Influence of La–Ce Rare‐Earth Addition Routes on Elemental Homogeneity and Inclusion Modification in H13 Hot‐Work Tool Steel

This study investigates the transport behavior and distribution characteristics of La–Ce rare‐earth (RE) alloys within an EAF‐based short‐process melt. We systematically evaluated how the addition timing and physical environment (ladle furnace refining vs. ingot casting) dictate RE recovery, elemental macrosegregation, and inclusion evolution mechanisms. The results show that local RE retention index is strongly dependent on the addition route. It ranges from 42.49% to 48.89% for LF‐end addition and from 58.71% to 74.26% at the sampled positions for ingot‐casting addition. Furthermore, the spatial uniformity of elements was found to be a function of the addition route. LF addition, driven by strong ladle stirring kinetics, ensures a more homogeneous RE distribution and suppresses sulfur macrosegregation. In contrast, casting addition yields a “low‐center, high‐periphery” RE distribution pattern but offers superior carbon uniformity. The chemical nature of inclusions is determined by the coupling of addition route and slag chemistry: LF‐end addition primarily produces RE oxysulfides due to slag influence, whereas casting addition favors RE sulfides. Thermodynamic analysis established a clear evolution sequence with increasing localized La concentration: (MnS + Al 2 O 3 ) → (LaAl 11 O 18 + LaAlO 3 ) → (La 2 O 3 + LaAlO 3 /La 2 O 2 S) → (La 2 O 2 S + La 2 S 3 ). These findings provide critical theoretical insights into the distribution kinetics of RE alloys and offer a practical framework for optimizing alloy homogeneity in short‐process steelmaking.