末端电磁搅拌对弹簧钢连铸坯内部质量的影响

Effect of F-EMS on inner quality of spring steel continuous casting billet

55SiCrA弹簧钢连铸坯容易出现内部质量问题,合理的末端电磁搅拌(F-EMS)能有效地改善连铸坯内部质量,但不合理的末端电磁搅拌会对连铸坯内部质量无改善作用甚至造成内部质量下降。为了提高连铸坯内部质量,得出最优末端电磁搅拌方案,研究了末端电磁搅拌参数对断面尺寸为150mm×150mm的55SiCrA弹簧钢连铸坯内部质量的影响。通过建立连铸过程凝固传热模型分析现行工艺下铸坯的凝固情况,确定末端电磁搅拌的位置为距弯月面8.45~8.73m处。在测定末端电磁搅拌下连铸坯中心磁感应强度的基础上,对电流与频率进行匹配研究,并开展相应的工业试验。结果表明,在采用末端电磁搅拌参数为300A/8Hz时,55SiCrA弹簧钢的中心碳偏析平均值达到1.007,连铸坯中心缩孔改善,中心等轴晶率提高,连铸坯综合质量最好。

The 55SiCrA spring steel is prone to be affected by inner quality problems in continuous cast billets.Appropriate final electromagnetic stirring(F-EMS)can effectively improve the inner quality of the billets,however,the unreasonable stirring parameters fail to improve the inner quality of the continuous casting billets,or even deteriorate the inner quality.In order to improve the inner quality of the continuous casting billets and to obtain the optimal F-EMS scheme,the influence of F-EMS parameters was studied on the inner quality of 55SiCrA billet with a section size of 150 mm×150 mm.The solidification condition of the casting blank under the current process was analyzed by establishing a solidification and heat transfer model,and the position of F-EMS was determined to be 8.45-8.73 m away from the meniscus.On the basis of measuring the center magnetic induction intensity of the billets under F-EMS,the matching of current and frequency is studied,and the corresponding industrial tests are conducted.The results indicate that the comprehensive quality of the continuous casting billet is best when the F-EMS parameter is 300A/8 Hz.For billets,the average center carbon segregation index reaches 1.007,the center pipe of the continuous casting blank is improved,and the central equiaxed crystal ratio is increased.