Mechanical properties and fatigue failure mechanisms of purely self-piercing riveted (SPR) and hybrid (SPR-bonded) joints under salt spray environment

Abstract

Automotive light-weighting has become an important direction for the development of the automotive industry, and the light-weighting materials are inevitable to be joined. Self-piercing riveting (SPR) is a kind of new process to joint various materials. The SPR and SPR-bonded (SPR-A) joints of AA6061 and DP590 sheets were prepared. The mechanical properties of SPR and SPR-A joints after exposure to neutral salt spray environments for different aging times were tested. The results showed that the shear and fatigue properties of the joints gradually reduced with the increase of salt spray time. In addition, the SPR-A joints not only have higher maximum failure loads but also have larger energy absorption values in shear tests when compared with that of the SPR joints under the same salt spray time. The fatigue test results showed that fretting wear between the rivet-foot and the lower sheet is the main failure mechanism of joints. Moreover, the salt spray time has no obvious effect on the fatigue failure modes of the two kinds of joints.