大型角钢顶角开裂的原因分析和优化控制

Cause analysis and optimization control of top corner cracking of large angle steel

Q355B角钢是一种比较常用的结构钢,广泛应用于各种建筑结构和工程结构中。唐山某钢厂在组织试轧Q355B大型角钢时出现了批量的顶角开裂缺陷,为此对角钢开裂部位以及同炉次的铸坯进行了取样检测。本文根据角钢开裂部位化学成分、显微组织以及同炉次铸坯低倍组织的检测结果,对角钢顶角开裂的原因进行了分析,并提出了工艺改进措施。通过连铸机进行重新对弧、控制钢水过热度和铸坯拉速、改善水质和加强喷嘴排查、调整二冷冷却制度等工艺的优化,将Q355B大型角钢顶角开裂甩废比例由8.8%降低到1%以下。

Q355B angle steel is a relatively commonly used structural steel, which is widely used in various building structures and engineering structures. When Tangshan a steel plant organized trial rolling of Q355B large angle steel, there were batch top corner cracking defects, therefore the angle steel of cracking part and the same furnace billets were sampled and tested. In this paper, according to the test results of the chemical composition and microstructure of the cracked part of angle steel, and macrostructure of the same furnace billet, analyzed the causes of top corner cracking of the angle steel,and put forward the process improvement measures. Through realigning the arc of the continuous casting machine, controlling the superheat and drawing speed of the molten steel,improving secondary cooling water quality and strengthening the cooling nozzle inspection, adjusting the secondary cooling system and other process optimizations, the ratio of the top corner of the Q355B large angle steel is cracked and discarded,decrease from 8.8% to less than 1%.