Effect of bake hardening treatment on the mechanical behaviors of aluminum alloy spot welding joints

Abstract

In this paper, the mechanical behaviors of the spot welding aluminum alloy in both baked and unbaked conditions are investigated. The spot welded specimens with two different base aluminum alloy sheets are studied by tensile and fatigue tests. The test results of unbaked specimens are compared with the baked which are baked at 185°C for 20 min. The stress distribution of the specimens and the fatigue life under different stress is simulated by finite element method (FEM). The paint bake treatment can increase the ductility of both base materials and spot joints. The fatigue life is increased with high loading stress due to the pinning effect; while with low fatigue load, it has the opposite rule because the compressive residual stress is released during the bake hardening process, which can restrain the fatigue crack growth rate in low stress. The simulated results of FEM model can well verify the experiment data.