e r r i t e i s f a i n t l y o u t l i n e d . T h e n t h e s p e c i m e n s w e r e e l e c t r o - e t c h e d i n 1 0 N KOH s o l u t i o n ( 5 6 gms K O H , 1 0 0 m£ w a t e r ) a t 2 . 5 V f o r a f e w s e c o n d s , t h i s s t a i n s t h e s i g m a p h a s e y e l l o w t o r e d d i s h - b r o w n a n d t h e f e r r i t e t o b l u i s h - g r e y . A u s t e n i t e i s n o t a t t a c k e d . One s p e c i - men f r o m t h e c o n v e n t i o n a l C F - 8 M c a s t i n g w a s k e p t a t 8 5 0 ° C f o r 32 14 h o u r s t o p r o m o t e s i g m a f o r m a t i o n a n d t h e n i t w a s e t c h e d w i t h t h e a b o v e p r o c e d u r e . F i g u r e 2 3 s h o w s t h e m i c r o s t r u c t u r e o f t h i s s p e c i m e n . T h e b l a c k r e g i o n s a r e t h e s i g m a - p h a s e , t h e d a r k g r e y r e g i o n s a r e t h e u n t r a n s f o r m e d f e r r i t e p h a s e , a n d t h e l i g h t g r e y a r e a i s t h e a u s t e n i t e . T h e a u s t e n i t e w h i c h h a s b e e n t r a n s - f o r m e d f r o m f e r r i t e i s a l s o s e e n . A s t h e c o n v e n t i o n a l c a s t i n g w a s r e c e i v e d i n t h e s o l u t i o n - t r e a t e d c o n d i t i o n , t h e m i c r o - s t r u c t u r e s g i v e n i n F i g u r e 24 s h o w s t h a t o n l y f e r r i t e a n d a u s t e n i t e a r e p r e s e n t . F i g u r e 25 s h o w s t h e m i c r o s t r u c t u r e o f a C F - 8 M E S C v a l v e N o . 9 i n t h e a s - c a s t c o n d i t i o n . S i g m a p h a s e w i t h i n t h e f e r r i t e b o u n d a r i e s i s e a s i l y d e t e c t e d . F i g u r e .26 s h o w s t h e s p e c i m e n s f r o m t h e s a m e v a l v e b u t i n t h e s o l u t i o n - t r e a t e d c o n d i t i o n . S i g m a p h a s e i s c o m p l e t e l y e l i m i n a t e d . M i c r o h a r d n e s s t e s t s on s i g m a a n d a u s t e n i t e w e r e a l s o c a r - r i e d o u t t o c o n f i r m t h a t w h a t h a s b e e n d i s t i n g u i s h e d t o b e s i g m a p h a s e f r o m m e t a l l o g r a p h y i s a c t u a l l y t h e h a r d a n d i n t e r - m e t a l l i c s i g m a p h a s e . F i g u r e 2 7 s h o w s t h e i d e n t a t i o n o f t h e d i a m o n d p y r a m i d h a r d n e s s i n d e n t o r o n s i g m a a n d a u s t e n i t e p h a s e s . T h e r e l a t i v e DPH v a l u e s c a l c u l a t e d f r o m t h e s e a r e - s i g m a p h a s e - 6 4 3 . 3 DPH a u s t e n i t e p h a s e - 2 5 5 . 0 DPH T h e m i c r o h a r d n e s s v a l u e o b t a i n e d f o r s i g m a p h a s e i s s o m e - w h a t l o w e r t h a n t h e v a l u e q u o t e d i n l i t e r a t u r e w h i c h i s 7 5 0 D P H . T h i s d i f f e r e n c e c o u l d b e b e c a u s e t h e i n d e n t a t i o n t a k e n 33 h e r e i s o v e r a n e t w o r k o f s i g m a p a r t i c l e s w h i l e t h e l i t e r a t u r e v a l u e i s w i t h i n a l a r g e i s o l a t e d s i g m a p a r t i c l e . 4.3.3 D e l t a F e r r i t e M e a s u r e m e n t s T h e i m p o r t a n c e o f d e l t a f e r r i t e i n a u s t e n i t i c s t a i n l e s s s t e e l c a s t a l l o y s h a s b e e n d i s c u s s e d b r i e f l y i n t h e l a s t s e c t i o n . I t b e c o m e s e s s e n t i a l , t h e r e f o r e , t o d e t e r m i n e t h e f e r r i t e c o n t e n t o f t h e c a s t i n g s . T h e f e r r i t e c o n t e n t w a s m e a s u r e d b y t h r e e d i f - f e r e n t i n s t r u m e n t s - a F e r r i t e I n d i c a t o r , a ; M a g n e G a g e , a n d a Q u a n t i m e t . F e r r i t e c o n t e n t w a s a l s o e s t i m a t e d f r o m t h e 66 S c h o e f e r ' s d i a g r a m . T h e F e r r i t e I n d i c a t o r u s e s m a g n e t s c a l i b r a t e d t o k n o w n f e r r i t e n u m b e r s t o ' b r a c k e t ' t h e f e r r i t e c o n t e n t o f t h e t e s t p i e c e b e t w e e n t w o f e r r i t e n u m b e r s . T h e f e r r i t e n u m b e r h a s b e e n a d o p t e d a s t h e a c c e p t e d i n d e x w h i c h q u a n t i f i e s t h e f e r - r i t e c o n t e n t . A l t h o u g h c l o s e l y r e l a t e d t o a c t u a l p e r c e n t a g e f e r r i t e c o n t e n t , p a r t i c u l a r l y a t l o w f e r r i t e c o n t e n t s , t h e f e r r i t e n u m b e r d o e s n o t c o r r e s p o n d p r e c i s e l y t o p e r c e n t f e r - r i t e . M e a s u r e m e n t s w e r e d o n e o n t h e s p e c i m e n s u s e d f o r m i c r o - e x a m i n a t i o n . T h e s u r f a c e w a s r o u g h p o l i s h e d t o a v o i d e r r o n - e o u s r e s u l t s d u e t o o x i d a t i o n . T a b l e I I s h o w s t h e f e r r i t e n u m b e r s o b t a i n e d f r o m d i f f e r e n t l o c a t i o n s i n t h e c a s t i n g s . A s t h e F e r r i t e I n d i c a t o r o n l y ' b r a c k e t s ' t h e f e r r i t e c o n t e n t , a i M a g n e - G a g e w a s u s e d t o f i n d o u t t h e s p e c i f i c 34 f e r r i t e c o n t e n t o f t h e c a s t i n g s . T h i s i n s t r u m e n t a l s o w o r k s m a g n e t i c a l l y a n d h a s a c a l i b r a t e d c o i l s p r i n g a t t a c h e d t o a p o i n t e r w h i c h m o v e s o n a d i a l . T h e d i a l r e a d i n g i n d i c a t e s t h e f e r r i t e c o n t e n t o f t h e t e s t s p e c i m e n i n f e r r i t e n u m b e r s . T h e s p e c i m e n s w e r e p o l i s h e d t o 3 2 0 g r i t t o p r o v i d e a n e v e n , c l e a n a n d s i m i l a r s u r f a c e s t o a l l s p e c i m e n s . T h e f e r r i t e c o n - t e n t s o b t a i n e d f r o m v a r i o u s l o c a t i o n s i n t h e c a s t i n g s a r e g i v e n i n T a b l e I I . T a b l e I I I g i v e s t h e a v e r a g e f e r r i t e n u m b e r o f e a c h c a s t i n g i n t h e a s - c a s t a n d h e a t - t r e a t e d c o n d i t i o n s . F r o m t h i s t a b l e i t c a n b e n o t i c e d t h a t f o r v a l v e n u m b e r s 5 , 6 a n d 7 , t h e f e r r i t e c o n t e n t s i n t h e h e a t - t r e a t e d c o n d i t i o n a r e 1 o w e r t h a n i n t h e a s - c a s t c o n d i t i o n . N o r m a l l y , a n o p p o s i t e r e s u l t w o u l d b e e x p e c t e d d u e t o t h e p r e s e n c e o f s i g m a p h a s e w i t h i n t h e f e r r i t e b o u n d a r i e s i n t h e a s - c a s t c o n d i t i o n . T h i s a n o m a l y c a n b e e x p l a i n e d b y t h e t h e r m a l h i s t o r y o f t h e h e a t - t r e a t e d s p e c i m e n s . T h e s p e c i m e n s f r o m t h e s e t h r e e v a l v e s w e r e h e a t - t r e a t e d i n s t a i n l e s s s t e e l b a g s t o a v o i d e x c e s s i v e o x i d a t i o n . I t w a s f o u n d t h a t q u e n c h i n g o f t h e s p e c i m e n s w a s n o t f a s t e n o u g h a s i t w a s d i f f i c u l t t o c u t o p e n t h e b a g s b e f o r e q u e n c h - i n g . H e n c e t h e m i c r o s t r u c t u r e s t i l l s h o w e d s o m e s i g m a p h a s e . T h e r e f o r e t h e s p e c i m e n s w e r e h e a t t r e a t e d a g a i i n w i t h o u t t h e s t a i n l e s s b a g s a n d q u e n c h e d i n w a t e r . I t s e e m s t h a t t h i s p a r t i c u l a r t h e r m a l c y c l e r e s u l t e d i n l o w e r f e r r i t e c o n t e n t . I t h a s b e e n i n d i c a t e d * ^ t h a t t h e r e s i d u a l f e r r i t e c o n t e n t o f d u p l e x a l l o y s i s s t r o n g l y i n f l u e n c e d b y t h e s o l u t i o n i n g t e m - p e r a t u r e a n d t h e s u b s e q u e n t c o o l i n g r a t e . 35 A n o t h e r p o i n t w h i c h e m e r g e s f r o m t h e f e r r i t e m e a s u r e - m e n t s i s t h a t t h e f e r r i t e c o n t e n t o f t h e t o p m o s t p a r t o f t h e c a s t i n g i s m u c h l o w e r t h a n t h e b u l k o f t h e c a s t i n g . T h i s i s p r o b a b l y d u e t o t h e v e r y s l o w c o o l i n g r a t e o f t h e t o p p a r t o f t h e c a s t i n g . T o w a r d s t h e e n d o f t h e r u n , t h e r e i s a b r i e f h o t t o p p i n g c y c l e a n d a f t e r t h e r u n h a s b e e n t e r m i n a t e d t h e s l a g b l a n k e t s o l i d i f i e s s l o w l y a n d a c t s a s a t h e r m a l i n s u l a - t o r f o r t h e l a s t p a r t o f m e t a l t o f r e e z e . F e r r i t e m e a s u r e m e n t s w e r e a l s o d o n e b y u s i n g t h e Q u a n t i m e t . A s t a i n e t c h w a s d o n e u s i n g t h e t e c h n i q u e d e - s c r i b e d i n t h e l a s t s e c t i o n . I t w a s f o u n d t h a t i t w a s d i f - f i c u l t t o g e t a g o o d a c c u r a c y i n t h e Q u a n t i m e t . T h e f e r r i t e f o r m s a n e t w o r k p a r t i c u l a r l y a t h i g h e r f e r r i t e c o n t e n t s a n d i t i s d i f f i c u l t t o c u t o u t t h e ' s n o w ' o r n o i s e i n t h e n o r m a l m o d e . T h e ' s n o w ' c a n be r e d u c e d b y u s i n g t h e ' g r o u n d c u t ' m o d e a n d l o w e r r e s o l u t i o n , b u t t h i s m o d e m a k e s i t d i f f i c u l t t o s e t t h e t h r e s h o l d v a l u e s w h i c h i n t u r n l e a d s t o v a r i a b l e r e s u l t s . T h e u s e o f a n y o t h e r m o r e s o p h i s t i c a t e d t e c h n i q u e w a s n o t c o n s i d e r e d t o b e n e c e s s a r y i n t h i s s t u d y . T h e o r e t i c a l e s t i m a t i o n o f t h e f e r r i t e c o n t e n t w a s a l s o c a r r i e d o u t u s i n g t h e S c h o e f e r ' s d i a g r a m . 6 6 S c h o e f e r h a s d e v e l o p e d a o n e - l i n e c o n s t i t u t i o n d i a g r a m f o r c a s t F e - C r - N i a l l o y s w i t h w h i c h t h e f e r r i t e c o n t e n t o f t h e 36 a l l o y c a n b e e s t i m a t e d a c c u r a t e l y k n o w i n g o n l y t h e a l l o y c o m - p o s i t i o n . I t w a s d e r i v e d f r o m S c h a e f f l e r ' s d i a g r a m f o r w e l d m e t a l . T h e S c h o e f e r ' s d i a g r a m r e q u i r e s t h e c o n v e r s i o n o f a l l f e r r i t e - p r o m o t i n g e l e m e n t s i n t o ' c h r o m i u m e q u i v a l e n t s ' a n d a l l a u s t e n i t e p r o m o t i n g e l e m e n t s i n t o ' n i c k e l e q u i v a l e n t s ' t h r o u g h t h e u s e o f c o e f f i c i e n t s r e p r e s e n t i n g t h e f e r r i t i s i n g o r a u s t e n i t i s i n g p o w e r o f e a c h e l e m e n t . T h e d i a g r a m i s s h o w n i n F i g u r e 2 8 . T a b l e M i l a l s o g i v e s t h e c a l c u l a t e d f e r r i t e c o n - t e n t s u s i n g t h e S c h o e f e r ' s d i a g r a m . I t c a n be s e e n t h e f e r r i t e n u m b e r s e s t i m a t e d f r o m S c h o e f e r ' s d i a g r a m a r e h i g h e r t h a n t h o s e o b t a i n e d b y M a g n e G a g e p a r t i c u l a r l y a t h i g h e r f e r r i t e c o n t e n t s . 6 2 T e n s i l e d a t a g e n e r a t e d b y o t h e r w o r k e r s on C .F -8M: ; s h o w s t h a t t h e s t r e n g t h l e v e l s a r e d i r e c t l y r e l a t e d t o t h e f e r r i t e c o n t e n t . C o m p a r i s o n o f t h e s t r e n g t h l e v e l s o b t a i n e d o n c o n - v e n t i o n a l C F - 8 M c a s t i n g s h o w e d t h a t t h e f e r r i t e c o n t e n t o b - t a i n e d b y M a g n e G a g e i s s i m i l a r t o t h a t f o u n d b y t h o s e w o r k e r s . A l s o , S c h o e f e r ' s d i a g r a m i s a p p l i c a b l e t o a s - c a s t r a t h e r t h a n h e a t - t r e a t e d c o n d i t i o n . A s m e n t i o n e d e a r l i e r t h e r e s i d u a l f e r - r i t e c o n t e n t s a r e g r e a t l y a f f e c t e d b y t h e s o l u t i o n i n g t e m p e r a - t u r e . Q u e n c h i n g f / runr 1 3 0 0 ° C r e s u l t s i n t w i c e a s m u c h f e r r i t e fi 7 a s q u e n c h i n g f r o m 1 1 5 0 ° C . 4 . 3 . 4 I n t e r d e n d r i t i c M i c r o s e g r e g a t i o n I t h a s b e e n f r e q u e n t l y c l a i m e d ^ ' ^ 9 t h a t i n t e r d e n d r i t i c m i c r o s e g r e g a t i o n i n e l e c t r o s l a g r e m e l t e d m a t e r i a l i s g r e a t l y 37 r e d u c e d f r o m t h a t i n t h e e q u i v a l e n t s e c t i o n i n c o n v e n t i o n a l c a s t i n g . I n g e n e r a l , l o w m e l t r a t e s a n d s m a l l c r o s s s e c t i o n s l e a d t o l o w m i c r o s e g r e g a t i o n . A s m e n t i o n e d i n S e c t i o n 2 . 1 . 2 a n o p t i m u m m e l t r a t e i s n e e d e d t o a c h i e v e l e a s t m i c r o s e g r e g a - t i on . M i c r o s e g r e g a t i o n w a s s t u d i e d b y e l e c t r o n m i c r o p r o b e a n a l y s i s o f s a m p l e s f r o m t w o C F - 8 M v a l v e c a s t i n g s ( i n t h e a s - c a s t c o n d i t i o n ) a n d t h e c o n v e n t i o n a l C F - 8 M c a s t i n g ( i n t h e h e a t - t r e a t e d c o n d i t i o n ) . L i n e s c a n s w e r e p e r f o r m e d i n s e l e c t e d a r e a s a n d a c r o s s t h e d e n d r i t i c d i r e c t i o n . B e f o r e a n a l y s i s t h e s a m p l e s w e r e e t c h e d a n d t h e l i n e s t o be t r a v e r s e d w e r e m a r k e d w i t h m i c r o h a r d n e s s i n d e n t a t i o n s s u c h t h a t t h e y w e r e 5 mm a p a r t ! . A f t e r p h o t o g r a p h i n g t h e s a m p l e s i n t h e e t c h e d a n d m a r k e d c o n - d i t i o n , t h e y w e r e r e p o l i s h e d b e f o r e t h e a n a l y s i s . T h e ' s e g r e - g a t i o n r a t i o ' ( d e f i n e d a s t h e r a t i o o f m a x i m u m c o m p o s i t i o n t o m i n i m u m c o m p o s i t i o n ) o f t h r e e a l l o y i n g e l e m e n t s ( C r , N i , M o ) w a s d e t e r m i n e d i n a l l t h e s a m p l e s . F i g u r e s 2 9 a , b a n d 3 0 a - c s h o w t h e l i n e s c a n o f t h e m i c r o p r o b e a l o n g w i t h v a r i a t i o n o f s o l u t e c o n c e n t r a t i o n a l o n g t h e l i n e , w h i l e T a b l e IV g i v e s t h e s e g r e g a - t i o n r a t i o s o b t a i n e d f r o m t h e a n a l y s e s . T h e r e s u l t s s h o w t h a t - a ) O u t o f e l e m e n t s a n a l y s e d , m o l y b d e n u m i s t h e m o s t h i g h l y 38 s e g r e g a t e d e l e m e n t f o l l o w e d b y n i c k e l a n d t h e n c h r o m i u m . b ) I n t e r d e n t r i t i c m i c r o s e g r e g a t i o n o r t h e s e g r e g a t i o n r a t i o i n c r e a s e s f r o m t h e e d g e t o t h e c e n t r e o f t h e c a s t i n g s . c ) M i c r o s e g r e g a t i o n i s m u c h l o w e r i n t h e E S C v a l v e s t h a n i n t h e c o n v e n t i o n a l c a s t i n g s f o r a n e q u i v a l e n t d i s t a n c e f r o m t h e e d g e . T h i s i s c l e a r l y d e p i c t e d f r o m t h e s e g r e g a t i o n r a t i o o f m o l y b d e n u m w h i c h i s a h e a v i l y s e g r e g a t i n g e l e m e n t . T h e s e g r e g a t i o n r a t i o , a s d e f i n e d h e r e , d o e s n o t r e p r e s e n t t h e t r u e i n t e r d e n d r i t i c m i c r o s e g r e g a t i o n b e c a u s e t h e a l l o y i n c o n s i d e r a t i o n h a s a d u p l e x s t r u c t u r e w i t h d e l t a f e r r i t e f o r m i n g i n t e r d e n d r i t i c a l 1 y d u r i n g s o l i d i f i c a t i o n . p r o c e s s . T h r e e s t a g e s o f s o l i d i f i c a t i o n i n 1 8 - 8 s t a i n l e s s s t e e l s h a v e b e e n r e p o r t e d . ^ T h e f i r s t p r e c i p i t a t i o n o f d e l t a f e r r i t e i s i n t e r r u p t e d b y t h e p r e c i p i t a t i o n o f a u s t e n i t e a n d a t t h e e n d o f s o l i d i f i c a t i o n t h e r e i s a t r a n s i t i o n b a c k t o p r e c i p i t a t i o n o f d e l t a f e r r i t e . A u s t e n i t e g r o w s i n t o a n d c o n s u m e s m o s t o f t h e d e n d r i t e s w h i c h f o r m i n i t i a l l y a s f e r r i t e a n d t h e n a t t h e e n d o f s o l i d i f i c a t i o n f e r r i t e i s p r e c i p i t a t e d f r o m t h e r e s i d u a l m e l t i n t h e i n t e r - d e n d r i t i c a r e a s . S o t h e s e g r e g a t i o n v a l u e d e t e r m i n e d h e r e i n - c l u d e s t h e p a r t i o n i n g o f a l l o y i n g e l e m e n t s b e t w e e n t h e a u s t e n i t e a n d f e r r i t e p h a s e s a n d h e n c e d o e s n o t p r e s e n t a t r u e p i c t u r e o f m i c r o s e g r e g a t i o n d u e t o s o l i d i f i c a t i o n d i r e c t l y f r o m t h e l i q u i d . F r o m t h e l i n e s c a n s i t c a n b e s e e n t h a t a n e n r i c h m e n t o f n i c k e l s h o w s a c o r r e s p o n d i n g d e p l e t i o n o f c h r o m i u m a s o n e w o u l d e x p e c t i n t h e a u s t e n i t e p h a s e . I n t h e f e r r i t e p h a s e a n o p p o s i t e e f f e c t 39 i s n o t i c e d . T h e r e f o r e , t h e s e g r e g a t i o n r a t i o s h o u l d be d e t e r - m i n e d f r o m t h e s e g r e g a t i o n o c c u r r i n g w i t h i n a u s t e n i t e o r f e r r i t e . 4 . 3 . 5 C o m p o s i t i o n A n a l y s i s a n d M a c r o s e g r e g a t i o n T o p t o b o t t o m a n d s i d e t o s i d e c o m p o s i t i o n a n a l y s i s o f t h e E S C v a l v e s a n d t h e c o n v e n t i o n a l c a s t i n g w a s c a r r i e d o u t u s i n g o p t i c a l e m i s s i o n s p e c t r o g r a p h , T a b l e s V - X s h o w t h e a v e r a g e c o m p o s i t i o n o f d i f f e r e n t r e g i o n s o f t h e c a s t i n g s a l o n g w i t h t h e e l e c t r o d e c o m p o s i t i o n f o r c o m p a r i s o n . I t c a n b e s e e n t h a t t h e r e i s a n e g l i g i b l e c o m p o s i t i o n d i f f e r e n c e b e t w e e n t h e e l e c t r o d e a n d t h e c a s t i n g . T h e a d v a n t a g e o f E S R f o r a s - c a s t m a t e r i a l i s t h e r a t h e r s m a l l p o o l v o l u m e w h i c h a p p r o x i m a t e l y g i v e s t h e s a m e s o l i d i f i c a - t i o n c o n d i t i o n s a t t h e c e n t r e a n d s u r f a c e i n t h e s e r e l a t i v e l y s m a l l s e c t i o n s . T h i s r e s u l t s i n l o w r a d i a l m a c r o s e g r e g a t i o n . H o w e v e r , l o n g i t u d i n a l s e g r e g a t i o n m i g h t o c c u r b e c a u s e o f t h e c h a n g e i n t h e s l a g c o m p o s i t i o n a n d o x y g e n p o t e n t i a l d u r i n g t h e m e l t i n g o p e r a t i o n . ^ 1 G e n e r a l l y t h i s i s a l s o s m a l l . - M a c r o s e g r e g a t i o n i n t h e E S C v a l v e s a n d t h e c o n v e n t i o n a l c a s t i n g w a s d e t e r m i n e d b y t h e c o m p o s i t i o n a n a l y s i s m e n t i o n e d a b o v e . T h e r e s u l t s w i t h r e s p e c t t o t o p t o b o t t o m a n d s i d e t o s i d e c o m p o s i t i o n v a r i a t i o n o f c h r o m i u m , n i c k e l , m o l y b d e n u m , a n d c a r b o n a r e g i v e n i n F i g u r e s 3 1 - 3 6 . No d e f i n i t e m a c r o - s e g r e g a t i o n t r e n d i s o b s e r v e d i n t h e c a s t i n g s a n d i t h e 40 v a r i a t i o n o f e l e m e n t s i s v e r y s m a l l . T h e o n l y p o i n t w h i c h c a n b e n o t i c e d i s t h a t w h e r e v e r t h e r e i s a p o s i t i v e d e v i a t i o n o f c h r o m i u m f r o m t h e m e a n c o n t e n t , t h e r e i s a c o r r e s p o n d i n g n e g a - t i v e d e v i a t i o n o f n i c k e l f r o m t h e m e a n c o n t e n t a n d v i c e v e r s a . F r o m t h e v a r i a t i o n o f c h r o m i u m i n V a l v e N o . 7 ( s e e F i g u r e 3 3 ) i t c a n b e s e e n t h a t c o m p o s i t i o n u n i f o r m i t y c a n e a s i l y b e o b t a i n e d b y c o n t r o l l e d a d d i t i o n o f c h r o m i u m d u r i n g t h e m e l t i n g o p e r a t i o n . H o w e v e r , a r e a s o n a b l e v a r i a t i o n i n c o m p o s i t i o n w i t h r e s p e c t t o c h r o m i u m a n d m o l y b d e n u m w a s o b s e r v e d i n V a l v e N o . 1 0 . I n t h i s v a l v e f e r r o - c h r o m e a n d f e r r o - m o l y b d e n u m p o w d e r w a s a d d e d d u r i n g t h e m e l t ( s e e F i g u r e 3 5 ) . T h e v a r i a t i o n i s d u e t o t h e i n a d e q u a t e f e e d i n g m e c h a n i s m w h i c h r e s u l t e d i n u n s t a b l e f e e d i n g o f t h e p o w d e r s . Two m a g n e t i c v i b r a t o r f e e d e r s s e t a t a p r e d e t e r m i n e d f e e d i n g r a t e w e r e u s e d . A f u n n e l w i t h a l o n g t u b e w a s u s e d t o f e e d t h e p o w d e r s . f r o m t h e v n b r a t o r s t o t h e E S C m o l d . D u r i n g t h e m e l t i n g o p e r a t i o n i t w a s n o t i c e d t h a t t h e f u n n e l w a s s m a l l t o h a n d l e t h e v o l u m e f l o w a n d t h e p o w d e r w a s f r e q u e n t l y j a m m e d i n t h e f u n n e l a n d h a d t o b e d i s l o d g e d m a n u a l l y . T h i s l e d t o a n u n e v e n f e e d i n g r a t e a n d p r o b a b l y r e s u l t e d i n s u d d e n a d d i t i o n s o f l a r g e q u a n t i t i e s o f t h e p o w d e r s . T h i s n o t o n l y r e s u l t e d i n a c o m p o s i t i o n v a r i a - t i o n b u t a l s o a g g l o m e r a t e d i n t o c l u s t e r s o f p o w d e r s w h i c h c o u l d n o t m e l t c o m p l e t e l y a n d a p p e a r e d a s l a r g e i n c l u s i o n s i n p o c k e t s i n t h e s o l i d c a s t i n g . T h e l a t t e r p o i n t i s d i s c u s s e d 41 i n d e t a i l l a t e r i n s e c t i o n 4 . 3 . 6 . T h e u s e o f a b e t t e r f e e d i n g a r r a n g e m e n t w o u l d e a s i l y o v e r - c o m e t h i s p r o b l e m a n d a s o u n d c a s t i n g w i t h u n i f o r m c o m p o s i t i o n c a n be p r o d u c e d ( a s i n V a l v e N o . 7 w i t h t h e a d d i t i o n o f c h r o m i u m c h i p s ) . I t i s f i r m l y b e l i e v e d t h a t c o n v e r t i n g o f A I S I 3 1 6 c o m p o s i t i o n t o A C I C F - 8 M c o m p o s i t i o n b y a d d i t i o n o f c h r o m i u m a n d m o l y b d e n u m w i l l n o t p r e s e n t a n y i n s u p e r a b l e p r o d u c t i o n p r o b - l e m s . 4 . 3 . 6 P r o b l e m s W i t h A l l o y i n g D u r i n g t h e E S C O p e r a t i o n A s o u t l i n e d a b o v e c o n t r o l l e d a d d i t i o n o f c h r o m i u m a n d m o l y - b d e n u m w a s m a d e d u r i n g t h e e l e c t r o s l a g c a s t i n g o p e r a t i o n o f V a l v e N o s . 7 a n d 1 0 . C h r o m i u m c h i p s w e r e a d d e d i n V a l v e N o . 7 w h i l e f e r r o - c h r o m e a n d f e r r o - m o l y b d e n u m w e r e a d d e d i n V a l v e N o . 1 0 . A l t h o u g h a s o u n d , s o l i d c a s t i n g w i t h u n i f o r m c o m p o s i t i o n c o u l d b e m a d e w i t h t h e a d d i t i o n o f c h r o m i u m c h i p s , t h e s a m e c o u l d n o t b e a c h i e v e d w i t h f e r r o - c h r o m e a n d f e r r o - m o l y b d e n u m a d d i t i o n s . I n t h e m a c r o s t r u c t u r e o f V a l v e N o . 