Modeling reoxidation behavior of Al–Ti-containing steels by CaO–Al₂O₃–MgO–SiO₂ slag

A kinetic model was developed using FactSage Macro Processing to simulate the reoxidation of Al–Ti-containing steels by CaO–Al₂O₃–SiO₂–MgO slags. The calculated results show a good agreement with the experimental data. Thus, the developed kinetic model can be used to predict changes in slag, steel, and inclusion compositions during the reaction process. During the slag reoxidation process, the reactions occurring at slag–steel interface and in the bulk steel were confirmed to be the reduction of SiO₂ by [Al] and [Ti] and the self-dissociation of SiO₂ into [Si] and [O]. Increasing the ratio of CaO to SiO₂ in the slag can significantly suppress the self-dissociation of SiO₂ in the slag and lower the amount of inclusions produced during reoxidation. The formed inclusions changed from solid Al₂O₃ to Al₂O₃–TiO _x inclusions, which was mainly dependent on the w([Al]) and w([Ti]). The amount of inclusions was obviously influenced by the composition of the top slag.