亚共析钢S48C连铸坯轧后表面缺陷原因分析  

Cause analysis on rolling surface defects of hypoeutectoid steel S48C after rolling

作　　者：范英同[1] 郭亮亮[2] 徐国栋[1] FAN Yingtong;GUO Liangliang;XU Guodong(Steelmaking Plant,Baoshan Iron & Steel Co. ,Ltd. , Shanghai 201900, China;Research Institute,Baoshan Iron & Steel Co. ,Ltd. , Shanghai 201999, China)

机构地区：[1]宝山钢铁股份有限公司炼钢厂,上海201900 [2]宝山钢铁股份有限公司中央研究院,上海201999

出　　处：《宝钢技术》2021年第1期51-55,共5页Baosteel Technology

摘　　要：亚共析钢S48C连铸坯轧后,发现热轧板中心纵裂纹和冷轧卷边部翘皮缺陷。采用热力学计算、金相显微镜、扫描电镜、高温拉伸试验等方法系统研究了缺陷成因。结果表明,S48C的热轧纵向裂纹位于凹陷底部,深度为0.7 mm,附近有明显的脱碳层;冷轧边部翘皮深度约20μm,有少量的二次氧化颗粒。S48C零塑性温度ZDT约1375℃,凝固初期坯壳厚度不均匀,易形成纵向凹陷;随着渗碳体析出,发生纵裂的倾向性增大。冷轧边部翘皮是由塞棒吹氩流量不稳定,氩气泡卷入铸坯形成皮下气孔、轧后延展导致。结晶器电磁搅拌、稳定吹氩流量和提高设备精度等措施,可有效解决S48C轧后表面缺陷问题。The longitudinal cracks of hot-rolling plate and edge sliver defects of cold-rolling strip have been observed on hypoeutectoid steel S48C.The mechanisms for formation of surface defects were investigated based on a series of related investigations,such as thermodynamic calculation,metallographic and scanning electron microscopy studies,as well as high-temperature tensile tests.The results showed that longitudinal cracks were located at the bottom of surface depressions,and the crack depth was around 0.7mm with decarburization.The edge sliver depth was about 20μm,together with secondary oxidation particles.The zero ductility temperature(ZDT)of S48C is~1375℃,and the longitudinal crack first occurred close to the solidification front,where the ductility was extremely low;furthermore,the shell growth was slower than in other regions,which led to a thinner shell and depressed shrinkage.The tendency of longitudinal cracks increased as the cementite precipitation.It has been proved that edge sliver defects of cold-rolling strip were induced by unstable argon flow rate of stopper entrapped by solidified shell and then were extended during continuous casting and rolling process,respectively.The surface quality of hypoeutectoid steel S48C can be improved by applying M-EMS,stabilizing argon flow rate,and optimizing equipment accuracy.

关 键 词：纵向裂纹 边部翘皮 亚共析钢 连铸 

分 类 号：TF777[冶金工程—钢铁冶金]