1 0 ( F i g u r e 1 8 ) , l a r g e i n c l u s i o n s c a n b e s e e n a n d t h e s e h a v e b e e n m a r k e d o n t h e p h o t o g r a p h f o r e a s y i d e n t i f i c a t i o n . O b s e r v i n g t h e s e a r e a s u n d e r t h e S c a n n i n g E l e c t r o n M i c r o s c o p e ( S E M ) i t b e c a m e o b v i o u s t h a t t h e y w e r e c l u s t e r s o f t h e f e r r o a l l o y p o w d e r . T h e S E M p h o t o g r a p h s o f a r e a s 1 a n d 2 a t d i f f e r e n t m a g n i f i c a t i o n s a r e s h o w n i n F i g u r e s 37. (a-d) a n d 3 8 ( a - d ) . F r o m t h e s e i t c a n b e s e e n t h a t t h e f e r r o a l l o y p o w d e r d i d n o t m e l t c o m p l e t e l y b u t i n s t e a d 42 w e r e l o o s e l y s i n t e r e d t o g e t h e r f o r m i n g ' s m a l l p o c k e t s ' i n t h e c a s t m a t e r i a l . T h e p o w d e r s e e m s t o h a v e b e e n p a r t i a l l y m o l t e n a s a d e n d r i t i c s t r u c t u r e c a n be o b s e r v e d a t 2 0 0 0 X m a g n i f i c a t i o n i n F i g u r e 3 8 ( d ) . To i d e n t i f y w h e t h e r i t i s F e - C r ' o r F e - M o p o w - d e r , t h e a r e a s s h o w n w e r e a n a l y s e d w i t h . E n e r g y D i s p e r s i v e X - r a y A n a l y s e r ( E D X A ) . T h e r e s u l t s o f E D X A o n t h e ' p a r e n t m e t a l ' a n d a r e a s 1 a n d 2 a r e s h o w n i n F i g u r e 3 9 . A r e a s 1 a n d 2 b o t h s h o w v e r y d i s t i n c t p e a k s f o r Mo a n d C r . A l t h o u g h t h e ' p a r e n t m e t a l ' s h o w s b o t h C r a n d Mo p e a k s , t h e y a r e n o t a s p r o - n o u n c e d a s t h e o n e s f r o m a r e a s 1 a n d 2 . F r o m t h i s i t i s o b v i o u s t h a t a r e a s 1 a n d 2 a r e m u c h r i c h e r i n C r a n d Mo t h a n t h e p a r e n t m e t a l . To d e t e r m i n e w h e t h e r t h e m a t e r i a l i n t h e ' p o c k e t s ' i s F e - C r o r F e - M o p o w d e r , t h e n o n - m e t a l l i c i n c l u s i o n s p r e s e n t i n a r e a s 1 a n d 2 a n d a l s o i n t h e o r i g i n a l F e - C r a n d F e - M o p o w d e r w e r e a n a l y s e d i n t h e S E M . T h e E D X A g r a p h s f o r t h e i n c l u s i o n s p r e s e n t i n a r e a 1 a n d 2 , i n F e - C r p o w d e r a n d i n F e - M o p o w d e r a r e s h o w n i n F i g u r e 4 0 . F r o m t h e s e i t c a n be s e e n t h a t t h e c o m p o s i t i o n o f i n c l u s i o n s p r e s e n t i n a r e a s 1 a n d 2 i s v e r y s i m i l a r t o t h e o n e s p r e s e n t i n F e - C r p o w d e r . T h e i n c l u s i o n s i n F e - M o a r e o f c o m p l e t e l y d i f f e r e n t c o m p o s i t i o n . T h i s c o u l d b e e x p e c t e d a s F e - C r a n d F e - M o a r e p r o d u c e d b y t w o e n t i r e l y d i f - f e r e n t p r o c e s s e s . F e - C r i s p r o d u c e d g e n e r a l l y i n a n e l e c t r i c - a r c f u r n a c e w i t h b a s i c d o l o m i t e l i n i n g a n d h e n c e t h e i n c l u s i o n s c o n t a i n C a a n d M g . F e - M o , on t h e o t h e r h a n d i s p r o d u c e d b y 4 3 a l u m i n o t h e r m i c r e d u c t i o n p r o c e s s a n d h e n c e t h e i n c l u s i o n m o r p h o l o g y a n d c o m p o s i t i o n i s c o m p l e t e l y d i f f e r e n t . T h i s s h o w s t h a t t h e m a t e r i a l p r e s e n t i n t h e p o c k e t s b a s i c a l l y c o n s i s t s o f F e - C r p o w d e r . . T o c o n f i r m t h i s b y a n o t h e r m e t h o d , a r e a s 1 a n d 2 w e r e a n a l y s e d i n t h e e l e c t r o n m i c r o p r o b e . T h e r e s u l t s o b t a i n e d f o r C r a n d Mo a r e s h o w n i n T a b l e X I . T h e C r a n d Mo c o n t e n t s o f t h e p a r e n t m e t a l a r e a l s o g i v e n f o r c o m p a r i s o n . I n i t i a l l y , t h e f e r r o - c h r o m e p o w d e r h a d a b o u t 70% C r a n d t h e f e r r o - m o l y b d e n u m p o w d e r h a d a b o u t 6 5 % M o . T h e r e s u l t s s h o w t h a t a r e a s 1 a n d 2 h a v e a b o u t 54% C r a n d 13% M o . F r o m t h i s i t i s c e r t a i n t h a t a r e a s 1 a n d 2 c o n t a i n m u c h m o r e C r t h a n Mo a n d t h a t i t i s , t h e f e r r o - c h r o m e p o w d e r w h i c h d i d n o t m e l t c o m p l e t e l y a n d f o r m e d p o c k e t s i n t h e v a l v e c a s t i n g . One w o u l d n o r m a l l y e x p e c t t h a t F e - M o w o u l d n o t g o i n s o l u - t i o n a s c o m p a r e d t o F e - C r b e c a u s e o f i t s h i g h e r m e l t i n g p o i n t ( m . p . o f 6 5 % F e - M o = 1 9 0 0 ° C , m . p . o f 70% F e - C r = 1 6 5 0 ° C ) a n d a l s o b e c a u s e i t i s h e a v i e r . S o t h e q u e s t i o n a s t o w h y F e - C r p o w d e r d i d n o t m e l t a n d f o r m e d a g g l o m e r a t e s i n p r e f e r e n c e t o 4 4 F e - M o c a n o n l y b e a n s w e r e d b y t h e f a c t t h a t t h e p a r t i c l e s i z e o f t h e F e - C r p o w d e r u s e d w a s l a r g e r t h a n F e - M o p o w d e r a n d a l s o t h a t t h e f e e d i n g r a t e w a s m u c h h i g h e r f o r F e - C r t h a n f o r F e - M o . ' ( 3 0 . 5.-. g m s / m i n . v s . 4 . 5 g m s / m i n ) . T h e s e i n c l u s i o n s o c c u r - r e d b e c a u s e o f t h e u n s t a b l e f e e d i n g o f t h e p o w d e r s a s d e s c r i b e d e a r l i e r i n S e c t i o n 4 . 3 . 5 . 4 . 3 . 7 P r o b l e m s W i t h U s i n g C a s t E l e c t r o d e s i n E S C O p e r a t i o n T o w a r d s t h e e n d o f t h e m e l t i n g o p e r a t i o n o f V a l v e N o . 5 , t h e r e w a s a m i n o r e x p l o s i o n i n s i d e t h e m o l d . T h e m e l t i n g w a s i m m e d i a t e l y t e r m i n a t e d a s a l e a k i n t h e w a t e r - c o o l e d m o l d c o u l d h a v e c a u s e d t h i s e f f e c t . A f t e r r e m o v i n g t h e c a s t i n g t h e m o l d s u r f a c e s w e r e c l e a n e d a n d i n s p e c t e d f o r l e a k s . H o w - e v e r , n o t r a c e o f a n y l e a k s w e r e f o u n d . A n o t h e r s o u r c e o f t h e e x p l o s i o n c o u l d h a v e b e e n a m a c r o p o r o s i t y i n t h e e l e c - t r o d e . T h e r e f o r e t h e e l e c t r o d e w a s s e c t i o n e d n e a r t h e t i p a n d i n d e e d t h e r e w a s a p o r o s i t y p r o b a b l y d u e t o s e c o n d a r y p i p i n g i n t h e c a s t e l e c t r o d e ( s e e F i g u r e 4 1 ) . When t h e p o r o s i t y w a s e x p o s e d , t h e e n t r a p p e d p r e s s u r i s e d g a s e s m u s t h a v e b e e n r e l e a s e d u n d e r t h e s l a g l a y e r c a u s i n g t h e e x p l o - s i o n . A l t h o u g h t h i s d o e s n o t p r e s e n t a t h r e a t t o t h e s a f e t y o f t h e E S R o p e r a t i o n , h o w e v e r , i t d o e s c a u s e c e r t a i n i n - s t a b i l i t i e s i n t h e m e l t i n g p r o c e s s a n d s h o u l d b e a v o i d e d . A n o t h e r p r o b l e m w h i c h i s m u c h m o r e s e r i o u s w a s e n c o u n t e r e d 45 w h e n a c a s t e l e c t r o d e w a s u s e d . A f t e r s e c t i o n i n g a n d m a c r o - e t c h i n g V a l v e N o . 9 , a n u n u s u a l p o o l p r o f i l e w a s n o t i c e d i n t h e t o p r i g h t p a r t a n d a l s o a f o r e i g n b o d y h a v i n g a d i f f e r e n t s t r u - c t u r e w a s o b s e r v e d i n t h e c e n t r e o f t h e c a s t i n g ( s e e F i g u r e 1 7 ) . T a k i n g t h e l a t t e r p o i n t i n t o c o n s i d e r a t i o n , i t i s t h o u g h t t h a t a f o r e i g n b o d y ( p o s s i b l y a n e l e c t r o d e p i e c e ) h a d d r o p p e d i n t o t h e l i q u i d m e t a l p o o l d u r i n g t h e m e l t i n g o p e r a t i o n . To c o n f i r m t h i s s p e c u l a t i o n a p i e c e w a s c u t f r o m t h i s a r e a a n d r e p o l i s h e d a n d e t c h e d t o r e v e a l t h e s t r u c t u r e . T h i s s t r u c t u r e i s s h o w n i n F i g u r e 4 2 . I t c a n b e s e e n f r o m t h i s p h o t o g r a p h t h a t t h e s t r u c t u r e o f t h e e l e c t r o d e p i e c e i s e n t i r e l y d i f f e r e n t t o t h e p a r e n t c a s t i n g . T h e e l e c t r o d e p i e c e i s c o m p o s e d o f r e - c r y s t a l l i s e d p o l y g o n a l g r a i n s w h i l e t h e ' p a r e n t c a s t i n g ' h a s t h e n o r m a l d e n d r i t i c s t r u c t u r e . A l t h o u g h t h e c a s t e l e c t r o d e h a s a c o a r s e d e n d r i t i c s t r u c t u r e ( s e e F i g u r e 4 3 ) , t h e t h e r m a l c y c l e w h i c h t h i s e l e c t r o d e p i e c e w e n t t h r o u g h i s e n o u g h t o c o n v e r t t h e d e n d r i t i c s t r u c t u r e i n t o p o l y g o n a l g r a i n s . T h e c o m p o s i t i o n o f t h e e l e c t r o d e i s m o r e o r l e s s s i m i l a r t o t h e c a s t i n g a n d t h e r e f o r e c h e m i s t r y a l o n e c a n n o t d i s t i n g u i s h b e t w e e n t h e e l e c t r o d e p i e c e a n d t h e c a s t i n g . H o w e v e r a s t h e e l e c t r o d e w a s c a s t b y a c o n v e n t i o n a l m e t h o d , t h e m o r p h o l o g y o f n o n - m e t a l l i c i n c l u s i o n s i n t h e e l e c t r o d e p i e c e w o u l d b e m u c h d i f f e r e n t t h a n t h e p a r e n t e l e c t r o s l a g c a s t i n g b u t s i m i l a r t o t h e o n e s p r e s e n t i n t h e e l e c t r o d e , p a r t i c u l a r l y a t t h e e l e c t - r o d e t i p . 46 S o t h e i n c l u s i o n s f r o m t h r e e a r e a s ( e l e c t r o d e p i e c e , p a r e n t c a s t i n g , a n d t h e e l e c t r o d e t i p ) w e r e e x a m i n e d i n a n o p t i c a l m i c r o s c o p e a n d t h e S E M . F i g u r e 4 4 s h o w s t h e i n c l u s i o n s f r o m t h e e l e c t r o d e p i e c e a n d t h e e l e c t r o d e t i p a s o b s e r v e d t h r o u g h o p t i c a l m i c r o s c o p e . A l l t h e i n c l u s i o n s h a v e a c o m p o s i t e ( m u l t i - p h a s e ) a n d s i m i l a r m o r p h o l o g y a l t h o u g h t h e a v e r a g e s i z e o f t h e i n c l u s i o n s f r o m t h e e l e c t r o d e t i p i s l a r g e r . T h e t h r e e a r e a s m e n t i o n e d a b o v e w e r e a l s o e x a m i n e d u n d e r t h e SEM a n d t h e c o m p o s i t i o n o f t h e i n c l u s i o n s w a s d e t e r m i n e d b y E D X A . T h e k i n d o f i n c l u s i o n s f o u n d i n t h e e l e c t r o d e p i e c e , t h e e l e c t r o d e t i p a n d t h e p a r e n t c a s t i n g a r e g i v e n i n F i g u r e 4 5 . : . • T h e c o r r e s p o n d i n g c o m p o s i t i o n s a r e g i v e n i n F i g u r e 4 6 . T h e f o l - l o w i n g c a n b e d e d u c e d f r o m t h e s e f i g u r e s - a ) T h e t y p e o f i n c l u s i o n s o b s e r v e d f r o m t h e e l e c t r o d e p i e c e a n d t h e e l e c t r o d e t i p a r e v e r y m u c h a l i k e e x c e p t t h a t t h e y a r e b i g g e r i n t h e l a t t e r . b ) T h e s h a p e o f t h e i n c l u s i o n s o b s e r v e d i n t h e p a r e n t c a s t i n g i s e n t i r e l y d i f f e r e n t a n d t h e s i z e i s m u c h s m a l l e r . A l s o t h e y a p p e a r t o h a v e n u c l e a t e d a n d g r o w n i n t h e i n t e r d e n d r i - t i c r e g i o n b e c a u s e t h e y i n t e r s e c t d e l t a f e r r i t e w h i c h f o r m s i n t e r d e n d r i t i c a l 1 y . c ) H o w e v e r , t h e p o i n t w h i c h c o n f i r m s t h a t i t i s a c t u a l l y a p i e c e o f e l e c t r o d e s i t t i n g i n t h e m i d d l e o f t h e v a l v e c a s t i n g i s t h e c o m p o s i t i o n o f t h e s e i n c l u s i o n s . F i g u r e 4 6 47 s h o w s t h a t b o t h t h e e l e c t r o d e p i e c e a n d t h e e l e c t r o d e t i p h a v e i n c l u s i o n s w h i c h a r e s i g n i f i c a n t l y r i c h i n s i l i c o n a n d m a n g a n e s e . I n f a c t t h e i r o v e r a l l c o m p o s i t i o n i s v e r y s i m i l a r . T h e c o m p o s i - t i o n o f t h e i n c l u s i o n s f r o m t h e p a r e n t c a s t i n g , o n t h e o t h e r h a n d , i s e n t i r e l y d i f f e r e n t . T h e y a r e b a s i c a l l y a l u m i n a - t y p e i n c l u s i o n s ; S i l i c o n i s c o m p l e t e l y a b s e n t . A l l t h e s e p o i n t s c o n f i r m t h e s p e c u l a t i o n t h a t t h e f o r e i g n b o d y o b s e r v e d i n t h e e l e c t r o s l a g c a s t i n g i s a c t u a l l y a p i e c e w h i c h h a s d r o p p e d f r o m t h e e l e c t r o d e d u r i n g t h e m e l t i n g o p e r a - t i o n . T h e p e c u l i a r p o o l p r o f i l e o b s e r v e d i n t h e c a s t i n g i s t h o u g h t t o b e a n e v e n t w h i c h o c c u r r e d a s a r e s u l t o f t h e f a l l e n e l e c t r o d e p i e c e . T h e p r o b a b l e e v e n t s w h i c h t o o k p l a c e b e f o r e a n d a f t e r t h e d r o p p i n g o f t h e l e c t r o d e p i e c e a r e s h o w n s c h e m a t i c a l l y i n F i g u r e 4 -7 . (a - . c . ) . T h e e l e c t r o d e w a s n o t i n t h e c e n t r e o f t h e m o l d d u r i n g t h e m e l t i n g p r o c e s s a n d t h i s r e s u l t e d i n a n a s y m m e t r i c p o o r p r o f i l e a s s h o w n i n F i g u r e 4 7 ( 4 ) . A s y m m e t r i c p o o l p r o f i l e s a r e common i f t h e e l e c t r o d e i s o f f - c e n t r e . T h i s w a s a l s o o b - s e r v e d i n a n o t h e r v a l v e c a s t i n g i n A I S I 4 3 4 0 s t e e l ( s e e F i g u r e 5 9 ) . A t s u c h a t i m e a p i e c e f r o m t h e e l e c t r o d e f e l l o f f . T h i s i s a p p a r e n t l y q u i t e common w i t h c a s t e l e c t r o d e s . T h e c a s t e l e c t - r o d e s i n v a r i a b l y h a v e a c e n t r e p o r o s i t y ( p e r h a p s r e p r e s e n t i n g s e c o n d a r y p i p i n g ) a n d t h i s m i g h t h a v e r e s u l t e d i n a p i e c e o f e l e c t r o d e b e i n g d e t a c h e d d u e t o m e l t i n g b y t h e s l a g e n t e r i n g 48 t h e p o r o s i t y . A f t e r t h i s p i e c e o f e l e c t r o d e f e l l o f f , t h e h i g h t e m p e r a t u r e z o n e w a s s h i f t e d m o r e t o w a r d s t h e c e n t r e ( s e e F i g u r e 4 7 ( b ) . A s a r e s u l t o f t h i s t h e l i q u i d m e t a l p o o l o n t h e r i g h t s i d e w a s s u d d e n l y c o o l e d a n d t h e l i q u i d u s a n d s o l i d u s a d v a n c e d r a p i d l y . T h e o r i e n t e d d e n d r i t i c g r o w t h w a s c u t o f f a n d t h e l i q u i d p o o l s o l i d i f i e d w i t h a f i n e a n d r a n d o m l y o r i e n t e d d e n - d r i t i c s t r u c t u r e . T h e p o o l p r o f i l e w a s s h i f t e d t o t h e l e f t a n d i t m a d e l i t t l e o r no " d i f f e r e n c e t o t h e l i q u i d u s a n d s o l i - d u s o n t h e l e f t s i d e ( s e e F i g u r e 4 7 ( c ) ) . T h e a f f e c t e d p o o l p r o - f i l e a r e a i s s h o w n i n F i g u r e 4 8 . One c a n n o t i c e t h a t t h e o r i e n t e d d e n d r i t i c c r y s t a l s h a v e s t o p p e d g r o w i n g a n d t h e r e i s a b a n d o f u n r e s o l v e d s t r u c t u r e w h i c h r e p r e s e n t s t h e s o l i d i - f i c a t i o n f r o n t p o s i t i o n c h a n g e t h r o u g h t h e e v e n t . A b o v e t h i s , a f i n e a n d r a n d o m d e n d r i t i c s t r u c t u r e i s o b s e r v e d . I t h a s b e e n 72 p o i n t e d o u t b y J a c k s o n a n d M i t c h e l l t h a t t h e r e i s a s t r u c - t u r e r e f i n e m e n t d u e t o t h e s u d d e n i n c r e a s e i n g r o w t h r a t e a n d c h a n g e s i n p r i m a r y d i r e c t i o n d u e t o t h e c h a n g e i n t h e h e a t f l o w p a t t e r n . M e t a l s w i t h l o w a n i s o t r o p y o f g r o w t h d i r e c t i o n ( e . g . 3 0 0 s e r i e s s t a i n l e s s s t e e l s ) w i l l r e n u c l e a t e i n t h e new h e a t - f l o w d i r e c t i o n i m m e d i a t e l y a f t e r t h e c h a n g e i n h e a t f l o w . C o m - p o s i t i o n c h a n g e s d u e t o s u d d e n g r o w t h r a t e o c c u r o n l y i n t h e c a s e o f e l e m e n t s h a v i n g s m a l l s e g r e g a t i o n c o e f f i c i e n t s ( e . g . C , S , P a n d 0 ) . H o w e v e r t h e s e g r e g a t i o n o f t h e s e e l e m e n t s w o u l d b e d i f f i c u l t t o d e t e c t i n C F - 8 M a s t h e y a r e p r e s e n t i n v e r y s m a l l q u a n t i t i e s . I t w o u l d b e w o r t h w h i l e t o m e n t i o n h e r e t h a t t h e p r e s e n c e 49 o f t h e e l e c t r o d e p i e c e i n s i d e t h e v a l v e c a s t i n g w o u l d n o t b e d e t e c t e d b y t h e NDT t e s t s ( e . g . R a d i o g r a p h y a n d U l t r a s o n i c t e s t ) , w h i c h a r e g e n e r a l l y u s e d t o q u a l i f y t h e v a l v e c a s t i n g s f o r n u c l e a r a p p l i c a t i o n s . I n f a c t s u c h a n e l e c t r o d e p i e c e w o u l d be r e m o v e d w h e n t h e v a l v e i s m a c h i n e d , b u t e v e n i f i t i s p r e s e n t i t w o u l d n o t b e d e t r i m e n t a l t o t h e p r o p e r t i e s o f t h e v a l v e . H o w - e v e r i f s u c h a ' d e f e c t ' o c c u r s i n a c o m p o n e n t w h i c h w o u l d b e s u b j e c t e d t o f a t i g u e s t r e s s i n g ( e . g . a l a n d i n g g e a r o f a n a i r - c r a f t ) , i t m i g h t b e a p o t e n t i a l s i t e f o r t h e n u c l e a t i o n o f a f a t i g u e c r a c k a s t h e f a t i g u e p r o p e r t i e s o f t h e e l e c t r o d e p i e c e a n d t h e p a r e n t c a s t i n g w o u l d b e v e r y d i f f e r e n t . 4 . 4 M e c h a n i c a l P r o p e r t i e s 4 . 4 . 1 T e n s i l e T e s t i n g T e n s i l e t e s t s w e r e c a r r i e d o u t o n s a m p l e s f r o m t h e E S C v a l v e s a n d t h e c o n v e n t i o n a l c a s t i n g . T h e t e s t s c o n f o r m e d t o t h e A S T M s t a n d a r d s ( A S T M A 3 7 0 - 3 7 6 ) . T h e s a m p l e s w e r e 0 . 2 5 " i n g a u g e d i a m e t e r ( s e e F i g u r e 4 9 ) a n d t h e y w e r e t e s t e d i n t h e s o l u t i o n - t r e a t e d c o n d i t i o n ( g i v e n b e f o r e i n s e c t i o n 4 . 3 . 2 ) . T e s t s w e r e c a r r i e d o u t b o t h i n t h e l o n g i t u d i n a l a n d t h e t r a n s - v e r s e d i r e c t i o n s . T h e r e s u l t s o f t h e s e t e s t s f o r V a l v e N o s . 5 , 6 a n d 7 a r e g i v e n i n T a b l e X I I w h i l e t h o s e f o r V a l v e N o . 9 a n d t h e c o n v e n t i o n a l c a s t i n g a r e g i v e n i n T a b l e X I I I . T h e t e n s i l e r e q u i r e m e n t s f o r f e r r i t i c a n d a u s t e n i t i c s t e e l c a s t i n g s ( A S M E S A - 3 5 1 / A S T M A 3 5 1 - 7 2 f o r C F - 8 M ) a n d f o r f o r g e d o r r o l l e d a l l o y 50 s t e e l v a l v e s e t c . f o r h i g h t e m p e r a t u r e s e r v i c e ( A S M E S A - 1 8 2 / A S T M A 1 8 2 - 7 4 f o r 3 1 6 ) a r e a l s o g i v e n i n T a b l e X I I I . T h e c o m - p l e t e s p e c i f i c a t i o n s a r e g i v e n i n A p p e n d i x 1 . F r o m t h e r e s u l t s g i v e n i n t h e s e t a b l e s , i t c a n b e s e e n t h a t a l l t h e E S C v a l v e s e x c e p t f o r t h e 3 1 6 v a l v e ( V a l v e N o . 6 ) s a t i s f y t h e t e n s i l e r e q u i r e m e n t s o f A S M E a n d A S T M c o d e f o r f o r g - i n g s a n d c a s t i n g s f o r v a l v e b o d i e s a n d t h e i r p a r t s u s e d i n h i g h - t e m p e r a t u r e s e r v i c e . T h e 3 1 6 v a l v e f a l l s s h o r t b y a b o u t 2 0 0 0 p s i i n t e n s i l e s t r e n g t h . T h e f o l l o w i n g t w o p o i n t s s h o u l d b e n o t e d i n r e f e r e n c e t o t h i s - 1 ) T h e A S T M / A S M E s p e c i f i c a t i o n s f o r v a l v e b o d i e s a n d p a r t s m a d e o u t o f 3 1 6 s t a i n l e s s s t e e l a r e f o r r o l l e d o r f o r g e d c o n d i t i o n . H e n c e t h e s p e c i f i e d s t r e n g t h s a r e f o r a f i n e s i z e d a n d w o r k e d m a t e r i a l a n d n o t f o r a c a s t m a t e r i a l ( l o w i n d e l t a - f e r r i t e c o n t e n t ) . 2 ) T h e c a s t c o u n t e r p a r t o f t h e r o l l e d o r f o r g e d 3 1 6 i s C F - 8 M w h e r e t h e c o m p o s i t i o n h a s b e e n a l t e r e d t o g i v e a l a r g e a m o u n t o f d e l t a - f e r r i t e i n o r d e r t o i h c r e a s e t h e s t r e n g t h v a l u e s a n d t h u s c o m p e n s a t e f o r t h e l o s s i n s t r e n g t h d u e t o t h e n o n - w o r k e d c o n d i t i o n . T h e s e t w o p o i n t s a d e q u a t e l y e x p l a i n t h e l o w e r t e n s i l e s t r e n g t h o b s e r v e d i n t h e 3 1 6 E S C v a l v e . S o i t c a n b e c o n - c l u d e d t h a t t e n s i l e p r o p e r t i e s o f t h e E S C v a l v e s 1 i e w e l l w i t h i n t h e A S M E / A S T M s p e c i f i c a t i o n p r o v i d e d t h e c o m p o s i t i o n r e q u i r e - m e n t s a r e m e t . T h i s i s a l s o e v i d e n t i f we c o n s i d e r t h e 51 p r o p e r t i e s o f V a l v e N o . 7 w h e r e t h e c h r o m i u m c o n t e n t w a s i n - c r e a s e d f r o m t h e 3 1 6 s p e c i f i c a t i o n t o C F - 8 M s p e c i f i c a t i o n ( i . e . t h e d e l t a f e r r i t e c o n t e n t w a s i n c r e a s e d ) . T h e t e n s i l e p r o p e r t i e s o f t h e c o n v e n t i o n a l c a s t i n g a r e a l s o w i t h i n t h e s p e c i f i c a t i o n s . I f t h e r e s u l t s o f V a l v e N o . 9 ( C F - 8 M ) a n d t h e c o n v e n t i o n a l C F - 8 M c a s t i n g a r e c o m p a r e d , i t c a n b e s e e n t h a t o n a v e r a g e t h e t e n s i l e s t r e n g t h o f t h e l a t t e r i s h i g h e r b y a b o u t 20QO p s i w h i l e t h e y i e l d s t r e n g t h i s h i g h e r b y a b o u t 4 0 0 0 p s i . T h i s c a n b e d u e t o t w o t h i n g s . F i r s t l y t h e d e l t a - f e r r i t e c o n t e n t o f t h e c o n v e n t i o n a l c a s t i n g i s h i g h e r t h a n E S C v a l v e N o . 9 b y a b o u t 24% a n d s e c o n d l y t h e g r a i n s i z e o f t h e c o n v e n t i o n a l c a s t i n g i s s m a l l e r . T h e l a t t e r p o i n t a c - c o u n t s f o r t h e h i g h e r y i e l d s t r e n g t h . On t h e o t h e r h a n d t h e d u c t i l i t y ( a s d e m o n s t r a t e d b y p e r c e n t e l o n g a t i o n a n d p e r c e n t r e d u c t i o n i n a r e a ) o f t h e c o n v e n t i o n a l c a s t i n g i s s i g n i f i - c a n t l y l o w e r t h a n t h e E S C V a l v e N o . 9 a n d a l t h o u g h p a r t o f t h i s c a n b e d u e t o t h e d i f f e r e n c e i n d e l t a f e r r i t e c o n t e n t , t h e r e s t c a n o n l y b e e x p l a i n e d b y t h e f a c t t h a t t h e e l e c t r o - s l a g c a s t i n g i s m u c h c l e a n e r ( w . r . t . n o n - m e t a l l i c i n c l u s i o n s ) , h a s l e s s m i c r o s e g r e g a t i o n a n d h a s a b e t t e r s o l i d i f i c a t i o n s t r u c t u r e . T h i s c a n a l s o b e s e e n b y c o n s i d e r i n g t h e p e r c e n t r e d u c t i o n i n a r e a w h i c h i s m o r e s e n s i t i v e t o n o n - m e t a l l i c i n - c l u s i o n c o n t e n t . T h e r e n s a s h a r p d e c r e a s e i n p e r c e n t r e d u c - t i o n i n a r e a f r o m t h e e d g e t o t h e c e n t r e o f t h e c o n v e n t i o n a l c a s t i n g w h i l e no s u c h d e c r e a s e i s o b s e r v e d i n t h e E S C V a l v e N o . 9 . 52 F r o m t h e t e n s i l e r e s u l t s i t a l s o b e c a m e e v i d e n t t h a t t h e d e l t a - f e r r i t e c o n t e n t o f t h e c a s t i n g s g r e a t l y i n f l u e n c e s t h e 7 3 p r o o f s t r e s s a n d t e n s i l e s t r e n g t h v a l u e s . I r v i n e e t a l . c o n - c l u d e t h a t d e l t a - f e r r i t e i n c r e a s e s t h e p r o o f s t r e s s a n d t e n - s i l e s t r e n g t h b y a d i s p e r s i o n s t r e n g t h e n i n g e f f e c t . T h e f e r - r i t e h a s a h i g h e r y i e l d s t r e s s t h a n t h e a u s t e n i t e a n d t h e s t r a i n c o n c e n t r a t i o n i n t h e s o f t e r a u s t e n i t e p h a s e c a u s e s i t t o w o r k h a r d e n t o a s t r a i n g r e a t e r t h a n t h e n o m i n a l 0 . 2 % , a n d t h e r e f o r e g i v e s a h i g h e r p r o o f s t r e s s v a l u e . I n t h e c a s e o f t h e t e n s i l e s t r e n g t h , a b o u t 80% o f t h e s t r e n g t h e n i n g d u e t o d e l t a - f e r r i t e i n c r e a s e s i s d u e t o p a r t i t i Q h i n g o f c a r b o n a n d n i t r o g e n t o t h e a u s t e n i t e , t h e r e b y i n c r e a s i n g t h e w o r k h a r d e n i n g r a t e . 