Low-Power Laser/Arc Hybrid Welding Behavior in AZ-Based Mg Alloys

The low-power laser/arc hybrid welding behaviors of the AZ-based Mg alloys in similar and dissimilar joints are examined in this study in terms of welding parameters, fusion-zone characteristics, mechanical properties, welding temperature fields, and laser-induced arc plasma/plume. Experiments were conducted using a low-power (300 W) pulsed Nd:YAG laser with a gas tungsten welding arc. The results show that the AZ-based Mg alloys can be easily welded by laser/arc hybrid welding process. The introduction of low-power laser beam can stabilize the welding arc even at a high-speed welding, and spattering behavior of laser welding disappeared due to the introduction of welding arc. With the increases of arc power, a higher weld depth can be obtained, and the weld depths for laser and arc acting in combination (laser/arc) are 2 times higher than those of for laser and arc acting separately (laser + arc) in optimal conditions. The postweld tensile strength of Mg alloys could recover ∼80 to 100 pct of the original strength in similar or dissimilar joints. The fatigue strength in laser/arc hybrid welded specimens is equal to that of the unweld base metal.