The influence of laser surface texturing on fretting damage of interference fit interface in service was studied by using the self-developed interference fit simulation experimental device. The train bogie was taken as the research object. The fretting experiment of interference fit interface was simplified by using the sleeve and hollow shaft. The outside surface of hollow shaft sample was textured by HGTECH LSF20D laser marking machine. The surface texture pattern is elliptical and has a surface density of 25%. The length ratio of the major axis to the minor axis of the ellipse is set to 0.618. The elliptical area is equal to that of the circle with a diameter of 100 μm. In order to ensure the consistent working conditions, the circumferential surface of the hollow shaft was divided into two equal regions in the axial direction. One half of the region was textured and the other half was kept in the original state. The fretting damage test was carried out through the WPA-20 testing machine. According to the actual working condition of the train bogie, the low cycle loading was adopted. The load frequency was set to 5 Hz, the load pressure was 5 kN, and the load amplitude was 1 mm.

The evolution characteristics of fretting damage of interference fit interface under different load frequencies were studied, and the load frequencies were selected as 30 000 cycles, 50 000 cycles, and 70 000 cycles, respectively. After the fretting damage test of each stage is completed, the specimens were cut by wire cutting, and the damage evolution of the textured area and the untextured area of the mating surface was analyzed by the laser measuring microscope (VK-X250, KEYENCE, Japan). The experimental results showed that the laser surface texturing enhanced surface strength and wear resistance of the interference fit interface, significantly reduced the fretting damage of the interference fit interface during service.

The experimental results were analyzed from the microstructure, residual stress and electron work function. After laser surface texturing, the surface layer of the specimen was strengthened according to the microstructure. Compared to non-textured samples, martensite phase was produced on the textured surface. The full width at half peak of the textured specimen significantly increased, and there was a certain diffraction peak shift. Therefore, grain refinement and dislocation strengthening occurred on the surface of the textured specimen. The hardness of surface layer of the textured sample reached 290 HV_0.025. When the depth was about 120 μm, the hardness gradually decreased to 195 HV_0.025, which was consistent with the hardness of the non-textured specimen. The grain refinement and dislocation strengthening enhanced the surface strength of textured surfaces, while the generation of martensite and the increase in surface hardness improved the wear resistance of textured surfaces. It could be seen from the residual stress test results (MAX2500VL, Rigaku, Japan) that the residual compressive stress of 280.15 MPa was produced on the textured surface, which delayed the fretting damage propagation. According to the test results of atomic force microscope (Dimension Icon, Bruker, Germany), the surface electron work function of the textured surface was increased by 4.4%, improving the peel resistance of the surface material.