Enhanced Refinement of Cr23C6 by Heterogeneous Nucleation in Annealed Nitrogen-Alloyed 4Cr5Mo2V Die Steel

The enhanced refinement of Cr23C6 by heterogeneous nucleation in annealed nitrogen-alloyed 4Cr5Mo2V die steel was investigated. The refinement was ascribed to the increase of undissolved V(C,N) that served as the nucleation of Cr23C6. A three-step reaction (M3C → M7C3 → M23C6) was assumed to explain the nucleation process of Cr23C6. The possibility of nucleation of M3C on V(C,N) was validated by classical nucleation theory, and the crystallographic relationship was accurately described using the Turnbull-Vonnegut disregistry.