Micro-porous layer generated during gas nitriding and induction quenching compound treatment affects tribological properties

In this study, a micro-porous layer (MPL) about 40 μm depth was fabricated on the surface of 55CrMo steel after gas nitriding and induction quenching (GN+IQ) hybrid treatment. A zirconia ceramic ball was used as the counter-body, and the tribological performance of MPL was analyzed under dry sliding and starved lubrication conditions with loads of 20 N and 100 N. Under dry sliding conditions, the wear rate of the MPL was higher during initial stages under a larger load of 100 N, however, the coefficients of friction (COF) decreased after GN+IQ treatment compared to induction quenching under either load. Under starved lubrication conditions, the COF decreased and remained relatively stable throughout the test process that owe to the extruded oil stored in the MPL, moreover, the anti-wear performance of GN+IQ hybrid treated sample was also enhanced by a single abrasive wear mechanism as opposed to a combination of adhesive wear and abrasive wear of in the IQ-treated sample.