Control technology and source of large-size calcium aluminate inclusions in automobile sheets
ZENG Li1, LUO Yanzhao2, LIU Yanqiang1, ZHAO Changliang1, JI Chenxi2, XU Haiwei1
1. Manufacture Department, Shougang Jingtang United Iron and Steel Co., Ltd., Tangshan 063200, Hebei, China; 2. Research Institute of Technology, Shougang Group Co., Ltd., Beijing 100043, China
Abstract：In recent years, the high quality automotive panel users both domestically and internationally have demanded "zero defects" for the cold-rolled steel sheet, galvanized steel sheet, and other products for automotive panels. The appearance of large-size calcium aluminate inclusions in the steel is the main cause of the defects in IF cold-rolled steel plates. In the subsequent stamping process of steel plates, these large-size inclusions may result in cracking during stamping. In order to solve the problem of large size calcium aluminate inclusions in cold rolled IF steel sheet for automobile, the source and control of calcium aluminate inclusions in cold rolled IF steel sheet in a domestic steel plant were studied. Firstly, the morphology and composition of large size calcium aluminate inclusions were analyzed by SEM and EDS, and it was determined that the ladle slag was the main source of calcium aluminate inclusions. The control process research of RH refining top slag modification, ladle slag quantity optimization, high weir in tundish and high level molten steel operation has been carried out. By increasing the w((CaO))/w((Al2O3))of slag to reduce the FeO activity in slag, the surface tension of slag can be improved, and the aggregation of Al2O3 inclusion particles can be inhibited. High weir structure was established in the tundish, and molten steel sampling analysis found that the number density of larger than 5 μm inclusions is 7.83/mm2 and 5.57/mm2 front and back of the weir,respectively. When the high liquid level operation of molten steel in tundish is applied, it was found that the average residence time increased by 30.3 s when the liquid level was increased by 140 mm. Based on the above key control measures, the stable control of large size calcium aluminate inclusions in IF steel cold-rolled automobile sheet was achieved, and the defect occurrence rate was reduced.
曾立, 罗衍昭, 刘延强, 赵长亮, 季晨曦, 徐海卫. 汽车板中大尺寸钙铝酸盐类夹杂来源及控制工艺[J]. 钢铁, 2023, 58(10): 67-74.
ZENG Li, LUO Yanzhao, LIU Yanqiang, ZHAO Changliang, JI Chenxi, XU Haiwei. Control technology and source of large-size calcium aluminate inclusions in automobile sheets[J]. Iron and Steel, 2023, 58(10): 67-74.
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2023, Vol. 58 
