Effects of displacement amplitude on fretting wear behaviors and mechanism of Inconel 600 alloy

Abstract

The fretting test on Inconel 600 alloy at different displacement amplitudes was conducted at room temperature in air with a relative humidity of 30–40% using an SRV IV fretting test rig. The effects of displacement amplitude on the ratio of tangential force to normal load and wear volume were analyzed. The worn surfaces and cross-sectional morphologies were subsequently investigated using optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). The results indicated that the displacement amplitude had a strong effect on fretting wear behaviors and wear mechanism. With the increase of fretting amplitude, the ratio of tangential force to normal load and wear volume increased, and the fretting mode gradually transformed from mainly adhesion to fully slide. Correspondingly, the wear mechanism transformed from local adhesive damage to the combination damage of oxidation and delamination wear. Microcracks in the wear scar strongly depended on fretting mode. There was no microcrack in the adhesion zone, however microcracks were usually found in the slide zone and the junction zone of slide and adhesion. As a result of plowing effect on the edge of the wear scar, the shape of the worn scar changed from round to ellipsoidal and the formation of delamination cracks in the subsurface. Fretting created a gradient strain in the subsurface of worn scar, and resulted in the formation of nanocrystalline in tribological transformed structure layer under the worn scar.