HP345板坯外弧角部横裂纹形成原因及控制

Cause and control of transverse crack at outer arc corner of HP345 slab

针对首钢京唐公司HP345板坯外弧角部横裂纹形成原因与影响因素进行了系统的调查研究,结果表明HP345板坯外弧角部横裂纹发生的主要原因是弯曲段板坯角部温度处于钢的第Ⅲ脆性区,外弧受到的应变力超过板坯所能承受的应力;分析发现,角部横裂纹发生率与板坯宽度有较强对应关系,在保证铸机状态的基础上采取了优化二冷水制度提高角部温度、控制w[N]×w[Al]质量分数等措施,有效地降低了HP345板坯角部横裂纹发生率。

Formation mechanism of transverse cracks at outer arc corner was investigated systematically about HP345 slab in Shougang Jingtang United Iron and Steel Co.,Ltd. The results show that the main cause for the appearance of transverse cracks at outer arc corner is that the slab corner temperature at bending part is in the third brittle zone of steel,and the stress on slab outer arc is over that slab can bear. It is found that the occurrence rate of corner transverse crack is related to the width of the slab.Counter measures such as secondary cooling optimization for increasing corner temperature and w[N] × w[Al] content controlare carried out,insuring casting machine maintenances,which decreased slab corner transverse cracks obviously.