780DH钢热轧卷翘皮缺陷原因分析及优化实践  

Cause analysis and optimization practice for the upwarping defect in hot rolling of 780DH steel

作　　者：张龙超 龚慧 陈培友 袁开通 ZHANG Longchao;GONG Hui;CHEN Peiyou;YUAN Kaitong(Pangang Group Xichang Steel Vanadium Co.,Ltd.,Product Development,Xichang 615000,Sichuang,China)

机构地区：[1]攀钢集团西昌钢钒有限公司产品发展部,四川西昌615000

出　　处：《四川冶金》2024年第5期57-60,65,共5页Sichuan Metallurgy

摘　　要：某钢厂生产的780DH增强成形双相钢热轧卷表面存在两种翘皮缺陷,一种是距边部50 mm范围内翘皮缺陷,一种是分布在热轧卷下表面大面肋部翘皮缺陷。通过板坯检查发现,板坯角部存在的横裂纹是导致热轧卷边部翘皮缺陷的直接原因;而对于大面肋部的翘皮缺陷,肉眼检查板坯对应位置并没有发现表面裂纹缺陷,但是通过热轧卷缺陷样金相及电镜分析判断其产生原因仍由板坯存在的原始裂纹导致,对板坯进行修磨3 mm左右后发现板坯皮下存在密集的横裂纹缺陷,由此确定780DH钢热轧卷表面两种翘皮缺陷均是由于板坯裂纹缺陷引起。在此基础上,优化780DH钢专用结晶器保护渣使用性能,将拉坯速度由0.9 m/min提高到1.05 m/min以上,二次冷却强度由0.46 L/kg提高到0.5~0.6 L/kg,同时更换调节精度差的二冷调节阀,避免二冷水波动,采取上述优化措施后可以将780DH钢热轧卷翘皮缺陷率控制在1%以下。There are two kinds of upwarping defects on the surface of the 780DH dual phase steel with high formability hot-rolled coil produced by a steel plant,one is upwarping defect within 50 mm from the edge,and the other is upwarping defect distributed in the large rib of the bottom surface of the hot rolled coil.It is found that the transverse cracks in the corner of the slab is the direct cause of the upwarping defect at the hot rolling edge.As for the upwarping defect in the large rib,no surface crack defect was found in the corresponding position of the slab by visual inspection,but the metallography and electron microscope analysis of the hot-rolled coil defect sample determined that the cause was still caused by the original crack existing in the slab.After grinding the slab for about 3 mm,it was found that there were dense transverse crack defects under the slab.It is determined that the two kinds of upwarping defects on the surface of 780DH steel hot rolled coil are caused by slab cracks.On this basis,the use performance of 780DH steel special mold protection slag is optimized:the casting speed increased from 0.9 m/min to 1.05 m/min or more,the secondary cooling intensity increased from 0.46 L/kg to 0.5~0.6 L/kg,and replace the secondary cooling regulating valve with poor adjustment accuracy to avoid the fluctuation of secondary cold water.After taking the above optimization methods,the defect rate of 780DH steel hot rolled coil can be controlled below 1%.

关 键 词：增强成形双相钢 高铝钢 热轧卷 翘皮 板坯 横裂纹 

分 类 号：TF777.1[冶金工程—钢铁冶金]