Abstract: Low secondary dendrite arm spacing (SDAS) and large center equiaxed crystal ratio (ECR) are beneficial to reduce center segregation of high-carbon steel casting bloom with M + F-EMS. A Cellular Automaton-Finite Element (CAFE) coupling model and secondary dendrite arm spacing (SDAS) model of 220 mm x 260 mm casting bloom of steel GCrl5 are established to study the effects of M-EMS, superheat and casting speed on central equiaxed crystal ratio (ESR) and SDAS. It is found that ECR in the center of bloom increases with decreasing superheat and increase intensifying M- EMS, while SDAS decreases with the decrease of superheat and with the increase of M-EMS. The results reveal that M- EMS and superheat has a significant effect on center ECR compared with casting speed. Casting speed has the obvious influence on solidification end and central solid fraction in strand. Industrial test results as compared supeheat 35 ℃ and casting speed 0. 75 m/min less than superheat 25 ℃ and casting speed 0.8 m/min and with M + F-EMS, the ECR in the center of bearing steel GCrl5 bloom increases from original 27% to 38% and the SDAS is effectively refined, center carbon segregation index decreases from original 1.06 ～ 1.39 to 0.93 ～ 1.13.

摘要： 铸坯高中心等轴晶率及小的二次枝晶臂间距有利于降低高碳钢M+E-EMS连铸坯中心偏析。通过建立GCr15钢220 mm×260 mm连铸坯耦合有限元-元胞自动机模型(CAFE)及二次枝晶臂间距(SDAS)模型,研究结晶器电磁搅拌、过热度和拉速对中心等轴晶率及二次枝晶臂间距的影响。结果表明,相比于拉速,过热度和结晶器电磁搅拌对其影响明显。随着过热度降低及结晶器电磁搅拌强度增加,铸坯中心等轴晶率增加而二次枝晶臂间距减小,而拉速对凝固终点和中心固相率影响大。工业试验结果表明,采用结晶器与凝固末端电磁搅拌,相比于过热度35℃和拉速0.75 m/min,控制过热度小于25℃且拉速调整为0.8 m/min时,轴承钢GCr15铸坯中心等轴晶率由原27%增加至38%且二次枝晶臂间距细化,中心碳偏析指数由原1.06～1.39降至0.93～1.13。

关键词: 220 mm×260 mm铸坯, GCr15轴承钢, 中心等轴晶, 二次枝晶臂间距, 中心偏析,