Abstract: Two groups of Al alloy substrates with different thicknesses were selected to prepare SA15 and SA25 self-piercing riveted joints and fatigue tests were conducted. The validity of fatigue data was verified by two-parameter Weibull distribution. Fatigue behavior of the joints was analyzed by S-N curves, which were fitted by empirical formula of fatigue three-parameter. The relation between fretting wear and fatigue failure was investigated by a scanning electron microscope (SEM). The results revealed that experimental data were valid because of they obeyed Weibull distribution. S-N curves of the joints can be well fitted by the empirical formula, the fatigue performance of SA25 joints is superior to that of SA15 joints. SA25 joints have excellent fatigue performance during middle-low fatigue life domain. SA15 joints failed in the upper substrate near rivet head, and SA25 joints fractured at the bottom substrate along the button. SA15 joints appeared severer fretting behavior at the riveting interface between two substrates, while SA25 joints appeared severer fretting wear at the interface between bottom substrate and rivet leg. Fatigue failure position coincided with the severer fretting wear position, which reveals that fretting wear is one of the significant factors for the fatigue failure of the joints.
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2017, Vol. 31 
