Formation and suppression mechanism of wavy edge in oscillating laser-arc hybrid fillet welding of aluminum alloy

Abstract

The weld surface characteristics of aluminum alloy fillet joints play a pivotal role in determining their performance. To enhance surface quality, oscillating laser-arc hybrid fillet welding was employed for aluminum alloy, along with a focus on the effect of beam oscillation on weld surface formation. Results revealed that a distinctive surface defect in aluminum alloy fillet welding manifested as a wavy edge on the main plate at oscillation frequencies (f) of 0 and 50 Hz. When f ≥ 150 Hz, the wavy weld edge was effectively suppressed. As a result, the tensile fracture location in the defect-free joint transferred from the main plate to the rib plate. The corresponding ultimate tensile strength reached 282.3 MPa, signifying a substantial 160.1 % improvement. Analysis indicated that the high-speed vortex generated by laser oscillation was the decisive factor in suppressing the wavy edge. This effect eliminated the depressed edge of the molten pool and mitigated droplet impact. Ultimately, a comprehensive examination of the forces acting on the molten pool unveiled the formation and suppression mechanism of the wavy edge. These insightful findings carry significant implications for enhancing the aluminum alloy fillet welding process and deepening comprehension of weld surface formation.