[{"key":"dc.contributor.author","value":"Park, Joong Kil","language":null},{"key":"dc.date.accessioned","value":"2009-10-01T19:38:23Z","language":null},{"key":"dc.date.available","value":"2009-10-01T19:38:23Z","language":null},{"key":"dc.date.issued","value":"2002","language":null},{"key":"dc.identifier.uri","value":"http:\/\/hdl.handle.net\/2429\/13475","language":null},{"key":"dc.description.abstract","value":"Thermo-mechanical phenomena during continuous thin slab casting have been studied\r\nwith the objectives of understanding the mechanism of mold crack formation, and the\r\neffect of mold design upon the mechanical behavior of the stand. To achieve these goals,\r\nseveral finite element models have been developed in conjunction with a series of\r\nindustrial plant trials.\r\nFirst, an investigation of mold crack formation in thin slab casting was undertaken to\r\nelucidate the mechanism by which cracks develop and to evaluate possible solutions to\r\nthe problem. Three-dimensional finite-element thermal-stress models were developed to\r\npredict temperature, distortion, and residual stress in thin-slab casting molds, comparing\r\nfunnel-shaped to parallel molds. Mold wall temperatures were obtained from POSCO in\r\nKorea and analyzed to determine the corresponding heat-flux profiles in thin-slab molds.\r\nThis data was utilized in an elastic-visco-plastic analysis to investigate the deformation of\r\nthe molds in service for the two different mold shapes. The results of a metallurgical\r\ninvestigation of mold samples containing cracks were used together with the results of\r\nthe mathematical models, to determine mechanisms and to suggest solutions for the\r\nformation of mold cracks. Large cyclic inelastic strains were found in the funnel\r\ntransition region just below the meniscus, due to the slightly higher temperature at that\r\nlocation. The cracks appear to have propagated by thermal fatigue caused by major level\r\nfluctuations.\r\n\r\nNext, two-dimensional thermo-elastic-visco-plastic analysis was performed for a\r\nhorizontal slice of the solidifying strand, which moves vertically down the mold during\r\ncasting. The model calculates the temperature distributions, the stresses and the strains in\r\nthe solidifying shell, and the air gap between the casting mold and the solidifying strand.\r\nModel predictions were verified with an analytical solution and plant trials that were\r\ncarried out during billet casting at POSCO.\r\nThe validated model from the billet study was next applied to thin slab casting, using\r\nmold temperature and distortion data from the mold cracking study. An investigation of\r\nthe effect of mold taper on the shrinkage of the solidifying shell, its gap formation, and\r\nstress evolution was carried out for different thin slab mold geometries. The model\r\npredicts that the shell in funnel molds develops a tensile stress at the slab surface in the\r\nfunnel transition region due to funnel retraction. This model also suggests that as the\r\nfunnel depth increases, the possibility of surface cracks at the funnel outside bed position\r\nincreases.","language":"en"},{"key":"dc.format.extent","value":"20805370 bytes","language":null},{"key":"dc.format.mimetype","value":"application\/pdf","language":null},{"key":"dc.language.iso","value":"eng","language":"en"},{"key":"dc.publisher","value":"University of British Columbia","language":null},{"key":"dc.rights","value":"For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https:\/\/open.library.ubc.ca\/terms_of_use.","language":null},{"key":"dc.title","value":"Thermo-mechanical phenomena in high speed continuous casting processes","language":"en"},{"key":"dc.type","value":"Text","language":null},{"key":"dc.degree.name","value":"Doctor of Philosophy - PhD","language":"en"},{"key":"dc.degree.discipline","value":"Materials Engineering","language":"en"},{"key":"dc.degree.grantor","value":"University of British Columbia","language":null},{"key":"dc.date.graduation","value":"2002-11","language":"en"},{"key":"dc.type.text","value":"Thesis\/Dissertation","language":"en"},{"key":"dc.description.affiliation","value":"Applied Science, Faculty of","language":null},{"key":"dc.description.affiliation","value":"Materials Engineering, Department of","language":null},{"key":"dc.degree.campus","value":"UBCV","language":"en"},{"key":"dc.description.scholarlevel","value":"Graduate","language":"en"}]