Influence of heat treatment on mechanical properties of clinched joints in titanium alloy sheets

Clinching is a widely used sheet material connection technology in different industrial fields. The effects of annealing and quenching on the mechanical performances of clinched titanium alloy joints were investigated in this research. Tensile–shear tests were carried out to study the join ability, load-bearing capacity, energy absorption, and failure modes of different clinched titanium alloy joints. The F–N curves were obtained from fatigue tests to characterize the fatigue properties of different types of clinched joints. The typical fracture interfaces were analyzed by scanning electron microscopy. Results show that the tensile–shear strength of the clinched titanium alloy joints was severely decreased by quenching, but both tensile–shear strength and energy absorption were improved by annealing. For all types of joints tested, fatigue cracks always appeared near the indentation of the upper sheet. Analysis of the microstructure suggested that the plasticity of the titanium was improved by annealing.