Texture and mechanical properties of metal inert gas welded 6082-T651 aluminum alloy joints

Metal inert gas (MIG) welding was conducted with 12 mm thick 6082-T651 aluminum alloy plate to investigate the microstructure and mechanical properties of welded joint. The microstructure and element distribution of weld seam were characterized by electron backscattered diffraction (EBSD) and electron probe microanalysis (EPMA). The weld seam has typical cube texture (001<100>) characteristics. The closer to the center of weld seam, the weaker the texture feature, the higher the proportion of high-angle grain boundaries. The average tensile strength of joint was 232 MPa which is up to 72% of 6082 aluminum alloy base metal, and the bending angle for the root bend test sample reached 90° without cracks. The lack of strengthening phase and the existence of welding pores and inclusions in the weld seam caused the degradation of mechanical properties of resultant joint. The microhardness increased from the weld center to the base metal, but the overaging zone caused by welding thermal cycle was softening part of the joint, which had lower hardness than the weld seam.