Friction Stir Welding is a variation of friction welding method. Accomplishing the optimal processing parameters for the best probable design is still a challenging task. This paper presents a novel methodology for the Experimental Investigation and Multiple Response optimization of welding parameters on dissimilar friction stir welded joints between AA7075-T6 aluminum alloys. The optimization was done using GRA & PCA.In this study, welding parameters namely rotational speed, welding speed, shoulder diameter, tool tilt angle, tool pin profile and tool material were optimized with the considerations of multi responses such as Ultimate Tensile Strength (UTS), Hardness (VHN) and Impact Load. L27 Orthogonal array was taken to conduct the experiments with the range 700 – 1100 revolutions per minute (rpm) for rotational speed and with welding speed from 20, 40 & 60 millimetre/minute (mm/min). The results obtained from GRA & PCA shows good convergence with the trial and the optimum process parameters combinations, where the maximum Ultimate Tensile Strength and the Hardness are obtained. The ranking of GRC and PCA were also displayed which shows same ranking was followed in both optimization techniques.

Aluminum Alloys: Friction Stir Welding (FSW); Grey relational analysis method (GRA); Principal Component Analysis (PCA); DEA rank based method; Ultimate Tensile Strength (UTS); Hardness (VHN).