连铸坯腐蚀性缺陷研究

Study on Corrosion Defects of Continuous Casting Billet

连铸坯凝固过程中靠近铸坯内弧边缘位置产生部分不耐腐蚀的区域,表现为连铸坯和轧材酸洗时类似裂纹现象。经过对轧材进行低倍金相和扫描电镜检测发现,类似裂纹并非真正的裂纹,而是由于该位置不耐腐蚀产生的“伪裂纹”,在“裂纹”中存在MnS夹杂物。由于该位置耐腐蚀性与其他位置有差异,造成MnS以及周围钢基体优先腐蚀,产生腐蚀坑,宏观上为“裂纹”。

During the solidification of the continuous casting slab,a part of non-corrosive area is generated near the edge of the inner arc of the casting slab,which shows similar cracks when the continuous casting slab and the rolled material are pickled.After the low-magnification metallographic and scanning electron microscopy inspections of the rolled material,it is found that the similar crack is not a real crack,but is a"pseudo crack"caused by the inability of corrosion at this location,and there are MnS inclusions in the"crack".Because the corrosion resistance of this location is different from other locations,the MnS and the surrounding steelmatrix are preferentially corroded,causing corrosion pits,which aremacroscopically"cracks".