Correlation of microstructure with hardness and wear resistance of (Cr3C2,CrB)/steel surface alloyed materials fabricated by high-energy electron beam irradiation

Abstract

The correlation of microstructure with the hardness and wear resistance of (Cr3C2,CrB)/steel surface alloyed materials fabricated using high-energy electron beam irradiation was investigated in this study. Two kinds of powder mixtures, 50Cr(3)C(2)-50STS304 and 50CrB-50STS304 (wt pet), were placed on a plain carbon steel substrate, which was then irradiated with an electron beam without adding flux. Surface alloyed layers 1.0 to 1.3 mm in thickness were successfully formed without defects; these layers contained a large amount (up to 58 Vol pct) of Cr7C3 or Cr1.65Fe0.35B0.96 in the austenite or martensite matrix. Both the hardness and wear resistance of the surface alloyed layer were directly influenced by hard carbides or borides, and were 2 to 3 times greater than those of the steel substrate. Particularly in the surface alloyed material fabricated with CrB and stainless steel powders, selective wear of the matrix was considerably reduced. This was due to the number of fine borides homogeneously distributed in the hard martensite matrix and, in turn, led to excellent wear resistance. These findings suggested that irradiation with a high-energy electron beam was useful in the development of surface alloyed materials with improved hardness and wear resistance.