Fretting degradation in large flat-on-flat contact under oil lubrication: Effect of displacement amplitude

Fretting degradation of self-mated quenched and tempered steel was studied by varying loading conditions via imposed tangential displacement amplitude in oil-lubricated flat-on-flat contact. Detailed microscopic characterization showed the effects of tangential loading and the presence of oil at the interface on (sub)surface damage. A thin, cracked carbonaceous layer, arising from oil decomposition, was detected at adhesion spots in the mixed slip-stick regime. Furthermore, surface oxidation was noticed at the highest imposed displacement amplitude of 45 µm in gross slip, despite the presence of oil. Based on the crack analysis, a substantial increase in crack size was observed by transitioning from mixed slip-stick to gross slip. • Crack size increased significantly by transition from mixed slip-stick to gross slip. • A thin, cracked carbonaceous layer formed at adhesion spots in mixed slip-stick. • Oxidation occurred near the outer edge at high displacement amplitude in gross slip. • Two types of third-body layers were noticed in distinct fretting scars in gross slip.