Fretting fatigue characteristics of self-piercing riveting in dissimilar sheets of TA1 pure titanium and 1420 aluminum-lithium alloys

Abstract

Using self-piercing riveting (SPR), the joinability of dissimilar sheet combinations in TA1 pure titanium (TA1) and 1420 aluminium-lithium (AL1420) alloy sheets were studied. SPR joints of TA1/AL1420 (TAF), AL1420/TA1 (ATF) and TA1/AL1420 (TAS) were fabricated from different rivets in the hardness of ≥ 44HRC and ≥ 46HRC, correspondingly. High cycle fatigue tests were conducted based on tensile-shear tests. Then F-N curves of different joints were fitted. Furthermore, fretting wear mechanisms of SPR joints were analysed by scanning electron microscopy (SEM) and energy disperse spectroscopy (EDS). Results show that the fatigue strength of ATF joints is better than that of the other joints. And the fatigue strength of TAS joints is superior to TAF joints at middle and high load level. Fatigue failure of all joints initiates in fretting wear areas, and fatigue wear results in fatigue crack initiation. Fretting degree is an important factor for affecting fatigue strengths. The serious fretting wear areas are different at different load levels, and then the initiated areas of fatigue cracks are different. Finally, different failure modes occur in the same SPR joints.

Keywords

• self-piercing riveting
• TA1 pure titanium
• 1420 aluminium-lithium alloy
• fatigue strength
• fretting wear