Microstructure and Mechanical Properties of Adding Adhesive-Layer Laser-Welded Joints of DP590 Dual-Phase Steel and 6061 Aluminum Alloy

In this study, the experiments of laser weld bonding for DP590 dual-phase steel and 6061 aluminum alloy were carried out. Plasma shape and welding spectra were collected and analyzed, and the effect of adding adhesive layer on the microstructure and mechanical properties of laser-welded joints was also investigated. Some defects, such as pore, crack and softening in heat-affected zone, can be avoided in the weld, the increased weld penetration and width are obtained by adding adhesive layer, and the average tensile-shear strength of joint exceeds than that of no-added joint. In laser weld bonding, the Al content reduces weld penetration depth, but increases both sides of weld, Fe-rich Fe-Al ICMs with better ductility are formed in steel/aluminum interface, the Al diffusion from the lower aluminum to the upper steel side is suppressed, and transverse area of joining steel to aluminum is increased due to increasing Al volume fraction on weld width. In addition, the uniform-sized grains are distributed in the weld, shear load is shared by adhesive layer and weld, and hence, mechanical properties of laser-welded joints are improved.