Effect of steel to aluminum laser welding parameters on mechanical properties of weld beads

The laser welding of DC 04 low carbon steel to a 6016 aluminum alloy was realized by fiber laser with an orthogonal design. The weld bead features were analyzed microscopically, and the intermetallic layers at the FeAl interface were investigated by SEM-EDS. The results showed that island-shaped solute with relatively high aluminum content appeared regardless of changes in the experimental conditions. The aluminum content decreased with an increase in the distance between the measuring point and the aluminum-welding interface, and exhibited strong fluctuations adjacent to the aluminum-weld interface. The gap between the iron and aluminum induced the formation of cracks which grew along the intermetallic layer. According to a range analysis, it is proved that welding velocity has the most significant impact on the quality of weld joints. Meanwhile, by a mechanical-strength test, it is proved that the welding joints of an iron-aluminum dissimilar metal failed along the brittle intermetallic phases.