1Cr-1.25Mo-0.25V 강 잉곳의 응고편석 및 균질화 거동 |
김동배1,3, 나영상2, 서성문2, 이재현3 |
1대구기계부품연구원 2한국기계연구원 부설 재료연구소 3창원대학교 나노신소재공학과 |
Solidification Segregation and Homogenization Behavior of 1Cr-1.25Mo-0.25V Steel Ingot |
Dong-Bae Kim1,3, Young-Sang Na2, Seong-Moon Seo2, Je-Hyun Lee3 |
1Dae-gu Mechatronics & Materials Institute, Daegu 42714, Republic of Korea 2Korea Institute of Materials Science, Gyeongnam 51508, Republic of Korea 3Changwon National University, Department of Metallurgy & Materials Engineering, Gyeongnam 51140, Republic of Korea |
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Received: 18 November 2015; Accepted: 17 March 2016. Published online: 5 September 2016. |
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ABSTRACT |
As a first step to optimizing the homogenization heat treatment following high temperature upset forging, the solidification segregation and the homogenization behaviors of solute elements were quantitatively analyzed for 1Cr-1.25Mo-0.25V steel ingot by electron probe micro-analysis (EPMA). The random sampling approach, which was designed to generate continuous compositional profiles of each solute element, was employed to clarify the segregation and homogenization behaviors. In addition, ingot castings of lab-scale and a 16-ton-sized 1Cr-1.25Mo-0.25V steel were simulated using the finite element method in three dimensions to understand the size effect of the ingot on the microsegregation and its reduction during the homogenization heat treatment. It was found that the microsegregation in a large-sized ingot was significantly reduced by the promotion of solid state diffusion due to the extremely low cooling rate. On the other hand, from the homogenization point of view, increasing the ingot size causes a dramatic increase in the dendrite arm spacing, and hence the homogenization of microsegregation in a large-sized ingot appears to be practically difficult. |
Keywords:
1Cr-1.25Mo-0.25V steel, solidification segregation, homogenization, secondary dendrite arm spacing, residual segregation index |
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