Effects of ultrasonic shot peening process parameters on nanocrystalline and mechanical properties of pure copper surface

Abstract

In this paper, the effects of ultrasonic shot peening (USP) and various process parameters on grain refinement, surface hardness, and tensile properties of pure copper surface layers were studied. USP was employed to obtain a grain-refined strengthening layer on the surface of pure copper, and the grains size of the strengthening layer were less than 10 nm, and the thickness of the grain-refined strengthening layer can reach 338 μm. The influence law of process parameters on microstructure was acquired. The hardness of surface increased by 233.5%, from 42.6 HV to 142.1 HV, the influence law of process parameters on surface hardness was grained. Obviously, it was found that the tensile strength was increased from 263 MPa to 308 MPa, which was 17.1% higher than that of the original pure copper specimens by using USP stretch on both sides of the tensile specimens. The influence law of process parameters on tensile strength was obtained. When the peening duration was 120 s, the optimal tensile strength can be obtained, sufficient plasticity can be retained meanwhile.