改善60Si2MnA弹簧钢小方坯中心碳偏析的研究

STUDY ON IMPROVEMENT OF CENTER CARBON SEGREGATION IN 60SI2MNA SPRING STEEL BILLET

研究了在拉速1.5 m/min、过热度30℃以下时,二冷比水量（0.3-1.4 L/kg）和末端电磁搅拌电流强度（220-380 A）对165 mm×165 mm的60Si2Mn A弹簧钢方坯中心碳偏析及等轴晶的影响,并与150 mm×150 mm铸坯的中心碳偏析对比。结果表明,随着二冷比水量增加,铸坯等轴晶率减小,中心碳偏析先增加后减小再增加,且结合射钉结果,确定最佳比水量为1.0 L/kg;末端电磁搅拌电流强度增加,等轴晶率增加,中心碳偏析先减小再增加,最佳末端电磁搅拌强度为340 A/6 Hz;150 mm×150 mm铸坯比165 mm×165 mm铸坯的平均中心碳偏析低,分别为1.04、1.06,且小断面铸坯的中心偏析指数波动更小。

Effects of secondary cooling water ratio （0.3 - 1.4 L/kg）, final electromagnetic stirring current （220 -380 A） on center carbon segregation and equiaxed grain of 165-by-165 mm billet of 60Si2MnA spring steel produced at casting speed of 1.5 m/min and superheat degree below 30 ℃ were investigated, and the center carbon segregation was compared with that of 150-by-150 mm billet. Results showed that the center carbon segregation increased first, then decreased, then increased again, and the equiaxed grain rate decreased with the increase of secondary cooling water ratio. Combining with the results of nail-shooting, 1. 0 L/kg was the best cooling water ratio; besides, the center carbon segregation decreased first, then increased, and the equiaxed grain rate increased with the increase of final electromagnetic stirring current, and 340 A/6 Hz was the best final electromagnetic stirring intensity. In addition, the center carbon segregation of 150-by-150 mm billet was lower than that of 165-by-165 mm billet, which were 1.04, 1.06 respectively, and the center carbon segregation fluctuation in the cross section of 150-by-150 mm billet was also lower.