Theory and industrial applications for improvement of ultra-thin stainless steel strip purity and inclusion plasticity by development of "two step slagging strategy"
GUO Jing1, CHEN Xing-run2, HAN Shao-wei3, YAN Yan1, GUO Han-jie1
1. School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China; 2. Hongxing Iron and Steel Co., Ltd., Jiuquan Iron and Steel Group Corporation,Jiayuguan 735100, Gansu, China; 3. Steelmaking Department, Beijing Shougang Co., Ltd., Qian′an 064400, Hebei, China
Abstract：Precision calendered ultra-thin stainless steel strip (<0.3 mm) is required with sound steel cleanness and non-inclusion plasticity to obtain high comprehensive properties and surface quality while the two aspects are in contradiction. In order to solve the conflicts between steel cleanness improvement and non-inclusion plasticity,thermodynamic analysis and laboratory-scale slag-metal equilibrium experiments were carried out for achievement of high purity for stainless steel and admirable inclusion plasticity. The results show that with the slag basicity decrease, the desulfurization and deoxidation are depressed, as well as the molten steel purity, the use of high basicity slag is a necessary condition for obtaining high purity of molten steel. The inclusion composition evolves from CaO-SiO2-Al2O3 based system to plasticized SiO2-Al2O3-MnO based system with the decrease of slag basicity. The content of Als in the steel decreases, and the content of Al2O3 in inclusions also decreases obviously, while the plasticity becomes better. Proper MgO content addition into the slag can restrain the corrosion of lining refractory effective. It proposes a new "two step slagging strategy" based on the thermodynamic analysis, in which high basicity slag is applied in AOD to desulfurization and deoxidation, low basicity slag is employed in LF refining process to plasticized inclusions in the steel. The industrial trial results verify that the new strategy can achieve high steel cleanness and inclusion plasticity. w(T[O]) is less than 0.002 5%,w([S]) is less than 0.001 0% and inclusion is SiO2-Al2O3-MnO dominated silicon-manganese aluminum-garnet inclusions with an average mass percent of Al2O3 lower than 20%, the plasticity is outstanding, which meets the requirement of ultra-thin stainless steel trip.
郭靖, 陈兴润, 韩少伟, 闫岩, 郭汉杰. “两次造渣法”冶炼不锈钢超薄带理论和工业应用[J]. 钢铁, 2021, 56(12): 43-51.
GUO Jing, CHEN Xing-run, HAN Shao-wei, YAN Yan, GUO Han-jie. Theory and industrial applications for improvement of ultra-thin stainless steel strip purity and inclusion plasticity by development of "two step slagging strategy"[J]. Iron and Steel, 2021, 56(12): 43-51.
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2021, Vol. 56 
