Original Article

Effect of Ce on inclusions, carbides, and solidification structures in Cr12MoV cold-work die steel

Center for Advanced Solidification Technology of Shanghai University, State Key Laboratory of Materials for Advanced Nuclear Energy, Shanghai 200444, PR China

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Received: 27 February 2026
Accepted: 29 May 2026

Abstract

The effect of Ce on inclusions, carbides, and solidification structures in Cr12MoV cold-work die steel was systematically investigated through high-temperature melting experiments, 3D electrolytic etching and thermodynamic calculations. The results showed that with increasing Ce content, inclusions evolved in the following sequence: Al₂O₃ + MnS → CeAlO₃ → Ce₂O₂S. Ce addition significantly refined the inclusions and promoted a more dispersed distribution within the steel matrix. Optimal inclusion modification was achieved with the Ce addition of 75 ppm, which effectively minimized the equivalent diameter of inclusions to approximately 3 μm and maintained an area fraction of around 0.05% throughout the ingot. Furthermore, although Ce addition did not alter the existing carbide types, which were identified as Cr-rich M₇C₃, Mo-rich MC, and fine Cr-rich M₂₃C₆, it effectively refined the morphology of the eutectic network carbides and reduced the prior austenite grain size. Quantitative analysis demonstrated that the optimal 75 ppm Ce treatment reduced the total carbide area fraction by nearly half, decreasing it from approximately 14–17% to 7–9%. By establishing the quantitative relationship between Ce content and microstructural refinement, this study provides a theoretical basis for optimizing rare earth treatments, offering valuable guidance for the industrial production of high-performance cold-work die steels and the broader application of rare earth elements in high-alloy steels.