Kinetic Analysis of Alumina Change in Mold Slag for High Aluminum Steel during Continuous Casting

A kinetic calculation model considering both a molten slag reaction with molten steel and an Al₂O₃ inclusion absorption in molten slag was developed to estimate the change in Al₂O₃ in molten slag during the continuous casting of high aluminum steel. Practical casting experiments of high aluminum steel were conducted to investigate the change in composition in the molten slag and to validate the proposed model. The calculated results show that the Al₂O₃ concentration in the molten slag increases quickly during the initial stage and gradually approaches a steady-state value after 900 seconds of casting, which agrees well with the experiment outcome. The change in Al₂O₃ in molten slag is mainly affected by the initial Al₂O₃ concentration w ⁰ of the mold powder, reaction equilibrium concentration of Al₂O₃ w* at the slag-steel interface, mass transfer coefficient \( {\text{k}}_{{{\text{F}},{\text{Al}}_{2} {\text{O}}_{3} }} \) in molten slag, Al₂O₃ inclusion concentration w _M , and absorption coefficient β in molten steel during continuous casting of high aluminum steel. The experiment result shows that the concentration of Al₂O₃ in molten slag increases significantly and that SiO₂ decreases strongly, while the other components in the molten slag can be negligible comparatively. Mold slag properties at 0, 5, and 45 minutes change greatly, which can deteriorate the performance of the mold slag.