Microstructure and tribological properties of complex nitrocarburized steel

Two kinds of tribological apparatus were employed to investigate the friction and wear performance of steel 1045 treated by quenching plus tempering and complex nitrocarburizing processes. The microstructures, phase identification, surface hardness and hardness profiles of the specimens were analyzed by optical metallography, microhardness tests and X-ray diffraction; at the same time the surface roughness of specimen surfaces was tested using a profilometer. The experimental results show that: the ε-phase formed on the specimen surface has a significant effect on reducing the friction coefficient and improving wear resistance; the oxidation after nitrocarburizing rarely changes the friction coefficient but decreases the wear resistance; and with oxidation plus polishing and secondary oxidation complex treatments being performed, the wear resistance of nitrocarburized specimens is improved even further.