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某钢厂生产的ML08Al小方坯铸坯表面缺陷主要表现为角部钩状振痕和表面凹陷。现行保护渣成分和理化性能分析结果表明,渣中Fe2O3含量较高,导致保护渣保温能力下降、液渣层减薄;保护渣熔点较高,且出现分熔现象,影响了熔渣熔化的均匀性,易结渣圈;保护渣不易结晶,恶化了ML08Al钢初始凝固时的均匀传热。针对铸坯出现的表面质量问题,明确了保护渣理化性能优化方向和思路,并结合结晶器内钢水凝固热力耦合模型的分析结果,提出适宜的保护渣熔点、黏度、熔速及碱度。实际生产表明,使用优化后的保护渣,铸坯表面质量得到明显改善。
The surface defects of the ML08Al billet slab produced by a steel mill mainly show the hook-shaped vibration marks and the surface dents. The present analysis of the physical and chemical properties of the mold powder shows that the higher Fe2O3 content in the slag leads to the decrease of the thermal insulation ability of the mold flux and the thinning of the slag layer. The melting point of the mold flux is higher and the melting phenomenon occurs, which affects the uniform melting of the slag Easy to form dregs, the powder is not easy to crystallize and the even heat transfer of ML08Al steel is deteriorated. According to the surface quality problems of cast slab, the optimization direction and thinking of physical and chemical properties of mold slag were clarified. Based on the analysis of the coupling model of molten steel solidification in molten steel, the suitable melting point, viscosity, melt speed and alkalinity of the mold flux were proposed. The actual production shows that using the optimized mold flux, the surface quality of the slab has been significantly improved.