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.

The cleanliness of Ti-containing ferritic stainless steel (Ti-FSS) has been improved via vacuum-oxygen-decarburization (VOD) and ladle treatment (LT) processes. However, the reoxidation phenomena inevitably occur during melt transfer from ladle to continuous casting tundish, resulting in a loss of titanium yield in conjunction with the formation of reoxidative inclusions. Hence, the present work aims to systematically investigate the combinational effect of different tundish fluxes on the reoxidation behavior of Al-killed Ti-FSS melt. Rice husk ash (RHA) and MgO (M) insulation powders, and calcium aluminate, CaO–Al 2 O 3 (CA) based flux were used for the experiments. When the molten steel was covered by M + CA fluxes, the average size of inclusions decreased. On the other hand, when the RHA + CA fluxes were added, the average size of inclusion decreased, whereas total number of inclusions significantly increased due to a reoxidation reaction by SiO 2 in RHA. When the M + RHA + CA combinative fluxes were added, the size of inclusion decreased, and the number of inclusions exhibited a value between the M + CA and RHA + CA conditions. Consequently, a decrease in total oxygen content in Ti-FSS was most effective in the M + CA flux combination.