Friction plug−riveting spot welding of AA 7075-T6 aluminum alloy and low carbon steel using 1045 steel rivet

7075-T6 aluminum alloy/low carbon steel joint was carried out via a novel friction plug−riveting spot welding process. This process utilized uniquely designed steel rivets with a tip and groove shape. The macro- morphology formation, microstructure, microhardness and lap shear performance of joints were investigated. As the spindle down distance increased, the rivet tip was friction welded with the lower steel sheet, resulting in the formation of a solid phase welding zone exhibiting metallurgical bonding. Additionally, a hook was formed in the joint, providing the mechanical locking. The results showed that under optimal parameters of spindle down distance of 3.4 mm, rotation speed of 4000 r/min, and spindle down speed of 2.4 mm/s, the lap shear load of the joints reached a maximum of 14.36 kN. Failure occurred at the aluminum alloy base metal.