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In order to optimize the heating schedule before forging and improve the breaking and deformation effects of carbides in high‐speed steel, it is of great significance to study the transformation of M 2 C carbides at high temperatures. The evolution of carbides in the industrial‐grade American Iron and Steel Institute M35 steel produced by electroslag remelting (ESR) is analyzed and observed using thermodynamic calculations and experimental methods. The results indicate that the carbides in the ESR ingot are mainly MC and M 2 C, and the microstructures of M 2 C carbides with the highest volume fraction are lamellar and brain like. As the heating temperature increases and holding time prolongs, the lamellar M 2 C carbides gradually transform into MC and M 6 C carbides, accompanied by protrusion, dissolution, separation, and spheroidization of the microstructure, until significant coarsening occurs at 1180 °C for 90 min. The newly transformed carbides are embedded and stacked with each other, occupying the original position of M 2 C carbides. Based on the theories of Gibbs free energy and atomic diffusion, the evolution mechanism of M 2 C carbides is discussed. Ultimately, the appropriate heating schedule is proposed, and it is validated by combining the characteristics of carbides after forging.
Liang et al. (Mon,) studied this question.