Evolution of Mold Flux Composition and Characteristics During Continuous Casting of Aluminum‐ or Silicon‐Containing Steel

During the production of high‐Al steel, Al in the molten steel tends to react with the mold flux at the steel‐slag interface, altering flux composition and degrading the slab quality and process stability. This study employs FactSage macro processing and an effective reaction zone model to simulate compositional evolution of mold flux during high‐alumina or high‐silicon steel‐slag interfacial reactions. Field‐acquired data are analyzed using FactSage to calculate the thermodynamic phase equilibrium and variations in flux viscosity and melting temperature, thereby validating the feasibility of model. The results indicate significant flux composition changes during the initial reaction stages; the Al 2 O 3 content increases, while the SiO 2 content decreases markedly, approaching equilibrium within 20 min. Additionally, the silicon content in the steel significantly affects the reaction rate in the first ten minutes, and a lower silicon content enhances the reaction rate owing to a stronger initial thermodynamic driving force. The minimal deviation between the simulated and measured data confirms the model's feasibility. X‐ray diffraction and scanning electron microscopy with energy dispersive spectroscopy analyses reveal that increasing the Al 2 O 3 content promotes the precipitation of calcium aluminate, thereby elevating the viscosity and melting point of the mold flux.