Effect of Nb Content on the Behavior of Primary Carbides in 0.4C-5Cr-1.2Mo-1V Steel

Niobium (Nb) microalloying can improve the material properties of H13 steel (0.4C-5Cr-1.2Mo-1V steel), but it also affects natures primary carbides. Therefore, effect Nb content and cooling rate on behavior carbides in was studied this paper. The matrix structure obtained by chemical etching, then formation location identified electron probe microanalysis (EPMA). three-dimensional (3D) characteristics, including morphology, number density, size, were a non-aqueous electrolysis method. enrichment alloying elements last-to-solidify region leaded to during solidification. Ti4C2S2 phase precipitated first, Mo-Cr-rich carbide formed around phase. During process, partly transformed into Nb-rich further V-rich carbide. There is huge difference between two-dimensional morphologies As increased, size decreased gradually density 3D observation increasingly increased. However, as decrease rate, increased rapidly markedly. thermodynamic kinetics calculation results agreed well with experimental observations.