Effect of pulsed laser and laser-arc hybrid on aluminum/steel riveting-welding hybrid bonding technology

The microstructure and properties of aluminum (Al)-steel dissimilar metal riveting-welding joints obtained by the pulse laser and laser-arc hybrid welding methods were investigated. For simple laser beam riveting-welding Al and steel joint, the maximum tensile shear load of the joints was 6.3 kN, as the average laser beam power was about 438 W. The microstructure of the fusion zone (FZ) of the joint was twin martensite (TM), and there were small cracks in the weld. The Al elements were uniformly distributed in a vortex-shaped in the mixed region consisting of QP980 steel, 6061 Al alloy, and Q460 rivet, and the intermetallic compounds (IMCs) at the Al-steel interface had FeAl, Fe2Al5, and FeAl3. For the laser-arc hybrid riveting-welding joint, the maximum tensile shear load of the joint with an average laser power of 160 W and a tungsten inert gas (TIG) current 100 A was 7.25 kN. Lath martensite (LM), ferrite (F), and retained austenite (RA) were generated in the FZ of the joint, and the Al element aggregates in bulk and sporadically distributed in the mixed zone consisting of the steel plate, Al plate, and rivets. Furthermore, the differentiated distribution mechanism of Al element in riveting-welding hybrid joints was discussed in this paper.