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민석홍(S. H. Min),조용수(Y. S. Cho),하태권(T. K. Ha) 한국소성가공학회 2014 한국소성가공학회 학술대회 논문집 Vol.2014 No.10
High temperature deformation behavior of cast 310S stainless steel has been investigated in this study by performing tensile and compression tests at temperatures from 900 to 1200℃. Rectangular ingots of which the dimensions were 350×350×100 in millimeter were cast using vacuum induction melting. Phase equilibrium was calculated using the FactSage<SUP>Ⓡ</SUP>, thermodynamic software and database. Thermal expansion coefficient was also measured on the ingot in the temperature range from room temperature to 1200℃. Tensile strength of cast 310S stainless steel was 9 MPa at 1200℃, which is a little higher than that of a wrought 310S. With temperature decreased, tensile strength increased rapidly and reached up to 72 MPa at 900℃. Elongation also increased with temperature decreased. Microstructure observation revealed that σ phase was precipitated along the grain boundary and within the matrix over 1200℃, which is detrimental to high temperature elongation.
Effect of Sn Content on Phase Equilibrium and Formability
J. H. Won(원주현),J. C. Kim(김지찬),H. W. Lee(이현우),S. H. Min(민석홍),T. K. Ha(하태권) 한국소성가공학회 2015 한국소성가공학회 학술대회 논문집 Vol.2015 No.10
Feasibility of Zn-Al-Sn alloy for the application to fuse material of protection device in lithium-ion battery was tested in this study. The effect of tin contents on the microstructure and formability of Zn-Al-Sn alloy, which has also been attracting intensive focus as a Pb-free solder material, was investigated in this study. Phase equilibrium has been calculated by using FactSage® to evaluate the composition and fraction of equilibrium phases. In the case of Zn-4Al-XSn(X=1, 3, 5, 7, 9) alloys, melting temperatures were expected and measured to decrease from 392.1℃ to 374.3℃ with Tin contents increased from 1 to 9 weight percent. Cold rolling was successful conducted for all alloys with various Tin contents into the sheets with the sheets with thickness of 1.5 mm.
김준호(J. H. Kim),민석홍(S. K. Min),문정호(J. H. Moon),하태권(T. K. Ha) 한국소성가공학회 2014 한국소성가공학회 학술대회 논문집 Vol.2014 No.5
Single crystals of pure Magnesium, Mg-1 Y, and Mg-1Ce alloy were successfully fabricated in this study by employing the modified Bridgman method. To determine the exact orientation of crystals, Laue back-reflection method and pole figure measurement were carried out on each single crystal. Dimensions of single crystals were 10 mm in diameter and 120 mm in length. Hardness and compression tests were conducted and the results revealed that hardness and the strength strongly depended on the orientation. The closer to basal one the orientation was, the higher hardness and compressive strength were. The effect of alloying was not higher than that of orientation. After compressive deformation of single crystals, the orientation of the crystals was found to rotate and to be parallel to the basal orientation. In this study, the anisotropic diffusion behavior of Al and Zn in Mg was also investigated using diffusion couple technique with single crystal of pure Mg at the temperatures ranging from 365 to 420℃ for Al and from 280 to 330℃ for Zn. The diffusion coefficients of Al and Zn within the basal plane are about 1.3 and 1.23 times, respectively, greater than that along normal direction of basal plane at the experimental temperatures.