Influence of microstructure evolution during the sliding wear of CL65 steel

Sliding wear experiments were performed on CL65 wheel steel to analyze the changes of the microstructure at the outermost layer of the wear surface and wear property at different wear stages. The study showed that during sliding wear, the wear mechanism of the wheel steel blocks' wear surfaces mainly concludes adhesion wear, abrasive wear and fatigue wear. The microstructure at the wear surface underwent changed, in the process of sliding wear, which accordingly altered the surface damage form and the wear weight. Based on the variation of wear weight, three stages could be divided: rapid wear, slow wear and stable wear. During the stage of rapid wear, the wear surface was mainly featured by furrow wear, with large spall at the same time, and the microstructure at the outermost layer was severe plastic deformation pearlite; during the stage of slow wear, the wear surface was mainly marked by furrow and adhesion wear, and the microstructures at the outermost layer were sub-micrometer ferrite subgrains and fragmented short-bar shaped cementite; during the stage of stable wear, the wear surface was characterized by small lamellar spall, and the microstructures at the outermost layer were equiaxed ferrite nanocrystalline grains and undissolved nanometer-sized cementite particles. In the process of sliding wear, abrasion resistance reached the peak when the microstructure at the outermost layer of CL65 wheel steel was subgrains. Compared with the plastic deformation pearlite layer, the nanocrystalline layer possessed sound abrasion resistance. However, between the nanocrystalline layer and the subgrain layer, stress was relatively large, which tended to cause cracks at their interface and further increased wear weight.