高耐候钢板坯表面纵裂成因分析与控制

针对高耐候钢连铸板坯生产实践中遇到的表面纵裂纹问题，对钢的成分、结晶器保护渣、结晶器冷却及二冷区冷却等影响因素进行了讨论分析，提出了连铸工艺改进优化方向。生产实践表明，采取控制镍铜比大于0.3，选用高碱度、高熔点、低黏度耐候钢专用保护渣，调整结晶器倒锥度每米1.0%～1.1%，结晶器及二冷区弱冷却；控制非稳态浇铸，维持钢水过热度在20～30 ℃，稳定液面波动在2%以内、拉速波动在±0.2 m/min等技术措施，板坯表面纵裂发生率从50%以上降低到3%左右。

Analysis and prevention of surface longitudinal cracks of atmospheric corrosion resisting steel slab

For surface longitudinal crack of the continuous casting slab of atmospheric corrosion resisting steel， in combination with the production practice， discussed the factors， such as composition， mold powder， mold cooling， secondary cooling， etc.， and put forward the improvement and optimization direction of continuous casting process. The production practice indicated that， by adjusting the Ni/Cu rate larger than 0.3， using a special powder of weathering resistant steel with high basicity， high melting point and low viscosity， adjusting the mould taper over 1.0% per meter， choosing the weak cooling in the mould and the secondary cooling zone， controlling the unsteady casting strictly， maintaining the superheat of molten steel at 20-30 ℃， stabling liquid surface fluctuation within 2%， casting speed fluctuation in ±0.2 m/min， the occurrence rate of the slab surface longitudinal cracks was reduced from more than 50% to 3%.