It is an underlying fact for the case of the joining process especially welding to have optimized parameters in order to achieve joints with outstanding mechanical characteristics. In the current work, aluminium 6061 pipes were welded using gas metal arc welding process with appropriate ER 4043 electrode and argon shielding gas. Optimum welding parameters (namely, current, voltage and travel speed) are investigated using analysis of variance ANOVA and grey relational analysis GRA statistical approaches. High tensile strength and low corrosion rate were set as required characteristics of quality welds. Since there are two responses and two objectives, multiple-criteria decision-making approach-GRA, and ANOVA are performed. Optimal parameters from these statistical approaches are converged to 110 A, 19 V and 3 cm/ min, respectively. It is deduced from this study that the optimal parameters are convergent irrespective of the two used techniques for the investigated experimental data.

T-welded joints are commonly seen in various industrial assemblies. An effort is made to check the applicability of friction stir welding for producing T-joints made of AA6063-T6 using a developed fixture. Quality T-joints were produced free from any surface defects. The effects of three parameters, such as the speed of rotation of the tool, axial force, and travel speed were analyzed. Correspondingly, mechanical characteristics such as tensile strength, hardness in three zones (thermal heat affected zone, heat affected zone, and nugget zone) and temperature distribution were measured. The full factorial analysis was performed with various combinations of parameters generated using factorial design and responses. Evident changes in the strength, hardness, and temperature profile were noticed for each combination of parameters. The three main parameters were significant in every response with p-values less than 0.05, indicating their importance in the friction stir welding process. Mathematical models developed for investigated responses were satisfactory with high R-sq and least percentage error.

The improvement in the mechanical properties of composites is always an essential requirement for technological development. In this work, hybrid aluminum matrix composites fabricated using the stir casting technique. Silicon carbide and graphite used as reinforcement to improve the mechanical properties. AMCs produced by adding various volume fraction of SiC (5%, 10% and 15%) whereas fixed volume fraction (10%) of the graphite used in composites. The fabricated AMC samples were tested to determine the tensile strength, hardness and wear rate. The wear rate was determined under the different loads (10 N, 20 N, 30 N and 40 N) and sliding velocities (0.4 m/s, 0.8 m/s, 1.2 m/s and 1.6 m/s). Mechanical properties of fabricated AMCs are evaluated and compared with Al6061 alloy. The results discovered that the tensile strength and hardness increased from 490 to 710 MPa and 65VHN to 85VHN respectively with the addition of silicon carbide and graphite particles. The wear rate also increased with the increase of applied load. However, for sliding velocity it surges till 1.2 m/s then decreased steeply.

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