Mechanism analysis and control of cold rolled edge strip defects of high strength IF steel
WANG En-rui1, CHEN Zi-gang1, LIU Feng-lin1, LI Bin1, ZHANG Ming2
1. Technology Center, HBIS Group Hansteel Company, Handan 056015, Hebei, China; 2. School of Mechanical and Equipment Engineering, Hebei University of Engineering, Handan 056038, Hebei, China
Abstract：The causes of black strip defects on the surface of HC250IF and its structural features and control measures during different processes were analyzed by optical microscope, scanning electron microscope, energy spectrum analysis and pickling simulation test. The results show that the fields near strip edge have been over pickled owing to the uneven distribution of oxide scale and insufficient scale breaking effects of tension straightening mill in the width direction of strip. Under the existing of surface enrichment and grain boundary segregation for phosphorus, HCl solution erodes the matrix grain boundary preferentially after removing the surface oxide scale. The erosion process develops along the grain boundaries and forms erosion channels, which extend from the strip surface to the inside, resulting in structure characteristic of staggered distribution of porous area and rough area with certain thickness difference. After cold rolling, the metal in the porous area deforms intensively, and a large number of micro-cracks are formed along the rolling direction. The present of cracks strengthens the roughness difference of surface locally, and leads to the strip defect with color difference near the edge area of cold rolled strip. On the basis for optimizing matching of hot rolling and pickling process parameters and improving the surface state of hot rolling strip steel before pickling, the occurrence of such defects can be effectively reduced by controlling the pickling process and improving the quality uniformity of pickling.
王恩睿, 陈子刚, 柳风林, 李斌, 张明. 高强IF钢冷轧边部条带缺陷机理分析与控制[J]. 中国冶金, 2022, 32(9): 97-104.
WANG En-rui, CHEN Zi-gang, LIU Feng-lin, LI Bin, ZHANG Ming. Mechanism analysis and control of cold rolled edge strip defects of high strength IF steel[J]. China Metallurgy, 2022, 32(9): 97-104.
2022, Vol. 32 
