Effect of ultrasonic surface shot peening on the microstructure and properties of Cu-8Cr alloy

Surface nanocrystalline layers were prepared on Cu-8Cr alloy using ultrasonic shot peening (USSP) technique by controlling the pellet size and shot peening time. The tissue morphology, microstructure, surface hardness, surface strength and corrosion resistance of the generated surface nanolayers were systematically characterized using x-ray diffractometer (XRD), scanning electron microscope (SEM), and the corresponding test methods. The results showed that the USSP treatment did not change the surface phase of Cu-8Cr alloy, but only refined the surface grains into nanocrystals. The pellet size and shot peening time had a large effect on the surface properties of Cu-8Cr alloy. The best overall surface properties were obtained with a shot size of 2 mm and a shot time of 30 min The average grain size of the nano-layer is about 66 nm, the surface hardness is increased to 126.69 HV0.05, the tensile strength reached 417 MPa, and the corrosion resistance of the alloy is significantly enhanced. The USSP treatment provides a new method for the preparation of CuCr alloys with excellent surface properties.