Experimental Study on the Behavior of TiN and Ti2O3 Inclusionsin Contact with CaO-Al2O3-SiO2-MgO Slags

TiN and Ti2O3are the predominant inclusion types in Ti-alloyed ferritic chromium stainless steels. In order to ensure the requiredsteel cleanness level, an effective removal of such inclusions in the slag during secondary metallurgy is essential. This inclusionremoval predominantly takes place via dissolution of the inclusion in the slag. The dissolution behavior of TiN and Ti2O3in CaO-SiO2-Al2O3-MgO slags as well as their agglomeration behavior in the liquid steel is investigated using High Temperature LaserScanning Confocal Microscopy and Tammann Furnace experiments. Thermodynamic calculations are performed using FactSage7.0. The behavior of TiN is observed to be completely different to that of oxides. Ti2O3dissolves quickly in slags, and its dissolutionbehavior is comparable to that of other already well examined oxides. In contrast, TiN shows a very intense gas reaction whichis attributed to the release of nitrogen during contact with slag. Slags with higher SiO2content show a significantly higher abilityfor the dissolution of TiN as compared to Al2O3-rich slags. The gas reaction is found to also significantly influence the final steelcleanness. Despite the easy absorption of TiN in the slag, the formed nitrogen supports the formation of pinholes in the steel.