Precipitation of TiS in Al–Ti Simultaneously Deoxidized Steel

Abstract

Herein, the precipitation of TiS in an Al–Ti simultaneously deoxidized steel is observed, and the results confirm the precipitation of single TiS, two‐layered oxide (Al2O3 or TiOx)–TiS composite, and three‐layered Al2O3–TiOx–TiS composite inclusions in the steel. Thermodynamic calculations reveal that TiS precipitated in the experimental steel during the solidification process when the solid fraction (xs) is 0.880. In addition, the precipitation of TiOx during solidification depends on the equilibrium partition of O. When the O content in steel is very low, TiS rather than TiOx is precipitated. In addition, the enrichment of O in the residual liquid steel results in the precipitation of TiOx during the solidification process. Oxide–TiS is formed by TiS precipitation on the surface of Al2O3 and TiOx precipitation in the liquid steel or at the initial stage of solidification. However, Al2O3–TiS is formed only in preformed solid steel with low oxygen content. The lattice misfit results suggest that it is easier to match TiS to TiO and TiO2, while the misfit of TiS(001)/bcc Fe(100) is 6.06.