提高Q345B钢板探伤合格率的工艺措施

针对南阳汉冶特钢有限公司250mm×1 650mm断面连铸坯生产的低合金Q345B钢板探伤不合格现象,通过对不合格钢板取样进行电镜检测分析,得出中心锰偏析、硫化锰夹杂、氧化铝夹杂是导致探伤不合格的主要原因。通过优化成分来降低钢中锰元素质量分数、提高钢水洁净度、降低钢水硫质量分数、优化连铸二冷制度、严控铸机开口度等措施,铸坯中心偏析得到了改善,轧后钢板探伤质量合格率得到了提高。

Technological measures for improving qualified rate of Q345B steel plate flaw detection

In order to solve the problem of the disqualification of the flaw detection for the low alloy Q345B plate produced by the 250 mm×1 650 mm section continuous caster in Nanyang Hanye Special Steel Co., the unqualified steel was sampled and detected by the electron microscope. It can be concluded that the main reasons for the disqualification of the flaw detection was the center segregation of manganese, the manganese sulfide inclusions and the aluminium oxide inclusions. Through optimizing the component to reduce the manganese mass fraction in the steel, improving the purity in the molten steel, reducing the sulfur mass fraction in the molten steel, optimizing the second cooling system and strictly controlling the opening degree of the caster, the center segregation of the slab was improved, and the quality qualification rate of the steel plate flaw detection after rolling was increased.