轻压下对220mm×260mm轴承钢大方坯内部质量的改善

Improving internal quality of 220mm×260mm bearing steel bloom with soft reduction

通过方坯射钉试验验证220mm×260mm轴承钢大方坯凝固传热数学模型准确性,在拉速一定的条件下利用模型计算确定了合理的轻压下区间并应用于工业试验。试验结果表明采用凝固末端轻压下技术,拉速提高后中心偏析和中心缩孔有很大程度的改善,而不合理的压下位置与压下量分配会引起铸坯出现内裂纹且中心偏析改善不佳。

This study established a mathematical model of solidification and heat transfer for 220mm×260mm bloom,which was verified through the nail-shooting experiments in the narrow side of the bearing steel bloom.The solidification heat transfer model was calculated for the pull down and soft reduction section and the results were applied to industrial test.The results show that the center segregation and shrinkage cavity significantly improve when the casting speed is adjusted to meet the required soft reduction zone as a matter of priority.Except for the internal crack,the internal quality of the bloom has not been improved obviously because of the unreasonable soft reduction position and distribution of reduction amount.