连铸坯表面夹渣分析及预防措施

Analysis and the Preventive Measures of Surface Wrapped Slag in Continuously Cast Billet

三角口裂纹、直线裂纹和渣孔是连铸坯表面夹渣的主要表现形式。通过金相观察、扫描电镜及电子探针分析了裂纹的形貌特征及夹渣的分布,夹渣的主要组成是高温氧化物,即FeO、MnO、SiO2和Al2O3,是由结晶器保护渣形成的,渣圈是形成这种氧化物聚集带的原因。钻孔模拟试验表明,深度2 mm以内的渣孔轧制后不会形成裂纹。连铸坯表面夹渣可通过合理使用结晶器保护渣、保持结晶器内液面平稳、保持中间包水口对中、稳定拉速等措施加以控制。

Triangle crack, linearity crack and slag eye are main form of surface wrapped slag in continuously cast billet. The shape characteristics and distribution of the cracks were analyzed by microscope, scan electronic microscope and electronic probe. The surface wrapped slag was mostly composed of high temperature oxide . FeO, MnO, SiO2 and Al2O3 and came from the mould power. The slag circle was exclusive reason of formed collective area of the high temperature oxide. Simulated boring test showed that the slag eye the depth of which is less than 2 mm did not form crack as rolling. The surface wrapped slag can be controlled by right use the mould power, keeping the calm surface of molten steel in mould, keeping stopper nozzle for middle ladle inserting in the center of moutd, and stabilizing the withdrawal speed etc.