Microstructural and mechanical characteristics of welded joints in type 6082-T6 aluminium alloy

Aluminium alloys are used extensively, whenever the advantages of high strength-to-density ratio, reduction of dead weight and corrosion resistance, make these alloys competitive with other materials. The major markets for structural application of aluminium alloys are civil engineering and the transport industry, in particular, aircraft construction and more recently, that of electric and low emission cars. One of the difficulties to be overcome in using aluminium alloys is the reduction of mechanical properties due to HAZ (Heat Affected Zone) deterioration caused by welding. The mechanical and microstructural characteristics of MIG welded joints in 6082-T6 plate alloy were investigated by means of tensile tests, fatigue bending tests, microhardness analysis, and optical and SEM metallography. The reduced hardness and tensile strength in the HAZ have been linked to the mechanisms of deterioration of constituents initially present in the alloy, originating from quenching and thermal ageing treatment.