6 2 B e c k , S c h o e f e r e t a l . c o n c l u d e d f r o m t h e r e s u l t s f r o m a b o u t 62 C F - 8 M a n d 2 7 7 C F - 8 h e a t s t h a t t h e t e n s i l e a n d y i e l d s t r e n g t h s a r e d i r e c t l y r e l a t e d t o t h e f e r r i t e c o n t e n t . F i g u r e 5 0 s h o w s t h e v a r i a t i o n o f l o n g i t u d i n a l t e n s i l e a n d y i e l d s t r e n g t h s w i t h f e r r i t e n u m b e r f o r t h e E S C v a l v e s . I t c a n b e s e e n t h a t t h e s t r e n g t h i s a d i r e c t f u n c t i o n o f t h e f e r r i t e c o n t e n t . H o w e v e r , d u c t i l i t y ( a s d e t e r - m i n e d b y p e r c e n t e l o n g a t i o n ) d o e s n o t s h o w a n y d e f i n i t e r e l a t i o n t o t h e f e r r i t e c o n t e n t . When t h e a v e r a g e t e n s i l e a n d y i e l d s t r e n g t h s o f t h e c o n v e n t i o n a l c a s t i n g a r e p l o t t e d o n t h e g r a p h , t h e f o r m e r l i e s a b o u t 1 0 0 0 p s i b e l o w t h e l i n e w h i l e t h e l a t t e r s h o w a p o s i t i v e d e v i a t i o n o f a b o u t 4 0 0 0 p s i f r o m t h e l i n e . T h i s h i g h e r v a l u e o f t h e y i e l d s t r e n g t h i s q u i t e s i g n i f i c a n t a n d c o u l d b e e x p l a i n e d b y t h e f a c t t h a t t h e c o n v e n t i o n a l c a s t i n g h a s a m u c h s m a l l e r g r a i n s i z e t h a n t h e 53 e l e c t r o s l a g c a s t i n g a n d t h i s r e s u l t s i n a h i g h e r y i e l d s t r e s s . T h i s i s a l s o o b v i o u s f r o m t h e f a c t t h a t t h e y i e l d s t r e n g t h o f t h e s a m p l e s f r o m t h e e d g e o f t h e c o n v e n t i o n a l c a s t i n g i s a b o u t : . 2 -1 .5% h i g h e r t h a n t h e s a m p l e s a w a y f r o m t h e e d g e . T h e f r a c t u r e d a n d d e f o r m e d a r e a s o f t h e 0 . 2 5 i n c h d i a m e t e r t e n s i l e s a m p l e s e x h i b i t e d t h e c h a r a c t e r i s t i c s o f a l a r g e g r a i n s i z e d m a t e r i a l ( s e e F i g u r e 5 1 ) . C o a r s e g r a i n m a t e r i a l s a p p r o a c h 6 4 m o r e c l o s e l y t h e b e h a v i o u r o f s i n g l e c r y s t a l s . To p r e s e n t a v a l i d r e s u l t , a s u f f i c i e n t n u m b e r o f g r a i n s i n t h e c r o s s s e c t i o n o f t h e s p e c i m e n a r e r e q u i r e d s o t h a t t h e r e l a t i v e l y f r e e g r a i n s n e a r t h e s u r f a c e a r e t o o f e w i n n u m b e r t o a f f e c t a p p r e c i a b l y t h e p r o p e r t i e s o f t h e w h o l e a g g r e g a t e o f g r a i n s . I n t h e c a s e o f t i n , P e l 1 - W a l p o l e 7 4 f o u n d t h a t t h e t e n s i l e s t r e n g t h o f r o l l e d m a t e r i a l i n c r e a s e s b y 6 0 - 1 0 0 % w i t h i n c r e a s e i n t h e n u m b e r o f g r a i n s f o r 1 t o 2 0 - 3 0 , a n d v e r y s l i g h t l y i n c r e a s e d b y f u r t h e r r e f i n e m e n t . He a l s o c o n c l u d e d t h a t i t i s t h e n u m b e r o f g r a i n s i n t h e c r o s s - s e c t i o n r a t h e r t h a n t h e a b s o l u t e g r a i n s i z e w h i c h c o n t r o l s t h e g r a i n s i z e / u l t i m a t e t e n s i l e s t r e n g t h r e l a t i o n s h i p . W o r k d o n e o n p o l y c r y s t a l 1 i n e a l u m i n u m a l s o s h o w s t h a t t h e c o a r s e g r a i n e d s p e c i m e n s w o r k h a r d e n s u b s t a n t i a l l y l e s s t h a n t h e f i n e r g r a i n e d s p e c i m e n t s , a l t h o u g h t h e g e n e r a l f o r m o f t h e s t r e s s - s t r a i n c u r v e s i s s i m i l a r , a n d t h e e f f e c t o f g r a i n s i z e o n t h e 75 e l a s t i c l i m i t i s p a r t i c u l a r l y m a r k e d . I t b e c a m e o b v i o u s , p a r t i c u l a r l y f r o m t h e 3 1 6 t e n s i l e 54 s a m p l e s , t h a t t h e g r a i n s i z e o f t h e E S C v a l v e s w a s l a r g e a n d t h e r e w e r e v e r y f e w g r a i n s i n t h e c r o s s - s e c t i o n o f 0 . 2 5 i n c h d i a m e t e r s a m p l e s . A s a r e s u l t t h e t e n s i l e p r o p e r t i e s o f t h e s m a l l s p e c i m e n s d i d n o t r e p r e s e n t t h e b u l k t e n s i l e p r o p e r t i e s . To o v e r c o m e t h i s p r o b l e m , i t w a s d e c i d e d t o t e s t l a r g e r s p e c i - m e n s . . L a r g e s i z e s p e c i m e n s w i t h a - g a u g e d i a m e t e r o f 1 i n c h a n d a g a u g e l e n g t h o f 4 i n c h e s ( s e e F i g u r e 4 9 ) „ w e r e m a c h i n e d f r o m V a l v e N o . 6 ( 3 1 6 ) a n d V a l v e N o . 9 ( C F - 8 M ) . T h e s e w e r e s o l u t i o n t r e a t e d ( i n t h e s a m e w a y a s m e n t i o n e d b e f o r e ) p r i o r t o t h e f i n a l m a c h i n i n g o p e r a t i o n a n d w e r e t e s t e d i n t h e MTS m a c h i n e . T h e s e s p e c i m e n s w e r e 16 t i m e s l a r g e r i n t h e c r o s s - s e c t i o n a l a r e a t h a n t h e s m a l l e r s p e c i m e n a n d t h e r e f o r e s h o u l d h a v e a b o u t 16 t i m e s m o r e g r a i n s i n t h e c r o s s s e c t i o n . T h e r e s u l t s o f t h e s e s p e c i m e n s a r e g i v e n i n T a b l e X I V . T h e d e - f o r m e d r e g i o n n e a r t h e f r a c t u r e d s u r f a c e s t i l l s h o w s t h e p r e - s e n c e o f l a r g e g r a i n s a n d t h e s l i p l i n e s o n t h e g r a i n s a r e c l e a r l y v i s i b l e . T h e f r a c t u r e d s u r f a c e s h o w s a n i r r e g u l a r o u t - l i n e . A c l o s e up o f o n e o f t h e b r o k e n t e n s i l e s a m p l e s i s s h o w n i n F i g u r e 5 2 . To m e a s u r e t h e p r o j e c t e d a r e a o f t h e f r a c t u r e d s u r f a c e , b o t h t h e e n d s o f t h e . s a m p l e w e r e p h o t o - g r a p h e d a n d t h e n t h e a r e a w a s m e a s u r e d by a p l a n i m e t e r . T h e a v e r a g e v a l u e o f b o t h t h e e n d s w a s t a k e n as. t h e f r a c t u r e d a r e a f o r t h a t s a m p l e . C o m p a r i s o n o f t h e t e n s i l e r e s u l t s o f t h e l a r g e a n d s m a l l s p e c i m e n s ( s e e T a b l e s X I I , X I I I a n d X I V ) s h o w s t h a t t h e y i e l d 5 5 a s w e l l a s t h e t e n s i l e s t r e n g t h o f t h e l a r g e r s p e c i m e n s w e r e l o w e r t h a n t h e s m a l l e r s p e c i m e n s f o r b o t h 3 1 6 a n d C F - 8 M . T h e p e r c e n t e l o n g a t i o n o f t h e l a r g e r s p e c i m e n s w a s s i m i l a r t o t h e s m a l l e r s p e c i m e n s i n t h e c a s e " o f ' 3 1 6 a n d m u c h l o w e r i n t h e c a s e o f C F - 8 M , w h i l e t h e r e d u c t i o n i n a r e a f o r C F - 8 M w a s s i m i l a r f o r b o t h s i z e d s p e c i m e n s . T h i s i s c o m p l e t e l y o p p o s i t e t o w h a t w a s e x p e c t e d . I t i s p o s s i b l e t h a t b e c a u s e o f t h e d i f f e r e n c e i n t h e s i z e o f t h e s a m p l e s , t h e r e w a s a v a r i a t i o n i n t h e h e a t t r e a t - m e n t w h i c h c o u l d h a v e o c c u r r e d d u r i n g t h e h e a t i n g o r q u e n c h i n g o f t h e s p e c i m e n s , a n d t h a t t h i s h a d a m u c h g r e a t e r i n f l u e n c e i n t h e m e c h a n i c a l p r o p e r t i e s t h a n t h e n u m b e r o f g r a i n s i n t h e c r o s s s e c t i o n . S o t o i n v e s t i g a t e t h i s p o s s i b i l i t y s m a l l s a m p l e s w e r e m a c h i n e d f r o m t h e u n d e f o r m e d r e g i o n i n t h e t h r e a d e d g r i p s e c t i o n o f t h e l a r g e t e n s i l e s p e c i m e n s f r o m V a l v e N o . 9 ( C F - 8 M ) . I n a l l t h r e e t e n s i l e s a m p l e s ( t w o f r o m t h e e d g e a n d o n e f r o m t h e c e n t r e ) w e r e t e s t e d . T h e r e s u l t s ( g i v e n i n T a b l e X I V ) s h o w t h a t t h e y i e l d a n d u l t i m a t e t e n s i l e s t r e n g t h a n d p e r c e n t r e d u c - t i o n i n a r e a a r e - o n l y m a r g i n a l l y h i g h e r t h a n t h e l a r g e s a m p l e s T h i s s h o w s t h a t t h e d i f f e r e n c e i n h e a t t r e a t m e n t o f t h e s m a l l a n d l a r g e s p e c i m e n i s r e s p o n s i b l e f o r t h e d i f f e r e n c e i n m e c h a n i - c a l p r o p e r t i e s r a t h e r t h a n t h e n u m b e r o f g r a i n s i n t h e c r o s s s e c t i o n . I n c o n c l u s i o n i t c a n b e s a i d t h a t t h e t e n s i l e p r o p e r t i e s o f t h e E S C v a l v e s c a n e a s i l y m e e t t h e r e q u i r e d A S M E / A S T M c o d e s i f t h e c h e m i c a l c o m p o s i t i o n i s c o n t r o l l e d w i t h i n t h e r e q u i r e d r a n g e . 56 B . LOW A L L O Y S T E E L V A L V E C A S T I N G S S i x v a l v e s w e r e m a d e u s i n g A I S I 4 3 4 0 ( 0 . 3 8 - 0 . 4 3 % C , 0 . 6 - 0 . 8 % M n , 0 . 0 4 % P , 0 . 0 4 % S , 0 . 2 0 - 0 . 3 5 % S i , 1 . 6 5 - 2 . 0 0 % N i , 0 . 7 0 - 0 . 9 0 % C r a n d 0 . 2 0 - 0 . 3 0 % M o ) r o l l e d b a r a s e l e c t r o d e . 4 . 5 R e m e l t i n g L o g f o r A I S I 4 3 4 0 E S C V a l v e s T a b l e XV g i v e s t h e m e l t i n g c o n d i t i o n s f o r t h e E S C v a l v e s . T o w a r d s t h e e n d o f t h e m e l t i n g i n V a l v e N o . 3 , t h e c a b l e s c o n - n e c t e d t o t h e t o p m o l d w e r e h e a t e d up a n d s t a r t e d s m o k i n g . T h i s w a s b e c a u s e t h e c a s t i n g l o s t c o n t a c t w i t h t h e b a s e p l a t e a n d s o m o s t o f t h e c u r r e n t w a s c a r r i e d b y t h e c a b l e s . T h e s e c a b l e s w e r e n o t d e s i g n e d t o c a r r y s u c h h i g h c u r r e n t s a n d s o t h e y w e r e h e a t e d . T h e i n s i d e o f t h e m o l d ( w h e r e t h e c a b l e s w e r e c o n n e c t e d ) w a s n o t d a m a g e d . I n a l l f u r t h e r c a s t i n g s , t h i s p r o b l e m w a s o v e r c o m e b y j o i n i n g t h e b a s e p l a t e a n d s t a r t e r p i a t e w i t h s c r e w s . T h e s l a g c o m p o s i t i o n w a s c h a n g e d a f t e r V a l v e N o . 3 . A r a r e e a r t h o x i d e {La^Q^) w a s u s e d . V a l v e N o . 8 w a s m a d e w i t h o u t a n y p r o b l e m s a n d t h e c a s t i n g w a s s o u n d . H o w e v e r , V a l v e N o s . 11 a n d 1 2 h a d t o b e r e j e c t e d b e c a u s e o f p o r o s i t y d u e t o m o i s t u r e . O n l y d i m e n s i o n a l m e a s u r e m e n t s c o u l d b e d o n e o n t h e s e v a l v e s . V a l v e N o s . 1 3 a n d 14 w e r e a l s o s o u n d . A t y p i c a l e l e c t r o s l a g c a s t i n g o f a v a l v e b o d y i n A I S I 4 3 4 0 s t e e l i s s h o w n i n F i g u r e 5 3 . 57 4 . 6 N o n - D e s t r u c t i v e T e s t i n g ( N P T ) 4 . 6 . 1 D y e P e n e t r a n t T e s t A s V a l v e N o s . 11 a n d 12 s h o w e d p o r o s i t y d u e t o m o i s t u r e , t h e o t h e r v a l v e s w e r e s e c t i o n e d a n d t e s t e d f o r c r a c k s . V a l v e N o s . 3 , 8 a n d 1 3 d i d n o t s h o w a n y c r a c k . H o w e v e r , V a l v e N o . ; . 14 s h o w e d c r a c k s a l l o v e r t h e s e c t i o n ( s e e F i g u r e 5 4 ) . T h i s v a l v e w a s h e a t t r e a t e d a s o n e w h o l e p i e c e a n d t h e s e c r a c k s w e r e d u e t o i m p r o p e r h e a t t r e a t m e n t . T h i s p o i n t w i l l b e d i s - c u s s e d l a t e r i n t h i s c h a p t e r . 4 . 6 . 2 U l t r a s o n i c , ; T e s t U n l i k e C F - 8 M v a l v e c a s t i n g s , A I S I 4 3 4 0 v a l v e c a s t i n g s d i d n o t p r e s e n t a n y p r o b l e m s i n u l t r a s o n i c t e s t i n g . T h e f u l l s e c t i o n t h i c k n e s s c o u l d be p e n e t r a t e d . T h e r e s u l t s o f u l t r a - s o n i c t e s t i n g o n t w o c a s t i n g s s h o w e d t h a t t h e y w e r e s o u n d . 4 . 6 . 3 R a d i o g r a p h y T e s t R a d i o g r a p h y w a s p e r f o r m e d u s i n g t h e c o b a l t - 6 0 s o u r c e . T h e r a d i o g r a p h s o b t a i n e d w e r e s a t i s f a c t o r y a n d no f l a w s c o u l d be d e t e c t e d . T h e r a d i o g r a p h s o f V a l v e N o . 3 a r e s h o w n i n F i g u r e 5 5 . 4 . 7 D e s t r u c t i v e T e s t i n g ( D . T . ) T h e s e c t i o n i n g p r o c e d u r e h a s b e e n m e n t i o n e d i n S e c t i o n 4 . 3 . 58 4 . 7 . 1 M a c r o s t r u c t u r e s T h e A I S I 4 3 4 0 s t e e l w a s m a c r o e t c h e d i n a n a c i d s o l u t i o n ()50% H C £ , 50% H 2 0 ) a t a b o u t 6 5 - 7 0 ° C f o r 1 - 2 h o u r s . T h e m a c r o - s t r u c t u r e s o f l o n g i t u d i n a l s e c t i o n s f r o m V a l v e N o s . 3 , 8 , 1 3 a n d 14 a r e s h o w n i n F i g u r e s 5 6 - 5 9 . O n e - h a l f o f t h e s e c t i o n f r o m V a l v e N o . 3 w a s e t c h e d i n 10% a n i m o n i u m p e r s u l p h a t e s o l u - t i o n . F i g u r e 6 0 s h o w s a t r a n s v e r s e s e c t i o n t h r o u g h a m i l d s t e e l E S C v a l v e . A l l t h e m a c r o s t r u c t u r e s a r e f r e e o f d e f e c t s e x c e p t t h e o n e f r o m V a l v e N o . 14 a s s h o w n i n F i g u r e 5 9 . C r a c k s r u n n i n g l o n g i t u d i n a l l y ( p r o b a b l y i n t e r - d e n d r i t i c ) c a n b e s e e n . T h e t o p p a r t ( w h i c h w a s e t c h e d f o r a l o n g e r t i m e ) c l e a r l y s h o w s t h e c r a c k s . A l s o a s l a g e n t r a p m e n t o n t h e t o p i n d i c a t e s i n - s u f f i c i e n t h o t - t o p p i n g c y c l e . T h e m a c r o s t r u c t u r e a l s o s h o w s t h a t t h e p o o l p r o f i l e w a s a s s y m m e t r i c a n d t h i s m u s t b e d u e t o t h e e l e c t r o d e b e i n g o f f - c e n t r e w i t h r e s p e c t t o t h e m o l d . Some i n d i c a t i o n s o f t h i s a r e a l s o n o t i c e d f r o m t h e m a c r o s t r u c t u r e o f V a l v e N o . 8 ( s h o w n i n F i g u r e 5 7 ) . F r o m t h e m a c r o s t r u c t u r e o f t h e t r a n s v e r s e s e c t i o n i t c a n b e s e e n t h a t t h e g r a i n s i z e n e a r t h e e d g e ( s u r f a c e o f t h e c a s t i n g ) i s s m a l l e r t h a n i n c e n t r e . S p e c i m e n s f r o m e d g e , m i d - r a d i u s , ; c e n t r e a n d t o p o f V a l v e N o . 3 w e r e e t c h e d i n O b e r h o f f e r ' s s o l u t i o n ( 3 0 gms F e C ^ * 2 gm C u C £ 2 , 0 . 5 gms S n C £ 2 , 3 5 0 nu H C £ , 5 0 0 nu e t h y l a l c o h o l , 5 0 0 nu d i s t i l l e d w a t e r ) . t o r e v e a l t h e d e n d r i t i c s t r u c t u r e . T h e s e a r e s h o w n i n F i g u r e 6 1 ( a n d ) . T h e d e n d r i t e s a r e f i n e a t t h e e d g e a n d b e c o m e c o a r s e r t o w a r d s t h e c e n t r e , b u t t h e y a r e a l l 59 o r i e n t e d d i r e c t i o n a l l y . H o w e v e r , t h e p h o t o g r a p h o f t h e s p e c i - men f r o m t h e t o p s h o w s c o a r s e d e n d r i t e s i n r a n d o m o r i e n t a t i o n f o r m i n g e q u i a x e d g r a i n s ( d u e t o v e r y s l o w c o o l i n g a t t h e t o p . ) 4 . 7 . 2 S u l p h u r P r i n t s S u l p h u r p r i n t i n g r e v e a l s t h e d i s t r i b u t i o n o f s u l p h u r i n i n g o t s a s w e l l a s r o l l e d o r f o r g e d p r o d u c t s . S u l p h u r p r i n t s w e r e t a k e n f r o m V a l v e N o s . 3 a n d 8 a l o n g w i t h a p i e c e o f e l e c t r o d e . T h e s e a r e s h o w n i n F i g u r e s 62 a n d 6 3 . T h e v a l v e s d o n o t s h o w a n y s u l p h u r s e g r e g a t i o n a n d t h e p r i n t s a r e l i g h t e r t h a n t h o s e f r o m t h e e l e c t r o d e i n d i c a t i n g t h a t t h e s u l p h u r c o n - t e n t o f t h e v a l v e c a s t i n g s i s m u c h l o w e r t h a n t h a t o f t h e e l e c t r o d e . 4 . 7 . 3 I n t e r d e n d r i t i c M i c r o s e g r e g a t i o n U s i n g t h e s a m e t e c h n i q u e a s d e s c r i b e d i n S e c t i o n 4 . 3 . 4 , m i c r o s e g r e g a t i o n a t t h e c e n t r e o f t h e A I S I 4 3 4 0 E S C v a l v e s w a s d e t e r m i n e d . T h e l i n e s c a n s o f t h e m i c r o p r o b e a l o n g w i t h v a r i a t i o n o f s o l u t e c o n c e n t r a t i o n o f C r , N i , a n d Mo a r e s h o w n i n F i g u r e s 6 4 - 6 6 . A l s o T a b l e X V I g i v e s t h e s e g r e g a t i o n r a t i o s o b t a i n e d f r o m t h e a n a l y s e s . F r o m t h i s we s e e t h a t t h e s e g r e g a - t i o n r a t i o i s m a x i m u m f o r M o . A l s o , t h e s e g r e g a t i o n r a t i o o f Mo i n V a l v e N o . 1 3 i s l o w w h i l e n o v a l u e c o u l d b e g i v e n f o r V a l v e N o . 14 a s t h e m i n i m u m c o u n t w a s s i m i l a r t o t h e b a c k g r o u n d c o u n t . T h e l o w s e g r e g a t i o n r a t i o o f Mo i n V a l v e N o . 1 3 c o u l d 60 be d u e t o t h e h e a t - t r e a t m e n t a n d / o r t h e f a c t t h a t t h e s p e c i m e n w a s l o c a t e d a w a y f r o m t h e c e n t r e d u e t o t h e m a c h i n e d h o l e . 4 . 7 . 4 C om p o s - i - t i on A n a 1 y s i s a n d M a c r o s e g r e g a t i on C o m p o s i t i o n v a r i a t i o n o f c h r o m i u m , n i c k e l , m o l y b d e n u m a n d c a r b o n w a s s t u d i e d i n t h e A I S I 4 3 4 0 E S C v a l v e s . T h e v a r i a t i o n o f t h e s e e l e m e n t s a l o n g t h e h e i g h t a n d w i d t h o f t h e c a s t i n g s a r e s h o w n i n F i g u r e s 6 7 - 7 0 , w h i l e T a b l e s X V I I t o XX g i v e t h e c o m p l e t e c o m p o s i t i o n a n a l y s e s o f t h e s t a r t i n g e l e c t r o d e a n d t h e c a s t i n g s . No a p p r e c i a b l e c h a n g e i n c h e m i s t r y d u e t o r e m e l t i n g i s o b s e r v e d e x c e p t i n t h e c a s e o f s u l p h u r . B e s i d e s u s i n g o p t i c a l e m i s s i o n s p e c t r o s c o p y , t h e s u l p h u r c o n - t e n t o f t h e v a l v e c a s t i n g s a n d t h e e l e c t r o d e w a s a l s o d e t e r - m i n e d b y " c o m b u s t i o n a n a l y s i s " u s i n g L e c o S u l p h u r A n a l y s e r . T h e r e s u l t s a r e s h o w n i n T a b l e X X I . F r o m t h i s we c a n s e e t h a t t h e s u l p h u r c o n t e n t i s d e c r e a s e d b y a b o u t 70% t h r o u g h e l e c t r o s l a g p r o c e s s i n g o f t h e m a t e r i a l , e v e n w h e n t h e s u l p h u r c o n t e n t o f t h e s t a r t i n g m a t e r i a l w a s l o w . 4 . 7 . 5 H e a t T r e a t m e n t a n d M i c r o s t r u c t u r e s T h e m e c h a n i c a l p r o p e r t i e s o f s t e e l a r e g r e a t l y a f f e c t e d b y t h e h e a t t r e a t m e n t a n d h e n c e t h e r e s u l t i n g m i c r o s t r u c t u r e . A l l t h e m e c h a n i c a l t e s t s w e r e d o n e i n t h e h e a t - t r e a t e d c o n - d i t i o n . U n m a c h i n e d i n d i v i d u a l s p e c i m e n s f r o m V a l v e N o s . 3 61 a n d 8 w e r e a u s t e n i t i s e d a t a b o u t 8 4 5 ° C a n d o i l q u e n c h e d . T h e y w e r e t e m p e r e d a t a b o u t 4 8 0 ° C a n d 5 5 0 ° C . T h e e x a c t h e a t t r e a t - m e n t d o n e f o r e a c h s e t o f t e s t s a r e g i v e n i n t h e m e c h a n i c a l p r o p e r t y s e c t i o n . V a l v e N o . 1 3 w a s m a c h i n e d w i t h a v e r t i c a l h o l e o f 3 i n c h d i a m e t e r a n d a h o r i z o n t a l h o l e ( t h r o u g h t h e s i d e p r o t r u s i o n s ) o f 2 i n c h d i a m e t e r . T h e m a c h i n e d v a l v e i s s h o w n i n F i g u r e 7 1 ( a ) , w h i l e F i g u r e 7 1 ( b ) s h o w s a l o n g i t u d i n a l s e c t i o n o f t h i s v a l v e . V a l v e N o . 14 w a s n o t m a c h i n e d . I n s t e a d o f h e a t t r e a t - i n g i n d i v i d u a l s p e c i m e n s ( f o r m e c h a n i c a l t e s t i n g ) f r o m V a l v e N o s . 1 3 a n d 1 4 , b o t h t h e s e v a l v e s w e r e h e a t t r e a t e d a s a w h o l e p r i o r t o t h e s e c t i o n i n g s t e p . B o t h t h e s e v a l v e s w e r e a u s t e n i - t i s e d i n a s a l t b a t h a t 8 4 5 ° C a n d o i l q u e n c h e d . T h e y w e r e t e m p e r e d a t 5 6 0 ° C . A f t e r t h e h e a t t r e a t m e n t , t h e v a l v e s w e r e s e c t i o n e d f o r t h e d e s t r u c t i v e t e s t s . When V a l v e N o . 1 4 w a s c u t l o n g i t u d i n a l l y , v e r y f i n e c r a c k s w e r e o b s e r v e d . T h e s e c r a c k s s h o w e d up c l e a r l y w h e n a d y e p e n e - t r a n t t e s t w a s d o n e ( s e e F i g u r e 5 4 ) a n d a l s o w h e n t h e p l a t e s w e r e m a c r o e t c h e d ( s e e F i g u r e 5 9 ) , M a c r o e t c h i n g a l s o r e v e a l e d t h a t t h e c r a c k s w e r e i n t e r d e n d r i t i c a n d t h e y w e r e c o n c e n t r a t e d i n s i d e t h e c a s t i n g r a t h e r t h a n o n t h e s u r f a c e . A b a r w i t h 0 . 5 i n c h s q u a r e c r o s s s e c t i o n c u t f r o m t h i s v a l v e s e p a r a t e d a l o n g a c r a c k w i t h o u t m u c h f o r c e . T h e s e p a r a t e d s u r f a c e s w e r e s m o o t h a n d s h i n y a n d t h e d e n d r i t i c s t r u c t u r e w a s r e v e a l e d ( s e e F i g u r e 7 2 ) . T h e m a c h i n e d c a s t i n g d i d n o t s h o w a n y s u c h c r a c k s . 62 F r o m t h e a b o v e r e s u l t s i t c a n b e s a i d c o n c l u s i v e l y t h a t t h e c r a c k s i n V a l v e N o . 14 w e r e c a u s e d d u e t o i m p r o p e r h e a t t r e a t - m e n t . H a r d n e s s m e a s u r e m e n t s w e r e d o n e t o f i n d o u t t h e v a r i a - t i o n o f h a r d n e s s a l o n g t h e h e i g h t a n d w i d t h o f t h e h e a t - t r e a t e d v a l v e s . T h e s e a r e s h o w n i n F i g u r e s 7 3 a n d 7 4 . V a l v e N o . 14 s h o w s a l a r g e v a r i a t i o n i n h a r d n e s s , p a r t i c u l a r l y a l o n g t h e w i d t h o f t h e c a s t i n g . T h e s u r f a c e s h o w s a h i g h e r h a r d n e s s t h a n t h e c e n t r e . I n V a l v e N o . 1 3 t h e h a r d n e s s v a r i a t i o n i s n o t a s l a r g e . T h i s i s d u e t o t h e d i f f e r e n c e i n c r o s s s e c t i o n b e t w e e n t h e t w o v a l v e s . V a l v e N o . 14 h a d a s e c t i o n t h i c k n e s s o f a b o u t 8 i n c h e s c o m p a r e d t o 2% i n c h e s i n V a l v e N o . 1 3 ( d u e t o t h e m a c h i n e d h o l e ) . T h e a b o v e p o i n t s s t r o n g l y s u g g e s t t h a t v a l v e c a s t i n g s s h o u l d b e r o u g h m a c h i n e d t o t h e i r f i n a l s h a p e p r i o r t o h e a t t r e a t m e n t . B e s i d e t h e s e , o t h e r a d v a n t a g e s i n c l u d e r e d u c e d h e a t t r e a t i n g c y c l e d u e t o s m a l l e r c r o s s s e c t i o n a n d w e i g h t , a n d t h a t i t w o u l d b e e a s i e r t o m a c h i n e t h e v a l v e i n t h e a s - c a s t c o n d i t i o n b e c a u s e i t i s s o f t e r t h a n i n t h e h e a t - t r e a t e d c o n - d i t i o n . F o r m i c r o s t r u c t u r a l e x a m i n a t i o n , t h e s p e c i m e n s w e r e p o l i s h e d a n d e t c h e d i n 2% n i t a l . T h e m i c r o s t r u c t u r e s o b t a i n e d i n a s - c a s t a n d h e a t - t r e a t e d c o n d i t i o n s a r e s h o w n i n F i g u r e 7 5 ( a - d ) . 63 T h e a s - c a s t c o n d i t i o n h a s a c o a r s e b a i n i t i c s t r u c t u r e w h i l e t h e q u e n c h e d a n d t e m p e r e d c o n d i t i o n s h o w s a s t r u c t u r e c o m p o s e d e n t i r e l y o f t e m p e r e d m a r t e n s i t e . Same i s t r u e f o r t h e q u e n c h e d a n d t e m p e r e d s p e c i m e n f r o m t h e e l e c t r o d e . T h e m i c r o s t r u c t u r e o f a s p e c i m e n f r o m V a l v e N o . 1 3 s h o w e d a d i f f e r e n t s t r u c t u r e . F i g u r e 7 6 . s h o w s t h a t t h e m i c r o s t r u c t u r e i n t h e i n t e r d e n d r i t i c a r e a i s d i f f e r e n t t h a n t h a t i n t h e d e n d r i t e s . A t h i g h e r m a g n i f i c a - t i o n i t i s s e e n t h a t t h e l i g h t a r e a s ( d e n d r i t e s ) h a v e a b a i n i t i c s t r u c t u r e w h i l e t h e d a r k e r a r e a s s h o w s t h e p r e s e n c e o f m a r t e n - s i t e . Some f e r r i t e i s a l s o p r e s e n t . T h i s m i x e d m i c r o s t r u c t u r e r e s u l t e d i s l o w d u c t i l i t y w h e n t e n s i l e t e s t w a s d o n e o n t h i s m a t e r i a l ( s e e T a b l e X X I I I ) - T h i s m i c r o s t r u c t u r e i s l a r g e l y d u e t o i m p r o p e r h e a t t r e a t m e n t , b u t i n t e r d e n d r i t i c s e g r e g a t i o n h a s a l s o c o n t r i b u t e d t o i t . T h i s s u g g e s t s t h a t ' n o r m a l i s i n g ' m i g h t b e c o m e a n i m p o r t a n t s t e p i n h e a t t r e a t m e n t p r o c e s s . H e a t t r e a t - m e n t o f A I S I 4 3 4 0 s t e e l ( h o m o g e n i s i n g e f f e c t s o n m e c h a n i c a l p r o p e r t i e s , o v e r h e a t i n g d u r i n g n o r m a l i s i n g , e t c . ) i s w e l l d o c u - m e n t e d i n t h e l i t e r a t u r e , a n d we b e l i e v e t h a t h e a t t r e a t m e n t o f E S C v a l v e w o u l d n o t p r e s e n t a n y p r o b l e m s . 