Abstract: Nail-shooting technique is applied to measure shell thickness of typical high-carbon chromium bearing steel GCrl5 240 mm x240 mm casting bloom, and the electromagnetic stirring position at different casting speed is calculated by the solidification law which can determine the length of the liquid core and the solidification coefficient according to the solidification rate 0. 65 and 0.75. Meanwhile, compared with the calculation results of the secondary model of the casting machine, the influence of the casting speed on the quality of the continuous casting bloom is discussed without changing the position of final electromagnetic stirring (9.4 m). And the magnetic stirring strength of the final electromagnetic stirring is measured by using the tesla meter HT201 to determine the optimal process parameters of final electromagnetic stirring. The results show that increased pulling speed from 0. 68 m/min to 0. 75 m/min has better effect； the optimized electric stirring parameters are current 450 A and frequency 8 Hz ； after process improved, the qualified rate of central segregation is increased from original 75% to 92%.

摘要： 利用射钉法测定了240 mm×240 mm断面高碳铬轴承钢GCr15的铸坯凝固坯壳厚度,并根据凝固定律计算了其液相穴长度和综合凝固系数,针对凝固率0.65、0.75进行计算得出F-EMS在不同拉速条件下的电磁搅拌位置。同时,与该铸机二级模型计算结果进行对比,在不改变末端电搅位置(9.4 m)的情况下,讨论了拉速对连铸坯质量的影响。并采用特斯拉计HT201对末端电磁搅拌磁感应强度进行了测量,找出凝固末端电磁搅拌最佳工艺参数。结果表明,拉速由原来的0.68 m/min提高至0.75 m/min,效果更好;电搅参数优化为电流450 A,频率8 Hz;工艺改进后,中心碳偏析合格率从75%提高至92%。