连铸坯表面纵裂产生原因及控制对策

Causes of longitudinal surface cracks on continuous casting slab and control measures

针对宝钢股份炼钢厂一炼钢分厂1号和3号连铸机频繁发生板坯表面纵裂缺陷。综合分析了板坯表面纵裂产生的原因以及影响因素,制定并采取了相应的控制措施。在实际钢种设计中尽量避开w(C)为0.09%～0.15%区间范围内的钢种;降低钢中w(S),增加w(Mn),从而提高w(Mn)/w(S);降低钢中夹杂物含量,提高钢水纯净度;适度调整保护渣的成分,提高保护渣的粘度,降低碱度。采取这些措施,铸坯表面的纵裂状况得到了明显改善。

In the light of the situation that longitudinal cracks on wide slab frequently occur in the No. 1 and No. 3 caster of the No. 1 Steelmaking Plant, the causes of cracks forming and influencing factors were analyzed and then conrresponding measures had been taken. In the design of steel grades, the steels with w（C）0.09 %-0. 15% should be chosen as few as possible. Other measures included： decreasing the amount of inclusions, enhancing the purity of molten steel, adjusting the compositions of mould flux, increasing the viscosity of mould flux and decreasing its basicity. Thanks to these measures, the longitudinal cracks on the slab have been improved significantly in the plant.