4 . 7 . 6 D i m e n s i o n a l M e a s u r e m e n t s D i m e n s i o n a l m e a s u r e m e n t s w e r e d o n e o n t h e m o l d a n d v a l v e c a s t i n g N o s . 1 1 , 12 a n d 1 3 . A f t e r t h e m o l d h a s b e e n a s s e m b l e d , t h e i n n e r d i m e n s i o n s b e t w e e n c e r t a i n p o i n t s w e r e t a k e n . A f t e r t h e c a s t i n g w a s m a d e , m e a s u r e m e n t s b e t w e e n t h e s a m e p o i n t s w e r e a g a i n t a k e n . A l s o t h e s l a g t h i c k n e s s a t t h e s e p o i n t s w a s 64 d e t e r m i n e d . F r o m t h e s e d a t a , ' r e a l p e r c e n t s h r i n k a g e ' a n d ' p s e u d o p e r c e n t s h r i n k a g e ' w e r e o b t a i n e d . T h e s e a r e d e f i n e d b e l o w a n d a r e l i s t e d i n T a b l e X X I I . r e a l p e r c e n t s h r i n k a g e D i - D f - 2 T s 1 0 0 D i p s e u d o p e r c e n t s h r i n k a g e =. D i - D f 1 0 0 L 1 w h e r e D i - i n n e r d i m e n s i o n o f t h e m o l d D f - f i n a l d i m e n s i o n o f t h e c a s t i n g T s - s l a g t h i c k n e s s . T h e ' p s e u d o p e r c e n t s h r i n k a g e ' , a s d e t e r m i n e d h e r e , i s o f p r a c t i c a l s i g n i f i c a n c e a n d i m p o r t a n c e t o f o u n d r y m e n . T h e m a x i - mum v a l u e f o r t h i s i s a r o u n d 4 . 6 % . I t w a s f o u n d t h a t t h e m a x i - mum ' s h r i n k a g e ' i s a t t h e c o r n e r s a n d e d g e s o f t h e c a s t i n g s . T h i s i s b e c a u s e o f t h e v e r y h i g h h e a t t r a n s f e r a n d h e n c e l a r g e s l a g t h i c k n e s s a t t h e s e p o i n t s . 4 . 8 M e c h a n i c a l P r o p e r t i e s 4 . 8 . 1 T e n s i l e T e s t i n g A s m e n t i o n e d i n S e c t i o n 4 . 4 , t e n s i l e t e s t s w e r e c a r r i e d o u t o n A I S I 4 3 4 0 E S C V a l v e N o s . 3 , 8 a n d 1 3 . B o t h t h e l o n g i - t u d i n a l a n d t r a n s v e r s e s a m p l e s w e r e t e s t e d i n t h e q u e n c h e d a n d t e m p e r e d c o n d i t i o n . T h e d e t a i l s o f t h e h e a t t r e a t m e n t h a v e 65 b e e n m e n t i o n e d b e f o r e . T h e r e s u l t s a r e g i v e n i n T a b l e X X I I I . T e s t s w e r e a l s o d o n e o n A I S I 4 3 4 0 r o l l e d b a r a n d t h e r e s u l t s a r e g i v e n i n T a b l e X X I V . Some t e n s i l e r e s u l t s w h i c h h a v e b e e n q u o t e d i n l i t e r a t u r e f o r a i r m e l t e d , v a c u u m a r e r e m e l t e d a n d e l e c t r o s l a g r e m e l t e d A I S I 4 3 4 0 h a v e a l s o b e e n i n c l u d e d i n T a b l e s X X V t o X X V I I f o r c o m p a r i s o n . T h e y i e l d a n d t e n s i l e s t r e n g t h s a r e n o t s o i m p o r t a n t a s d i f f e r e n t s t r e n g t h l e v e l s c a n b e a c h i e v e d b y s u i t a b l e h e a t t r e a t m e n t s . H o w e v e r , d u c t i l i t y a t a c e r t a i n s t r e n g t h l e v e l i s i m p o r t a n t , p a r t i c u l a r l y f o r t r a n s v e r s e s p e c i m e n s . I n E S C v a l v e s , t h e d u c t i l i t y ( a s r e p r e - s e n t e d b y p e r c e n t r e d u c t i o n i n a r e a a n d p e r c e n t e l o n g a t i o n ) o f t h e l o n g i t u d i n a l s p e c i m e n s i s m o r e o r l e s s s i m i l a r t o t h a t o f t h e t r a n s v e r s e s p e c i m e n s . H o w e v e r i f we c o n s i d e r t h e c o n v e n - t i o n a l r o l l e d b a r , t h e l o n g i t u d i n a l v a l u e s o f % RA a n d % E l o n g a - t i o n a r e 1 5 0 % a n d 90% h i g h e r r e s p e c t i v e l y t h a n t h e t r a n s v e r s e v a l u e s a t t h e s a m e s t r e n g t h l e v e l . O b v i o u s l y t h e b a r h a d b e e n s u b j e c t e d t o e x t e n s i v e p l a s t i c d e f o r m a t i o n a n d h e n c e t h e d u c t i l i t y i s a n i s o t r o p i c . ' .:. T h e m e c h a n i c a l p r o p e r t i e s ( p a r t i c u l a r l y d u c t i l i t y ) c a n d r o p d r a s t i c a l l y i f A I S I 4 3 4 0 , s t e e l i s s u b j e c t e d t o i m p r o p e r h e a t t r e a t m e n t . When t h e t e n s i l e s p e c i m e n s f r o m V a l v e N o . 1 3 w e r e t e s t e d , t h e y e x h i b i t e d v e r y p o o r d u c t i l i t y v a l u e s e v e n a t m u c h l o w e r s t r e n g t h ( T a b l e X X I I I ) . » .'The d r o p i s d i r e c t l y r e l a t e d t o t h e m i c r o s t r u c t u r e . A s m e n t i o n e d e a r l i e r , V a l v e N o . 1 3 w a s h e a t t r e a t e d a s o n e p i e c e a n d d u e t o i n a d e q u a t e h e a t - t r e a t m e n t i t s h o w e d t h e p r e s e n c e o f b a i n i t e , t e m p e r e d m a r t e n s i t e a n d 66 s o m e f e r r i t e ( s e e F i g u r e 7 6 ) . When i n d i v i d u a l t e n s i l e s p e c i - m e n s w e r e r e - h e a t t r e a t e d ( a u s t e n i t i s e d , q u e n c h e d a n d t h e n t e m - p e r e d ) t h e t e n s i l e p r o p e r t i e s w e r e r e c o v e r e d b e c a u s e t h e m i c r o - s t r u c t u r e s h o w e d t h a t o n l y t e m p e r e d m a r t e n s i t e w a s p r e s e n t . C o n s i d e r i n g t h e t e n s i l e p r o p e r t i e s o f t h e A I S I 4 3 4 0 E S C v a l v e s i n g e n e r a l , a n d c o m p a r i n g t h e m t o t h e l o n g i t u d i n a l t e n - s i l e p r o p e r t i e s o f h o t - r o l l e d E S R 4 3 4 0 s t e e l ( g i v e n i n T a b l e X X V I ) a n d t o t h e t r a n s v e r s e t e n s i l e p r o p e r t i e s o f f o r g e d E S R 4 3 4 0 s t e e l ( g i v e n i n T a b l e X X V I I ) , i t c a n b e s e e n t h a t t h e E S C s p e c i m e n s s h o w s l i g h t l y l o w e r d u c t i l i t y v a l u e s t h a n t h e l o n g i - t u d i n a l s p e c i m e n s b u t s i m i l a r d u c t i l i t y v a l u e s a s t h e t r a n s - v e r s e s p e c i m e n s . I t i s n o t e w o r t h y t h a t t h e t r a n s v e r s e t e n s i l e p r o p e r t i e s g i v e n i n T a b l e X X V I I f o r f o r g e d A I S I 4 3 4 0 s t e e l a r e p e r h a p s t h e b e s t o n e c a n o b t a i n . F o r t h e s a m e r e a s o n s a s s t a t e d i n S e c t i o n 4 . 4 , l a r g e r t e n s i l e s p e c i m e n s o f 0 . 7 5 i n c h g a u g e d i a m e t e r ( s e e F i g u r e 4 9 ) a n d t h e r e f o r e h a v i n g 9 t i m e s l a r g e r c r o s s - s e c t i o n a l a r e a t h a n t h e s m a l l s p e c i m e n s , w e r e a l s o t e s t e d i n t h e NITS m a c h i n e . T h e o p t i c a l f r a c t o g r a p h s o f t h e s e l a r g e s p e c i m e n s a r e s h o w n i n F i g u r e 7 7 . T h e r e s u l t s ( g i v e n i n T a b l e X X V I I I ( a ) ) d o n o t s h o w a n y i m p r o v e m e n t i n t e n s i l e p r o p e r t i e s o v e r t h e s m a l l s p e c i m e n s . To e l i m i n a t e a n y p o s s i b l e e f f e c t o f h e a t - t r e a t m e n t , o r i e n t a - t i o n e t c . o n t h e m e c h a n i c a l p r o p e r t i e s , s m a l l s p e c i m e n s w e r e c u t f r o m t h e t h r e a d e d r e g i o n o f t h e l a r g e t e n s i l e s p e c i m e n s . 67 T h e r e s u l t s a r e g i v e n i n T a b l e X X V I I ( b ) , a n d t h e y a r e s i m i l a r t o t h e r e s t . T h i s s h o w s t h a t n u m b e r o f g r a i n s i n t h e c r o s s - s e c t i o n d o e s n o t h a v e s i g n i f i c a n t e f f e c t o n t h e t e n s i l e p r o - p e r t i e s . 4 . 8 . 2 I m p a c t T e s t i n g S t a n d a r d C h a r p y V - N o t c h i m p a c t t e s t s c o n f o r m i n g t o A S T M E 2 3 - 7 2 s p e c i f i c a t i o n s w e r e c a r r i e d o u t o n E S C V a l v e N o s . 3 , 8 a n d 1 3 a n d a l s o o n A I S I 4 3 4 0 r o l l e d b a r ' e l e c t r o d e . T h e t e s t s w e r e d o n e i n t h e q u e n c h e d a n d t e m p e r e d c o n d i t i o n . S p e c i m e n s f r o m b o t h l o n g i t u d i n a l a n d t r a n s v e r s e d i r e c t i o n s w e r e t e s t e d i n V a l v e N o s . 3 a n d 1 3 a n d i n t h e A I S I 4 3 4 0 r o l l e d b a r e l e c t - r o d e w h i l e i n V a l v e N o . 8 s p e c i m e n s f r o m l o n g i t u d i n a l , t r a n s - v e r s e ( h a v i n g a l o n g i t u d i n a l a n d t r a n s v e r s e n o t c h ) a n d f r o m t h e e d g e w e r e t e s t e d . F i g u r e 7 8 s h o w s t h e s p e c i m e n a n d n o t c h o r i e n t a t i o n o f t h e c h a r p y s p e c i m e n s . T h e r e s u l t s o f a l l t h e s e t e s t s a r e p r e s e n t e d i n F i g u r e s 7 9 - 8 1 . E a c h p o i n t r e p r e s e n t s a n a v e r a g e o f a t l e a s t 3 t e s t s . I t w a s d i f f i c u l t t o e s t i m a t e t h e p e r c e n t b r i t t l e f r a c t u r e f r o m t h e b r o k e n c h a r p y s p e c i m e n s a s t h e f r a c t u r e s u r f a c e w a s v e r y i r r e g u l a r . H e n c e i t w a s a l s o d i f f i c u l t t o p l o t p e r c e n t b r i t t l e f r a c t u r e v e r s u s t e m p e r a t u r e a n d t h u s d e t e r m i n e t h e F r a c t u r e A p p e a r a n c e T r a n s i t i o n T e m p e r a - t u r e ( F A T T ) . F r o m F i g u r e 79 w h i c h s h o w s t h e c h a r p y r e s u l t s o f V a l v e N o . 3 a n d t h e e l e c t r o d e , i t c a n b e s e e n t h a t a t t h e s a m e h a r d n e s s 68 l e v e l , t h e l o n g i t u d i n a l s p e c i m e n f r o m t h e e l e c t r o d e e x h i b i t b e t t e r t o u g h n e s s v a l u e s t h a n t h e l o n g i t u d i n a l s p e c i m e n s f r o m t h e E S C v a l v e . H o w e v e r , t h e t r a n s v e r s e v a l u e s o f t h e e l e c t - r o d e a r e m u c h l o w e r t h a n t h e E S C v a l v e . A l s o t h e t r a n s i t i o n t e m p e r a t u r e f o r t h e l o n g i t u d i n a l s p e c i m e n s f r o m t h e e l e c t r o d e s e e m s t o b e h i g h e r t h a n f o r t h e l o n g i t u d i n a l s p e c i m e n s f r o m t h e E S C v a l v e . F i g u r e 8 0 s h o w s t h e C h a r p y r e s u l t s o f V a l v e N o . 8 . T h e l o n g i t u d i n a l s p e c i m e n s s e e m t o h a v e h i g h e r e n e r g y v a l u e s t h a n t h e t r a n s v e r s e s p e c i m e n s w i t h a l o n g i t u d i n a l n o t c h . A l t h o u g h t h e t r a n s v e r s e s p e c i m e n s w i t h t r a n s v e r s e n o t c h ( T T ) s h o w b e t t e r t o u g h n e s s t h a n t h e t r a n s v e r s e s p e c i m e n s w i t h l o n g i - t u d i n a l n o t c h ( T L ) , n o t h i n g c o n c l u s i v e c a n b e s a i d a s t h i s d i f f e r e n c e c o u l d e n t i r e l y b e d u e t o t h e d i f f e r e n c e i n h a r d - n e s s . H o w e v e r , t h e d u c t i l e - b r i t t l e t r a n s i t i o n c h a r a c t e r - i s t i c s o f t h e s p e c i m e n s f r o m t h e e d g e a r e m u c h s u p e r i o r a s i t s h o w s r e a s o n a b l e t o u g h n e s s a t v e r y l o w t e m p e r a t u r e s . T h i s c o u l d a g a i n b e d u e t o t h e s m a l l g r a i n s i z e a t t h e e d g e . T h e d u c t i l e - b r i t t l e t r a n s i t i o n c h a r a c t e r i s t i c s o f V a l v e N o . 1 3 a r e s h o w n i n F i g u r e 81 a n d t h e y a r e s i m i l a r t o V a l v e N o . 8 , b u t t h e c u r v e s s e e m t o h a v e s h i f t e d t o t h e r i g h t . T a b l e X X I X g i v e s t h e F A T T v a l v e s e s t i m a t e d f r o m t h e 69 d u c t i l e - b r i t t l e - t r a n s i t i o n c h a r a c t e r i s t i c s . T h e y s h o w t h a t t h e F A T T i s l o w e r f o r t h e E S C m a t e r i a l . T h e o p t i c a l f r a c t o g r a p h s o f t h e s p e c i m e n s f r o m E S C V a l v e N o . 8 w i t h v a r i o u s n o t c h o r i e n t a t i o n s a r e s h o w n i n F i g u r e s 8 2 ( a - d ) a n d t h e l o n g i t u d i n a l a n d t r a n s v e r s e s p e c i m e n s f r o m t h e e l e c t r o d e a r e s h o w n i n F i g u r e 8 3 . T h e r e i s a g r e a t d i f f e r e n c e i n f r a c t o g r a p h y b e t w e e n t h e E S C v a l v e a n d t h e e l e c t r o d e s p e c i - m e n s . T h e l o n g i t u d i n a l s p e c i m e n s f r o m t h e e l e c t r o d e s h o w a n e v e n , s m o o t h f r a c t u r e d s u r f a c e w i t h l a r g e s h e a r l i p s c h a r a c t e r - i s t i c o f h i g h e n e r g y f r a c t u r e . T h e t r a n s v e r s e s a m p l e s f r o m t h e e l e c t r o d e , o n t h e o t h e r h a n d s h o w a n i r r e g u l a r " l a m i n a t e d s t r u c t u r e a n d s h e a r 1','i-ps a r e a b s e n t e v e n a t 1 0 0 ° C . T h e s p e c i - m e n s f r o m t h e E S C v a l v e , o n t h e o t h e r h a n d , e x h i b i t e n t i r e l y d i f f e r e n t f r a c t u r e c h a r a c t e r i s t i c s . T h e f r a c t u r e s u r f a c e i s v e r y i r r e g u l a r a n d t h e r e a r e a r e a s w h e r e v e r t i c a l r i d g e s a r e p r e s e n t a n d t h e s u r f a c e i s s m o o t h a n d s h i n y . T h i s i s c l e a r l y s h o w n i n F i g u r e 8 4 ( a ) . T h e s e r i d g e s a r e p r e d o m i n a n t l y p r e s e n t a t l o w t e m p e r a t u r e s . T o d i s t i n g u i s h t h e m o d e o f f a i l u r e i n d i f f e r e n t r e g i o n s o f t h e s a m e s p e c i m e n , t h e s p e c i m e n s w e r e e x a m i n e d u n d e r t h e SEM. T h e g e n e r a l a p p e a r a n c e o f a b r o k e n c h a r p y s p e c i m e n i s s h o w n i n F i g u r e 8 4 ( a ) . A r e a s w h e r e ' c r a c k s ' o r v e r y s m a l l r i d g e s a p p e a r a r e s h o w n i n F i g u r e 8 4 ( b ) . T h e c l e a v a g e f r a c t u r e i s q u i t e a p p a r e n t . F o u r d i f f e r e n t a r e a s w i t h d i f f e r e n t f r a c t u r e 70 c h a r a c t e r i s t i c s w e r e i d e n t i f i e d . I n s t e a d o f c h a r a c t e r i s i n g t h e m a s d u c t i l e / b r i t t l e f r a c t u r e s , t h e y h a v e b e e n t e r m e d a s ' l o w ' , ' i n t e r m e d i a t e ' o r ' h i g h e n e r g y ' f r a c t u r e s . T h e d i f - f e r e n t a r e a s a r e s h o w n i n F i g u r e s 8 5 ( a - d ) a n d i d e n t i f i e d b e l o w : - A r e a 1 - T h i s i s t h e r e g i o n o n t h e v e r t i c a l s i d e s o f t h e r i d g e a r e a . T h i s r e p r e s e n t s ' l o w e n e r g y f r a c t u r e ' a s f l a t a n d f a c e t e d f r a c t u r e mode i s s e e n . T h e r e a r e a l s o s o m e r o u n d a r e a s w h e r e t e a r i n g i s o b s e r v e d ( p r o b a b l y l a r g e d i m p l e s ) . A r e a 2 - T h i s i s t h e r e g i o n a t t h e b a s e o f t h e r i d g e a r e a . T h e f r a c t o g r a p h . . f r o m t h i s a r e a s h o w s v e r y c o a r s e d i m p l e s w i t h s o m e f l a t a r e a s . T h i s c a n b e t e r m e d a s t h e ' t r a n s i t i o n z o n e ' w i t h ' i n t e r m e d i a t e e n e r g y f r a c t u r e ' . A r e a 3 - T h i s r e p r e s e n t s t h e g e n e r a l a r e a ( a l l e x c e p t t h e r i d g e a n d t h e s h e a r l i p a r e a s ) a n d s h o w s t h a t f r a c t u r e i s d u e t o m i c r o v o i d - c o a l e s c e n c e b u t h e r e a l s o t h e d i m p l e s a r e s t i l l c o a r s e . T h i s i s t h e ' h i g h e n e r g y f r a c t u r e ' a r e a . A r e a 4 - T h i s c o m p r i s e s o f t h e s h e a r l i p s a r e a o n t h e i s p e c i m e n . T h e f r a c t u r e i s v e r y m u c h l i k e A r e a 3 , b u t h e r e t h e d i m p l e s a r e m u c h f i n e r . T h i s i s a l s o t h e ' h i g h e n e r g y f r a c t u r e ' a r e a . T h e s e a r e a s a r e r e p r e s e n t a t i v e o f a l l t h e c h a r p y s p e c i - m e n s f r o m E S C v a l v e s . T h i s k i n d o f f r a c t u r e i s p r o b a b l y d u e t o f i r s t l y t h e l a r g e g r a i n s i z e a n d s e c o n d l y d u e t o t h e c a s t s t r u c t u r e o f t h e E S C m a t e r i a l . C h a p t e r 5 71 O T H E R T R I A L S AND F U T U R E WORK A l t h o u g h t h e p r e s e n t w o r k s h o w s t h a t t h e e l e c t r o s l a g c a s t - i n g o f v a l v e b o d i e s i s a v i a b l e p r o c e s s , s o m e m o r e w o r k i s n e e d e d i n t w o m a j o r a r e a s w h i c h m i g h t l e a d t o l o w e r c o s t s a n d i m p r o v e d c a p a b i l i t i e s o f t h e p r o c e s s . T h e f i r s t a r e a o f i n t e r e s t i s t h e m a n u f a c t u r e o f h o l l o w e l e c t r o s l a g c a s t v a l v e s ( i . e . v a l v e s w i t h t h e c e n t r e h o l e ) . M u c h o f t h e w o r k d o n e o n t h i s a s p e c t o f E S C i s a g a i n o f S o v i e t o r i g i n a n d P a t o n a n d o t h e r w o r k e r s h a v e s h o w n t h e f e a s i b i l i t y 3 - 5 77 o f t h e p r o c e s s . ' F i g u r e 86 s h o w s t h e h o l l o w E S C v a l v e m a d e i n t h e P a t o n I n s t i t u t e , U . S . S . R . , a n d s e n t h e r e f o r e v a l u a - t i o n . T h e t w o m e t h o d s u s e d b y t h e S o v i e t s a r e t h e f i x e d m a n d r e l w i t h t h e v a l v e b e i n g c a s t i n a n i n v e r t e d p o s i t i o n a n d t h e m o v i n g m a n d r e l w i t h t h e v a l v e i n t h e u p r i g h t p o s i t i o n . T h e s e a r e s h o w n i n F i g u r e 8 7 . T h e p r o b l e m s a s s o c i a t e d w i t h c a s t i n g o f h o l l o w i n g o t s ( n o t v a l v e s ) w i t h d i f f e r e n t t e c h n i q u e s h a v e b e e n d i s - 7 8 7 9 8 0 c u s s e d t o s o m e e x t e n t b y B h a t ' a n d H o y l e , a n d t h e s e m i g h t p r o v i d e s o m e u s e f u l i n f o r m a t i o n a s t o w h i c h o f t h e t w o m e t h o d s m e n t i o n e d a b o v e w o u l d b e b e t t e r . A c o m p a r a t i v e s t u d y o f p r o - p e r t i e s o f h o l l o w a n d s o l i d E S C i n g o t s o f t h e s a m e s i z e h a s b e e n 81 d o n e b y P a t o n e t a l . , a n d t h e i r r e s u l t s s h o w t h a t t h e h o l l o w i n g o t s h a v e a b e t t e r s t r u c t u r e a n d m e c h a n i c a l p r o p e r t i e s . A l s o , h o l l o w v a l v e s w o u l d l o w e r t h e m a c h i n i n g c o s t . C o m p a r a t i v e 7 2 s t u d i e s s h o u l d t h e r e f o r e b e c o n d u c t e d o n h o l l o w a n d s o l i d E S C v a l v e s t a k i n g i n t o a c c o u n t t h e e c o n o m i c s o f b o t h t h e p r o c e s s r o u t e s . T h e o t h e r a r e a w h e r e i n v e s t i g a t i o n s a r e r e q u i r e d i s t h e t e c h n i q u e w h e r e b y s e p a r a t e l y p r e p a r e d a u x i l i a r y p a r t s a r e j o i n e d o r f u s i o n w e l d e d t o t h e m a i n b o d y d u r i n g t h e c a s t i n g p r o c e s s . B y u s i n g t h i s t e c h n i q u e i t i s p o s s i b l e t o j o i n i n l e t / o u t l e t f l a n g e s ( w h i c h h a v e b e e n m a d e b y t h e E S C p r o c e s s o r o t h e r w i s e ) t o t h e m a i n v a l v e b o d y . H e n c e m o r e c o m p l i c a t e d s h a p e s w h i c h a r e c l o s e t o t h e f i n a l p r o d u c t c o u l d b e m a d e . T h e S o v i e t s h a v e u s e d t h i s t e c h n i q u e t o p r o d u c e v e r y l a r g e c r a n k s h a f t ( w i t h a p i n d i a m e t e r o f 4 8 0 m m . ) f o r d i e s e l e n g i n e s u s e d i n s h i p s . * * Some p r e l i m i n a r y w o r k w a s d o n e h e r e t o s t u d y t h i s a s p e c t o f t h e E S C p r o c e s s . A f l a n g e m o l d w a s u s e d t o m a k e f l a n g e c a s t i n g s j o i n e d t o a t h i c k p l a t e . T h i s i s s h o w n i n F i g u r e 8 8 . T h e n t h e s e g m e n t o f t h e v a l v e m o l d w h i c h h a d t h e c u p p e d s i d e w a s r e p l a c e d w i t h a s i m i l a r s e g m e n t b u t w i t h a h o l e i n t h e s i d e . A n e l e c t r o d e p i e c e w a s p l a c e d i n t h i s h o l e t o a c t a s a n i n s e r t a n d t h e v a l v e c a s t i n g w a s m a d e . T h i s c a s t i n g i s s h o w n i n F i g u r e 8 9 . T h e m a c r o s t r u c t u r e o f t h e l o n g i t u d i n a l s e c t i o n o f t h i s c a s t i n g i s s h o w n i n F i g u r e 9 0 . F r o m t h i s i t ' c a n be s e e n t h a t t h e f u s i o n o f t h e i n s e r t t o t h e m a i n v a l v e 73 b o d y i s p o s s i b l e . T h e i n c o m p l e t e f u s i o n a t t h e t o p c a n p r o - b a b l y be c o r r e c t e d . A f l a n g e c a s t i n g c o u l d t h e r e f o r e b e p l a c e d i n s t e a d o f t h e i n s e r t a n d h e n c e j o i n e d t o t h e m a i n v a l v e . M o r e w o r k i s n e e d e d i n t h i s a r e a a n d t h e s o u n d n e s s a n d m e c h a n i c a l p r o p e r t i e s o f t h e w e l d r e g i o n s h o u l d b e s t u d i e d . B o t h t h e s e t e c h n i q u e s w a r r a n t f u r t h e r i n v e s t i g a t i o n a n d i f t h e y a p p e a r t o b e a c c e p t a b l e f r o m t h e p o i n t o f v i e w o f p r o - p e r t i e s a n d e c o n o m i c s , t h e y w o u l d c e r t a i n l y w i d e n t h e s c o p e o f t h e E S C p r o c e s s a n d m a k e i t m o r e v e r s a t i l e . 