Effect of ultrasonic surface rolling process on the surface properties of QAl10-3-1.5 aluminum bronze alloy

Abstract

The main purpose of this article is to study the effect of ultrasonic surface rolling process (USRP) on the surface properties of QAl10-3-1.5 aluminum bronze alloy under different rolling reduction and rolling times, providing ideas for improving the poor wear resistance of valve stem nuts and sealing rings. SEM, EDS and optical three-dimensional profiler were used to characterize the microstructure characteristics of the surface modified layer and the surface morphology of the wear traces. The results show that the surface layer of the USRPed sample has undergone severe plastic deformation. The α phase is elongated, and the microstructure structure shows a fine and uniform distribution state. And the grain size of α phases decreased, and the number density of β phases increased. Compared with the untreated sample (only cutting and polishing), the surface roughness of the USRPed sample reaches nearly Ra 0.04 μm; the maximum surface micro-hardness is 323.04 HV, increasing by 75%; the maximum depth of surface hardening layer is about 570 μm. The friction coefficient, wear mass loss and the width and depth of the wear traces of the USRPed samples are significantly reduced, while the wear resistance is significantly enhanced. By comparing the surface wear morphology of the samples under different process parameters, it is found that the main wear mechanism of the untreated samples is adhesive wear, while the main wear mechanism of the USRPed samples is abrasive wear. The improvement in wear resistance is attributed to the refined and homogenized surface microstructure, the smaller surface roughness, the larger surface micro-hardness and surface hardness layer depth after USRP.