采用超声表面滚压处理（USRP）技术对45钢表面进行强化处理，通过表面形貌和表层显微组织观察、表面粗糙度和摩擦磨损性能测试，研究了USRP对该钢摩擦学性能的影响及机理。结果表明：USRP试样的表面粗糙度由未处理试样的3.2 μm降低到0.23 μm；显微组织得到了细化，晶粒取向趋于随机分布，有大角度晶界出现；表面显微硬度比未处理试样的提高约56%，强化层厚度达到400 μm；USRP试样的摩擦因数小于未处理试样的，磨损量为未处理试样的1/4；未处理试样磨损过程中表面材料呈“片块状”脱落，磨损机制为黏着磨损，USRP试样磨损表面上存在犁皱形成的沟槽，磨损机制为磨粒磨损。

The surface strengthening of 45 steel was carried out by the ultrasonic surface rolling processing (USRP) technique. Then the influence of USRP on the tribological performance of the steel and the mechanism were studied by means of the surface morphology and surface microstructure observation, surface roughness and friction and wear performance tests. The results show that the surface roughness of the USRP specimen decreased from 3.2 μm of the untreated specimen to 0.23 μm; the microstructure was refined, the grain orientation tended to be randomly distributed and the high-angle grain boundary was observed; the microhardness at the surface was about 56% higher than that of the untreated specimen, and the thickness of the strengthening layer was up to 400 μm; the friction coefficient of the USRP specimen was lower than that of the untreated specimen and the wear loss was 1/4 of the untreated specimen. The surface materials of the untreated specimen showed a piece-like peeling during the wear process with the wear mechanism of adhesive wear. While on the wear surface of USRP specimen, the ploughing formed grooves were observed and the wear mechanism was abrasive wear.