Abstract: Based on self-piercing riveting (SPR) technology, the effective connection for TA1 titanium alloy sheets is realized. And TH and TR joints are fabricated with reducing the sheet hardness and raising the rivet hardness, respectively. The static and fatigue performances are studied, and the S-N curves are fitted using the S-N curve fitting method. Finally, the failure behaviors of the joints are analyzed in a macro perspective, and the micro fracture analysis for TR joints is conducted with a scanning electron microscope (SEM). The results showed that:TR joints are more practical than TH joints. The peak load and energy absorption value of TH joints are superior to those of TR joints, and their static failure modes are all rivet fracture. TR joints had a better fatigue performance than TH joints, they both failed because of locked sheet fracture or rivet fracture. Furthermore, it can be referred that the fatigue cracks of TR joints, which failed due to locked sheet fracture, initiated at the stress concentration point of the rivet feet, and extended along the sheet width direction first, and then along the thickness direction of the plate until the joints are completely broken. And the rivet fracture surfaces of TR joints are the typical fatigue brittle fracture characteristics.

Key words: failure behavior, fracture analysis, process research, self-piercing riveting, TA1 titanium alloy