09CrCuSb热轧卷边部缺陷的成因分析

Cause analysis of edge defects of 09CrCuSb hot rolled coil

为了解决09CrCuSb耐酸钢热轧卷分条切边过程中的边部分层问题,采用金相显微镜与SEM-EDS分析仪研究了3种09CrCuSb热轧卷边部缺陷,即边部分层、边部的端面凸起和平行于轧制方向的端面纵裂纹。结果表明,本边部分层缺陷实际上是由热轧侧导挤压所致,校正侧导位置后未再发生,判定边部分层缺陷产生原因的关键在于分层缺陷的内表面状态。端面凸起是因为连铸机精度偏差使铸坯发生边角裂,控制连铸机对弧与辊缝偏差在0.5 mm以内,缺陷发生率从5.4%降低到0.2%以下,端面凸起缺陷实际上是热轧卷烂边的初始形态。端面纵裂纹缺陷是因为连铸坯窄边存在群簇状气泡及钢种本身裂纹敏感性较强,通过降低连铸塞棒和水口氩气到4~6 L/min,按标准下限控制裂纹敏感性元素,缺陷发生率从8.7%降低到了0.45%。为控制09CrCuSb热轧卷边部缺陷提供参考。

In order to solve the problem of edge delamination during slitting and trimming of 09 CrCuSb acid resistant steel hot rolled coil, three typical edge defects of 09 CrCuSb hot rolled coil, namely edge delamination, side bulge on the edge end and longitudinal crack on the edge end parallel to the rolling direction are studied by metallographic microscope and SEM-EDS analyzer. The results show that the edge delamination defects are actually caused by hot rolled side guide extrusion, and do not occur again after correcting the side guide position. The key to determine the cause of edge delamination defects lies in the inner surface state of delamination defects. The side bulge is due to the edge and corner crack of the slab caused by the accuracy deviation of the continuous caster. The deviation of the arc alignment and roll gap of the continuous caster is controlled within 0.5 mm, and the defect incidence is reduced from 5.4% to less than 0.2%. The side bulge defect is actually the initial form of hot rolling roll edge. The longitudinal crack on the edge end is due to the cluster bubbles on the narrow edge of the continuous casting slab and the strong crack sensitivity of the steel itself. By reducing the argon of the continuous casting stopper and nozzle to 4-6 L/min and controlling the crack sensitive elements according to the standard lower limit, the defect occurrence rate is reduced from 8.7% to 0.45%. It provides a reference for controlling the defects of 09 CrCuSb hot rolling coil.