模具钢连铸坯内部质量优化实践

Practice of Optimizing Internal Quality of Continuous Casting Slabs of Die Steel

为降低模具钢轧后钢板内部缺陷发生率,采用酸洗、金相检验、原位分析的方法对连铸坯、钢板进行检验,结果表明,严重的中心偏析和中间裂纹是导致缺陷产生的主要原因。通过优化钢种成分、优化二次冷却工艺及设备精度控制后,铸坯中心偏析≤B0.5级的比例达100%,铸坯中间裂纹稳定控制在1.0级以下,提高了模具钢连铸坯内部质量,轧后钢板内部"硬芯"、"砂眼"缺陷发生率由1%以上降为零。

In order to lower the occurrence rate of internal defects in steel plates of die steels after rolling,the continuous casting slabs and steel plates of die steels were inspected by such methods as pickling,metallographic examination and in-situ analysis.The inspection results showed that the severe center segregation and middle cracks in slabs were the main causes leading to the defects.By taking such measures as optimizing compositions in steels with various grades,optimizing the secondary cooling process and optimizing the precision control on equipment,the ratio of the center segregation occurred in casting blanks with equal to or less than Level B0.5 was100%,while the intermediate cracks in casting blanks was stably controlled below Level 1.0.So the internal quality of continuous casting slabs of die steel was improved.As a result,the occurrence rate of defects such as Hard Cores and Blowholes in the steel plates after rolling was reduced to zero from more than 1%.