Experimental investigation on the pre-holed screw-drilling riveting process for joining dissimilar lightweight sheets

The use of lightweight sheets such as carbon fiber reinforced composites (CFRP), magnesium alloys, and aluminum alloys is of great significance to realize the lightweight of automobiles. However, the differences between the sheets make the joining processes of dissimilar sheets a great challenge. A pre-holed screw-drilling riveting (PH-SDR) process is proposed based on a study of existing joining processes, the rivet with threads is riveted into the sheets by rotating, and the effective joining between the sheets is achieved by embedding the sheets into the rivet threads. The joint strength of the PH-SDR and self-piercing riveting (SPR) was compared through the lap-shear test. It was found that in the case of 1 mm Al6061-T6 + 2 mm AZ31B, the strength of the PH-SDR joint was 3.09 kN, which is 30.9% higher than the SPR of 2.36 kN. In the case of 2 mm CFRP + 2 mm Al6061-T6, when the spindle speed was 600 rpm, the strength of 5.43 kN and the energy absorption of 20.3 J were obtained for the PH-SDR joint, which is 51.2% and 89.7% higher than the optimal SPR joint. The results show that the proposed PH-SDR process provides a feasible solution for the joining of dissimilar lightweight sheets.