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

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/cm²). 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 M₁₂C and M₂₃C₆. 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.