Correlation of microstructure with hardness and wear resistance in Cr3C2/stainless steel surface composites fabricated by high-energy electron beam irradiation

Correlation of microstructure with hardness and wear resistance in Cr3C2/stainless steel surface composites fabricated by high-energy electron beam irradiation was investigated in the present study. Three kinds of powder mixtures, i.e., 50Cr3C2-50CaF2(flux), 100Cr3C2 and 87.5Cr-12.5C (wt.%), were placed on an AISI 316L stainless steel substrate, which was then irradiated with electron beam. In the specimens fabricated without the flux addition, the surface composite layer of 3.5-4.8 mm in thickness was successfully formed without defects by the self-fluxing effect, and contained a large amount (up to 18 vol.%) of Cr7C3 carbides in the austenite matrix. The composite layer fabricated with Cr + C powders having lower melting points than Cr3C2 powders was thicker than that fabricated with Cr3C2 powders because of more effective melting of Cr + C powders during electron beam irradiation. The hardness and wear resistance of the surface composite layer were directly influenced by hard Cr7C3 carbides, and thus were about two times greater than those of the stainless steel substrate.