This study examines the effect of welding parameters on the mechanical properties and fracture behavior of MIG-welded AA6061-T6 aluminium joints. Specimens were fabricated using varying welding speeds (40, 50, 60, and 70 mm/min) and currents (110, 115, and 125 A). Tensile tests were performed according to ASTM E8, and fracture surfaces were evaluated macroscopically. The results show that all welded joints experienced a tensile strength reduction of approximately 12–18% compared to the base material, with ultimate tensile strength ranging from 69 to 78 MPa, depending on the applied heat input (1.51–3.60 kJ/mm). In some conditions, elongation increased, indicating enhanced ductility in thermally softened regions. Welding speed was identified as the dominant parameter influencing joint strength, whereas welding current exhibited a comparatively minor effect. Hardness measurements revealed consistent softening in the heat-affected zone (HAZ), which also coincided with the fracture location. SEM fractography confirmed ductile fracture behavior characterized by necking and micro-void coalescence, while higher welding speeds promoted HAZ softening and reduced overall ductility. This study provides a quantitative assessment of conventional MIG welding parameters under industrially relevant conditions, demonstrating that joint integrity in MIG-welded AA6061-T6 is governed primarily by HAZ softening rather than weld metal quality. The findings offer practical guidance for optimizing welding speed and heat input in conventional MIG processes for aluminium alloy structures.
Machfuroh et al. (Tue,) studied this question.
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