Dynamic interaction of refractory and molten steel: Corrosion mechanism of alumina-magnesia castables

Abstract

Refractory materials used for the lining of metallurgical vessels are in direct contact with moving molten steel during the entire refining process. The dynamic interaction between molten steel and refractory material will seriously affect the service life of the refractory lining and restrict the smelting safety and efficiency of steelmaking. In this paper, experiments on the interaction between an alumina-magnesia castable and molten steel under dynamic smelting conditions were performed. The corrosion behaviour of molten steel on the alumina-magnesia refractory, which is the prevailing lining material for the refining ladle, was analysed and discussed. The corrosion mechanism of the alumina-magnesia refractory indicated that the refractory castable reacts with the molten steel and forms a metamorphic layer at the interface that has a liquid phase at high temperatures. The liquid oxide layer is emulsified with the molten steel under dynamic conditions such that the castable is eroded into the molten steel first, and steel droplets are continuously diffused into the castable and grow, which expands the scope of the reaction layer and gradually degrades the refractory castable. Consequently, the castable is peeled into the molten steel, and the molten steel is polluted. The reaction products of refractory castable and molten steel with different chemical compositions vary, and the viscosity of the reaction layer at high temperatures is the key factor. The modified capillary number (Ca*) can be used to compare the refractory wear by estimating the critical velocity of the emulsification. Furthermore, the empirical formulas for the emulsion droplet size were established, providing guidance for the application of refractory materials in the smelting of high-quality steel.