St12冷轧卷条痕缺陷原因分析及预防

Cause Analysis and Precaution of Striation Defects of St12 Cold Rolled Coil

对St12冷轧卷条痕缺陷进行了分析,得出了产生缺陷的主要原因。结果表明:浇注试样存在明显角部横裂纹,低倍分析时存在三角区裂纹和针状气泡,但针状气泡级别较低,肉眼无法观测到;从缺陷宏观形貌和金相分析看,边部舌头状缺陷是由铸坯角裂轧制形成的;从冷轧板和热轧板的金相和电镜分析看,两者均/或出现含卷渣化学元素K、Na、Ca,部分试样的次表层存在的封闭缺陷为卷渣所致。建议炼钢连铸应进一步稳定液面、拉速和氩气流量控制,减少卷渣和气体。

Striation defects of Stl2 cold rolled coil were analyzed. The main reasons for the defects were obtained. The results show that： there are obvious transverse cracks in the cast specimens, and there are triangle area cracks and needle-like bubbles during the low-magnification analysis, but the level of needle bubble is lower, and the bubbles can not be observed by the naked eye. From the macro-morphology of defects and metallographic analysis of view, edge tongue shape defect is formed by casting slab comer crack rolling; from the view of the metallographic and the electron microscope analysis of the cold rolled plate and the hot rolled plate, in both/either of which the slag chemical elements K, Na, Ca appear. The closed defect of the sub surface layer of some samples is caused by the rolling slag. It is suggested that the liquid level and pulling speed should be further stabilized, argon flow rate shold be controlled and the slag and gas should be redttled in the steel making continuous casting.