Research on the Microstructure Characteristic and Tensile Property of Laser-MIG Hybrid Welded Joint for 5A06 Aluminum Alloy

Abstract

Laser-metal inter gas (MIG) hybrid welding technique provides higher overall productivity over the traditional fusion welding processes for joining medium-thick aluminum alloy. In this paper, laser-MIG hybrid welding experiment was performed by the TruDisk 12003 Laser and KUKA robot. The second fusion line, the laser-dominated region and laser-MIG hybrid-dominated region were introduced to this study to discuss the microstructure distribution. A three-dimensional finite element model was established by MSC. Marc to study the thermal field distribution of laser-MIG hybrid welding process. It found that the temperature in the laser-MIG hybrid-dominated region was much higher than the laser-dominated region. The formation of the second fusion line in the welded joint is mainly owing to the different heat effect of laser-arc hybrid-dominated region and laser-dominated region. The crystalline size of equiaxed dendrite grains in the laser-MIG hybrid-dominated region is finer than the laser-dominated region. In addition, the tensile property was measured to dissect the failure mechanism of the laser-MIG hybrid welding joints. The element content in fractured surface at the position of dimple and pore wall were comprehensively analyzed. The element content of Mg and O in pore wall are higher than dimple. In the solidification process, the growth of equiaxed dendrite grains is in part hindered by the existence of coarse pores in the laser-MIG hybrid-dominated region.