The influence of ultrasonic shot peening on the surface roughness, microstructure, and mechanical properties of TC2 thin-sheet

Abstract

The research aimed to find a physical strengthening method for thin-sheet metal parts using an ultrasonic shot peening (USP) method at room temperature. Herein, the influence of the USP treatments on the surface roughness, microstructure, micro-hardness, and tensile strength of the TC2 thin-sheet with a thickness of 0.5 mm was investigated systematically. The results showed that the Ra of the TC2 thin-sheets increased to 0.374, 0.418 and 0.479 μm after the USP treatments with the intensities of 0.189, 0.277 and 0.360 mmA, respectively. Compared with pneumatic shot peening (PSP) of similar Almen intensity, the surface quality of the alloy after USP treatment was significantly improved. The cross-sectional micro-hardness curves of the USP-treated TC2 thin-sheet showed ‘V’ shapes, and the micro-hardness of the surface layer increased as the shot peening intensity increased. When the Almen intensity was 0.360 mmA, the corresponding maximum micro-hardness of the surface layer was 362.9 HV0.025, which was 67.9 HV0.025 larger than that of the initial alloy. The USP treatment also improved the tensile strength of the TC2 thin-sheet, and the tensile strength increased as the shot peening intensity increased. When the Almen intensity was 0.360 mmA, the tensile strength was increased by about 6.23%, reaching 799.3 MPa. Therefore, the USP treatment method is a potential physical strengthening method for thin-walled parts at room temperature.