Hardness and Wear Resistance of (Cr_3C_2,CrB)/Steel Surface Composites Fabricated by High-Energy Electron Beam Irradiation

摘要

The present study is concerned with the improvement of hardness and wear resistance in (Cr_3C_2,CrB)/carbon steel surface composites fabricated by high-energy electron beam irradiation. Two kinds of powder mixtures, i.e., 50Cr_3C_2-50STS304, 50CrB-50STS304 (wt. percent), were placed on a plain carbon steel substrate, which was then irradiated with electron beam without using flux. The surface composite layer of 1.0-1.3 mm in thickness was successfully formed without defects, and contained a large amount (up to 58 vol. percent) of Cr_7C_2or Cr_(1.65)Fe_(0.35)B_(0.9) in the austenite or martensite matrix. The hardness and wear resistance of the surface composites layer were directly influenced by hard carbides or borides, and thus were about 2~3 times greater than those of the steel substrate. Particularly in the surface composite fabricated with CrB powders, selective wear of the matrix was considerably reduced as a number of fine borides were homogeneously distributed in the hard martensite matrix, thereby leading to the excellent wear resistance. These findings suggested that the high-energy electron beam irradiation was useful for the development of surface composites with improved hardness and wear resistance.