Study on wear and rolling contact fatigue behaviors of wheel/rail materials under different slip ratio conditions

The objective of this study is to evaluate the effect of slip ratio on the wear and rolling contact fatigue (RCF) of wheel/rail materials using a rolling-sliding wear testing apparatus. The results indicate that two wear types are presented in terms of wear rate: type I (mild wear) and type II (severe wear). In type I wear, cracks propagate parallel to the surface. While in type II, the peeling is aggravated and spalling can be observed. With the slip ratio increasing, the wear mechanism of rollers transforms from slight oxidation wear and peeling to severe fatigue wear and spalling. Due to the mild wear and light plastic deformation in type I, the angle and depth of cracks show no obvious differences between the wheel and rail rollers. The crack depth and angle increase in type II wear owing to severe plastic deformation, while the depth is smaller on the wheel rollers. The size of flake wear debris presents an increasing trend and the main composition is Fe2O3 and metallic iron, and the content of iron diminishes with increasing oxidation.