UBC Theses and Dissertations
Strengthening of ferrite due to dispersions of seond phase particles Pattanaik, Suryanarayan
Room temperature tensile tests were performed on aged Fe-Cu and tempered Fe-C martensites to study the strengthening of ferrite, due to dispersions of non-coherent second phase particles over a range of particle sizes. Electron Microscopy was used to determine the structure parameters. Strengthening was observed-in both the aged Fe-Cu, with a soft second phase and the tempered Fe-C martensite with a hard second phase dispersion. In the aged Fe-Cu, the yield strength seems to be due to the bowing out of dislocations between particles - an Orowan- type of mechanism where as in the tempered Fe-C martensite, the strengthening is possibly due to several mechanisms involving cementite dispersions, grain boundaries and excess carbon in solution. Aged Fe-Cu, did not exhibit any appreciable increase in work hardening over that of pure iron. But in the tempered Fe-C martensite, the work hardening was higher than that of pure iron and increased with cementite particle size. It was not possible to explain the observed work hardening behaviour with the help of the existing work hardening theories.
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