Fatigue property and failure mechanism of self piercing riveted joints of TA1 titanium alloy

The fatigue tests of self-piercing riveting TA1 titanium alloy were carried out by axial loading, and the fatigue strength of the joints under different factors was analyzed. The failure fracture and fretting wear of the joints were analyzed by scanning electron microscopy (SEM), and the failure mechanism of specimen was studied. The results show that the fatigue strength increases with the increase of stress ratio and decreases with the increase of maximum load value under the same riveting conditions. It is found that the fatigue cracks mainly occur on the outside of the rivet leg when the rivet is broken, and the fatigue cracks first occur in the contact area between the rivet tail and the lower sheet when the sheet is broken. There is a competitive mechanism for the fretting wear between the lower sheet and the the rivet. When the crack growth rate of the rivet was greater than that of the lower sheet, the rivet would be failure, and on the contrary, lower sheet would be failure.