Correlation of microstructure with hardness and wear resistance in Cr 3C 2/stainless steel surface composites fabricated by high-energy electron beam irradiation

Abstract

Correlation of microstructure with hardness and wear resistance in Cr 3C 2/stainless steel surface composites fabricated by high-energy electron beam irradiation was investigated in the present study. Three kinds of powder mixtures, i.e., 50Cr 3C 2–50CaF 2(flux), 100Cr 3C 2 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 Cr 7C 3 carbides in the austenite matrix. The composite layer fabricated with Cr + C powders having lower melting points than Cr 3C 2 powders was thicker than that fabricated with Cr 3C 2 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 Cr 7C 3 carbides, and thus were about two times greater than those of the stainless steel substrate.