提高转炉上连铸Q345B探伤质量的措施

针对南阳汉冶特钢有限公司250 mm×1 650 mm断面采取转炉直上连铸工艺路线生产的Q345B钢板探伤合格率低现象,对不合格钢板取样并进行电镜检测分析,得出中心锰偏析、硫化锰夹杂是导致探伤不合格的主要原因。通过优化转炉脱硫工艺降低硫含量、严控钢水过热度、优化成分降低锰含量、优化连铸二冷制度、钢板抢温下线缓冷等措施,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。

Measures to improve flaw detection quality of Q345B continuous casting on converter

According to the phenomenon that the qualified rate of Q345B steel plate produced by the process of converter straight up continuous casting on 250 mm×1 650 mm section of Nanyang Hanye Special Steel Co., Ltd. unqualified steel plate was sampled and analyzed by electron microscope. It is concluded that the main reasons for unqualified inspection are the central manganese segregation and the manganese sulfide inclusion. By optimizing the desulfurization process of converter to reduce sulfur content, strictly controlling the superheat of molten steel, optimizing the composition to reduce manganese content, optimizing the secondary cooling system of continuous casting and slow cooling of steel plate, central segregation of slab has been improved, and qualified rate of steel plate flaw detection has been improved after rolling.