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In this study, the mechanical properties of welded joints of AA-6082-T6 aluminium alloy obtained with friction stir welding (FSW) and conventional metal inert gas welding (MIG) were studied. FSW welds were carried out on a Friction stir welding machine. The performance of FSW and MIG welded joints were identified using tensile, metallographic and hardness tests. The joints obtained with FSW and MIG processes were also assessed for distortion that accompanied the welding processes. Taking into consideration the process conditions and requirements, FSW and MIG processes were also compared with each other to understand the advantages and disadvantages of the processes for welding applications of studied Al alloy. Better tensile strength was obtained with FSW welded joints. The width of the heat affected zone of FSW was narrower than MIG welded joints. The results show that FSW improves the mechanical properties of welded joints.

The wear is one of the main issues in friction-stir welding (FSW) of dissimilar aluminium alloys. Two dissimilar metals welded with FSW have different mechanical, metallurgical and chemical properties compared to the parent materials. Therefore, the wear resistance is an important property in an FSW process. In this research, AA7075-T6 and A384.0-T6 aluminium alloys with a thickness of 6.35 mm were selected and a design matrix was developed to produce FSW welds using the MINITAB-17 software. Friction-stir-welded pieces were made as test specimens and their ultimate tensile strengths (UTSs) were tested. In these experiments, the maximum-and minimum-UTS specimens were used for a wear-resistance analysis and its results were compared with the wear resistance of the parent metals. The results were obtained by keeping the revolutions per minute (min-1), time and sliding velocity as constants, while varying the load applied. The rpm, time and sliding velocity were 500, 300 s and 3.141 m/s, respectively. The loads applied were (20, 40 and 60) N. The conclusion is that, under all the applied loads, the wear of the friction-stir weld produced is lower than that of the A384.0-T6 aluminium base metal. On the other hand, the wear of the weld is higher than the AA7075-T6 aluminium base metal.

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Friction stir welding (FSW) is an innovative solid state joining technique and has been employed in industries for joining aluminum, magnesium, zinc and copper alloys. The FSW process parameters such as tool, rotational speed, welding speed, axial force, etc play major role in deciding the weld quality. A mathematical modeling was developed based on experiments to predict the tensile strength of dissimilar FSW aluminum alloys. The maximum tensile strength of 210 MPa can be obtained at the tool rotational speed of 1100 rpm, welding speed of 35mm/min and an axial load of 7 kN is the Optimum welding parameters.