Mechanical and Microstructural Properties of MIG Welded Aluminium Alloy

Abstract

Abstract The need for sustainable materials in engineering applications cannot be overemphasized. Engineering innovation and material manufacturing and processing are now geared towards longevity and safety. Aluminium is one of the few materials that meets the ever-increasing demand for lightweight and high strength materials for various industries, including; aircraft industries, marine, solar panels, automobile, construction companies and many other applications to mention but just a few. Aluminium is known to possess excellent mechanical properties which makes them very useful and desirable. However, the final metallurgical and mechanical properties which characterise the final quality and strength of every weld depends on: (i) the technique employed in the welding of the component together and (ii) the selected process parameters for the welding operation. This work focuses on analysing the effect of heat input as a function of welding current, welding voltage and welding speed on the mechanical and microstructural behaviour of 150 × 100 × 3 mm3 aluminium sheets produced by metal inert gas welding. The parameters were set to represent the low, medium and high heat input values. It is imperative to determine the mechanical properties as a function of the structural integrity of welds to ascertain their functionality and durability for typical applications. Tensile testing, vickers hardness and microstructural examination were performed. The result revealed finer grain structures at lower heat input and more grain deformation and elongation occurring as heat input increases. The hardness property reduces (from 43.57 HV to 39.48 HV in the fusion zone as heat input increases. The width of the weld bead increases (from 328 μm to 496 μm) as heat input increases. However, the selected welding parameters did not greatly influence the tensile properties of the welded joints.