Micro and Macrostructural Assessment of Welded 6082 Aluminium Alloy T-Connections

One of the main challenges in welding aluminium concerns structural integrity and a significant reduction in mechanical properties in the region adjacent to the weld. Design provisions can result in a drastic reduction, which may exceed 50% of the base metal resistance. This research aims to evaluate the accuracy of the HAZ extent values codified in Eurocode 9 for T-connections fabricated from artificially aged 6082 aluminium alloy, which is widely used in load-bearing structures. Three plate thicknesses (6, 8 and 10 mm) and two pulsed MIG welding processes (DC-MIG-P and AC-MIG-P) were used to fabricate 20 T-connection specimens (10 different configurations) in accordance with EN 1090-3. The study focuses on characterising the welding zones through hardness testing and metallographic examination. Results show that AC-MIG-P offers better control over thermal input and may reduce structural distortion, while DC-MIG-P provides more robust fusion and metallurgical continuity. Findings related to HAZ extent (12.77 mm and 15.36 mm maximum measured for AC-MIG-P and DC-MIG-P, respectively) suggest that Eurocode 9 may be overly conservative for pulsed MIG welding processes, particularly for greater plate thicknesses where a HAZ extent of 22.50 mm or more is specified. Consequently, adopting more precise, process-specific HAZ characterisations could lead to more realistic connection design and structural behaviour.