Effect of supersonic fine particle bombardment on the surface integrity and wear performance of DZ2 axle steel

DZ2 axle steel is a type of steel used in high-speed trains. The effects of supersonic fine particle bombardment (SFPB) under different air pressures (1, 1.5, and 2 MPa) on the surface integrity and wear properties of DZ2 axle steel were investigated by microstructural, residual stress (RS), surface morphology, and wear tests. After SFPB, the surface grains were refined. The results show that the material treated with higher pressure had a greater thickness of deformation layer, microhardness and compressive residual stress. In addition, no phase transition was observed in the deformation layer. The tribological properties of the treated samples were worse than that of the untreated samples because of the reduced surface roughness. However, the negative effects of surface roughness were offset at high load. Furthermore, the RS distribution of the SFPB-treated samples was more uniform than that of the untreated sample after the wear tests, which was beneficial to decreasing the stress concentration.