Abstract：Aiming at the serious problem of 430 stainless steel billet depression defects near the slab edge in TISCO, Gleeble 3800, high-temperature in-situ analyzer, viscosity analyzer and other technical means were used to systematically study the generation mechanism of 430 billet depression defects near the slab edge and the influence of mold flux on the depression near the slab edge. The results show that the main reason for 430 stainless steel billet depression defects near the slab edge is related to the controlled heat transfer of the mold flux. The basicity of mold flux is too small, and the crystallization ability is weak, while the cooling strength of billet shell in the mold is large, and solidification shrinkage induces a large corner torsion force, resulting in depression defects near the slab edge. At this moment, the defect mainly occurs in the mold. When the basicity of mold flux is too large, the crystallization capacity is strong, the cooling strength of billet is not enough, and the thickness of billet shell at mold outlet is thin, under the action of hydrostatic pressure of steel, the width of billet becomes wider, which leads to subsequent large solidification shrinkage and the formation of edge depressions. At this moment, the defect mainly occurs in the secondary cooling stage. The basicity of mold flux is controlled at 1.00, the crystallization ability of mold flux is appropriate, which not only avoids the slab depression caused by strong cooling in the mold, but also ensures the sufficient thickness and strength of mold shell, and finally makes depression depth reduced from 1.26 mm to 0.30 mm, which significantly changes the surface quality of billet.
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2022, Vol. 32 
