Effect of superheat on quality of central equiaxed grain zone of continuously cast bearing steel billet based on two-dimensional segregation ratio
Effect of superheat on quality of central equiaxed grain zone of continuously cast bearing steel billet based on two-dimensional segregation ratio作者机构：College of Materials Science and Engineering ChongqingUniversity Chongqing 400044 China
出 版 物：《Journal of Iron and Steel Research International》 (国际钢铁研究杂志)
年 卷 期：2018年第25卷第1期
页 面：9-18页
核心收录：
学科分类：080602[工学-钢铁冶金] 081704[工学-应用化学] 08[工学] 0817[工学-化学工程与技术] 0806[工学-冶金工程] 081701[工学-化学工程]
基 金：The authors are very grateful for National Natu- ral Science Foundation of China (No. 51504047) and Fundamental Research Funds for the Central Universities (No. CDJPY 14130001 ). Meanwhile the authors acknowledge very valuable discussion with Prof. Guang-hua Wen and Prof. Ping Tang from Chongqing University
主 题：Superheat Continuously cast billet Equiaxed grain zone Segregation Solidification time
摘 要：The quality of central equiaxed grain zone （CEGZ） of GCr15 bearing steel billets was investigated at different superheats （20, 25 and 35 ℃ by experimental observations and a finite element model in order to optimize superheat in continuous casting process. Several GCrl5 billets were collected from the continuous casting shop, and the same CEGZ was chosen for comparison of internal quality of GCrl5 billets. Considering the limitation of segregation index at some points, two- dimensional segregation ratio in CEGZ was introduced. Firstly, the segregation ratio and the area of center large dark points in CEGZ obtain the minimum at 25 ℃ superheat, which indicates that the quality of CEGZ at 25 ~C superheat is improved compared with those at 20 and 35 ℃ superheats for corresponding continuously cast billets. The highest superheat and the lowest superheat are not beneficial for improving the central zone quality in the billets. Secondly, the quality of CEGZ of GCr15 billets increases with a decrease in the secondary dendrite arm spacing of CEGZ. Finally, according to the established finite element model, it is deduced that the secondary dendrite arm spacing of CEGZ is closely related to its later solidifica- tion time at solid fraction of 0.5-1.0, and the former will be decreased when decreasing the latter.
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