Effect of shot peening on static and fatigue properties of self-piercing riveting joints

Abstract

The joint strength of self-piercing riveting is a key factor for evaluating riveting quality. Shot peening is a useful process to strengthen sheet metal. To improve the performance of self-piercing riveting joints, the shot peening process and self-piercing riveting process are combined in this work. The shot peening of AA5052-H32 aluminum alloy sheets, static and fatigue experiments of the self-piercing riveting joints are executed, the effects of shot peening on the mechanical performance of the joints are performed. The results show that: The shot peening process can induce residual compressive stress in the surface layer of aluminum sheets, which can improve the performance of the joints; In the shot peening process, the largest residual stress is around −187.3 ± 5.1 MPa; The shot peening process can improve the static strength of the joints by about 9.5%, and has little effects on the tensile failure forms of the joints; The fatigue strength of the shot-peened self-piercing riveting joints is increased by about 9.2%. The main fatigue failure type is the damage of the lower sheets at the contact zones with the rivet leg. The contact surfaces for the shot-peened self-piercing riveting joints are suffered less from the fretting damage than that of non-shot peened joints. The static strength, fatigue strength are increased, and the fatigue crack growth rate is decreased for shot-peened joints. The shot peening process can be innovatively combined with the self-piercing riveting process to improve self-piercing riveting joint performance. This work provides new ideas to improve the self-piercing riveting quality.

Keywords

• Self-piercing riveting
• Aluminum alloy
• Shot peening
• Residual stress
• Static tensile strength
• Fatigue strength