74 C h a p t e r 6 SUMMARY AND C O N C L U S I O N S T h e r e s u l t s r e p o r t e d a b o v e c l e a r l y i n d i c a t e t h a t t h e e l e c t r o s l a g c a s t i n g p r o c e s s i s a v i a b l e t e c h n i q u e t o p r o d u c e v a l v e b o d i e s . N o n - d e s t r u c t i v e t e s t s s h o w t h a t a l t h o u g h u l t r a - s o n i c t e s t i n g c a n b e u s e d i n t h e c a s e o f l o w a l l o y s t e e l E S C v a l v e s , t h e s a m e c a n n o t b e a p p l i e d t o a u s t e n i t i c s t a i n l e s s s t e e l v a l v e s d u e t o t h e i r i n h e r e n t l a r g e g r a i n s i z e . R a d i o - g r a p h y w o u l d t h u s b e c o m e a n i m p o r t a n t t o o l t o q u a l i f y t h e s t a i n l e s s s t e e l c a s t i n g s . T h e m a c r o s t r u c t u r e s s h o w t h a t t h e c a s t i n g s a r e e s s e n t i - ; a l l y f r e e o f s o l i d i f i c a t i o n d e f e c t s . H o w e v e r s p e c i a l p r e - c a u t i o n s a r e r e q u i r e d f i r s t l y t o a v o i d m o i s t u r e r e l a t e d p o r o - s i t y i n t h e c a s t i n g s a n d s e c o n d l y w h e n c a s t e l e c t r o d e s a r e u s e d . H e a t t r e a t m e n t a l s o b e c o m e s a n i m p o r t a n t s t e p t o a c h i e v e t h e d e s i r e d m i c r o s t r u c t u r e r e s u l t i n g i n o p t i m u m m e c h a n i - c a l p r o p e r t i e s . C h e m i c a l c o m p o s i t i o n o f s t a i n l e s s s t e e l c a s t - i n g s g r e a t l y a f f e c t s t h e f e r r i t e c o n t e n t , t h e p r e s e n c e o f w h i c h i s e s s e n t i a l t o o b t a i n g o o d m e c h a n i c a l p r o p e r t i e s a n d c o r r o s i o n r e s i s t a n c e . A l t h o u g h t h e i n t e r d e n d r i t i c m i c r o s e g r e g a t i o n i n c r e a s e s 75 f r o m t h e e d g e t o t h e c e n t r e o f t h e v a l v e c a s t i n g s , i t i s r e - d u c e d f r o m t h a t i n t h e e q u i v a l e n t s e c t i o n i n c o n v e n t i o n a l c a s t i n g . T h i s i s p a r t i c u l a r l y t r u e f o r Mo i n s t a i n l e s s s t e e l c a s t i n g s . I t i s n o t e w o r t h y t h a t t h e C F - 8 M v a l v e c a s t i n g w a s t e s t e d i n t h e a s - c a s t c o n d i t i o n w h i l e t h e c o n v e n t i o n a l C F - 8 M c a s t i n g w a s t e s t e d i n s o l u t i o n t r e a t e d c o n d i t i o n . T h e s e g r e g a - t i o n r a t i o i n s t a i n l e s s s t e e l c a s t i n g s , h o w e v e r , s h o u l d b e d e t e r m i n e d f r o m t h e s e g r e g a t i o n o c c u r i n g w i t h i n a u s t e n i t e o r f e r r i t e p h a s e s . M a c r o s e g r e g a t i o n s t u d i e s s h o w t h a t t h e v a r i a t i o n o f e l e m e n t s ( C r , N i , M o , C ) a l o n g t h e h e i g h t a n d w i d t h o f t h e v a l v e c a s t i n g s i s s m a l l . C o m p o s i t i o n u n i f o r m i t y c a n b e a c h i e v e d b y c o n t r o l l e d a d d i t i o n o f a l l o y i n g e l e m e n t s d u r i n g t h e m e l t i n g o p e r a t i o n w i t h a p r o p e r f e e d i n g a r r a n g e m e n t . T h e t e n s i l e p r o p e r t i e s o f . t h e s t a i n l e s s s t e e l v a l v e s c a n e a s i l y m e e t t h e r e q u i r e d A S M E / A S T M c o d e s i f c h e m i c a l c o m p o s i - t i o n i s c o n t r o l l e d w i t h i n t h e r e q u i r e d r a n g e . A l t h o u g h t h e s t r e n g t h v a l u e s o f t h e E S C v a l v e s w e r e s l i g h t l y l o w e r t h a n t h a t o f c o n v e n t i o n a l C F - 8 M c a s t i n g . , t h e d u c t i l i t y v a l u e s w e r e s i g n i f i c a n t l y h i g h e r . S t r e n g t h o f t h e s e v a l v e s w a s f o u n d t o b e a d i r e c t f u n c t i o n o f t h e f e r r i t e c o n t e n t . A t a b o u t t h e s a m e s t r e n g t h l e v e l , t h e l o n g i t u d i n a l a n d t r a n s - v e r s e d u c t i l i t y o f A I S I 4 3 4 0 E S C v a l v e s w a s s i g n i f i c a n t l y 76 h i g h e r t h a n t h e t r a n s v e r s e d u c t i l i t y o f t h e c o n v e n t i o n a l r o l - l e d b a r a n d e q u i v a l e n t t o t h e t r a n s v e r s e d u c t i l i t y o f t h e f o r g e d E S R s t e e l . I n c r e a s i n g t h e c r o s s - s e c t i o n a l a r e a o f t h e t e n s i l e s p e c i m e n s d i d n o t a l t e r t h e m e a s u r e d p r o p e r t i e s s h o w - i n g t h a t t h e n u m b e r o f g r a i n s i n t h e c r o s s - s e c t i o n d o e s n o t h a v e a s i g n i f i c a n t e f f e c t o n t h e m e a s u r e m e n t o f t e n s i l e p r o - p e r t i e s i n t h e s e s a m p l e s . T h e i m p a c t r e s u l t s s h o w t h a t t h e d u c t i l e - b r i t t l e - t r a n s i t i o n c h a r a c t e r i s t i c s o f t h e E S C m a t e r i a l a r e b e t t e r t h a n t h e c o n v e n t i o n a l r o l l e d m a t e r i a l . T h e i m p a c t s t r e n g t h o f t h e E S C m a t e r i a l w a s m u c h h i g h e r t h a n t h e t r a n s - v e r s e i m p a c t s t r e n g t h o f t h e r o l l e d m a t e r i a l . A l s o t h e e s t i m a t e d F A T T w a s l o w e r f o r t h e E S C m a t e r i a l . T h e f r a c t u r e d s u r f a c e o f t h e E S C m a t e r i a l w a s v e r y i r r e g u l a r d u e t o l a r g e g r a i n s i z e a n d a s - c a s t s t r u c t u r e . E l e c t r o s l a g c a s t i n g o f h o l l o w v a l v e s a n d j o i n i n g o f i n d i v i d u a l l y c a s t c o m p o n e n t s t o t h e m a i n v a l v e b o d y d u r i n g t h e c a s t i n g o p e r a t i o n a r e p r o m i s i n g p o t e n t i a l a p p l i c a t i o n s o f t h e p r o c e s s a n d n e e d f u r t h e r i n v e s t i g a t i o n . A t t h i s p o i n t t w o p r o b l e m s n e e d a t t e n t i o n : T h e p r o b l e m o f c o d e q u a l i f i c a t i o n f o r t h e E S C m a t e r i a l m u s t b e r e s o l v e d . A l t h o u g h i t i s a c a s t i n g , i t h a s b e e n s h o w n t o b e o f a h i g h q u a l i t y a n d t h e r e f o r e s h o u l d b e p e r m i t t e d t o b e u s e d i n a p p l i c a t i o n s w h e r e c o d e s p r e s e n t l y r e q u i r e f o r g i n g s . A l s o , 77 i f f a b r i c a t i o n o f t h e f i n a l s h a p e i s d o n e w i t h s i m u l t a n e o u s c a s t i n g a n d w e l d i n g , t h e c o d e s s h o u l d a c c o m m o d a t e t h i s . H o w e v e r , t h e r e a l p r o b l e m d o e s n o t l i e i n t h e p r o d u c t b u t i n t h e p r o c e s s c o n t r o l . T h e q u e s t i o n i s - c a n t h e E S C p r o c e s s b e c o n t r o l l e d s u c h t h a t t h e e l e c t r o s l a g c a s t i n g c a n b e q u a l i f i e d b y a g e n e r i c t e s t o n t h e e l e c t r o d e s t o c k r a t h e r t h a n o n t h e i n d i v i d u a l c a s t i n g s ? T h i s m i g h t b e d i f f i c u l t i f a l l o y i n g a d d i t i o n s a r e m a d e d u r i n g t h e c a s t i n g o p e r a t i o n b e - c a u s e t h e r e w i l l b e a p p r e c i a b l e d i f f e r e n c e s b e t w e e n t h e e l e c t - r o d e a n d t h e E S C a n a l y s e s . H o w e v e r , i f s u c h a c o d e q u a l i f i c a - t i o n c a n n o t be e s t a b l i s h e d , t h e p r o c e s s m i g h t b e c o m e e c o n o m i - c a l l y l e s s f e a s i b l e d u e t o h i g h t e s t i n g c o s t s . I n c o n c l u s i o n , we may s a y t h a t e l e c t r o s l a g c a s t i n g p r o - c e s s c a n be u s e d t o c a s t s i m p l e v a l v e - b o d y s h a p e s i n s t a i n l e s s a n d l o w a l l o y s t e e l f r o m c a s t o r w r o u g h t e l e c t r o d e s . T h e p r o p e r t i e s o f t h e E S C v a l v e s c a n e a s i l y m e e t t h e r e q u i r e d s p e c i f i c a t i o n s w i t h p r o p e r h e a t t r e a t m e n t . T h e E S C v a l v e s a r e t h e r e f o r e e q u i v a l e n t t o o r b e t t e r t h a n c o m m e r c i a l c a s t i n g s a n d f o r g i n g s a n d c a n b e s u b s t i t u t e d f o r t h e m w i t h o u t a n y p e n a l t y . 78 R E F E R E N C E S 1 . A . M i t c h e l l : • ' M o d e r n C a s t i n g ' , N o v . 1 9 7 . 8 , p . 8 6 . 2 . A . M i t c h e l l a n d A . A k h t a r : A S M E M P C - 6 , ' E f f e c t s o f M e l t i n g a n d P r o c e s s i n g V a r i a b l e s o n t h e M e c h a n i c a l P r o p e r t i e s o f S t e e l : e d . , G . V . S m i t h , 1 9 7 7 , p . l . 3 . V . I. R a b i n o v i c h e t a l . : ' S p e c i a l E l e c t r o m e t a l l u r g y ' , 1 9 7 2 , K i e v . p . 2 3 1 . 4 . B . E . P a t o n e t a l . : i b i d , p . 1 6 9 . 5 . B . E . . P a t o n e t a l . : P r o c . 3 r d I n t e r n a t i o n a l S y m p o s i u m o n E S R , P i t t s b u r g h , 1 9 7 1 , p . 1 3 5 . 6 . B . E . P a t o n e t a l . : R e p o r t o f E . O . P a t o n E l e c t r i c W e l d i n g I n s t i t u t e , K i e v , U . S . S . R . 7 . B . E . P a t o n e t a l . : P r o c . 5 t h I n t e r n a t i o n a l S y m p o s i u m o n E S R , P i t t s b u r g h , e d s . G . K . B h a t a n d A . S i m k o v i t c h , 1 9 7 4 , p . 2 3 9 . 8 . B . E . P a t o n e t a l . : P r o c . 4 t h I n t e r n a t i o n a l S y m p o s i u m o n E S R , J a p a n , J u n e 1 9 7 3 , p . 2 0 9 . 9 . E . F . D u b r o v s k a y a e t a l . : ' V e s t M a s h i n o s t ! , 1 9 7 5 , I V , p . 6 2 ( c i t e d a s R e f . 17 i n R e f . 2 ) . 1 0 . A . U j i i e e t a l . : ' E l e c t r o s l a g R e f i n i n g ' , I r o n a n d S t e e l I n s t i t u t e , L o n d o n , 1 9 7 3 , p . 1 1 3 . 1 1 . A . U j i i e e t a l . : P r o c . 4 t h I n t e r n a t i o n a l S y m p o s i u m o n E S R , J a p a n , J u n e 1 9 4 3 , p . 1 6 8 . 1 2 . A . U j i i e e t a l . : P r o c . 5 t h I n t e r n a t i o n a l S y m p o s i u m o n E S R , P i t t s b u r g h , e d s . G . K . B h a t a n d A . S i m k o v i t c h , 1 9 7 4 , p . 2 5 1 1 3 . M . P . 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M i t c h e l l e t a l : P a p e r p r e s e n t e d a t W a r w i c k C o n f e r e n c e , E n g l a n d , S e p t . 1 9 8 0 . 4 4 . A . M i t c h e l l : ' C a n a d i a n M e t a l l u r g i c a l Q u a r t e r l y ' , v o l . 2 0 , n o . 1 , 1 9 8 1 , p . 1 0 1 . 4 5 . A . M i t c h e l l a n d J . C a m e r o n : ' M e t a l l u r g i c a l T r a n s a c t i o n s ' , v o l . 2 , D e c . 1 9 7 1 , p . 3 3 6 1 . 4 6 . A . M i t c h e l l a n d R . M . S m a i l e r : ' I n t e r n a t i o n a l M e t a l s R e v i e w s ' , n o s . 5 a n d 6 , 1 9 7 9 , p . 2 3 1 . 4 7 . A . M i t c h e l l a n d M. E t i e n n e : T r a n s , o f t h e M e t a l l u r g i c a l S o c i e t y o f A I M E ' , v o l . 2 4 2 , J u l y 1 9 6 8 , p . 1 4 6 2 . 4 8 . K . C . M i l l s a n d B . J . K e e n e : 1 I n t e r n a t i on a 1 Met :a . I s R e v i e w s , n o . 1 , 1 9 8 1 , p . 2 1 . 4 9 . W. H o t z g r u b e r e t a l . : ' S p e c i a l E l e c t r o m e t a l l u r g y ' , 1 9 7 2 , K i e v , p . 1 6 1 . 81 5 0 . H . J a e g e r e t a l . : P r o c . 5 t h I n t e r n a t i o n a l S y m p o s i u m o n E S R , P i t t s b u r g h , e d s . G . K . B h a t a n d A . S i m k o v i t c h , 1 9 7 4 , p . 3 0 6 . 5 1 . R . F . S t e i g e r w a l d : ' C o r r o s i o n ' , v o l . 3 3 , n o . 9 , S e p t . 1 9 7 7 , p . 3 3 8 . 5 2 . ASM M e t a l s H a n d b o o k , 8 t h E d i t i o n , v o l . 1 , p . 4 3 3 . 5 3 . J . W . F l o w e r s e t a l . : ' C o r r o s i o n ' , v o l . 1 9 , 1 9 6 3 , p . ! 8 6 t . 5 4 . F . B . P i c k e r i n g : ' T h e M e t a l l u r g i c a l E v o l u t i o n o f S t a i n - l e s s S t e e l s ' , ASM M e t a l s S c i e n c e S o u r c e B o o k , p . l . 5 5 . F . R . B e c k i t t : ' J o u r n a l s o f T h e I r o n a n d S t e e l I n s t i t u t e ' , May 1 9 6 9 , p . 6 3 2 . 5 6 . E . C . B a i n s a n d W . E . G r i f f i t h s : T r a n s a c t i o n s A I M E , v o l . 7 5 , 1 9 2 7 , p . 1 6 6 . 5 7 . E . O . H a l l a n d S . H . A l g i e : ' M e t a l l u r g i c a l R e v i e w s ' , v o l . 1 1 , 1 9 6 6 , p . 6 1 . 5 8 . L . S m i t h a n d K . W . J . B o w e n : J o u r n a l o f T h e I r o n a n d S t e e l I n s t i t u t e , M a r c h 1 9 8 4 , p . 2 9 5 . 5 9 . A . J . L e n a : ' M e t a l P r o g r e s s ' , J u l y 1 9 5 4 , p . 8 6 . 6 0 . C . E . S p a e d e r , J r . a n d K . G . B r i c k n e r : A d v a n c e s i n T e c h n o l o g y o f S t a i n l e s s S t e e l s ' , A S T M - S T P 3 6 9 , 1 9 6 5 , p . 1 4 3 . 6 1 . R . B l o w e r a n d G . J . C o x : J o u r n a l o f I r o n a n d S t e e l I n - s t i t u t e ' , A u g . 1 9 7 0 , p . 7 6 9 . 6 2 . F . H . B e c k e t a l . : ' A d v a n c e s i n T e c h n o l o g y o f S t a i n l e s s S t e e l s ' , A S T M - S T P 3 6 9 , 1 9 6 5 , p . 1 5 9 . 6 3 . E . J . D u l i s a n d G . V . S m i t h : ' T h e N a t u r e , O c c u r r e n c e , a n d E f f e c t s o f S i g m a P h a s e ' , A S T M S T P 1 10 , 1 9 5 0 , p . 3 . 6 4 . A S M M e t a l s H a n d b o o k , 8 t h E d i t i o n , v o l . 1 , p . 4 1 9 - 4 2 2 . 6 5 . R . J . G r a y e t a l . : ' J o u r n a l o f M e t a l s ' , N o v . 1 9 7 8 , p . 1 8 . 6 6 . ' H a n d b o o k o f S t a i n l e s s S t e e l s ' , e d s . D . P e c k n e r a n d I . M . B e r n s t e i n , p u b l i s h e d b y M c G r a w - H i l l , p . 1 0 - 1 0 . 6 7 . ' L . C o l o m b i e r a n d J . H o c h n i a u n : ' S t a i n l e s s a n d H e a t R e s i s t i n g S t e e l s ' , p u b l i s h e d b y E d w a r d A r n o l d L t d . , 1 9 6 5 , p . 1 0 9 . 82 6 8 . W. H o l z g r u b e r : P r o c . 5 t h I n t e r n a t i o n a l S y m p o s i u m o n E S R , P i t t s b u r g h , e d s . G . K . B h a t a n d A . S i m k o v i t c h , 1 9 7 4 , p . 7 0 . 6 9 . R . P . D e V r i e s : P r o c 2 n d I n t e r n a t i o n a l S y m p o s i u m o n E S R , P i t t s b u r g h , 1 9 6 9 . 7 0 . H . F r e d r i k s s o n : ' M e t a l l u r g i c a l T r a n s a c t i o n s ' , v o l . 3 , N o v . 1 9 4 2 , p . 2 9 8 9 . . 7 1 . H . F r e d r i k s s o n a n d 0 . J a r l e b o r g : J o u r n a l o f M e t a l s , S e p t . 1 9 7 1 , p . 3 2 . 7 2 . R . O . J a c k s o n a n d A . M i t c h e l l : ' J o u r n a l o f V a c u u m S c i e n c e a n d T e c h n o l o g y 1 , V o l . 9 , n o . 6 , N o v . - D e c . 1 9 7 2 , p . 1 3 0 1 . 7 3 . K . J . I r v i n e e t a l . : ' T h e M e t a l l u r g i c a l E v o l u t i o n o f S t a i n l e s s S t e e l s ' , A S M M e t a l s S c i e n c e S o u r c e B o o k , p . 3 7 9 . 7 4 . W . T . P e l l - W a l p o l e : ' J o u r n a l , I n s t i t u t e o f M e t a l s ' , v o l . 6 9 , 1 9 4 3 , p . 1 3 1 . 7 5 . ASM M e t a l s H a n d b o o k , 9 t h E d i t i o n , v o l . 1 , p . 4 2 7 - 4 2 8 . 7 6 . E S R 4 3 4 0 s t e e l d a t a f r o m C a b o t C o r p o r a t i o n , T e x a s , 1 9 7 7 . 7 7 . B . E . P a t o n e t a l . : P r o c . 2 n d I n t e r n a t i o n a l S y m p o s i u m o n E S R ; , P i t t s b u r g h , 1 9 6 9 . 7 8 . G . K . B h a t : P r o c . 3 r d I n t e r n a t i o n a l S y m p o s i u m o n E S R , P i t t s b u r g h , 1 9 7 1 , p . 2 4 1 . 7 9 . G . K . B h a t : P r o c . 4 t h I n t e r n a t i o n a l S y m p o s i u m o n E S R , J a p a n , J u n e 1 9 7 3 , p . 1 9 6 . 8 0 . G . H o y l e : ' E l e c t r o s l a g R e f i n i n g ' , I r o n a n d S t e e l I n s t i t u t e , L o n d o n , 1 9 7 3 , p . 1 3 6 . 8 1 . B . E . P a t o n e t a l . : ' S p e c i a l E l e c t r o m e t a l l u r g y ' , 1 9 7 2 , K i e v , p . 1 7 4 . 82a TABLES TA8i_E_I_ Rene'iting Log for Stainless Steel ESC Valves Valve No. 5 Valve Mo. 6 Valve No. 7 Valve No. 9 . Valve No. 10 Electrode Material CF-8M Rolled 316 Rolled 316 CF-8M Rolled 316 Electrode Diameter 3.5" (8.9 mm) 3.0" (76.2 mm) . 3.0" (76.2 mm) 3.5" (8.9 mm) 3.0" (76.2 mm) Slag Composition 702CaF2/15%Al203/15%Ca0 70SCaFo/15%A!.„0,/15XCa0 70«CaF2/l 5%A)i,03/15XCaO 70«CaF2/15XAi203/"i 5SCa0 702CaF2/15ftU,u3/153!CaO Slag Weight 6.8 kgs 6.8 kgs 6.6 kgs 6.8 kgs 6.8 kgs Slag Condition Hot, dry, prefused Hot, dry, prefused. Hot, dry, prefused . Hot and dry Hot and dry Average Secondary Current 3.72 KA 2.41 KA 3.50 KA 4.04 KA 3.71 KA Average Voltage 37.1V 38.0 V 38.0 V 3.4 V 37.0 V Average Melt Rate C.942 kg/min 0.83  kg/min 0.868 kg/min 0.86  kg/min 0.88 kg/min — Total Malt Tir.e 88 mins 101 mins 33 mins 17 mins 97 mins Hot Toping Cycle None 6.8 mins at 2.3 KA 6.9 mins at 2.1 KA 6.1 mins at 2.2 KA 5 mins at 2.2 KA Deoxidant A? powder Aa powder As. powder A2 powder Al powder Rate of Deoxidation 1.2 grns/min 1.5 gms/min 1.6 gms/min 1.2 gms/min 1.3 gms/min Heltino Atmosphere Air Partial Argon Partial Argon Partial Argon Partial Argon Al Joying Additions J None None Cr chips at 2.3 gms/mir None FeCr-30;4 gms/min FeMo-<4.5 gms/min CO OJ 84 -TABLE I I F e r r i t e N u m b e r s o f S t a i n l e s s S t e e l C a s t i n g s V a l v e N o . 5 - C F - 8 M ( i ) Spec imen L o c a t i o n F e r r i t e I n d i c a t o r Magne-Gage ( F . N . ) * As C a s t Hea t T r e a t e d As C a s t Hea t T r e a t e d Top C e n t r e Edge * F . N . - F e r r i t e 10<F.N.<15 15<F.N.<20 15<F.N.<20 No. 10<F.N.<15 7.5<F.N.<-10 10<F.N.< 15 9.1 16 .51 1 7 . 1 8 1 .56 1 0 . 6 1 1 . 5 V a l v e N o . 6 - 3 1 6 ( i i ) Spec imen F e r r i t e I n d i c a t o r Magne-Gage ( F . N . ) L o c a t i o n As C a s t Hea t T r e a t e d As C a s t Heat T r e a t e d Top < 0.91 0 . 5 5 C e n t r e F .N.<2 F.N.<>2 0.161 0 . 1 6 M i d - R a d i u s E v e r y w h e r e E v e r y w h e r e 0 . 9 4 0 . 4 3 Edge 0 . 4 0 0 . 4 7 N o . 7 - 3 1 6 + C r ( i i i ) Spec imen F e r r i t e I n d i c a t o r Magne-Gage ( F . N . ) L o c a t i o n As C a s t Heat T r e a t e d As C a s t Hea t T r e a t e d Top 2<F.N.<5 F.N<2 3 . 3 4 1 .37 C e n t r e 2<F.N.<5 5<F .N .<7 .5 5 . 5 6 5 . 2 9 Bo t tom 5<F .N .<7 .5 5<F .N .<7 .5 4 .31 5 . 7 5 M i d - R a d i u s 5<F .N .<7 .5 5<F .N .<7 .5 4 . 7 2 5 . 0 5 Edge 5 < F . N . < 7 . 5 2<F.N.<5 5 . 6 8 3 . 2 8 85 T A B L E I I F e r r i t e N u m b e r s o f S t a i n l e s s S t e e l C a s t i n g s ( C o n t i n u e d ) V a l v e No C F - 8 M ( i v ) Spec imen L o c a t i o n F e r r i t e I n d i c a t o r Magne-Gage ( F . N . ) As C a s t Heat T r e a t e d As C a s t Hea t T r e a t e d Top C e n t r e Bo t tom M i d - R a d i u s Edge 5<F .N .<7 .5 15<F.N.<20 15<F.N.<20 15<F.N.<20 15<F.N.<20 5£F.N<.<7.5 15<F.N.<20 10<F.N.<15 20<F.N.<25 15<F.N.<20 6 . 3 3 1 4 . 8 5 14.71 1 6 . 0 9 1 4 . 7 5 5 . 0 0 1 5 . 3 5 1 2 . 6 2 1 9 . 4 6 15 .81 C o n v e n t i o n a l C a s t i n g - C F - 8 M (v ) Spec imen L o c a t i o n F e r r i t e I n d i c a t o r Magne-Gage ( F . N . ) Hea t I r e a t e d Hea t I r e a t e d Top 3 / 4 H e i g h t C e n t r e 1/4 H e i g h t Bo t tom M i d - R a d i u s Edge 20'<F.N.<25 20<F.N.<25 20<F.N.<25 20<F.N.<25 F<N.<25 15<F.N.<20 20<F.N.<25 2 0 . 5 7 2 0 . 6 7 2 0 . 4 5 1 8 . 9 9 2 6 . 7 8 1 6 . 9 9 2 8 . 7 0 T A B L E I I I A v e r a g e F e r r i t e N u m b e r s o f S t a i n l e s s S t e e l C a s t i n g s D e t e r m i n e d b y M a g n e - G a g e . a n d S c h o e f e r ' s D i a g r a m C a s t i n g As C a s t Hea t T r e a t e d * S c h o e f e r ' s D iag ram V a l v e N o . 5 - (CF-8M) 1 6 . 8 5 1 0 . 8 0 1 6 . 8 V a l v e N o . 6 - (316) 0 . 6 5 0 . 3 5 <-!0 V a l v e N o . 7 - (316+Cr) 5 .07 4 . 8 4 4 . 5 V a l v e N o . 9 - (CF-8M) 1 5 . 1 0 15.81 22 C o n v . C a s t - (CF-8M) - 1 9 . 5 3 32 *F rom Magne-Gage 86 T A B L E IV I n t e r d e n t r i t i c M i c r o s e g r e g a t i o n R a t i o s o f C F - 8 M C a s t i n g s C a s t i n g a n d P o s i t i o n S e g r e g a t i o n R a t i o (C m a x / C m i n ) C h r o m i urn N i c k e l M o l y b d e n u m V a l v e N o . 5 * ( C F - 8 M ) C e n t r e V a l v e N o . 9 * ( C F - 8 M ) E d g e C e n t r e C o n v . C a s t i n g * * ( C F - 8 M ) E d g e M i d - R a d i u s C e n t r e 1 . 3 4 9 1 . 2 5 1 . 1 8 1 . 1 6 7 1 . 3 0 5 2 . 3 3 7 2 . 37 2 . 1 9 2 . 4 8 1 . 6 2 5 2 . 1 7 8 2 . 5 8 7 2 . 1 0 1 . 7 4 2 . 6 0 3 . 5 6 8 3 . 8 5 9 3 . 2 9 9 * i n a s - c a s t c o n d i t i o n * * i n s o l u t i o n - t r e a t e d c o n d i t i o n 87 TABLE V Chemical.Composition of Valve No. 5 (CF-8M) (wt.SS) C Mn Si P S Ni Cr Cu Mo hi Nb Co Ti Zr Electrode 0.06 0.3  1.19 0.027 0.016 10.19 20.31 0.4  2.51 - 0.073 0.108 0.08 0.06 Top 0.086 0.34 1.06 0.021 0.010 10.08 19.48 0.37 2.5  - 0.0C5 0.15 NA* NA* Centre 0.063 0.26 0.74 0.019 0.010 9.80 19.86 0.15 2.53 - 0.060 0.150 11 II Side (L) 0.05  0.25 0.73 0.019 0.09 9.8  19.39 0.16 2.5  - 0.060 0.150 II II Side (R) 0.056 0.26 0.73 0.20 0.010 9.91 19.72 0.16 2.58 • - 0.061 0.158 ••• II N.A. - not analysed TABLE VI Chemical Composition of Value No. 6 (316) '(wt'.*) C Mn Si , P s Ni .Cr . Cu . Mo- A£ . Nb Co Ti Zr Electrode 0.049 1.89 0.67 0.030 0.031 1.60 17.56 0.09 1.98 - 0.062 0.45 0.08 0.06 Top 0.072 1.89 0.64 0.031 0.01 1.91 16.84 0.13 2.1 - 0.061 0.278 N.A.* N.A.* Centre 0.073 1.85 0.64 0.030 0.01 1.80 16.89 0.12 2.09 - 0.059 0.26  II » Botom 0.075 .1.84 0.64 0.03  0.01 1.65 17.09 0.12 2.12 - 0.059' 0.263 " II Side (L) 0.069 1.84 0.63 0.034 0.01 1.42 16.74 0.12 2.05 - 0.061 0.258 II 11 Side.(R) 0.070 . 1.86 0.65 0.031 0.01 1.80 17.08 0.13 2.08 - 0.060 0.283 II II *N.A. - not analysed 88 TAG l E VII Chemical Composition of Valve No, 7 (316-tCr ) (w t. %) C tin Si P , S K i | C r u Ko . A i Nb | Co Ti Zr Electrode 0.019 1.S9 0.67 0.030 0.031 1.60 17. 56 0.09 1 .S3 - 0.052 0.195 0.08 0.06 Top 0.074 1.87 0.61 0.035 0.012 1 .18 .91 0.12 2.01 - 0.061 0.285 (.'.A.* N.A.* Centre 0.078 1.80 0.58 0.029-0.012 n.37' IS.93 O.o2 1.98 - 0.61 0.261 Botom 0.072 1.79 0.5-5 0.036 0.01 1.13 19.25 0.12 2.0  0.60 0.256 II » Side (R) 0.062 1.81 0.57 0.056 0.013 1.26 19.8  0.12 2.01 - 0.61 0.290 - *N.A. - not analysed TABLE VIII Chemical Composition of Valve Ho. 9 (CF-8H) (wt.,%) C Hn Si P S Ni Cr Cu Mo At Nb Co Ti Zr Electrode 0.06  0.3  1.19 0.027 0.016 19.19 20.31 0.1 2.51 - 0.073 0.108 0.08 0.06- Top 0.058 0.35 1.01 0.028 0.09 10.3  19.87 0.10 2.51 - 0.068 0.089 0.013 0.05 "Centre 0.036 0.19 0.6 0.018 0.09 10.15 19.67 0.13 2.5  - 0.060 0.159 0.05 0.01 Botom 0.037 0.27 0.67 0.021 0.09 9.73 20.12 0.15 2.1 - 0.063 0.176 0.05 0.06 Side (L) 0.039 0.21 0.72 0.021 0.09 9.63 20.51 0.13 2.19 - 0.061 0.185 0.05 0.06 Side (R) 0.01  0.20 0.70 0.020 0.09 9.90 20.19 0.13 2.51 - C.063 0.193 0.01 0.06 89.. TABLE IX Chemical Composition of Valve No. 10 (316+Cr+Mo) { v i t . % ) C Mn Si P S Ni Cr Cu Mo At Nb Co Ti Zr Electrode 0.049 1.89 0.67 0.030 0.031-1.60 17.56 0.09 1.98 - 0.062 0.45 0.08 0.04 Top 0.05  1.69 0.43 0.030 0.010 12.10 18.47 0.10 2.32 - 0.063 0.102 0.07 0.05 Centre 0.046 1.65 0.41 0.027 0.01 1.91 19.14 0.07 2.32 - 0.064 0.134 0.07 0.05 Botom 0.051 1.62 0.28 0.027 0.09 12.1  18.78 0.10 2.26 - 0.064 0.127 0.07 0.05 Side (L) 0.048 1.65 0.40 0.028 0.01 1.96 19.2  0.08 2.3  - 0.065 0.13  0.07 0.05 Side (R) 0.040 1.61 0.39 0.024 0.010 1.90 19.05 0.09 2.51 - 0.065 0.135 0.07 0.06 TABLE X Chemical Composition of the Conventional Casting (CF-8M) (wt.SS) C Mn Si . P S Ni Cr Cu Mo An Nb Co Ti Zr Top- 0.029 0.61 1.24 0.027 0.010 9.13 19.41 0.25 2.02 - 0.087 0.067 0.09 0.03 Centre 0.023 0.62 1.21 0.026 0.010 8.90 19.80 0.2  2.0  - 0.086 0.071 0.09 0.03 Botom 0.019 0.65 1.24 0.031 0.010 9.34 19.67 0.23 2.06 - 0.089 0.068 0.08 0.03 Mid-radius 0.024 0.63 1.25 0.029 0.010 9.05 19.85 0.23 2.04 - 0.087 0.072 0.08 0.03 Side (R) 0.020 0.63 1.24 0.031 0.010 9.57 19.36 0.23 2.10 - 0.087 0.06  0.08 0.03 T A B L E X I P e r c e n t c o m p o s i t i o n o f C r a n d Mo i n a r e a s 1 a n d 2 a n d t h e P a r e n t V a l v e N o . 10 A r e a A n a l y s e d C h r o m i urn ( w t . % ) M o l y b d e n u m ( w t . % ) A r e a 1 5 4 . 8 8 1 2 . 5 6 A r e a 2 5 4 . 2 1 1 3 . 1 2 . P a r e n t 2 2 . 1 0 1 . 7 9 T A B L E X I I T e n s i l e P r o p e r t i e s o f V a l v e N o s . 5 , 6 a n d 7 C a s t i n g No. and E l o n a a t i o n In Y i e l d S t r e n g t h , U l t i m a t e T e n s i l e Te s t D i r e c t i o n 1 i n c h (25 .4 mm) 0 2% o f f s e t , S t r e n g t h % K s i ( K P a ) K s i (MPa ) V a l v e No. 5 (CF-8M) L o n a i t u d i n a l - 1 45 3 36 ( 2 5 1 . 7 ) 77. 2 (532 ..3) - 2 51 3 47 3 + 35 8 ( 2 4 6 . 8 ) 37 0f 74 1 ( 5 1 0 . 9 ) 77 .8+ - 3 45 2 38 6 (266 .1 ) 255 \ 82 I ( 5 6 6 . 4 ) 536 . 4 T r a n s v e r s e 1 46 3 36 2 ( 2 4 9 . 6 ) 71 7 ( 4 9 4 . 4 ) - 2 5 3'. 4 50 39 0 ( 2 6 8 . 9 ) 36 9 1 75 3 ( 5 1 9 . 2 ) 7 2 . 6 + - 3 50 6 35 5 ( 2 44 , 8 ) 254 4 70 7 ( 4 8 7 . 5 ) 500 . 6 V a l v e No. 6 (316) L o n g i t u d i n a l - 1 62 1 34 1 (235 .1 ) 71 1 ( 4 9 4 . 4 ) - 2 68 8 64 8 + 31 1 ( 2 18 . 6 ) 32 J . 5 ' 69 7 ( 4 8 0 . 6 ) 6 8 . 3 + - 3 63 6 31 1 ( 2 14 . 4 ) 224 1 64 1 ( 4 4 2 . 0 ) 4 70 . 9 T r a n s v e r s e 1 69 6 32 3 ( 2 2 2 . 7 ) 68 0 ( 4 6 8 . 9 ) - 2 62 4 65 4 + 34 0 ( 234 . 4 ) 32 5 + 69 4 ( 4 7 5 . 8 ) 69 . 3 + - 3 64 1 31 2 ( 2 15 . 1 ) 224 1 70 6 ( 4 8 6 . 8 ) 4 7 7 . 8 Va l v e No. 7 (316+Cr) L o n g i t u d i n a l - 1 51 1 34 9 ( 2 40 . 6 ) 73 6 ( 5 0 7 . 5 ) 71 .7 + _ 2 6 8 . 6 57 J . 9 ' 35. 2 ( 2 42 . 7 ) 34 7 + 68 .4 ( 4 7 1 . 6 ) 494 .4 • - 3 54 0 33 9 ( 2 33 . 7 ) 239 3 73 2 ( 5 0 4 . 7 ) T r a n s v e r s e 1 56 0 ' 34 0 ( 2 3 4 . 4 ) 66 3 ( 4 5 7 . 1 ) - 2 53 4 61 3 + 39 0 (268.9) 35 7  + 75 3 ( 5 1 9 . 2 ) 7 0 . 8 + - 3 74 5 34 2 ( 2 35 . 8 ) 246 2 70 7 ( 4 8 7 . 5 ) 488 . 2 + Ave rage v a l u e . TABLE XI I I Tensile Properties of Valve No. 9, Conventional Casting and ASME/ASTM Standards for AISI 316 and ACI CF-8H Casting No. and Test Direction Reduction In Area, % Elongation In 1 Inch (25.4 mm) X Yield Strength, 0.2% of fset , Ks1 (MPa) Ultimate Tensile Strength Ks1 (MPa) .Valve No. 9 (CF-8M) Lonqltudlnal - 1 80.0 70.7 39.3 (271.0) 82.4 (568.1) - 2 82.0 C l .O* 71.3 71.0 f 42.4 (292.3) 40.9 + 82.1 (566.1) 82.3 f 567.5 Transverse - 1 82.4 70.0 41.8 (288.2) 282.0 82.3 (567.5) - 2 - 3 78.7 77.9 73.0 71.2* 70.5 42.1 (290.3) 42.6 (293.7) 42.4 + 291.0 81.1 (559.2) 83.2 (573.7) 82.2 + 566.8 Edge - 1 79.4 73.7 44.2 (304.8) 86.3 (595.0) - 2 82.0 80.7* . 69.0 71.4 f 42.8 (Z95.1) 43.5 + 315070" 84.5 (582.6) 85.4 + 588.8 t Average value. Conventional Cast (CF-8M) Lonqltudlnal* - 0.25 Inches from the edge 74.3 46.6 57.0 (393.0) 82.5 (568.8) 2.50 " » - • 72.6 52.0 45.0 (310.3) 82.0 (565.4) 4.25 " ' " " " 70.1 58.9 46.7 (322.0) 85.2 (587.5) 6.00 " " " " 62.0 53.Z 46.7 (322.0) 85.8 (591.6) 7.75 " " " " 63.4 56.7 45.9 (316.5) 84.6 (583.3) Transverse* 1.90 Inches from the edge 72.2 58.3 46.4 (319.9) 84.5 (582.6) 3.75 « . . 75.2 55.5 46.0 (317.2) 83.2 (573.7) 5.60 " " " " 65.7 55.3 46.6 (321.3) 84.7 (584.0) * Each value represents an average of 3 tests . ASME SA-182 or ASTM A-18Z-77a(316) 50 (m1n) 30 (min)* 30 (207) m1n 70 (483) min ASME SA-351 or ASTM A-351 r77(CF-8M) not specif ied 30 (min)* . 30 (207) m1n 70 (483) m1n * Elongation 1n 2 Inches (50.8 nm) 10 TABLE X IV . T e n s i l e P r o p e r t i e s o f La rge Spec imens f rom Va l v e Nos. 6 and 9 and Sma l l Specimens f rom a Large Spec imen . C a s t i n g No. and Te s t D i r e c t i o n R edu c t i o n In A r e a , % E l o n g a t i o n In 1 i n c h (25 .4 mm) % Y i e l d S t r e n g t h 0.2% o f f s e t , K s i (MPa) U l t i m a t e T e n s i l e S t r e n g t h Ks i (MPa) Va l v e No. 6 (316) L o n g i t u d i n a l - 1 - 2 - 3 Va l v e No. 9 (CF-8M) L o n g i t u d i n a l - 1 - 2 78 .8 82 . 0 8 1 . 3 f 83 . 0 85 . 2 80 .7 8 3 . 0 + 70.9 69 . 3 6 6 . 0 + 57 . 8 47 .9 4 7 . 5 4 7 . 7 + 32 .6 ( 224 . 8 ) 29 .0 ( 200 . 0 ) 30.9+ 31 .0 ( 213 . 