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The current work is concerned with the synthesis of aluminium (AA6061-T6) matrix composites (AMCs) reinforced with 15 and 20 weight percentages of silicon nitride (Si3N4) particulates using the indigenously fabricated electric stir casting furnace with bottom discharge arrangement. The major concern in the synthesis of AMCs of ceramic particles with the aluminium matrix is wettability in the casting route, and it was overcome by adding 2% of magnesium in the melt, proper incorporation time, and appropriate stirring speed. The microstructure and mechanical characteristics of the synthesized AMC were analyzed. Si3N4 particles in the matrix are uniformly dispersed in the optical and scanning electron micrographs (SEM). Adding reinforcement particles of Si3N4 to the AA6061 matrix increased microhardness, macrohardness, and ultimate tensile strength significantly. Microhardness and macrohardness of the AA6161/20 wt.% Si3N4 composite were 98 VHN and 91 BHN, respectively, which were 117.8% and 111.63% higher than those of the AA6061 matrix alloy, respectively. Ultimate tensile strength (UTS) of AA6061 was 159.82 MPa which was increased to 249.12 MPa in the AA6061/20 wt.% Si3N4 composite. Percent elongation of the AA6061/Si3N4 composite was reduced with the addition of Si3N4 reinforcement.

AA6063 aluminium alloy joints were fabricated by alternating current tungsten inert gas (ACTIG) welding process and the effects of post weld heat treatment (PWHT) on the tensile properties, impact strength, microstructure, microhardness and fractography of the welded joints were investigated. The ACTIG welding process was adopted because it bears higher strength, more ductility and no apparent microstructure defect. The welded samples were divided into as-welded (AW) sample and PWHT sample. The PWHT method used on the samples was solution treatment (535 °C, 2h), water quenching and artificial aging (165 °C, 18h). The experimental results show that, compared with the AW samples, the microstructure characteristics and mechanical properties of the AA6063 joints after PWHT were significantly improved. The improvement of ultimate tensile strength, and impact strength are 3.72% and 22.22% respectively.

Friction stir welding is a promising solid-state joining process to weld light materials like aluminum alloys. In this paper, an attempt has been made to optimize the friction stir corner welding process parameters using Taguchi grey relational analysis to attain the improved mechanical properties of dissimilar thickness AA5086 and AA6061 dissimilar aluminum alloys with plate thicknesses of 6 mm and 4 mm, respectively. The input parameters of the welding play a crucial role to achieve the desired weld properties. The friction stir welding experiments were conducted according to the L9 orthogonal array. The input process parameters are tool rotation speed (900–1100 r/min), welding speed (100–190 mm/min), and plunge depth (0.1–0.3 mm). The processes parameters were optimized and ranked based on the results of the grey relational analysis. The percentage contribution of each input process parameter on the weld quality was quantified using analysis of variance (ANOVA). The optimal process parameters were determined at tool rotation speed of 1100 r/min, welding speed of 150 mm/min, and tool plunge depth of 0.2 mm. The percentage contribution of the welding speed was 40.50% and revealed a significant influence on multiple responses followed by plunge depth 25.84% and rotational speed 18.13%. The microstructures of various regions were observed and analyzed. The fracture mode and fracture surface of the welded sample were observed and discussed.

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.