Primary Carbide Refinement in AISI M50 Steel by Dislocation Engineering via Pre-deformation Treatment

A novel mechanism was proposed to accelerate the refinement of metastable M2C in M50 steel by implementing a well-designed pre-deformation treatment. Compared with the samples treated by traditional diffusion, the new mechanism decreased the M2C area percentage by nearly 30 pct. Deformation dislocations caused the transition mechanism of M2C to transform into a coexisting interfacial and internal nucleation mode. The nucleation sites and alloying element rapid diffusion channels were increased through deformation, which accelerated the transformation and diffusion dissolution of M2C. The significant refinement of the primary carbide led to longer fatigue life and greater reliability under fatigue loading.