弹簧钢小方坯成分偏析改善实践

Improvement in Segregation of Spring Steel Billet

化学成分偏析对弹簧钢棒材的力学性能、显微组织均匀性等均有重要影响。为改善某钢厂150 mm×150 mm弹簧钢小方坯的成分偏析,采用热酸腐蚀分析铸坯低倍组织、碳硫仪分析铸坯化学成分分布并结合传热数学模型,研究了拉速、比水量、过热度、电磁搅拌参数等连铸工艺参数对铸坯成分偏析的影响。结果表明,控制拉速为2.1 m/min、比水量为0.45 L/kg、末端电磁搅拌参数为400 A/10 Hz,可消除铸坯中心附近区域的负偏析,将中心正偏析度控制在1.15以下,且中心缩孔极为轻微。采用优化工艺后,弹簧钢棒材组织均匀性明显改善。

Segregation has most important influence on the mechanical properties and microstructure uniformity of spring steel bar.To improve the segregation of billet150mm by150mm,the influence of continuous casting parameters,such as casting speed,specific water flow,superheat and final electromagnetic stirring(F-EMS)parameters etc.on the segregation of billet was investigated with the methods of hot acid etching,infrared absorption carbon-sulfur analyzing and mathematical models of solidification and heat transfer.Experiment results indicated that when the casting speed was2.1m/min,specific water flow was0.45L/kg,F-EMS parameter was400A/10Hz,negative segregation near the billet center could be eliminated,center positive segregation degree could be controlled under1.15and little center shrinkage could be detected.Plasticity and microstructure uniformity of spring bar was obviously improved after using the optimized parameters.