7 ) 2 1 3 - 1 \ 36 .2 ( 249 . 6 ) 36.7+ 37.1 ( 255 . 8 ) 2 5 3 - 0 66 . 8 (460 .6 ) 61 .8 (426 .1 ) 63.7+ 62 .6 (431 .6 ) 4 3 9 - 2 73 .0 (503 .3 ) 73.5+ 74 . 0 (510 .2 ) 5 0 6 - 8 Va l ve No. 9 (CF-8M) (From l a r g e L o n g i t u d i n a l -1 Edge - 1 Edge - 2 Cen t r e - 1 87 .0 87.1 86 24 .2 • 35 .8 73.1 71.1 + 84 .5 38 .7 ( 266 .8 ) 38 .4 ( 264 .8 ) 38.0+ 37 .0 ( 255 .1 ) 2 6 2 - ° 78 .2 (539 .2 ) 73 .0 ( 503 .3 ) 75.0+ 73.7 (508 .2 ) 5 1 7 - 1 t Ave rage v a l u e . TABLE XV Remelting Log for AISI 4340 Steel ESC Valves Valve No. 3 Valve No. 8 Valve No. 1 Valve No. 12 Valve No. 13. Valve No. 14 Electrode Materia"! Rolled 4340 Rolled 4340 Rolled 4340 Soiled 4340 Rolled 4340 Rolled 4340 Electrode Diameter 3.25" (82.6 mm) 3.25" (82.6 mm) 3.25" (82.6 mm) 3.25" (82.6 mm) 3.25" (82.6 mm) 3.25" (82.6 mm) Slag Composition 61.75%CaF2/6.5%M203/ 1.75%Ca0 46%CaF2/17»203/ 17%Ca0/20%La203 46%CaF2/17«At203/ 17%Ca0/20%La203 46XCaF2/mAt203/ 17SSCa0/202La203 46%CaF2/172At203/ mCaO/20XLa203 462CaF2/173!Ai203/ 173XaO/20XLa203 Slag Weight 9.1 kg 6.8 kg 6.8 kg 6.8 kg 6.8 kg 6.8 kg Slag Condition Liquid CaF„, Hot A«203 and CaO Hot and Dry Hot and Dry Hot and Dry . Hot and Dry Hot and Dry Average Secondary| Current 2.73 KA 3.72 KA 3.59 KA 3.60 KA 3.5 KA 3.60 KA j Average ' 1 Voltage 36.9 V 37.1 V 36.9 V 36.8 V 35.4 V 36.0 V Average Melt Rate 1.02  kg/min 0.938 kg/mins . 0.967 kg/min 0.854 kg/min 0.785 kg/min 0.812 kg/min Total Melt Time 87 mins 98 mins 98 mins • 12 mins 13 mins 10 mins Hot Toping Cycle 3.2 mins at 2.6 KA 7.2 mins at 2.2 KA 6.7- mins at 2.2 KA 8.3 mins at 2.2 KA -6.7 mins at 2.2 KA 9  mins at 2.3 KA . Deoxidant At powder At powder At powder At powder At powder At powder Rate of Oeoxidation 2.4 gms/min 1.2 gms/min 1.2 gms/min 1.2 gms/min 1.4 gms/min 1.4 gms/min Melting |Atmosphere Air Partial Argon Partial Argon' Partial Argon Air Air OJ 94 T A B L E X V I I n t e r d e n d r i t i c M i c r o s e g r e g a t i o n a t t h e C e n t r e o f A I S I 4 3 4 0 E S C V a l v e s V a l v e N o . S e g r e g a t i o n R a t f o (C m a x / C m i n ) C h r o m i u m N i c k e l M o l y b d e n u m V a l v e N o . 3 * V a l v e N o . 8 * V a l v e N o . 1 3 * * ( A t m i d - r a d i u s ) V a l v e N o . 1 4 * * 1 . 3 9 1 . 3 4 1 . 1 2 1 . 3 0 1 . 1 3 1 . 1 4 1 . 6 0 1 . 0 5 2 . 1 5 2 . 2 1 1 . 2 4 * I n a s - c a s t c o n d i t i o n * * T h e w h o l e v a l v e w a s h e a t - t r e a t e d . TABLE XVII Chemical Composition of Valve No. 3 (4340) (wt.%) C Mn Si P S Ni Cr Cu Mo An Nb Co V B W Ti Zr Electrode 0.42 0.7  0.37 0.021 0.015 1.87 0.80 0.10 0.21 0.013 0.053 0.029 0.012 0.006 0.018 0.01 0.03 Top 0.42 0.78 0.41 0.021 0.04 1.84 0.83 0.07 0.2 0.095 0.024 0.03 0.017 0.014 0.026 N.A. N.A. Centre 0.40 0.76 ' 0.40 .019 0.04 1.80 0.81 0.08 0.21 0.082 0.023 0.031 0.016 0.01 0.026 II " Botom 0.40 0.73 0.37 0.018 0.04 1.79 0.80 0.08 0.21 0.127 0.020 0.028 0.016 0.013 0.024, II Side (L) 0.40 0.75 0.38 0.018 0.03 1.81 0.81 0.08 0.21 0.085 0.0H 0.028 0.016 0.009 0.02 « •• Side (R) 0.42 0.78 0.40 0.019 0.03 1.83 0.82 0.08 0.2 0.073 0.02; 0.031 0.016' i 0.010 0.024 *N.A. - not analysed C O TABLE XV11I Chemical Composition of Valve No. 8 (4340) (wt.%) C Mn Si P S Ni Cr Cu Mo M Nb Co V B w Ti Zr Electrode 0.42 0.7 0.37 0.021 0.015 1.87 0.80 0.10 0.21 0.031 0.053 0.029 0.012 0.006 0.018 0.01 0.03 Top 0.43 0.80 0.3  0.030 0.04 1.90 0.81 0.1 0.2  0.035 0.056 0.042 0.013 0.007 0.024 0.05 0.04 Centre 0.41 0.7 0.34 0.028 0.04 1.86 0.80 0.1 0.2  0.048 0.056 0.039 0.012 0.007 0.023 0.05 0.04 Botom 0.40 0.75 0.20 0.29 0.03 1.74 0.76 0.10 0.21 0.051 0.052 0.030 0.012 0.005 0.016 0.04 0.03 Side (L) 0.41 0.75 0.34 0.29 0.03 1.80 0.78 0.10 0.21 0.043 0.053 0.032 0.012 0.007 0.016 0.05 0.04 Side (R) 0 '.-41 0.79 0.34 0.28 0.02 1.87 0.81 0.1 0.2  0.045 0.051 0.024 0.012 0.006 0.019 0.04 0.03 LO CXl TABLE XIX Chemical Composition of Valve No. 13 (1310) (wt.%) C Mn Si P S Ni Cr Cu Mo At Nb Co V • B W Ti Zr Electrode 0.42 0.7 0.37 0.021 0.015 •1.87 0.80 0.10 0.21 0.031 0.053 0.029 0.012 0.06 0.018 0.01 0.03 Top 0.43 0.84 0.18 0.030 0.03 1.89 0.86 0.31 0.21 0.020 0.053 0.05 0.01 0.004 0.041 0.03 0.02 Centre 0.42 0.86 0.1 0.030 0.01 1.8 0.86 0.3o 0.21 0.021 0.053 0.057 0.01 0.004 0.04 0.02 0.02 Botom 0.42 0.76 0.04 0.030 0.01 1.79 0.83 0.30 0.21 0.017 0.052 0.059 0.010 0.004 0.039 0.03 0.03 Side (L) 0.40 0.80 0.09 0.029 0.02 1.75 0.82 0.31 0.20 0.021 0.052 0.062 0.01 0.004 0.03 0.04 0.03 Side (R) 0.41 0.82 0.10 0.030 0.02 1.80 0.84 0.31 0.21 0.02 0.05 0.065 0.01 0.004 0.037 0.04 0.03 TABLE X  Chemical Composition of Valve No. 1 4 (4340) (wf.%) C Mn Si P S Ni Cr Cu Mo At Nb Co, V B w Ti Zr Electrode 0.42 0.7 0.37 0.021 0.015 1.87 0.84 0.10 0.21 0.031 0.053 0.029 0.012 0.006 0.018 0.01 0.03 Top 0.4 0.84 0.19 0.03  0.04 1.90 0.86 0.31 0.21 0.018 0.058 0.071 0.012 0.006 0.050 0.03 0.04 Centre 0.45 0.8  0.14 0.032 0.02 1.98 0.8 0.30 0.2 0.02 0.057 0.06 0.012 0.006 0.056 0.01 0.03 Botom 0.46 0.87 0.05 0.03  0.02 2.03 9.90 0.30 0.2 0.013 0.059 0.072 0.012 0.005 0.064 0.01 0.04 Side (L) 0.45 0.89 0.09 0.03  0.02 1.94 0.87 0.31 0.2 0.018 0.059 0.08 0.013 0.006 0.050 0.03 0.04 Side (R) 0.45 0.89 0.09 0.032 0.02 1.97 0.8  0.30 0.2 0.016 0.060 0.090 0.012 0.006 0.05 0.01 0.04 t o 98 TABLE XXI Sulphur Contents of AISI 4340 Electrode and ESC Valves Electrode Valve No. 3 Valve No. 8 Valve No. 13 Valve No. 14 Sulphur Content (wt.%) 0.0146 0.0040 0.0037 0.0055 0.0053 T A B L E X X I I D i m e n s i o n a l Measurements on V a l v e N o s . 1 1 , 12 and 13 Val ve No . S h r i n k a g e Type % S h r i n k a g e and L o c a t i o n ; a b c d e f 9 h i V a l v e No.11 Rea l Pseudo 2 . 3 7 3 . 6 0 2 . 6 8 4 . 1 0 2 . 3 3 3 . 7 5 1 .35 3 . 0 5 1 .97 3 . 0 9 2 . 5 5 4 . 5 5 1 .48 4 . 3 4 1 .67 4 . 1 7 1 .92 4 . 1 2 V a l v e No .12 Rea l Pseudo 1 .87 3 . 3 6 1.07 2.31 1 .72 2 . 8 0 1 .29 2 . 7 0 2 . 3 4 3 . 2 6 0 . 4 7 1 .73 0 . 9 7 2 . 2 2 1 .27 2 . 5 2 1.61 2 . 8 7 V a l v e No. 13 Rea l Pseudo 2 . 4 3 4 . 6 4 2.01 4 . 2 6 2 . 5 3 4 . 2 5 2 . 3 6 4 . 2 2 2 . 2 7 3 . 3 0 . 2 . 1 8 3 . 3 6 2 . 2 3 3 . 3 0 2 . 1 9 3 . 3 7 2 . 9 9 4 . 1 7 TABLE XXIII Tensile Properties of AISI 4340 Electroslag Cast Valves Casting No. and Test Direction Valve No. 3 (a) Longitudinal - Transverse Valve No. 8 (b) Longitudinal - Transverse Edge Valve No. 13 (c) Longitudinal - Transverse Valve No. 13 (d) Longitudinal - Transverse Reduction 1n Area, % 48.0 3.3 30.1 3.9 37.8 36.4 46.0 42.2 47.7 41.8 4.2 4.7 51.3 46.1 7.1 9.4 10.9 1.7 8.7 9.4 39.9 42.0 32.9 31.7 37.11 36.0T 45.3T 43.61 48.7 9.1' 9.9 + 41.0T 32.3T Elongation In 1 inch (25.4 mm), 10.1 7.2 8.5 9.3 1.2 8.4 16.5 14.7 17.9 15.5 17.0 17.8 14.1 17.5 3.7 4.2 5.8 3.5 4.9 4.5 16.7 18.5 17.0 13.3 8.6+ 9.1 + 16.4+ 16.8T 15.8T 4.6 + 4.3 + 17.6T 15.2T Yield Strength 0.2% offset, Ksi (MPa) 174.6 (1197.0) 176.8 (1212.1) 176.2+ 179.1 (1234.9)1214'9 174.0 (119917) 171.8 (1184.6) 172.7+ 172.9 (1187.3) 1190,8 149.9 (1033.6) 149.3 (1029.4) 140.01 150.7 (1039.1)1034'3 151.8 (1046.7) 153.0 (1054.9) 152.6 (1052.2)105K5 152. $ 149.1 (1028.0) 150.5 (1037.7) 149.8 1032.9 120.1 120.1 (828.1) (828.1) 120.1 (828.1) 12.4 (843.9) 120.1 (828.1) 120.1 (828.1) 147.7 (1018.4) 147.3 (1015.6) 146.2 (1008.0) 14.3 (994.9) 120. V 828.1 20.tf 83.6 147.5+ 101.8 Ultimate Tensile Strength Ksi (MPa) 185.1 (1276.3 87.8 (1292.8 18.0 (1296.3 184.1 (1269.4 14.7 (1273.5 182.7 (1259.7 164.7 (130.8 643 (132.8 165.1 (138.4 16.3 (146.5 167.2 (152.8 165.8 (143.2 160.4 (106.0 165.2 (139.1 142.1 138.8 136.6 134.1 135.4 136.8 (979.8 (957.0 (941.9 (924.6 (93.6 (943.2 159.8 (101.8 1017.0| 15g3 (1098.4 145.3+1 157.9 (108.7 15.3 (1070.8 187.0 + 1289.4 183.8+ 1267.3 164.7+ 135.6 16.4' 147.3 62.8 12.5 139.2 959.8 135.4+ 93.6 159.6T 10.4 156.6+ 1079.8 (a) Tempered at 482°C to a hardnes  of 38 Rc. (bj Tempered at 50°C to a hardnes  of 35 Rc. (c) The whole valve was heat-treated and tempered at 560°C. Average hardnes  of the tensile specimens was 31 Rc. (d) The specimen bars were re-heat-treated and tempered at 560°C to a hardnes  of 33 Rc. t Average value. C D C D TABLE XIV Tensile Properties of Conventional AISI 4340 Hot Rolled Bar Specimen No. and Test Direction Reduction In Area, Elongation In 1 inch (25.4 mm) Yield Strength at Lower Yield Point Ksi (MPa) Ultimate Tensile Strength Ksi (MPa) Lonqitudinal - 1 - 2 - 3 Transverse - 1 - 2 - 3 57.7 58.2 57.8+ 57.5 21.9 2,7 22.7f 23.5 19.2 19.5 18.3f 16.2 9.4 9.5 9JS+ 10.5 150.7 (1039.1) 150.0 (1034.3) 150.8+ 151.8 (1046.7)1039'8 150.3 (1036.3) 149.1 (1028.0) 150.2+ 151.3 (1043.2)1035-6 162.8 (1122.5) 164.3 (1132.8) 163.61" 163.6 (1128.0)1,28'° 162.0 (1117.0) 161.1 (1110.8) 162.0+ 162.8 (1122.5)ll7-° (a) Tempered at 560°C to a hardnes  of 3.5 Rc' Diameter of the bar was 3.25 inches (82.6 mm) t Average value. TABLE XV Transverse Tensile Properties of Air Melted and Vacum Arc Melted 4340 Steels Tempering Temperature Reduction % in Area, Elongation In , 2 inches (50.8 m), % Yield Strength Ksi (MPa) Tensile Strength Ksi (MPa) Air Melted 480°C 14 9 8.0 173 (1192.8) 20  (1379) 540°C 22 0 10.0 163 (1123.9) 180 (1241.1) Vacum Arc Remelted 480°C 20 0 9.0 175 (1206.6) 20  (1379) 540°C 24 0 10.5 160 (1103.2) 180 (1241.1) * Properties listed are averages of several heats from the same producer; billet size and amount of hot redi were not available. TABLE XXVI Lonqitudinal Mechanical Properties of Bar Stock Made From Remelted 4340 Steel Melting Method Reduction In Area, % Elongation In 4D. % Yield Strength Ksi (MPa) Tensile Strength Ksi (MPa) Hardnes  (MRc) VAR<b> ESR<C> 61.2 59.0 16.4 16.1 163 (1123.9) 158 (1089.4) 175 (1206.6) 171 (1179.0) 37 37 (a) Bars were normalised at 90°C, oil quenched from 845°C, and tempered 2 hrs. at 541°C. All specimens taken from mid-radius. (b) 3.62 inch round. (c) 4.625 inch round. TABLE XXVII Mechanical Properties of ESR 4340 Material in the Transverse Direction Heat-Treated to Different Strength Levels.*76 Tempering Temperature Reduction in Area, % Elongation - % 0.2* Yield Strength Ksi (MPa) Tensile Strength Ksi (MPa) 538°C 56°C 45.1 49.2 12.9 14.6 169.4 (1168.0) 158.3 (1091.5) 180.6 (1245.2) 173.0 (1192.8) * Data from Cabot Corporation. Notes (1) Tensile data were generated from a 0.357 in. (9m) diameter test fears machined from heat-treated 1-in. diameter transverse bars taken from a. 24-in. diameter ESR ingot forged 3:1 to 14-in. diameter. (2) All samples were normalised at 1750°F (954°C) prior to heat-treating, then austenitized at 1525°F (830°C) and tempered at various temperatures. (3) Tensile values are average of five tests. TABLE XXVII 1 (a) Tensile Properties of Large Specimen from ESC Valve of AISI 4340 Steel. Casting No. and Test Direction Reduction In Area, % Elongation In 3 inches (76.2 mm) % Yield Strength, 0.2% offset, Ksi (MPa) Ultimate Tensile Strength, Ksi (MPa) Valve No. 8* Longitudinal - 1 - 2 48.1. 47.9  1 47.6 19.7 18.1 1' 16.5 14.9 (99.1 ) 145.5' 1  146.0 (1006.7) 1003-2 160.6 (1107.3) 160.5+ 160.3 (1105.3)1106-6 * Tempered at 50°C to a hardnes  of 34.5 Rc. + Average value. T A R I F XXVITTIM Tensile Properties of Small Specimens Cut From Large Tensile Specimens Specimen No. and Test Direction Reduction In Area, % Elongation In 1 inch (25.4 mm) % Yield Strength, 0.2% offset, Ksi (MPa) Ultimate Tensile Strength, Ksi (MPa) Value No. 8 (From Large Longitudinal -1) Edge - 1 Edge - 2 Centre r 1 45.2 48.6 46.5f 45.7 16.7 17.4 17.41 18.0 149.7 (1032.2) 14.7 (997.7) 146.31' 14.5 (996.3)1008'7 164.8 (1136.3) 159.7 (1101.1) 161.4 + 11? 9 159.7 (1101.1) "U o + Average value. 102 T A B L E X X I X F A T T V a l u e s E s t i m a t e d f r o m D u c t i l e B r i t t l e T r a n s i t i o n C h a r a c t e r i s t i c s o f A I S I - 4 3 4 0 E S C V a l v e s a n d E l e c t r o d e , T y p e a n d O r i e n t a t i o n o f S p e c i m e n E s t i m a t e d F A T T V a l v e N o . 3 -- L o n g . - 4 0 ° C E l e c t r o d e - L o n g . - T r a n s . 5 ° C 4 5 ° C V a l v e N o . 8 • - L o n g . . - T r a n s . - T r a n s . - E d g e ( T ) ( L ) - 2 5 ° C - 3 0 ° C - 3 5 ° C - 3 2 ° C V a l v e N o . 1 3 -- L o n g . - T r a n s . 2 0 ° C 2 0 ° C N o t e s : ( 1 ) T h e F A T T v a l u e s h a v e b e e n e s t i m a t e d a c c o r d i n g t o a s u g g e s t e d m e t h o d i n A S T M E 2 3 - 7 2 . ( 2 ) F A T T h a s b e e n d e t e r m i n e d a s t h e t e m p e r a t u r e c o r r e s p o n d i n g t o t h e e n e r g y v a l u e 50% o f t h e d i f f e r e n c e b e t w e e n v a l u e s o b t a i n e d a t 1 0 0 % a n d 0% f i b r o u s f r a c t u r e . ( 3 ) T h e s p e c i m e n s h a v e b e e n a s s u m e d t o b e 1 0 0 % f i b r o u s a t 1 0 0 ° C a n d 0% f i b r o u s a t - 1 0 0 ° C . T h e l a t t e r i s n o t e x a c t l y t r u e a s s o m e a r e a s w e r e f o u n d t o b e d u c t i l e e v e n a t - 1 0 0 ° C . ( 4 ) T h e h i g h F A T T f o r V a l v e N o . 1 3 i s p r o b a b l y d u e t o t h e i n a d e q u a t e h e a t t r e a t m e n t . ( 5 ) T h e s e a r e j u s t e s t i m a t e d v a l u e s a n d n o t e x a c t b e c a u s e o f t h e k i n d o f f r a c t u r e d s u r f a c e ( a s m e n t i o n e d i n t h e t e x t ) . 100a F I G U R E S \ (d) F i g u r e 1 . E l e c t r o s l a g C a s t P r o d u c t s . 8 (a) V a l v e B o d i e s ; (b) R o l l s ; ( c ) D e n t u r e s (d ) C r a n k s h a f t w i t h p i n d i a m e t e r o f 480 mm. 104 1 straight tube, 2 source material, 3 ring- type mould, 4 molten-slag bath, 5 molten- metal pool, 6 slag film, 7 start piece, 8 feed roller for source material, 9 drawing apparatus, 10 electric power source, 11 cool- ing water F i g u r e 2 . ' Y 0 Z 0 ' p r o c e s s o f M i t s u b i s h i H e a v y I n d u s t r i e s L t d : 11 12 p r o d u c t s p i pe , t u b e . ' E L E C T R O D E ^ . „ „ „ . i , POWER SUPPLY TRANSFORMER or RECTIFIER X S L A G P O O L M E T A L P O O L SOLIDIFIED C A S T I N G S L A G SKIN C O O L I N G W A T E R C R U C I B L E B A S E P L A T E F i g u r e 3. S c h e m a t i c o f t h e E S C p r o c e s s o F i g u r e 4 . F r a c t u r e t o u g h n e s s o f E S C A I S I 4 3 4 0 s t e e l 2 c o n t a i n i n g v a r y i n g a m o u n t s o f s u l p h u r . F i g u r e 5 . E l e c t r o s l a g c a s t i n g i n s t a l l a t i o n a t U . B . C . 108 F i g u r e 6. O r t h o g o n a l v i e w s o f E S C v a l v e b o d y . 1 0 9 F i g u r e 7 ( a ) . P l a n v i e w s o f t h e v a l v e m o l d s e g m e n t s . 110 Section A-A Section A'-A1 Figure 7(b). Sections through the valve mold segments. F i g u r e 9 . S l a g m e l t i n g f u r n a c e . F i g u r e 1 0 . S o l i d i f i e d s l a g s k i n o n t h e c a s t i n g . 113 F i g u r e 1 2 . S t a i n l e s s s t e e l ESC v a l v e . 115 F i g u r e 1 3 . L o n g i t u d i n a l h o l e s i n t h e c a s t i n g s d u e t o m o i s t u r e . F i g u r e 1 4 . S c h e m a t i c o f t h e s e c t i o n i n g p r o c e d u r e o f t h e v a l v e s . F i g u r e 1 5 . M a c r o s t r u c t u r e o f V a l v e N o . 5 ( C F - 8 M ) F i g u r e 1 6 . M a c r o s t r u c t u r e o f V a l v e N o . 6 ( 3 1 6 ) . 118 F i g u r e 1 7 . M a c r o s t r u c t u r e o f V a l v e N o . 9 ( C F - 8 M ) . F i g u r e 1 8 . M a c r o s t r u c t u r e o f V a l v e N o . 10 ( 3 1 6 + C r + M o ) . 120 F i g u r e 1 9 . M a c r o s t r u c t u r e o f c o n v e n t i o n a l c a s t i n g ( C F - 8 M ) . 6 4 0 x F i g u r e 2 0 ( a ) . M i c r o s t r u c t u r e o f C F - 8 M E S C v a l v e s b e f o r e h e a t t r e a t m e n t ( e t c h a n t - o x a l i c a c i d ) . 122 6 4 0 x F i g u r e 2 0 ( b ) . M i c r o s t r u c t u r e o f C F - 8 M E S C v a l v e s a f t e r h e a t t r e a t m e n t ( e t c h a n t - o x a l i c a c i d ) . 2 1 0 x 5 4 0 x 1 1 0 0 x F i g u r e 2 1 . M i c r o s t r u c t u r e o f a s - c a s t ESC V a l v e N o s . 5 , 6 and 7 ( e t c h a n t - o x a l i c a c i d ) . Top Row - V a l v e No. 5 ( C F - 8 M ) , M i d d l e Row - V a l v e No . 6 ( 3 1 6 ) , Bo t tom Row - V a l v e No. 7 ( 3 1 6 + C r ) . 124 2 1 0 x 5 4 0 x 1 1 0 0 x F i g u r e 2 2 . M i c r o s t r u c t u r e o f h e a t - t r e a t e d ESC V a l v e N o s . 5 , 6 and 7 ( e c h a n t - o x a l i c a c i d ) . Top Row - V a l v e No. 5 ( C F - 8 M ) , M i d d l e Row - V a l v e No. 6 (316) Bot tom Row - V a l v e No. 7 ( 3 1 6 + C r ) . 125 6 4 0 x 1 3 0 0 x F i g u r e 2 3 . M i c r o s t r u c t u r e o f C F - 8 M s p e c i m e n h e a t e d t o 8 5 0 ° C ( e t c h a n t - K O H ) . l i g h t g r e y a r e a - a u s t e n i t e p h a s e d a r k g r e y a r e a - f e r r i t e p h a s e b l a c k a r e a - s i g m a p h a s e F i g u r e 2 4 . M i c r o s t r u c t u r e o f h e a t - t r e a t e d C F - 8 M c o n v e n t i o n a l c a s t i n g ( e t c h a n t - K O H ) . 127 F i g u r e 2 5 . M i c r o s t r u c t u r e o f V a l v e N o . 9 i n a s - c a s t c o n d i t i o n ( e t c h a n t - K O H ) . 128 F i g u r e 2 6 . M i c r o s t r u c t u r e o f V a l v e N o . 9 i n h e a t - t r e a t e d c o n d i t i o n ( e t c h a n t - K O H ) . 7 0 0 x F i g u r e 2 7 . M i c r o h a r d n e s s i n d e n t a t i o n s o n s i g m a a n d a u s t e n i t e p h a s e s . F i g u r e 2 8 . S c h o e f e r ' s d i a g r a m f o r d e t e r m i n a t i o n o f f e r r i t e n u m b e r s o f s t a i n l e s s s t e e l c a s t i n g s . F i g u r e 2 9 ( a ) . V a r i a t i o n o f C r , Ni and Mo a c r o s s t he d e n d r i t i c d i r e c t i o n i n V a l v e No. 9 a t t h e e d g e . 132 • TRAVEL t H 1-0 mm F i g u r e 29(b) V a r i a t i o n o f C r , N i and Mo a c r o s s t h e d e n d r i t i c d i r e c t i o n i n V a l v e No. 9 a t t h e c e n t r e .   135 • T R A V E L i 1 10 mm. d i r e c t i o n i n c o n v e n t i o n a l c a s t i n g a t t h e c e n t r e O.II6| 0.066 0.016 2.65 2.55 2.45 10.41 9.91 9.41 20.04 19.54 19.04 • • • • • • o 0 0 o 0 —© —8— O — A — 0 — w —9 • o • • o o o - 6 O o 0 8 9 10 II .7 12 13 14 15 8 195 mm. 10 I 2 3 4 / Microprobe 12 13 14 15 C M o Ni Cr E e in _ i _ _ i _ _i_ ^ 1̂" — iDiOuD O IT) O ^ . ° ! ^ . i f i lD — lO — o i c r i b o ^ ° ^ Q cJcvJcvj r i ° ° . CM O O F i g u r e 3 1 . C o m p o s i t i o n v a r i a t i o n i n V a l v e No. 5 ( C F - 8 M ) . (The s o l i d l i n e shows t h e o v e r a l l a v e r a g e c o m p o s i t i o n . ) • • 9 • • • -• • o • • • • • o o m o • o o o O o o o —o o u • • \j • • • • • • • # W W 0 o o o o o o o o - 0 0 o o U - 10 II 12 13 14 15 16 3 17 18 19 20 21 22 23 10 0.089 0.069 0.049 2.13 2.08 2.03 12.19 11.69 11.19 1732 16.82 16.32 295 mm- 12 13 14 15 16 17 18 19 20 21 22 23 cn <r> cr> ^ & 0 0 CD 0 1 m rOCOro srtoco roCOrO ^ <X> 22 Q C2 O Q Q >̂ ^ t : r = ™ c\i o j <\i o d d o 0 F i g u r e 3 2 . C o m p o s i t i o n v a r i a t i o n i n V a l v e No. 6 (316) (The s o l i d l i n e shows t h e o v e r a l l a v e r a g e c o m p o s i t i o n . ) 138 0.094 0.069 0.044 2.05 ZOO 1.95 11.86 11.36 10.86 19.62 19.12 18.62 - o o o o o o o 6 • • * • • _ • o u CJ o o - • • • • • • • • 4 II 12 13 14 15 16 17 c Mo Ni Cr 8 9 10 -155 mm. 12 13 14 16 17 e £ m O CVJ 8 9 10 Cr Ni Mo C C\JC\JC\I co ID co L Q C ; in "tf cn <3- CO _ CD COrOOO CT) CJ O <X> <X> crjcricT) o — — — ^ ^ o o o b o o F i g u r e 3 3 . C o m p o s i t i o n v a r i a t i o n i n V a l v e No. 7 ( 3 1 6 + C r ) . (The s o l i d l i n e shows t h e o v e r a l l a v e r a g e c o m p o s i t i o n . ) 139 0-061 0041 0021 263 2-51 239 10-49 9-99 9 4 9 20-48 19 98 19-48 - - o o o 0 o o ^ n n 0 v—O— 6 o o • • • ° n o - o 0 o o I9|2C|2I |22|23|24|25ll0|26 27 28 29 30|3I 32 Mo Ni Cr microprobe -295 mm. Cr Ni Mo j2\|22|23l24|25 10 26|27|28|29l30|3l|32 E E in N ro 1 o • 2 • 3 > • 0 • 4 0 • o • 5 o m o • 6 < o • 7 0 0 • e 0 o • 9 o o • 10 ( 0 • 11 0 0 • 12 o a • 13 0 > • 14 o o 15 3 • o 16 0 • 0 17 0 • 0 18 I - . ? t i 1 oo oo oo cn cn cn -̂ cn ? t cn if ch w o ch cn o £ ft X o do o oo F i g u r e 3 4 . C o m p o s i t i o n v a r i a t i o n i n V a l v e No. 9 ( C F - 8 M ) . (The s o l i d l i n e shows t h e o v e r a l l a v e r a g e c o m p o s i t i o n . ) 140 0-059 0O49 0-039 289 239 I- 89 12-56 12-06 II- 56 1940 18-90 18-40 - • o • 0 - A • • • W w • - 0 O o o u 0 o O u - n • • • • • • • • • - o Q 0 o "D o o o -o o u 15 1-6 17 18 19 6 20 21 22 23 24 I Q R mrr Mo NI Cr 15 16 17 18 19 10 I I 12 13 14 20 21 22 23 24 E 6 I D Cr NI Mo 1 o • < > • 2 o c » 3 o o • 4 c » c ( » 5 < • 0 • 6 o • 1 ) • 7 o « c • 8 o « c ( 9 o • c • 10 o • c < 1 1 0 • 0 < 12 c • o • 13 ) • 0 • 14 0 1 1 1 * 1 1< 1 1 1 ( »1 O O O <£<0<£ ©0105 t o * - " O p i p c b r o e o cb cb — — OJ men g> oo o 6 6 6 F i g u r e 3 5 . C o m p o s i t i o n v a r i a t i o n i n V a l v e No. 10 (316+Cr+Mo). (The s o l i d l i n e shows t h e o v e r a l l a v e r a g e c o m p o s i t i o n . ) 141 0027 0022 0 017 2 0 8 2 0 3 1-98 9-65 9-15 8 € 5 2019 19-69 1919 • • • o ... ... Q o ° o O O O o O " u o o o • • • o o o 17 18 19 2021 22 23 24 25 26 27 230mm.- 1 2 3 4 5 6 7 8 micr o probe • 9 17 18 19 20 21 2 2 23 24 25 26 27 10 II 12 13 14 15 16 Mo Ni Cr 10 12 13 14 15 16 Cr o 0 o o o _ l _ o o o o o o Ni Mo _i_ O o o o _L •I L —$ — S — 58 ® t o <p 5ch o cb cn ch — CVICVJ CN Q Q SOU CO r-CJ r- CO O 6 F i g u r e ; 3 6 . C o m p o s i t i o n v a r i a t i o n i n c o n v e n t i o n a l c a s t i n g . (The s o l i d l i n e shows t h e o v e r a l l a v e r a g e c o m p o s i t i o n . ) F i g u r e 37. SEM p h o t o g r a p h s o f a g g l o m e r a t e d f e r r o a l l o y p o w d e r i n a r e a 1 i n V a l v e N o . 1 0 . F i g u r e 3 8 . S E M p h o t o g r a p h s o f a g g l o m e r a t e d f e r r o a l l o y p o w d e r i n a r e a 2 i n V a l v e N o . 1 0 . to •E 3 o o o hi • t' »• # » r ; : ..* • J . Parent Metal . ' I . * • 1 Area I Area 2 • •• • t. • •• •» • • • • • • • • ••• • • • * • • • • • • • • • • • • # M » • * • • • • • • • • • » » W • • • • • • • • • • • M * • / K /f\ / K /N /N /K • • • • « • • • • • • A - . . Mo Cr Cr Fe Fe Ni Ni Mo X-ray Energy (K eV) F i g u r e 39. EDXA p l o t s o f a g g l o m e r a t e d f e r r o a l l o y powder i n a r e a s 1 and 2 and t h e p a r e n t m e t a l ( V a l v e No. 1 0 ) . 4^ Areas 18 2 : o u o Fe-Cr Powder A * * • • • /N /K / N /N Mg Al Si S Co Ca Ti X-ray Energy (KeV) Cr Mn Fe Fe cn F i g u r e 40 ( a ) . EDXA p l o t s o f i n c l u s i o n s i n a r e a s 1 and 2 and F e - C r - p o w d e r . Areas I 8 2 • -.v V*.- (A C 3 O o o Fe-Cr Powder v..V.- ••„.••.•. ̂ * • * * M • A • ^ ^ ^ /K /ts. /*> Mg Al Si Ca Co Ti Cr Mn Fe Fe X-ray Energy (KeV) CD F i g u r e 4 0 ( b ) . EDXA p l o t s o f i n c l u s i o n s i n a r e a s 1 and 2 and F e - C r powder . S S Co Co. Fe X-ray Energy ( K e V ) F i g u r e 4 0 ( c ) . EDXA p l o t s o f i n c l u s i o n s i n Fe-Mo powder . F i g u r e 4 1 . M a c r o p o r o s i t y i n t h e C e n t r e o f t h e C F - 8 M e l e c t r o d e . 149 F i g u r e 43 . M a c r o s t r u c t u r e o f t h e CF-8M e l e c t r o d e . ( 5 . 5 x ) 150 F i g u r e 4 4 . I n c l u s i o n s i n t h e e l e c t r o d e p i e c e d r o p p e d i n V a l v e N o . 9 a n d e l e c t r o d e t i p ( o p t i c a l p h o t o - g r a p h s ) . E l e c t r o d e P i e c e 2000 x E l e c t r o d e P i e c e 4000 x E l e c t r o d e T i p 950 x E l e c t r o d e T i p 1900 x P a r e n t C a s t i n g 4000 x P a r e n t C a s t i n g 8000 x F i g u r e 4 5 . I n c l u s i o n s i n t h e e l e c t r o d e p i e c e d r o p p e d i n V a l v e No. 9 , e l e c t r o d e t i p and t h e p a r e n t c a s t i n g ( V a l v e No. 9 ) . Electrode Piece » .* • • *V* •••••• *.* •»... v. c o o o Electrode Tip . .. . * 4s A ^ Al Si P Ti Cr Mn Fe X-ray Energy (KeV) Fe Ni ro F i g u r e 4 6 ( a ) . EDXA p l o t s o f i n c l u s i o n s i n t he e l e c t r o d e p i e c e d r o p p e d i n V a l v e No. 9 and t h e e l e c t r o d e t i p . 1 4\ tt ^ 4* 4> M P S Co Ti Cr Mn Cr Fe Fe Ni X-ray Energy (K eV) co F i g u r e 4 6 ( b ) . EDXA p l o t s o f i n c l u s i o n s i n t h e p a r e n t c a s t i n g ( V a l v e No. 9 ) , 154 F i g u r e 4 7 . S c h e m a t i c t o e x p l a i n t h e p e c u l i a r poo l p r o f i l e o b s e r v e d i n V a l v e No. 9 . 155 u r e 4 8 . M a c r o s t r u c t u r e o f t h e o b s e r v e d i n V a l v e N o . p e c u l i a r p o o l p r o f i l e 9 . ( 5 . 5 X ) 156 I I I S m a l l Spec imen (316. .CF-8M and 4340) L a r g e Spec imen (316 and CF-8M) L a r g e Spec imen (4340 D 0 . 2 5 i n c h e s 1 .00 i n c h e s 0 . 7 5 i n c h e s 6 1 .00 " 4 . 0 0 " 3 . 0 0 " A 1 .25 " 5 . 0 0 " 3 . 