Wear damage and microstructure evolution of high-speed wheel steel under low slip ratios

Abstract

A rolling wear test was carried out to investigate the wear damage and microstructure evolution of high-speed wheel steel under low slip ratios. The results indicate that in the initial stage of wear, the wear mechanism changes from oxidative and adhesive wear to fatigue wear with an increasing slip ratio. With an increasing number of wear cycles, the fatigue wear of the sample surface increases. Wear damage mainly depends on crack initiation and propagation on the surface and in the cross-section. Cracks mainly initiate and propagate at the interface between the deformed proeutectoid ferrite and pearlite under low tangential force. However, with increasing tangential force, cracks extend through the adjacent softer proeutectoid ferrite during propagation. In the cross-sectional direction, when proeutectoid ferrite is present near the crack tip, the crack preferentially propagates through the this ferrite or along the interface between proeutectoid ferrite and pearlite. As the slip ratio increases, the depth of the refined proeutectoid ferrite and pearlite and the degree of refinement increase; in addition, the depth of cementite bending and fracture increases, and the degree of cementite fragmentation becomes remarkable. On the worn surface, with increasing slip ratio and number of wear cycles, ferrite is refined into a fibrous microstructure and cementite is refined from short rods into particles until almost no cementite is observed.