The effect of pulsed electron beam melting on microstructure, friction and wear of WC–Hadfield steel hard metal

Abstract

Both structure and phase transformations in subsurface layers as well as the tribological characteristics of WC+30 wt.% Hadfield steel hard metal subjected to pulsed electron beam melting and then rubbed against a disk made of tool steel have been investigated. The melting was induced by a low-energy (10–40 keV), high-current electron beam (2.5 μS, 5–40 J/cm 2). It has been established that the pulsed melting and following high-speed quenching of the subsurface layers resulted in reducing the grain size of both initial carbide and binding phases as well as in forming metastable carbides of type M 12C and M 23C 6. It has been shown that the microstructural changes provided an increase in the surface microhardness by a factor of 1.5, a decrease in the friction coefficient by a factor of 2, and enhanced wear resistance, as compared to the untreated material.