Microstructure analysis and mechanical characteristics of tungsten inert gas and metal inert gas welded AA6082-T6 tubular joint: A comparative study

• Published in: Transactions of Nonferrous Metals Society of China Vol. 27; no. 1; pp. 17 - 24
• Main Authors: IMAM FAUZI, E.R., CHE JAMIL, M.S., SAMAD, Z., MUANGJUNBUREE, P.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.01.2017
• Subjects: AA6082 aluminium alloy; mechanical properties; metal inert gas (MIG); microstructure analysis; tungsten inert gas (TIG); tungsten inert gas (TIG); metal inert gas (MIG); microstructure analysis; mechanical properties; AA6082 aluminium alloy
• ISSN: 1003-6326
• DOI: 10.1016/S1003-6326(17)60003-7

The present study is aimed to compare the microstructure characteristics and mechanical properties of AA6082 in T6 condition of tubular joints fabricated by tungsten inert gas welding (TIG) and metal inert gas welding (MIG) processes. The effect of welding processes was analysed based on optical microscopy image, tensile testing, and Vickers micro-hardness measurements. The results showed that the tensile strengths of the TIG-welded joints were better than those of the MIG-welded joints, due to the contribution of fine equiaxed grains formation with narrower spacing arms. In terms of joint efficiency, the TIG process produced more reliable strength, which was about 25% higher compared to the MIG-joint. A significant decay of hardness was recorded in the adjacent of the weld bead zone, shown in both joints, related to phase transformation, induced by high temperatures experienced by material. A very low hardness, which was about 1.08 GPa, was recorded in the MIG-welded specimens. The extent of the heat-affected-zone (HAZ) in the MIG-welded joints was slightly wider than those of the TIG-welded specimens, which corresponded with a higher heat input per unit length.