Effect of tundish fluxes on the degradation of MgO-based refractory linings in continuous casting process

The corrosion of MgO-based tundish refractory linings due to the addition of various fluxes, such as rice husk ash (RHA) insulation powder, and RHA+CaO-Al 2 O 3 flux (RCA), were investigated using a finger rotating test (FRT) at 1773 K, which simulated the industrial tundish metallurgy process involved in producing stainless steel. FactSage™ (ver. 8.2) thermochemical computing software was used to reveal the degradation mechanism of MgO-based refractory lining. Local corrosion was observed at the slag-metal interface after 60 min of RHA insulator addition. However, the refractory rod was fractured after the addition of the RCA multi-flux. Olivine, (Mg,Fe,Ca) 2 SiO 4 , and chromium-spinel, (Mg,Mn,Fe)Cr 2 O 4 , phases were predicted to form at the slag-refractory interface when the refractory was corroded by the RHA insulator, while the aluminum-spinel, (Mg,Fe)Al 2 O 4 , phase was simulated when corroded by RCA multi-flux. The different physicochemical properties of the liquid slag significantly influenced the corrosion of the refractory lining. The liquid slag compositions after 60 min of RHA insulator and RCA multi-flux addition can be classified as the SiO 2 -MnO-MgO-10%Cr 2 O 3 system (RHA-S) and the SiO 2 -Al 2 O 3 -CaO-10%MgO system (RCA-S), respectively. Interfacial tension between the RCA-S and liquid stainless steel was higher than that between the RHA-S and liquid stainless steel. Nevertheless, the RHA-S had a greater contact angle and viscosity compared with RCA-S. These results indicate that the penetration depth of the RCA-S into the refractory was larger than that of RHA-S under a fixed radius of the capillary and a fixed penetration time, creating the more severe corrosion of the refractory by RCA-S than RHA-S.