Behavior and Quality Evaluation of Electroplastic Self Piercing Riveting of Aluminum Alloy and Advanced High Strength Steel

Abstract

The hybrid use of dissimilar lightweight materials, such as aluminum alloy and advanced high strength steel (AHSS), has become a critical approach to reduce the weight of ground transportation vehicles. Selfpiercing riveting (SPR) as a preferred coldforming fastening method is facing problems like weak interlocking and insufficient penetration, due to the reduced formability of AHSS. In this paper, a new process named electroplastic selfpiercing riveting (EPSPR) was proposed to reduce the deformation resistance of AHSS DP780, by applying a direct current (dc) to it during the riveting process. The influence of dc on force and displacement characteristics throughout the riveting process, joint physical attributes and quasistatic performances for two sheet combinations, e.g., AA6061T6 to DP780 (combination 1) and DP780 to AA6061T6 (combination 2), were studied and compared with the traditional SPR joints. The results showed that compared with the traditional SPR joints, the EPSPR ones increased by 12.5% and 23.3% in tensileshear strength and crosstension strengths for combination 1, respectively. For combination 2, even though the EPSPR joints decreased by 5.8% in tensileshear strength, it could reduce the penetration risk of bottom AA6061T6, and present a better energy absorption capability for the increased undercut amount. In addition, the corresponding crosstension strength of EPSPR joints still increases by 6.1%.