Cause and Control of Surface ��Black Line�� Defects of Cold-Rolled Low Carbon Sheet in JISCO
YANG Zuo-hong1,ZOU Ming2,ZHENG Yue-qiang2
1. Chief Engineer Room, Jiuquan Iron and Steel Group Co., Ltd., Jiayuguan 735100, Gansu, China 2. Carbon Steel Rolling Mill Plant, Jiuquan Iron and Steel Group Co., Ltd., Jiayuguan 735100, Gansu, China
Abstract��The surface defects of long and short "black line" appeare on the low carbon steel sheet from the CSP cold rolling process in JISCO were analyzed by optical microscopy (OM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Combining the analysis of production processes, it shows that the "long black line" defect is caused by foreign inclusions formed during continuous casting and exposed after cold rolling. The"short black line" defect is due to the rolled-in oxide scale in the bottom surface of hot-rolled plates, which is caused by the roll ring nodulation in soaking furnace. Based on the result, the corresponding solutions to improve production processes were suggested. After improving, the surface qualified rate of the cold-rolled sheet increases by 6%.
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YANG Zuo-hong,ZOU Ming,ZHENG Yue-qiang. Cause and Control of Surface ��Black Line�� Defects of Cold-Rolled Low Carbon Sheet in JISCO. Chinese Journal of Iron and Steel, 2013, 31(5): 28-32.
2013, Vol. 31 
