Mass Action concentration model of CaO-MgO-FeO-Al2O3-SiO2 slag systems and its application to the formation mechanism of MgO center dot Al2O3 spinel-type inclusion in casing steel

摘要

Large-size MgO center dot Al2O3 spinel-type inclusions in casing steel are harmful to the surface quality and performance of casing. In order to effectively control them in production, their existence in casing steel was analysed by scanning electron microscope and energy dispersive spectrometer, and the formation mechanisms were studied using the coexistence theory of slag structure. The mass action concentration model of CaO-MgO-FeO-Al2O3-SiO2 slag systems was established. The effect of the slag basicity, aluminium content in molten steel, degree of vacuum during vacuum treatment of molten steel and furnace lining on the magnesium content in molten steel is discussed. The results show that magnesium content increases with increasing slag basicity and aluminium content, and decreases with increasing CO partial pressure.