55Mn冷轧带钢边裂的产生原因及冷轧控制措施

Reason for Edge Cracking of Cold-Rolled 55Mn Strip Steel and the Cold-rolling Control Measures

采用光学显微镜、扫描电镜及能谱仪等分析了55Mn冷轧带钢边裂缺陷的形成原因,提出了优化的冷轧控制措施并进行了验证。结果表明:因铸坯本身有微小裂纹,致使其在热轧加热过程中产生局部脱碳是造成冷轧带钢边裂的直接原因;通过将拉矫机的延伸率参数设定为正常时的50%,酸洗液质量浓度较正常的增大5%~10%,酸洗速度降至正常时的70%,前两个机架的负荷分配设定为总压下量的70%以上,机架间的微拉应力控制在正常时的70%以内,能够有效控制此边裂现象的出现。

The cause of the edge cracking of cold-rolled 55Mn strip steel was analyzed by means of the optical microscopy,scanning electron microscopy,energy dispersive spectroscopy and so on,and the optimal control measures of cold-rolling were proposed and confirmed.The results show that the local decarburization produced in the hot-rolling process,due to the microcracks in the slab,was the direct cause of the edge cracking of cold-rolled strip steel.This edge cracking can be controlled effectively by the measures of setting the elongation of straightening to 50% of the normal elongation,increasing the mass concentration of pickling solution by 5%-10% of the normal concentration,slowing down the pickling speed to 70% of the normal speed,setting the load distribution of the first two racks to 70% of the total reduction and controlling the micro tensile stress between racks less than 70% of the normal one.