Effects of beam oscillation on interface layer and mechanical properties of laser-arc hybrid lap welded Al/Mg dissimilar metals

Here we propose an effective method to suppress the interface reaction between Al and Mg using Ti as interlayer and improve the uniformity of interface layer by laser-arc hybrid welding via beam oscillation. With the optimized oscillating frequency of 90 Hz, the Ti interlayer was uniformly melted to form an Al–Mg–Ti ternary system at the interface, which reduced the formation of brittle Al3Mg2 and Al12Mg17 and benefited to improve the shear force of lap-welds up to 3.3 kN. The beam oscillation not only avoids the local unreaction or over-reaction at the interface by homogenizing the laser energy distribution, but also increases the effective connection width of interface layer by enlarging its melting range, which significantly strengthens the weld.