Effect of defocused electron beam surface Ni/VC alloying on microstructure and properties of 40Cr steel

ABSTRACT The use of alloying technology can improve the surface mechanical properties of 40Cr steel and prolong its service life. In this study, the Ni/VC surface alloying modification treatment of 40Cr steel was carried out using electron beam defocusing. The results show that after defocusing electron beam treatment, the cross-section of the specimen is composed of alloying layer, heat-affected zone and matrix. When the VC content is 80%, the maximum hardness is 1030 HV0.1, which is 4.3 times higher than that of the 40Cr matrix (240 HV0.1), and the lowest coefficient of friction (COF) is 0.395, which is 1.9 times lower than that of the matrix (0.757). The wear mechanism of the matrix is mainly severe abrasive wear, and the wear mechanisms of the three specimens are mainly slight abrasive wear, slight fatigue wear and adhesive wear.