Thermodynamic behaviour of TiO2 in CaO-Al2O3-MgO-TiO2 slag at high temperatures

High-Cr and Ti-bearing ferritic stainless steel (FSS) has superior corrosion resistance compared to other steels. The Ti-bearing FSS requires not only high corrosion resistance and formability, but also high cleanliness of the cold rolled sheet. Specifically, the cleanliness of Ti-bearing FSS has been improved through the vacuum oxygen decarburisation (VOD) and the ladle treatment (LT) processes. Nevertheless, there are still unsolved problems such as large fluctuations in Ti yield due to various factors including Al deoxidation practice and slag-metal reactions after Ti alloying. The activity of TiO2 in the CaO-Al2O3-based slag must be measured to determine the equilibrium of the reaction between Ti and O in the molten steel and TiO2 in the slag. Moreover, in continuous casting tundish, the internal cleanliness of molten steel is significantly affected by the reoxidation due to the reaction with the atmosphere as well as tundish flux and insulation cover powder. Therefore, the present study aims to provide a systematic understanding the reaction between Ti-bearing FSS melt and the slag and to investigate the thermodynamic behaviour of TiO2 in the CaO-Al2O3-MgO-TiO2 slag.