Self-piercing riveting of aluminium-lithium alloy sheet materials

The self-piercing riveting (SPR) of 1420 aluminium-lithium alloy sheets is investigated. Static tests with lapshear loads and fatigue tests using the tension-tension loading mode were applied to obtain the joint performances and failure modes. The mechanism analysis regarding failure and fretting was employed using a scanning electron microscope (SEM) and an energy dispersive X-ray spectroscopy (EDX). The 1420 Al-Li alloy sheets can be joined effectively using SPR. The fatigue load-fatigue life curve with a 95% confidence level is obtained using a variation coefficient method. The joints failed in the rivet pulled out from the locked sheet in static trials, and the locked sheet fractured during the fatigue tests. The fretting wear can be observed at the contact interface between the rivet tail and the locked sheet or between both sheets at different load levels. The fretting region changes at a high or low load level, and it is highly relevant to the fatigue rupture paths.