低碳钢表面纵裂与夹渣缺陷改善

Improvement of surface cracks and inclusions defect in low carbon steel

国内某厂板坯较高拉速1. 8 m/min时,连铸坯表面同时出现大量表面纵裂纹和铸坯表面及皮下夹渣缺陷。经过分析探讨其产生的原因,设计了连铸保护渣,但是在高拉速情况下,连铸保护渣控制传热能力和润滑能力之间矛盾就凸显出来,二者兼顾不到位会引发粘结报警及漏钢事故。通过加入Li2O(3%)、MnO(3. 5%)对连铸保护渣配方进行优化设计,连铸保护渣的润滑能力和控制传热能力得到兼顾,经过工业试验,连铸坯表面纵裂纹率由4. 5%下降到0. 2%,钢板夹渣缺陷率由5%下降到0. 3%,连铸坯的质量得到改善,确保了连铸工艺的顺行,达到了用户的需求。

When high casting speed was 1.8 m/min in domestic steel plant, both of longitudinal surface cracks and surface and subsurface slag inclusion defects appeared frequently. The new casting powder was devised after analyzing the cause of these defects, but the contradiction of thermal transfer ability and lubricating ability was highlighted when the casting speed was higher, and alert and breakout would be triggered if the two aspect were not combined. To combine the ability of lubricating and thermal transfer, Li20（3 % ）,MnO（3.5 % ） were added into casting powder. The results showed that the detect rate of longitudinal cracks decreased from 4.5 % to 0.2 %, and the defect rate of inclusion decreased from 5 % to 0.3 %, which successfully improved the quality of slab, ensured the process of continuous casting and satisfied the needs of customer.