Influence of La Addition on the Precipitation Behavior of Ti‐Containing Inclusions During Solidification of High‐Titanium Wear‐Resistant Steel

Ti‐containing inclusions play a crucial role in determining the wear resistance and mechanical strength of high‐titanium wear‐resistant steel. In this study, the evolution of inclusions during the solidification process of La‐treated high‐titanium wear‐resistant steel was systematically investigated by combining high‐temperature simulation experiments with thermodynamic calculations. The results indicate that, under the La → Ti addition sequence, the precipitation sequence of inclusions during solidification is oxide → Ti(C,N) → (Mo, Ti)C → Ti 4 C 2 S 2 . As the La content increases, the oxide inclusions change successively from Al 2 O 3 to LaAlO 3 and then to La 2 O 2 S. When La treatment is applied after Ti alloying, the overall precipitation sequence remains basically unchanged, but Ti 4 C 2 S 2 inclusions didn’t form. In addition, the (Mo, Ti)C inclusions, which exhibit the highest number density, are significantly refined, with the average size reduced to 2.76 μm. This refinement is mainly attributed to two factors: first, La thermodynamically delays TiC precipitation and reacts with S to promote La 2 O 2 S formation, thereby suppressing Ti 4 C 2 S 2 formation; second, La 2 O 2 S may provide a favorable heterogeneous nucleation site for TiC. These findings suggest that applying La treatment after Ti alloying is beneficial for refining Ti‐containing inclusions.