Investigation of Joint Quality 980 MPa Grade GA Steel Sheet and 5052 Aluminum Alloy by Electromagnetic Self-Piercing Riveting

Abstract

Generally, an approximately 1% weight reduction in a 200 kg automobile improves the fuel economy by 20~26% and acceleration performance by 8%. Hence, various techniques for automotive lightweighting have been developed to satisfy environmental regulations of the automotive industry. The joining of dissimilar materials is critical for assembling lightweight body structures, but fusion welding is inapplicable owing to the difference in mechanical properties between materials. Thus, the development of an appropriate dissimilar material-joining process is required to produce high-quality joints. Self-piercing riveting is a representative joining process that is applied by pressure punching without prehole piercing. Operationally, this process is widely used for joining because it can produce joints with high shear strengths. However, the development of lighter and higher-strength materials indicates that the required force for SPR machines to form high-quality joints is increasing. Thus, high-speed E-SPR has been developed for joining ultrahigh tensile steels. In this study, SGAFC980/A5052-H34 was applied to the E-SPR process, and the joint characteristics were analyzed via cross-sectional analysis and shear strength tests. With an increase in the fastening speed, the interlock distance and the tensile shear load increased.