7 5 " R 3 / 1 6 " 3 / 4 9 / 1 6 " T 3 / 8 2 2 F i g u r e 4 9 . S c h e m a t i c o f t h e t e n s i l e s p e c i m e n s u s e d . 80h 70 £ 60 ca 50 3 UJ 40 i 30 ca UJ or »- CO 20 10 O Tensile Strength • Yield Strength A Elongation _L 8 10 12 14 FERRITE NUMBER 16 600 500 400 o a. 300 S| or CO 200 100 18 20 F i g u r e . 5 0 . V a r i a t i o n o f t e n s i l e p r o p e r t i e s w i t h f e r r i t e n u m b e r o f s t a i n l e s s s t e e l c a s t i n g s . F i g u r e 5 1 . P h o t o g r a p h o f t h e d e f o r m e d a n d f r a c t u r e d a r e a s o f s m a l l t e n s i l e s p e c i m e n f r o m V a l v e N o . 6 . F i g u r e 5 2 . P h o t o g r a p h o f t h e d e f o r m e d a n d f r a c t u r e d a r e a s o f l a r g e t e n s i l e s p e c i m e n f r o m V a l v e N o . 6 . F i g u r e 5 3 . A I S I 4 3 4 0 E S C v a l v e . F i g u r e 55. R a d i o g r a p h s o f V a l v e N o . 3. 162 163 F i g u r e 57. M a c r o s t r u c t u r e o f V a l v e No. 8 (HC& e t c h ) . F i g u r e 58. M a c r o s t r u c t u r e o f V a l v e No. 13 {HCz e t c h ) . F i g u r e 5 9 . M a c r o s t r u c t u r e o f V a l v e No. 14 (Hc£ e t c h ) ( t o p p a r t e t c h e d f o r a l o n g e r t i m e ) .  F i g u r e 61 . D e n d r i t i c s t r u c t u r e o f V a l v e N o . ( a ) e d g e ( b ) m i d - r a d i u s (c) c e n t r e ( d ) t o p 3 . F i g u r e 6 2 . S u l p h u r p r i n t s o f V a l v e N o . 3 . 169 F i g u r e 6 3 . S u l p h u r P r i n t s o f V a l v e N o . 8 . 170 F i g u r e 64 . V a r i a t i o n o f C r , Ni and Mo a c r o s s t h e d e n d r i t i c d i r e c t i o n i n V a l v e No. 8 . 171 i 1 1-0 mm F i g u r e 6 5 . V a r i a t i o n o f C r , Ni and Mo a c r o s s t h e d e n d r i t i c d i r e c t i o n i n V a l v e No . 1 3 .  173 microprobe 15 16 17 18 19 _7_ _8_ _9_ 10 12 _I3 14 2 d 21 22 23 24 ' E E m rO 1 o » o 2 O I 0 3 » o i I 4 1 ( 3 5 • c < 3 6 » o < 1 7 • o ( 8 J < 3 9 1 J 1 < i 10 4 ( » II o 3 12 3 13 o < 14 i 0 1 1 ^ < 1 tO-r <£> t£> — tO to — to SQQl f ) 00 QO fs_ 00 op ^ CM CM tO rj- o d d — — — o d d o d d F i g u r e 6 7 . C o m p o s i t i o n v a r i a t i o n i n V a l v e N o . 3 . ( T h e s o l i d l i n e s h o w s t h e o v e r a l l a v e r a g e c o m p o s i t i o n . ] 0 4 6 0-41 0-36 0-27 0- 22 0 1 7 1- 94 1-84 1-74 0-84 0-79 0-74 u o u u o u 0 0 u 0 0 0 0 0 0 O o o 0 u 0 0 ° o r> n O n O 16 17 18 192 0 21 22 4 23 24 25 26 27 28 29 Mo Ni Cr 290 mm. 16 17 18 19 20 21 22 12 microprobe 23 2425 26 27 28 29 E E O CD C\J Cr Ni Mo 1 o • < > 2 o • < > 3 3 • < ) 4 < ) < » ( ) ( 5 0 • < > < 6 o • < > { _7 • ( > ( _8 O • ( ) _9 O • ( ) JO 0 • ( > II C • c 12 0 • c 13 o • o 14 o • c •5 0 _. 1 . • I 1 1° 1 1 * 1 <f 0) *t t 't r -OJ p- CO -r CD f> r - co co cn — c\i CVJ ro * * o o o — - - °o 6 6 Q o F i g u r e 68. C o m p o s i t i o n v a r i a t i o n i n V a l v e No . 8. (The s o l i d l i n e shows t h e o v e r a l l a v e r a g e c o m p o s i t i o n . ) 175 0-47 0-42 0-37 026 0- 21 016 1- 94 I 84 1-74 0-90 0-65 0-80 XS—O—O—9 O 9—O D—O 9 ©" _o o o - e - - e - - e - o o o o ~o 19 20 21 22 23 12 24 25 26 27 28 Mo Ni Cr -220 mm.- 20 21 2223 S 8 10 12 13 14 15 16 17 18 microprobe 24 25 26 2728 8 10 12 13 14 15 I6. 17 18 Cr D 0 D 0 o _L _L Ni Mo T " _L o m o tori co NCJ h- §§§ III sSg 8 S S F i g u r e 6 9 . C o m p o s i t i o n v a r i a t i o n i n V a l v e N o . 1 3 . ( T h e s o l i d ' 1 i n e s h o w s t h e o v e r a l l a v e r a g e c o m p o s i t i o n . ) 176 0 5 0 0-45 0 4 0 0 2 7 0- 22 0 1 7 202 1- 97 1-92 0-90 0-88 0-86 ho O O O 0 U ° O O L ) 0 U 0 0 0 0 o o o o o o o o o 21122123^4125 262712 28 2930 31 3233134 MO Ni Cr •295 mm. 2112212324 25E6 27 1 15 16 UJ 18 J9J microprobe 2J28|29|30|3l|32|33|34| Cr Ni Mo C 1 o • c 2 o • c 3 o • c 4 o • c 5 o • c 6 < > < i c 7 < > < < ) 8 < ) • q 9 > 0 10 11 < 0 ) • • < 0 ) 12 ( ) * ( > 13 0 • ( ) 14 o • < > 15 o • < » 16 o • c i £ 0 • ( ) 18 o • < > 19 o • < > 20 1 ? i i i Sfi » Q CO CO CO 6 6 6 CM r- CM cn c n o — —Cvl 0 17  02 2 0- 27  04 0 04 5 0- 50  F i g u r e 7 0 . C o m p o s i t i o n v a r i a t i o n i n V a l v e No. 1 4 . (The s o l i d l i n e shows t h e o v e r a l l a v e r a g e c o m p o s i t i o n . ) ( a ) ( b ) F i g u r e 7 1 . M a c h i n e d A I S I 4 3 4 0 E S C v a l v e 178 F i g u r e 7 2 . S e p a r a t e d s u r f a c e s a l o n g a c r a c k i n V a l v e N o . 1 4 . g u r e 7 3 . H a r d n e s s v a r i a t i o n i n h e a t - t r e a t e d V a l v e N o . 1 3 . 180 I i l l i i • BOTTOM I I I I I L_ 29 30 31 32 33 HARDNESS (Rc) F i g u r e 7 4 . H a r d n e s s v a r i a t i o n i n h e a t - t r e a t e d V a l v e N o . 1 4 . 181 ( c ) 6 4 0 x ( d ) 8 0 0 x F i g u r e 7 5 . M i c r o s t r u c t u r e A I S I 4 3 4 0 v a l v e i n a s - c a s t a n d h e a t - t r e a t e d c o n d i t i o n s ; e l e c t r o d e i n h e a t t r e a t e d c o n d i t i o n , ( a ) , ( b ) a n d ( c ) - E S C V a l v e N o . 8 ( d ) - E l e c t r o d e ( a ) 95 x ( b ) 1 7 5 x ( c ) 8 0 0 x ( d ) 8 0 0 x F i g u r e 7 6 . M i c r o s t r u c t u r e o f A I S I 4 3 4 0 E S C V a l v e N o . 1 3 i n h e a t - t r e a t e d c o n d i t i o n , ( b ) - w h i t e a r e a s - f e r r i t e r s - g r e y a r e a s - b l a c k a r e a s - b a i n i t e ( s h o w n i n ( c ) ) - M a r t e n s i t e ( s h o w n i n ( d ) ) F i g u r e 7 7 . F r a c t o g r a p h s o f l a r g e t e n s i l e s p e c i m e n s o f A I S I 4 3 4 0 f r o m E S C V a l v e N o . 8 . F i g u r e 7 8 . O r i e n t a t i o n o f t h e c h a r p y s p e c i m e n s a n d t h e n o t c h i n V a l v e N o . 8 . 185 40 30 ENERGY (Ft. Lbs.) 20 T — i — r T — r i i i * ESC Valve (Long.) • Electrode (Long.) o Electrode (Trans.) J 1 1 1 L 1 1 1 -100-80-60-40-20 0 20 40 60 80 100 TEMPERATURE (°C) 60 50 40 (Joules) 30 20 10 F i g u r e 7 9 . D u c t i l e B r i t t l e t r a n s i t i o n c h a r a c t e r i s t i c s o f V a l v e No. 3 and t h e e l e c t r o d e . Meat T r e a t m e n t : 1 hour a t 845°C - o i l q u e n c h . Temper a t 482°C t o a h a r d n e s s o f 39 R c . 187 i — i 1 — l — I — i — i — i — i — i — r • Trans. —i—i i i i i i i i i i -100-80-60-40-20 0 20 40 60 80 100 TEMPERATURE (°C) F i g u r e 8 1 . D u c t i l e b r i t t l e t r a n s i t i o n c h a r a c t e r i s t i c s o f V a l v e No. 1 3 . Hea t T r e a t m e n t : 1 hour a t 845°C - o i l q u e n c h . Temper a t 560°C t o a h a r d n e s s o f 35 R c .  65°C 100°C 24°C 65°C 100°C F i g u r e 8 2 . O p t i c a l f r a c t o g r a p h s o f c h a r p y s p e c i m e n s f r o m V a l v e No . 8 t e s t e d a t d i f f e r e n t t e m p e r a t u r e s and o r i e n t a t i o n s . c ) - L d) - E F i g u r e 8 3 . O p t i c a l f r a c t o g r a p h s o f c h a r p y f r o m t h e A I S I 4 3 4 0 e l e c t r o d e , a ) - L o n g . b ) T r a n s . s p e c i m e n s 191 F i g u r e 8 4 . S E M f r a c t o g r a p h s o f c h a r p y s p e c i m e n ( a ) r i d g e a r e a ( b ) m i c r o - c r a c k s . 192 ( c ) 2 1 0 0 x ( d ) 2 0 0 0 x F i g u r e 8 5 . SEM f r a c t o g r a p h s o f d i f f e r e n t r e g i o n s o f a c h a r p y s p e c i m e n . (a ) A r e a 1 ( R i d g e A r e a ) , 'Low E n e r g y F r a c t u r e 1 . (b ) A r e a 2 (Base o f t h e R i d g e ) , 1 I n t e r m e d i a t e E n e r g y F r a c t u r e ' . ( c ) A r e a 3 ( G e n e r a l A r e a ) , ' H i g h Ene rgy F r a c t u r e ' . (d) A r e a 4 ( S h e a r L i p A r e a ) , ' H i g h Ene rgy F r a c t u r e ' . F i g u r e 8 6 . S o v i e t e l e c t r o s l a g c a s t v a l v e . a b fixed (upside down) (a) and moving (b) core die 1-Consumable electrode; 2-Water- cooled mold ( c r y s t a l l i z e r ) ; 3-Slag bath; 4-Metal bath; 5- casting; 6-Die; 7-Seed charge. F i g u r e 8 7 . S c h e m a t i c o f t h e m e t h o d s u s e d f o r m a k i n g h o l l o w E S C v a l v e s . 3 195 F i g u r e 9 0 . M a c r o s t r u c t u r e o f t h e E S C v a l v e w i t h t h e w e l d e d i n s e r t . DO NOT COPY LEAVES 1 9 7 - 2 1 2 . APPENDIX 1 ASME/ASTM SPECIF ICATIONS 197 4SI [AMERICAN NATIONAL] iS lANDAHDl ANSI/ASTM A 351 - 77 Used in USAEC-RDT Standards Standard Specification for A U S T E N I T I C S T E E L C A S T I N G S FOR H I G H - T E M P E R A T U R E S E R V I C E 1 This Standard is issued under the fixed designation A 351; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last.revision. A number in parentheses indicates the year of last rcspproval. 1. Scope 1.1 This specification* covers austenilic steel castings for valves, flanges, fittings, and oiher pressure-containing parts (Note 1) in- tended for high-temper2ture and corrosive service (Note 2). NOTE 1—Carbon steel castings for pressure-con- taining parts are covered by Specification A 2 1 6 , and low.alloy steel castings by Specification A 2 1 7 . NOTE 2— T h e committee formulating this specifi- cation has included 1 7 grades of materials extensively used for the present purpose. It is not the intent that this specification should be limited to these grades. Other compositions will be considered for inclusion by the committee as the need arises. Since these grades possess varying degrees of suitability for high-temperature and corrosion-resistant service, it is the responsibility of the purchaser to determine which grade shall be furnished; due consideration being riven to the requirements of the applicable construc- tion codes. 1.2 Eighteen grades of austenitic steel cast- ings are included in this specification. Selection will depend on design and service conditions, mechanical properties, and the high-tempera- ture and corrosion-resistant characteristics. NOTE 3—The values stated in U.S. customary units are to be regarded as the standard. 2. Applicable Documents 2.1 AS^f Standards: A 216 Specification for Carbon-Steel Cast- ings Suitable for Fusion Welding for High- Temperature Service* A 217 Specification for Martensitic Stainless Steel and Alloy Steel Castings for Pres- sure-Containing Parts Suitable for High- Temperature Service' A 488 Recommended Practice for Qualifi- cation of Procedures and Personnel for the Welding of Steel Castings4 A 703 Specification for General Require- ments Applicable to Steel Castings for Pressure-Containing Parts3 E 109 Dry Powder Magnetic Particle In- spection5 E 138 Wet Magnetic Particle Inspection5 E 165 Recommended Practice for Liquid Penetrant Inspection Method5 2.2 Manufacturers Standardization Society of the Valve and Fittings Industry Standard: SP 55 Quality Standard for Steel Castings for Valves. Flanges and Fittings and Other Components (Visual Method)* 3. General Conditions for Delivery 3.1 Material furnished to this specification shall conform to the applicable requirements of Specification A 703, including the supplemen- tary requirements that are indicated on the purchaser's order. 3.2 The post weld heat treatment require- ments of Supplementary Requirement S l l may be specified when austenitic castings other than HK or H T are to be subjected to severe corrosive service. 'This specification is under the jurisdiction of A S T M Committee A- l on Steel, Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee A01.1S on Castings. Current edition approved Oct. 28, 1977. Published December 1977. Originally published as A 351 - 52 T. Last previous edition A 351 - 76. 'For A S M E Boiler and Pressure Vessel Code applica- tions, see related Specification SA-351 in Section II of that code. ' Annual Book of ASTM Standards. Paris I and 2. 'Annual Book of ASTM Standards, Part 2. ' A nnuol Book of ASTM Standards. Part 11. 'Available from Manufacturers Standardization Society of the Valve and Fillings Industry, 1815 N. Fort Meyer Drive, Arlington. Va. 22209. 1 9 8 4. Ordering Information 4.1 The inquiry and order shall include or indicaf the following: 4.1.1 A description of the casting by pattern number or drawing. Dimensional tolerances shall be included on the casting drawing. 4.1.2 Grade of steel. 4.1.3 Options in the specification. 4.1.4 The supplementary requirements de- sired including the standards of acceptance. 5. Process 5.1 Steel shall be made by the electric furnace process. 6. Heat Treatment 6.1 All castings shall receive a heat treat- ment proper to their design and chemical composition, except the HK and HT grades which shall be furnished in the as-cast condi- tion. 6.2 Grade CD4MCu shall be healed to 2050°F (1120oC) for sufficient time to heat casting uniformly to temperature, furnace cooled to 1900°F (1040°C), held for a mini- mum of 15 min and quenched in water or rapidly cooled by other means so as to de- velop acceptable corrosion resistance. 6.3 The austenitic grades, except Grades HK and HT. shall be solution-treated by the manufacturer. 7. Chemical Requirements 7.1 The steel shall conform to the require- ments as to chemical composition prescribed in Table 1. 8. Tensile Requirements 8.1 Steel used for the castings shall con- form to the requirements as to tensile proper- ties prescribed in Table 2. 9. Flanges 9.1 Flanged castings that have the flanges removed by machining to make welding end A 351 castings shall not be furnished under this speci- fication. 10. Quality 10.1 The surface of the casting shall be ex- amined visually and shall be free of adhering sand, scale, cracks, and hot tears. Other sur- face discontinuities shall meet the visual ac- ceptance standards specified in the order. Visual Method SP 55 or other visual standards may be used to define acceptable surface dis- continuities and finish. Unacceptable visual surface discontinuities shall be removed and their removal verified by visual examination of the resultant cavities. 10.2 When additional inspection is desired, Supplementary Requirements S5, S6, and S10 may be ordered. 10.3 The castings shall not be peened, plugged, or impregnated to stop leaks. 11. Repair by Welding 11.1 Repairs shall be made using pro- cedures and welders qualified under Recom- mended Practice A 488. 11.2 Weld repairs shall be inspected to the same quality standards that are used to inspect the castings. When castings are produced with Supplementary Requirement S5 specified, weld repairs on castings that have leaked on hydro- static test, or on castings in which the depth of any cavity prepared for repair welding exceeds 20 % of the wall thickness or 1 in. (25 mm), whichever is smaller, or on castings in which any cavity prepared for w-elding is greater than approximately 10 in.8 (65 cm*), shall be radiographed to the same standards that are used to inspect the castings. When castings are produced with Supplementary Requirement S6 specified, weld repairs shall be inspected by liquid penetrant examination to the same stan- dards that are used to inspect the castings. NOTE 4—When austenitic steel castings are to be used in services where ihey will be subject to stress corrosion, the purchaser should so indicate in his order and such castings should be solution-heat treated following all weld repairs. SUPPLEMENTARY REQUIREMENTS The following supplementary requirements shall not apply unless specified in the purchase order. A list of standardized supplementary requirements for use at the option of the purchaser is included in Specification A 703. Those which are ordinarily considered suitable for use with this specification are given below. Others enumerated in A 703 may be used with this specification upon agreement between the manufacturer and purchaser. 199 S2. Destruction Tests. 55. Radiographic Inspection. 56. Liquid Penetrant Inspection. S10. Examination of Weld Preparation. S10.1 The method of performing the mag- netic particle or liquid penetrant test shall be in accordance with Method E 109, Method A 351 E 138, or Recommended Practice E 165. S l l . Post Weld Heat Treatment. SI 1.1 All austenitic castings, except Grades HK and HT. which have been subjected to weld repairs shall be given a post weld solu- tion heat treatment. TAni.K. 1 Chemical Hcqiiircmrnls Klcmcnl. % (max. Hsccpt Where Range is (iiven) CI-'.', CI MA Cl rR. CI RA CI'.'M. CF.1MA CI-RM CIRC CI 18 CI 110 CI 120 CK20 11K .10 IIK40 irr.m CI I0MC CN7M C04MC Carbon 0.03 0.0R 0.0.1 0.08 0.08 0.08 0.10 (1.20 0.20 0.25-0.35 0.15-0.45 0.25-0.35 0.10 0.07 0.04 Manganese 1.50 I.JO 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 2.00 1.50 1.50 1.00 Silicon 2.00 2.00 1.50 1.50 2.00 1.50 2.01) 2.00 1.75 1.75 1.75 2.50 1.50 1.50 l.(X) Sulfur 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.04 Phosphorus 0.040 0.040 0.040 0.040 0.040 0.040 0.010 0.040 0.040 0.O40 0.040 0.040 0.040 0.040 0.04 Chromium 17.0- 18.0- 17.0- 18.0- 18.0- 22.0- 22.0- 22.0- 23.0- 23.0- 23.0- 1.1.0- 15.0- 19.0- 24.5- 21.0 21.0 21.6 21.0 21.0 26.0 26.0 26.0 27.0 27.0 27.0 17.0 18.0 22.0 26.5 Nickel 8.0- 8.0- 9.0- 9.0- 9.0- 12.0- 12.0- 12.0- 19.0- 19.0- 19.0- 33.0- 13.0- 27.5- 4.75- 12.0 11.0 13.0 12.0 12.0 15.0 ..15.0 15.0 22.0 22.0 22.0 37.0 16.0 30.5 6.00 Molybdenum 2.0- 20 - 0.50 1.75- 2.0- 1.75- 3.0 3.0 2.25 3.0 2.25 Columbium . . . . . . . . . . . . . . ' . . . . . . . . . . . . . . . . . . . . . " . . . . . . Copper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . J.0- 2.75- 4.0 3.25 * Grade CF8C shall have a columbium contcnl of not less lhan R limes the carbon cnnlcnl but nol over 100 %. " Grade CFI0MC shall have a columbium conlenl of no! less lhan 10 limes the carbon content bul nol over 1.20 %. TABI.F. 2 Tensile Requirement CF3 CF- 3 A ' CFR CF- 8 A ' CF- 3M CT- 3MA CI- RM CIRC CUR CI 110 CI 120 CK20 1IK30 IIK40 11130 CI-- I0MC CN7M CU - 4MCu Tensile .strength, min, ksi 70 77 70 77 70 •80 70 70 65 70 70 65 65 62 65 70 62 100 (MPa) (4851 (530) (4R5) (530) (485) (550) (485) (485) (450) (4R5) (4R5) (450) (4 50) (425) (450) (4R5) (425) (690) Yield strength." min, ksi (MPa) 30 35 30 35 30 37 30 30 2R 30 30 2K 35 35 28 30 25 70 (205) (240) (205) (240) (205) (255) (205) (205) (195) (205) (205) (195) (240) (240) (195) (205) (170) (485) Elongation in 2 in. or 50 35.0 35.0 35.0 35.0 30.0 30.0 30.0 30.0 30 0 30.0 30.0 30.0 10.0 10.0 15.0 20.0 35.0 16.0 mm. min. % Rcduclion of area. min. % * The properties shown are obtained by adjusting the composition within the limits shown in Table t to obtain a fcrritc-ausicnitc ratio that wilt result in the higher ultimate and yield strengths indicated. Because of the thermal instability of Grades CF3A, CF3MA. and CFKA, they arc not recommended for service at temperatures in excess of 800"F (425"C). * Determine by either 0.2 % offset method or 0.5 % cxlcnsion-undc'r-load mclhod. The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, is entirely their own responsibility. 201 (AMERICAN NATIONAL") (STANDARD! ANSI/ASTM A 182-77a .Endorsed by Manufacturers Standardization Society of the Valve and Finings Industry Used in USAEC-RDT standards Standard Specification for F O R G E D OR ROLLED A L L O Y - S T E E L PIPE F L A N G E S , F O R G E D FITTINGS, AND V A L V E S AND PARTS FOR H IGH-TEMPERATURE S E R V I C E 1 This Standard is issued under the fixed designation A 182; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of iast reapprovaj. • 1, Scope 1.1 This specification covers forged low alloy and stainless steel piping components for use in pressure systems. Included are flanges, fittings, valves, and similar pans to specified dimensions or to dimensional stand- ards such as the ANSI specifications that are referenced in Section 2. 1.2 Other forgings for other applications may be made to this specification. 1.3 Thirty-three grades are covered includ- ing sixteen ferritic or. martensitic steels and seventeen austenitic stainless steels. Selection will depend upon design and service require- ments. 1.4 Supplementary requirements are pro- vided for use when additional testing or in- spection is desired. These shall apply only when specified individually by the purchaser in the order. N O T E 1—The values staled in U . S . customary units are to be regarded as the standard. 2. Applicable Documents 2.1 ASTM Standards: A 234 Specification for Piping Fittings of Wrought Carbon Steel and Alloy Steel for Moderate and Elevated Tempera- tures5 A 275 Magnetic Particle Examination of Steel Forgings5 A 370 Mechanical Testing of Steel Prod- ucts4 A 509 Definition of a Steel Forging3 E 30 Chemical Analysis of Steel, Cast Iron. Open-Hearth Iron, and Wrought Iron5 E 165 Recommended Practice for Liquid Penetrant Inspection Method6 E 353 Chemical Analysis of Stainless, Heat-Resisting, Maraging, and Other Similar, Chromium-Nickel-Iron Alloys 5 E 381 Rating Macroetched Steel3-6 2.2 Manufacturers' Standardization Soci- ety of the Valve and Fittings Industry Stand- ard: 7 SP 25 Standard Marking System for Valves, Fittings. Flanges and Unions. 2.3 ASME Boiler and Pressure Vessel Code:* Section IX Welding Qualifications SFA-5.4 Specification for Corrosion-Resist- ing Chromium and Chromium-Nickel Steel Covered Welding Electrodes SFA-5.5 Specification for Low-Alloy Steel Covered Arc-Welding Electrodes 2.4 American National Standards Insti- tute Standards:' B16.5 Dimensional Standards for Steel Pipe Flanges and Flanged Fittings 1 This specification is under the jurisdiction of A S T M Committee A - l on Steel. Stainless Steel and Related A l - loys, and is the direct responsibility of Subcommittee A01.22 on Valves and Finings. Current edition approved Oct. 28. 1977. Published December 1977. Originally published as A 182 - 35 T. Last previous edition A 182 - 77. ' Annual Book of A S T M Standards, Pan 1. ' Annua! Book of A S T M Standards, Pan 5. ' Annual Book of A S T M Standards, Pans 1 , 2 , 3 , 4 , 5 , and 10. • Annual Book of A S T M Standards, Pan 12. • Annual Book of A S T M Standards, Pan 1 ]. ' Available from Manufacturers' Standardization Soci- ety of the Valve and Fittings Industry. 1815 N. Fon Myer Drive, Arlington, Va. 22209. 1 Available from American Societv of Mechanical Engi- neers, 345 E. 47th St., New York. N.Y. 10017. • Available from American National Standards Insti- tute, 1430 Broadway, New York, N. Y . 10018. 2 0 2 B16.ll Forged Steel Fittings, Socket Weld, and Threaded B16.10 Face-lo-Face and End-to-End Di- mensions of Ferrous Valves 3. Basis of Purchase 3.1 Orders for material under this specifica- tion shall include the following information, as necessary, to describe adequately the de-. sired material: 3.1.1 Name of forging, 3.1.2 ASTM specification number includ- • trig grade, 3.1.3 Size and pressure class or geometry, 3.1.4 Quantity, 3.1.5 Test report if required, and 3.1.6 Supplementary requirements, if any. 4. Manufacture , 4.1 The low-alloy ferritic steels may be made by the open-hearth, electric-furnace, or basic-oxygen process. The basic-oxygen process shall be limited to steels containing less than 2 % chromium. 4.2 The stainless steels shall be melted by one of the following processes: (a) electric- furnace (with separate degassing and refining optional); (b) vacuum-furnace; or (c) one of the former followed by vacuum or electro- slag-consumable remelting. Grade XM-27 may be produced by electron-beam melting. 4.3 A sufficient discard shall be made to secure freedom from injurious piping and un- due segregation. . 4.4 The material shall be forged as close as practicable to the specified shape and size. Forged or rolled bar may be used without additional hot working for small cylindrically shaped parts within the limits defined by Specification A 234. 4.5 The finished product shall be a forging as defined by Definition A 509. 5. Heat Treatment 5.1 The ferritic grades and the martensitic grade shall be annealed, or normalized and tempered, except as permitted in 5.2. If fur- nished in the normalized and tempered condi- tion, the tempering temperature for Grades F 1, F 2, F 11 and F 12 shall be not less than 1150°F (620°C). The minimum tempering temperature for Grades F5. F5a, F6a Class 2, F7, F9, F21, and F22 shall be 1250°F A 162 - ' ; v V i - (667°C). Grade F6a Class 1 shall be tern-* pered at not less than 132ST (717°C); Grade F6a Class'3 at not less than 1100°F (593°C); and F6a Class 4 at not less than lOOO'F-. (538°C). 5.1.1 Grade F 6a (martensitic) Classes 1 and 2 need be tempered only, provided the tempering temperature for Class 1 is not less than 1325T (667°C) and for Class 2, not less than 1250°F(667 eC).... 5.1.2 Grade F 6NM shall be furnished in the normalized and tempered condition; the tempering temperature shallbe not less than 1040°F (560eC) nor greater than 1120°F (600oC). 