中厚板边部裂纹的原因及措施

CAUSES AND MEASURES OF EDGE CRACKS IN MEDIUM AND THICK PLATES

板坯连铸机设备改造后钢板边部裂纹发生率异常增高,对钢板裂纹微观形貌进行分析得出:钢板边部裂纹来源于连铸坯。对连铸坯表面宏观形貌、保护渣、钢水成分、结晶器冷却、连铸设备维护以及结晶器振动参数等因素进行了对比与分析,结果表明:连铸坯四个角振痕不均匀、不规则、有时错乱且分布不规律,结晶器振动参数不合理、连铸机工况不佳是钢板边部裂纹产生的主要原因。通过调整结晶器振动起始位置到中位、延长结晶器振幅变化的斜坡时间、提高连铸机工况条件等,使钢板边部裂纹发生率由5%~50%降低至1%以内。

After the improvement of slab caster equipment,the proportion of edge cracks of steel plate increased abnormally,and the analysis on the microstructure of the cracks shows that the edge cracks of steel plates originate from the billet.The comparison and analysis of the surface morphology of continuous casting billet,the protective slag,the composition of the molten steel,mold cooling,equipment maintenance and mold vibration parameters were conducted.The results show that the four corner vibration marks of continuous casting billet are not uniform,irregular,sometimes disordered and irregularly distributed,so the unreasonable mold vibration parameters and poor continuous casting machine working conditions are the main causes of the edge cracks.By adjusting the starting position of mold vibration to the middle position,extending the ramping time of amplitude change,and improving the working conditions of continuous casting machine,the ratio of crack at the edge of the steel plate is reduced from 5%~50%to less than 1%.