1. Materials Genome Institute, Shanghai University, Shanghai 200444, China; 2. Center for Advanced Solidification Technology, Shanghai University, Shanghai 200444, China; 3. Research Institute of Baoshan Iron and Steel Co., Ltd., Shanghai 201900, China; 4. Steel Making Plant, Baoshan Iron and Steel Co., Ltd., Shanghai 201900, China
Abstract：Abnormal growth of austenite grains on the surface of casting slab is one of leading cause for transverse cracks. Studying the influences of cooling process on austenite growth behavior is meaningful to the scientific formulation of continuous casting process and the reduction of crack sensitivity. Innovative thermal simulator was designed for continuous casting slab solidification process studying, which had been applied to reproduce the cooling and solidification of EH40 low carbon ship plate steel with two kinds of mold cooling intensity, and the grain growth behaviors of surface austenite were observed under the condition of traditional slab continuous casting. The results show that at the mold cooling stage, most of minor axis size of austenite grain within 5 mm to the surface of thermal simulation slab are not more than 0.5 mm, but coarse grains are already appeared, and the average and maximum austenite grain sizes are larger under the condition of strong cooling, which are 2.5 times and 2.0 times that of weak cooling, respectively. From the foot roller to the straightening point, the surface austenite grains grow very slowly, and the average size still does not exceed 0.5 mm. At the straightening point, the maximum grain minor axis size at 20 mm of surface on thermal simulation slab with strong cooling in the mold is 2.2 mm, which is 1.7 times that of weak cooling. In conclusion, the growth behaviors of austenite grains are different in each stage of continuous casting, and weak cooling in mold is more conducive to obtain relatively fine surface austenite grains in EH40 steel slab.
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2022, Vol. 32 