5.2 Liquid quenching followed by temper- ing shall be permitted when agreed to by the purchaser. The same, minimum tempering temperature as specified in 5.1 shall be re- quired for each grade. Parts that are liquid quenched and tempered shall be marked "QT" and shall be inspected for quench cracks by the magnetic particle method in accordance with Method A 275. 5.3 All austenitic material shall be fur- nished in the heat-treated condition. The heat treatment shall consist of heating the material to a minimum temperature of 1900'F (1040°C) and quenching in water or rapidly cooling by other means, except for grades F 321H. F 347H, and F 348H, which shall be solution treated at 1925T (1050°C) min. 5.4 Heat treatment may be performed be- fore machining. "; 6. Chemical Requirements 6.1 The steel shall conform to the require- ments as to chemical composition for the grade ordered as listed in Table 1. For referee purposes, Methods E 30 or E 353 shall be used. - 6.2 Grades to which lead, selenium, or other elements are added for the purpose of rendering the material free-machining shall not be used. 7. Cast or Heat (formerly Ladle) Analysis 7.1 An analysis of each heat of steel shall be made from samples taken preferably dur- ing the pouring of the heat and the results shall conform to Table 1. 8. Product Analysis 8.1 The purchaser may make a product 203 analysis on forgings supplied to this specifica- tion. Samples for analysis shall be taken from midway between the center and surface of solid forgings, midway between the inner and outer surfaces of hollow forgings, midway between the center and surface of full-size prolongations, or from broken mechanical test, specimens. The chemical composition thus determined shall conform to Table 1 with the tolerances as staled in Table 2 or 3. 9. Mechanical Requirements : 9.1 The material shall conform to the re- quirements as to mechanical properties for the grade ordered as listed in Table 4. 9.2 Mechanical test specimens shall be ob- tained from production forgings after heat treatment, or from separately forged test blanks prepared from the stock used to make the finished product. Such test blanks shall receive approximately the same working as the finished product. The test blanks shall be heat-treated with the finished product and shall approximate the maximum cross section of the forgings they represent. 9.3 For normalized and tempered, or quenched and tempered forgings, the central axis of the specimen shall correspond to the 'I* t plane or deeper position in the thickest section, /, of the represented forgings and the gage length shall be at least t distance from a second heat-treated surface. When section thickness or geometry interferes, the speci- men shall be positioned as near as possible to the prescribed location. 9.4 For annealed ferritic and martensitic grades and also for austenitic stainless steels, the test, specimen may be taken from any convenient location, e : 9.5 Tension Tests:] •• •* - ..• 9.5.1 Ferritic and Martensitic Grades — One tension test shall be made for each heat in each heat treatment charge. 9.5.1.1 When the heat-treating cycles are the same and the furnaces (either batch or continuous type) are controlled within ± 25°F" (± 14°C) and equipped with recording pyrome- ters so that complete records of heat treat- ment are available, then only one tension test from each heat of each forging type (Note 2) and section size is required instead of one test from each heat in each heat-treatment charge. --i;.-. A 182 9.5.2 Austenitic Stainless Steel Grades- One tension test shall be made for each heat. N O T E 2 — "Type" in this case is used to describe the forging shape such as a flange, ell, tee, etc. .9.5.3 Testing shall be performed in accord- ance with Methods A 370 using the largest feasible of the round specimens. The gage length for measuring elongation shall be four, times the diameter of the test section. 9.6 Hardness Tests: 9.6.1 Sufficient number of hardness meas- urements shall be made in accordance with Methods A 370 to assure that the forgings are within the hardness limits given for each grade in Table 4. The purchaser may verify that the requirement has been met by testing at any location on the forging provided such testing does not render the forging useless. 9.6.2 When the reduced number of tension tests permitted by 9.5.1.1 is applied, addi- tional hardness tests shall be made on forgings or samples as defined in 9.2. scattered throughout the load (Note 3). At least.eight samples shall be checked from each batch load and at least one check per hour shall be made from a continuous run. When the furnace batch is less than eight forgings, each forging shall be checked. If any check falls outside the prescribed limits, the entire lot of forgings shall be reheat treated and the requirements of 9.5.1 shall apply. N O T E 3—The tension test required in 9.5.1 is used to determine material capability and conform-ance in addition to verifying the adequacy of the heat-treatment cycle. Additional hardness tests in accordance with 9.6.2 are required when 9.5.1.1 is applied to assure the prescribed heat-treating cycle and uniformity throughout the load. ... 10. Retreatment 10.1 If the results of the mechanical tests do not conform to the requirements specified, the manufacturer may reheat treat the forg- ings and repeat the tests specified in Section 9. 11. Finish 11.1 The forgings shall be free of scale, machining burrs which might hinder fit-up, and other injurious imperfections as defined herein. The forgings shall have a workman- like finish and machined surfaces (other than surfaces having special requirements) shall have a surface finish not to exceed 250 AA 2 0 4 (ariihmetic average) roughness height. 11.2 At the discretion of the inspector rep- resenting the purchaser, finished forgings shall be subject to rejection if surface imper- fections acceptable under 11.4 are not scat- tered but appear over a large area in excess of what is considered to be a workmanlike fin- ish. 11.3 Depth of Injurious Imperfections— Linear imperfections shall be explored for depth. When the depth encroaches on the minimum wall thickness of the finished forg- ing, such imperfections shall be considered injurious. 11.4 Machining or Grinding Imperfections Not Classified as Injurious—Surface imper- fections not classified as injurious shall be treated as follows: 11.4.1 Seams, laps, tears, or slivers not deeper than 5 % of the nominal wall thickness or Vi« in. (1.6 mm), whichever is less, need not be removed. If these imperfections are removed, they shall be removed by machin- ing or grinding. 11.4.2 Mechanical marks or abrasions and pits shall be acceptable without grinding or machining provided the depth does not ex- ceed the limitations set forth in 11.4.1. Imper- fections that are deeper than '/it in. (1.6 mm), but which do not encroach on the minimum wall thickness of the forging shall be removed by grinding to sound metal. 11.4.3 When imperfections have been re- moved by grinding or machining, the outside dimension at the point of grinding or machin- ing may be reduced by the amount removed. Should it be impracticable to secure a direct measurement, the wall thickness at the point of grinding, or at an imperfection not required to be removed, shall be determined by deduct- ing the amount removed by grinding from the nominal finished wall thickness of the forg- ing, and the remainder shall be not less than the minimum specified or required wall thick- ness. 12. Repair by Welding 12.1 Weld repairs shall be permitted (see Supplementary Requirement S7) at the dis- cretion of the manufacturer with the following limitations and requirements: 12.1.1 The welding procedure and welders shall be qualified in accordance with Section A 182 IX of the ASME Boiler and Pressure Vessel Code. 12.1.2 The weld metal shall be deposited using the electrodes specified in Table 5. The electrodes shall be purchased in accordance with ASME Specifications SFA-5.4 or SFA- 5.5. 12.1.3 Defects shall be completely re- moved prior to welding by chipping or grind- ing to sound metal as verified by magnetic particle inspection in accordance with Method A 275 for the ferritic or martensitic grades, or by liquid penetrant inspection in accordance with Recommended Practice E 165 for ferritic, martensitic, or austenitic grades. 12.1.4 After repair welding, the welded area shall be ground smooth to the original contour and shall be completely free of de- fects as verified by magnetic-particle or liq- uid-peneirant inspection, as applicable. 12.1.5 The preheat, interpass tempera- ture, and post-weld heat treatment require- ments given in Table 5 shall be met. 12.1.6 Repair by welding shall not exceed 10 % of the surface area of the forging nor 33 >h % of the wall thickness of the finished forging or  llt in. (9.5 mm), whichever is less, without prior approval of the purchaser. 12.1.7 When approval of the purchaser is obtained, the limitations set forth in 12.1.6 may be exceeded, but all other requirements of Section 12 shall apply. 13. Marking 13.1 Identification marks consisting of the manufacturer's symbol or name, designation of service rating, the specification number, the designation, F 1, F 2, etc.. showing the grade of material, and the size shall be legibly stamped on each forging or the forgings may be marked in accordance with Standard SP 25 of the Manufacturers' Standardization Soci- ety of the Valve and Fittings Industry, and in such position so as not to injure the useful- ness of the forging. 13.1.1 Quenched and tempered ferritic or martensitic forgings shall be stamped with the letters QT following the ASTM designation. 13.1.2 Forgings repaired by welding shall be marked with the letter "W" following the ASTM designation. 13.1.3 When test reports are required, the 2 0 5 0» markings shall consist of the manufacturer's symbol or name, the grade symbol, and such other markings as necessary to identify the part with the test report (13.1.1 and 13.1.2 shall apply). 14. Inspection 14.1 The manufacturer shall afford the pur- chaser's inspector all reasonable facilities necessary to satisfy him that the material is being furnished in accordance with the pur- chase order. Inspection by the purchaser shall not interfere unnecessarily with the man- ufacturer's operations. All tests and inspec- tions shall be made at the place of manufac- ture unless otherwise agreed upon. 15. Certification 15.1 For forgings made to specified dimen- sions, when agreed upon by the purchaser, and for forgings made to dimensional stand- ards, the application of identification marks A 182 as required in 13.1 shall be the certification that the forgings have been furnished in ac- cordance with the requirements of this specifi- cation. 15.2 Test reports, when required, shall in- clude certification that all requirements of this specification have been met, the results of all required tests, and 'the type of heat treatment. 16. Rejection 16.1 Each forging that develops injurious defects during shop working operations or in service shall be rejected and the manufac- turer notified. 17. Rehearing 17.1 Samples representing material re- jected by the purchaser shall be preserved until disposition of the claim has been agreed upon by the manufacturer and the purchaser. SUPPLEMENTARY REQUIREMENTS The following supplementary requirements shall apply only when specified by the purchaser in the inquiry, contract, and order. » 51. Macroetch Test Sl.l A sample forging shall be sectioned and etched to show flow lines and internal imperfections. The test shall be conducted according to Method E 381. Details of the test shall be agreed upon between the manu- facturer arid the purchaser. 52. Product Analysis S2.1 A product analysis in accordance with Section 8 shall be made from one ran- domly selected forging representing each size and type (Note 2) of forging on the order. If the analysis fails to comply, each forging shall be checked or the lot rejected. All re- sults shall be reported to the purchaser. 53. Heat Identification and Tension Tests S3.1 In addition to the requirements of Sec- tion 9, the heat identification shall be marked on each forging and one tensile specimen shall be obtained from a representative forg- ing from each heat at a location agreed upon between the manufacturer and the purchaser. The results of the test shall comply with Ta- ble 4 and shall be reported to the purchaser. 54. Magnetic Particle Examination S4.1 All accessible surfaces of the finished forging shall be examined by a magnetic-parti- cle method. The method shall be in accord- ance with Method A 275. Acceptance limits shall be as agreed upon between the manufac- turer and purchaser. 55. Liquid Penetrant Examination S5.1 All accessible surfaces shall be exam- ined by a liquid penetrant method in accord- ance with Recommended Practice E 165. Ac- ceptance limits shall be as agreed upon be- tween the manufacturer and the purchaser. 56. Hydrostatic Testing S6.1 A hydrostatic test at a pressure agreed upon between the manufacturer and the purchaser shall be applied by the manufac- turer. 206 • 4SID S7. Repair Welding S7.1 No repair welding shall be permitted without prior approval of the purchaser. If permitted, the restrictions of Section 12 shall apply- A 182 S8. Heat Treatment Details S8.l The manufacturer shall furnish a de-' tailed test report containing the information required in 15.2 and shall include all pertinent details of the heat-treating cycle given the forgings. ; TAM.F, I Chemical Requirement* Identi- fication Symbol Composition. % Grade Phos- Carbon Manganese phorus. max Sulfur, max Silicon Nickel Chromium Molybdenum Colum- bium plus Tanta- lum Tanta- lum, max Tita- nium Ferritic Steels F 1 carbon-molybdenum 0.28 max 0.60-0.90 0.045 0.045 0.15-0.35 0.44-0.65 F 2« 0.5 % chromium, 0.5 % molyb- 0.21 max 0.30-0.80 0.040 0.04(1 0.10-0.60 0.50-0.81 0.44-0.65 denum F3» 4 to 6 % chromium 0.15 max 0.30-0.60 0.030 0.030 0.50 max 0.50 max 4.0-6.0 0.44-0.65 F 5a* 4 to 6 % chromium 0.25 max 0.60 max 0.040 0.0.30 0.50 max 0.50 max 4.0-6.0 0.44-0.65 F6a 13 % chromium 0.15 max 1.00 max 0.040 0.030 1.00 max 0.50 max 11.5-13.5 F 6 b 13 % chromium, 0.5 % 0.1S max 1.00 max 0.02 0.02 1.0 max 1.0-2.0 11.5-13.5 0.40-0.60 molybdenum F 6NM 13 % chromium. 4 % nickel 0.06 max 0.50-1.00 0.030 0.030 0.30-0.60 3.50-4.50 12.00-14.00 0.30-0.70 F 7 6 to 8 % chromium 0.15 max 0.30-0.60 0.030 0.030 0.50-1.00 6.0-8.0 (1.44-0.65 F 9 9 % chromium 0.15 max 0.30-0.60 0.030 0.030 0.50-1.00 8.0-10.0 0.90-1.10 F 11 1.25 % chromium, 0.5 % mo- 0.10-0.20 0.30-0.80 0.040 0.040 0.50-1.00 1.00-1.50 0.44-0.65 lybdenum F 12 1 % chromium, 0.5 % molyb- 0.10-0.20 0.30-0.80 0.040 0.040 0.10-0.60 0.80-1.25 0.44-0.65 denum F 21 chromium-molybdenum 0.15 max 0.30-0.60 0.040 0.040 0.50 max 2.65-3.35 0.80-1.06 F 22 chromium-molybdenum 0.15 max 0.30-0.60 0.040 0.040 0.50 max 2.00-2.50 0.87-1.13 F XM-27* 27 chromium, 1 molybdenum 0.010 max 0.40 max 0.020 0.020 0.40 max 0.50 max 25.00-27.50 0.75-1.50 F 429 15 chromium 0.12 max 1.00 max 0.040 0.030 0.75 max 0.50 max 14.0-16.0 F430 17 chromium 0.12 max 1.00 max 0.040 0.030 0.75 max 0.50 max 16.0-IR.O Other Elements Cu 0.50 max Other F.lcmcnts N 0.015 max Cu 0.20 max CO t o Austenitic Steels F 304 18 chromium, S nickel 0.08 max 2.00 max F 30411 18 chromium, 8 nickel 0.04-0.10 2.00 max F304L 18 chromium, 8 nickel, low car- 0.035 max 2.00 max bon F304N' 18 chromium, 8 nickel, modi- 0.08 max 2.00 max Tied with nitrogen F.1I0 25 chromium, 20 nickel 0.15 max 2.00 max F316 18 chromium, 8 nickel, modi- 0.08 max 2.00 max Tied with molybdenum F 31AM 18 chromium, 8 nickel, modi- 0.04-0.10 2.00 max fied with molybdenum F 3 I 6 L 18 chromium, 8 nickel, modi- 0.035 max 2.00 max Tied with molybdenum, low carbon 0.040 0.030 1.00 max 8.00-11.00 IR.00-20 0.040 0.030 1.00 max 8.00-11.00 IR.00-20 0.040 0.030 1.00 max 8.00-13.00- 18.00-20. 0.030 0.030 0.75 max 8.00-10.50 18.00-20. 0.040 0.040 0.030 1.00 max 19.00-22.00 24.00-26 0.030 i.OOmax 10.00-14.00 16.00-18, 0.04 0 0.030 I.OOmax 10.00-14.00 16.00-18 0.040 0.030 I.OOmax 10.00-15.00 16.00-18. 00 . . . 00 . . . 00 . . . .00 . . . .00 . . . ,00. 2.00-3.00 00 2.00-3.00 00 2.00-3.00 O <1 TAIiLF. i Continued Identi- fication Symbol Composition. % Gnulc Carbon Phos- Manganese phorus, max SulHir. max Silicon Nickel Chromium Molybdenum Colli m- bium plus 'Ianta- lum Tantn- lum, max Tiln- nium F316N ' 18 chromium, 8 nickel, modi- 0.08 max 2.00 max 0.030 0.030 0.75 max 11.00-14.00 16.00-18.00 fied with molybdenum and ni- trogen F 321 18 chromium, 8 nickel modified with titanium 0.08 max 2.00 max 0.030 0.030 1.00 max 9.00-12.00 17.00 min F 32111 ]R chromium, 8 nickel, modi- fied with titanium 0.04-0.10 2.00 max 0.030 0.030 1.00 max 9.00-12.00 17.00 min F347 18 chromium, R nickel modified with columbium 0.08 max 2.00 max 0.030 0.030 1.00 max 9.00-13.00 17.00-20.00 F 34711 18 chromium, 8 nickel, modi- fied with columbiuni 0.04-0.10 2.00 max 0.030 0.030 1.00 max 9.00-13.00 17.00-20.00 F348 IR chromium, 8 nickel modified with columbium 0.08 max 2.00 max 0.030 0.030 1.00 max 9.00-13.00 17.00-20.00 F 348H IR chromium, R nickel, modi- fied with columbium 0.04-0.10 2.Of) max 0.030 0.030 1.00 max 9.00-13.00 17.00-20.00 F X M - 1 9 22 chromium, 13 nickel, 5 man- 0.06 max 4.00-6.00 0.040 0.030 1.00 max 11.50-13.50 20.50-23.50 ganese -3.00 -3.00 0.10-0.30 Other Elements N 0.20-0.40 V 0.10-0.30 F 10 20 nickel, 8 chromium t 0.10-0.20 0.50-0.80 0.030 0.030 1.00-1.40 19.00-22.00 7.00-9.00 * Grade F 2 was formerly assigned lo the I % chromium, 0.5 % molybdenum grade which is now Grade F 12. * The present grade F 5a (0.25 max carbon) previous to 1955 was assigned the identificatiop symbol F 5. Identification symbol F 5 in 1955 was assigned lo the 0.15 max carbon grade to be consistent with ASTM specifications for other products such as pipe, lulling, boiling, welding fittings, etc. c Grade F XM-27 shall have a nickel plus copper content of 0.50 max % . Product analysis tolerance over the maximum specified limit for carbon and nitrogen shall be 0.002 %. * Grades F 304N and F 3I6N shall have a nitrogen content of 0.10 to 0.16 %. ' Grade F 321 shall have a titanium content of not less than five times the carbon content and not more than 0.60%. 'Grade F 321H shall have a titanium content of not less lhan 4 times the carbon conlcnl and not more lhan 0.60 %. * Grades F 347 and F 348 shall have a columbium plus tantalum conlcnl of not less than ten limes the cnrbon content and not more lhan 1.00 %. * Grades F 34711 and F 348H shall have a columbium plus tantalum content of not less than 8 times Ihc carbon content and nor more lhan 1.00 %. 209 iSlI5 A 182 T A B L E 2 Product Analysis Tolerances for Low-Alloy Steels Element Limit or Maximum of Tolerance Over Maximum Limit or Under Minimum Limit for Size Ranges Shown. * • Specified Range, % 100 in. 1 (6.45 x 10* mm«). or less Over 100 to 200 in.' (1.290 x lO* mm'), incl Over 200 to 400 in.' (2.58! x 10= mm'), incl Over 400 in.' Manganese to 0.90 incl 0.03 0.04 0.05 0.06 over 0.90 to I.00 incl 0.04 0.05 0.06 0.07 Phosphorus to 0.045 incl 0.005 0.010 0.0)0 0.010 Sulfur to 0.045 incl 0.005 0.010 0.010 0.010 Silicon to 0.40 incl 0.02 0.02 0.03 0.04 over 0.40 to l.OO incl 0.05 0.06 0.06 0.07 Nickel to 0.50 0.03 0.03 0.03 0.03 Chromium to 0.90 incl 0.03 0.04 0.04 0.05 over 0.90 to M O incl 0.05 0.06 0.06 0.07 over 2.10 to 3.99 incl 0.10 0.10 0.12 ' 0.14 Molybdenum to 0.20 incl 0.01 0.01 0.02 0.03 over 0.20 to 0.40 incl 0.02 0.03 0.03 0.04 over 0.40 to LIS incl 0.03 0.04 0.05 0.06 •.Cross-seciionaJ area 210 lull? A 182 T A B L E 4 Tensile and Hardness Requirements T.„,;I. c, , .„„-v Yield Strencih. Elongation in c . • , Brinell Hard-r-.A- c. _ u , i tensile Mrenpin, , . , ., . r « Reduction of X. , Grade Symbol . w ; , W c L , mm. ksi (MPa) 2 in. or 50 mm. Zj' A ness Number, mm. ksi (MPa) (0.2 * offset) m i n , * Area, min, % m a x Fcrriiic Steels: F 1 70 (483) 40(276) 25.0 35.0 143-192 F 2 70(483) 40 (276) 20.0 30.0 143-192 F 5 70 (483) 90 (621) 40 (276) 20.0 35.0 143-217 F 5a 65 (44 S) " 22.0 50.0 187-248 F 6a Class 1 70 (483) 40 (276) 18 35.0 143-187 F 6a Class 2 85(586) 55 (379) IS 35.0 167-229 F6a Class 3' 110 (758) 85 (586) 18 35.0 207-302 F 6a Class 4' 130 (896) 1 10 (758) 18 35.0 263-321 F 6b 110-135 (758-930) 90 (621) 16 45.0 235-285 F 6NM 110-135(758-930) 90 (621) 15 35.0 235-285 F 7 70 (483) 40(276) 20.0 35.0 143-217 F 9 85 (586) 55(379) 20.0 40.0 179-217 F 11 70 (483) 40 (276) 40(276) 20.0 30.0 143-207 F 12 70 (483) 20.0 30.0 143-207 F 21 75 (517) 45 (310) 20.0 30.0 156-207 F 22 75 (517) 45 (310) 20.0 30.0 156-207 F XM-27 60 (414) 35 (241) 20.0 45.0 190 max F429 60(414) 35(241) 20.0 45.0 190 max F 4 30 60(414) 35 (241) 20.0 45.0 190 max \usienitic Steels: F 304 75 (517)" 30 (207) 30 50 F 304'H 75 (517f 30 (207) 30 50 F 304L 70 (483)° 25 (172) 30 50 F 504 N 80 (552) 35(241) 30" 50 1 F310 75 (517)- 30 (207) 30 50 F 316 75 (S17)r 30 (207) 30 50 F 316H 75 (517F 30 (207) 30 50 F 316L 70 (483^ 25 (172) 30 50 F 316N 80 (552) 35 (241) 30" 50" F 347 75 (517)" 30 (207) 30 50 F 347H 75 (517)° 30 (207) 30 50 F 348 75 (517)" 30(207) 30 50 F 34SH 75(517)" 30 (207) 30 50 F 321 75 (517f 30 (207) 30 50 F 321H 75 (517)° 30 (207) 30 50 F XM-19 100 (690) 55 (380) 35 55 F 10 80(552) 30 (207) 30 50 • For sections over 5 in. in thickness, the minimum tensile strength shall be 70 ksi (483 MPa). ' For sections over 5 in. in thickness, the minimum tensile sttength shall be 65 ksi (448 MPa). ' Longitudinal. The transverse elongation shall be 25 % in 2 in. or 50 mm, min. ' Longitudinal. The transverse reduction of area shall be 45 % min. ' No weld repair is permitted for these classes. 211 iSlfr A182 TABLE 3 Product Analysis Tolerances for Higher A Do; and Stainless Steels" Elements Limit or Maximum of Specified Range, % Tolerance Over the Maximum Limit or Under the Minimum Limit Carbon 0.030, ind over 0.030 to 0.20 ind 0.005 0.01 Manganese to 1.00, ind over 1.00 to 2.00, ind 0.03 0.04 Phosphorus to 0.040, ind 0.005 Sulfur to 0.030, ind 0.005 Silicon to 1.00, ind over 1.00 to 1.40, ind 0.05 0.10 Chromium over 4.00 to 10.00, ind 0.10 over 10.00 to 15.00, ind 0.15 over 15.00 to 20.00, ind 0.20 over 20.00 to 27.50, ind 0.25 Nickel to 1.00, ind 0.03 over 1.00 to 5.00, ind 0.07 over 5.00 to 10.00, ind . 0.10 over 10.00 to 20.00, ind 0.15 over 20.00 to 22.00, incl 0.20 Molybdenum over 0.20 to 0.60, incl 0.03 over 0.60 to 1.75. ind 0.05 over 1.75 to 3.00, ind ..10 Titanium aU ranges 0.05 Columbi urn- aU ranges 0.05 tantalum 0.02 Tantalum to 0.10, ind Cobalt 0.05 to 0.20, ind 0.01» Nitrogen to 0.16, ind 0.01 « This table does not apply to heat analysis. ' Product analysis limits for cohalt under 0.05% have not been established and the producer should be consulted for those limits. 212 # A 182 T A B L E 5 Repair Welding Requirements Grade Symbol Ferritic Steels: F 1 F 2 F 5 F 5a F 6 a F 6b F 6NM F 7 F 9 F 11 F 12 F 21 F 11 F XM-27 F429 F430 Austenitic Steels: F304 F 304L F 304H F 304N F 310 F316 F 316L F 316K F 31bN F 321' F321H ' F347 F 347H F34S F34SH F XM-19 F 10* Electrodes* Recommended Preheat and Inter- pass Temperature Range; 0 F C O Minimum Post Weld Heat- Treatment Temperature °F 0 Q E 7018-A 1 E 801 g-B 1 E 502-15 or 16 E 502-15 or 16 E 410-15 or 16 13 % Cr, l'/j % Ni , '/.- % Mo 13 % Cr , 4 % Ni E 7 Cr-15 E 505-15 or 16 E 8018-B 2 E 8018-B 2 E9018-B3 E 9018-B 3 26 * Cr , 1 % Mo E 430-16 E 430-16 E 308-15 or 16 E 308L-15 or 16 E 308-15 or 16 E 308-15 or 16 E 310-15 or 16 E 316-15 or 16 E 3I6L-15 or 16 ~ E 316-15 or 16 E 316-15 or 16 E 347-15 or 16 E 347-15 or 16 E 347-15 or 16 E 347-15 or 16 E 347-15 or 16 E 347-15 or 16 XM-J9W 200-400 (95-205) 300-600 (150-315) 400-700 (205-370) 400-700 (205-370) 400-700 (205-370) 400-700 (205-370) 300-700 (150-370) 400-700 (205-370) 400-700(205-370) 300-600(150-315) 300-600(150-315) 300-600(150-315) 300-*00(150-315) NR< 400-700 (205-370) NR NR NR NR NR NR NR NR NR NR NR NR NR NR N R NR NR NR 1150 (620) 1150(620) 1250 (677) 1250 (677) 1400 (760) 1150 (620) 1050 (565) 1250 (677) 1250 (677) 1150 (620) 1150 (620) 1250 (677) 1250 (677) NR 1400 (760) 1400 (760) 1900(1040) + WQ< 1900(1040) + WQ 1900(1040) + WQ 1900(1040) + WQ 1900(1040) + WQ 1900(1040) + WQ 1900(1040) + WQ 1900(1040) + WQ 1900(1040) + WQ 1900(1040) + WQ 1925 (1050) + WQ 1900(1040) + WQ 1925 (1050) + WQ 1900(1040) + WQ 1925 (1050) + WQ NR NR • Electrodes shall comply with A S M E SFA 5.4 or SFA 5.5. • Purchaser approval required. ' NR = not required. • WQ = water quench. TntArntricanSo^ryforTts,^

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