Investigation on microstructure and mechanical properties of the dissimilar lap welding of Al alloy to steel with different filler materials and laser powers

Two types of filler materials, FeCoCrNiMn and Al-10Si-0.3 Mg powder, were utilized to achieve lap welding of 5083 aluminum alloy to DP780 steel using laser deposition welding at various laser powers. By conducting a comparative analysis of the macroscopic morphology, microstructure, hardness, and shear properties of two groups of welded joints, the effects of multi-principal filler material and heat input on the weld formation, microstructure evolution, and shear properties of dissimilar lap joints were evaluated and discussed. An interesting finding was that, compared to the Al-10Si-0.3 Mg powder, the FeCoCrNiMn powder used as filler material had significant advantages in reducing the hardness of the weld zone and improving the shear properties of the lap-welded joints. The multi-principal powder of FeCoCrNiMn was unable to prevent the formation of Fe-Al intermetallic compounds in the weld metal. However, it did alter the elemental compositions and grain morphologies in the weld metal when compared to the Al-10Si-0.3 Mg powder. Moreover, selecting welding parameters with a low heat input was appropriate for the dissimilar metal joining of aluminum to steel using laser deposition welding.