Hardness Characterisation of Butt-Welded 5083-H321 Aluminium Alloy Connections

Welding aluminium alloys presents several challenges, most notably strength reduction in the heat-affected zone and pronounced welding-induced deformations. Current design provisions for welded connections, such as those in Eurocode 9, can result in substantial reductions in the structural capacity of welded components. With the ongoing development of welding processes that enable metal fusion with reduced heat input and potentially less degradation in the heat-affected zone, re-evaluation of these provisions is essential. This paper presents the results of hardness measurements conducted on butt-welded connections made from EN AW-5083-H321 aluminium alloy to qualify and quantify the extent of the heat-affected zone. The experimental programme included 12 specimens with plate thicknesses of 10 mm, 8 mm, and 6 mm, fabricated using DC-MIG-P and AC-MIG-P welding processes. The measured extents of the heat-affected zone were between 1.73 and 2.64 times smaller than the Eurocode 9 values for the DC-MIG-P welding process and between 2.29 and 4.62 times smaller for the AC-MIG-P process. Significant variability in the measured extents of the heat-affected zone was observed.