Effect of annealing treatment on fatigue behavior of titanium alloy clinched joints

Clinching technology was used to connect titanium alloy sheet， one group of the specimens was untreated， and the other group was annealed. Quasi static mechanics performance experiment and fatigue tests were adopted to test the property of the two kinds of joints. It can be seen from experiments that the tensile-shear strength was 4 363.64 N， the displacement was 1.48 mm. And the tensile-shear strength and displacement of the annealed joints were respectively 3 879.74 N and 1.85 mm. It can be concluded that the untreated clinched joints has a superior fatigue performance than the annealed clinched joints. The cracks of the two kinds of joints were always appear at the first force bearing point of the button， and the stress concentered in that location and there exist several fatigue sources and the fracture had feature of brittle fatigue fracture. The fracture of the annealed joints at the minimum thickness of the neck had a feature of ductile fracture.