Production of sound deep-penetration hybrid weld in aluminum alloy with YAG laser and MIG arc

Abstract

Hybrid welding is receiving considerable attention and is used in practical lines. And so YAG laser and MIG arc hybrid welding was performed on A5052 aluminum alloy plate to understand the mechanism of penetration and reduced welding defects as well as to investigate the effect of welding direction on the weld penetration and porosity formation level.In the case of YAG-MIG (laser-head-leading) hybrid welding, the surfaces of weld beads were by far prettier than MIG-YAG hybrid welding. The optimum distances between the laser-focused point and the MIG wire target for deeper penetration were about 2 to 4 mm, and the reason was interpreted in terms of the interaction of a laser beam to droplet, molten pool or solid plate. The penetration increased but porosity was reduced with the increase in MIG arc current. These reasons were attributed to the formation of a concave molten pool surface due to high arc pressure at a high current.In the case of MIG-YAG (MIG-nozzle-leading) hybrid welding, deeper welds were formed especially at high laser power than those made by YAG-MIG hybrid welding. However, a large amount of porosity was formed in the case of the laser beam shot perpendicularly. Such porosity was reduced by declining a laser beam just like the forehand welding, and sound deep weld beads could be produced in MIG-YAG hybrid welding. According to X-ray transmission in-situ observation, these results were interpreted by considering the formation of the wider top inlet of a keyhole produced with a YAG laser to consequently suppress the generation of bubbles. The surface of a MIG-YAG hybrid weld could be cleaned by cleaning action with DCEP-TIG heat source.Hybrid welding is receiving considerable attention and is used in practical lines. And so YAG laser and MIG arc hybrid welding was performed on A5052 aluminum alloy plate to understand the mechanism of penetration and reduced welding defects as well as to investigate the effect of welding direction on the weld penetration and porosity formation level.In the case of YAG-MIG (laser-head-leading) hybrid welding, the surfaces of weld beads were by far prettier than MIG-YAG hybrid welding. The optimum distances between the laser-focused point and the MIG wire target for deeper penetration were about 2 to 4 mm, and the reason was interpreted in terms of the interaction of a laser beam to droplet, molten pool or solid plate. The penetration increased but porosity was reduced with the increase in MIG arc current. These reasons were attributed to the formation of a concave molten pool surface due to high arc pressure at a high current.In the case of MIG-YAG (MIG-nozzle-leading) hybrid welding, deeper welds were fo...