多模式全连续铸轧产线卷渣缺陷分析及控制

通过扫描电镜和能谱分析仪对低碳低硅铝镇静钢表面卷渣缺陷微观形貌进行观察和能谱分析。结果表明,低碳低硅铝镇静钢表面较短条状卷渣缺陷的主要成分为钙、铝和氧,为典型的钙铝酸盐夹杂物;较长条状卷渣缺陷的主要成分为钙、硅、氟、钠和氧,为典型的保护渣成分。针对不同类型的卷渣缺陷及其成因,分别在炼钢工艺的挡渣出钢、精炼工艺的升温时间和钙含量以及连铸工艺的中间包控流装置、中间包保护气氛、结晶器液面波动、钢包下渣和结晶器保护渣等方面进行改造、控制和优化。采取上述措施后,因低碳低硅铝镇静钢表面卷渣缺陷造成的产品降级率由大于10.0%降至1.5%以下,产品质量得到明显提升。

Analysis and control of slag entrapment defects in multi-mode continuous casting-rolling line

The morphology of slag entrapment defects on the surface of low-carbon low-silicon aluminum-killed steel was observed and analyzed by SEM and EDS. The results show that the main components of short-strip slag defects on the surface of low-carbon low-silicon aluminum-killed steel are calcium, aluminum and oxygen, which are typical calcium aluminate inclusions. The main components of long-strip slag defects are calcium, silicon, fluorine, sodium and oxygen, which are typical components of mold powder. In view of different types of slag defects and their causes, the transformation, control and optimization are carried out in aspects of slag retaining and tapping during the steelmaking process, reheating time and calcium contents during the refining process, tundish flow control during the continuous casting process, tundish protective atmosphere, liquid level fluctuation in the mold, outflow slag at ladle and mold powder. After the above measures are taken, the product degradation rate caused by slag defects on the surface of low-carbon low-silicon aluminum-killed steel is reduced from more than 10.0% to less than 1.5%, and the product quality is significantly improved.