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结合国内某钢厂CSP生产实践,对其表面纵裂纹的影响因素进行了统计分析。统计认为降低钢水硫、氮含量,使w(Mn)/w(S)提高到62以上,并使w(N).w(AlS)<0.015×10-6有利于裂纹的减少;降低拉速的波动频率和范围,控制拉速在4 m/min左右时裂纹最低;随着结晶器传热强度的提高,裂纹发生率上升,故建议结晶器传热采用弱冷;保护渣的液渣层厚度及耗渣量不足,故应对保护渣的性能进行优化;结晶器的流场下部过强,向上分流带入的热量不足,保护渣熔化不好,导致卷渣。通过采取相应的解决措施,CSP铸坯表面质量得到很大改善,纵裂纹发生率降低到了0.59%。
Combined with the domestic CSP production practice of a steel mill, the influencing factors of longitudinal cracks on the surface were statistically analyzed. It is considered that reducing the content of sulfur and nitrogen in the molten steel increases the w (Mn) / w (S) to over 62 and w (N) .w (AlS) <0.015 × 10-6 in favor of reducing the crack; The frequency and the range of the fluctuation, the control of pulling speed at 4 m / min or so when the crack minimum; with the mold heat transfer strength increased, the incidence of cracks increased, so the proposed heat transfer using weak cold mold; Thickness and consumption of slag is not enough, so should optimize the performance of the mold flux; crystallizer lower part of the flow is too strong, the upward diversion into the lack of heat, slag melting is not good, leading to slag. By adopting corresponding measures, the surface quality of CSP slab has been greatly improved, and the vertical crack incidence has been reduced to 0.59%.