Influence of FSW Process Parameters on Formability and Mechanical Properties of Tailor Welded Blanks AA6082-T6 and AA5083-O Using RSM with GRA-PCA Approach

Tailor welded blank sheets made of friction stir welding (FSW) process have found many applications in aerospace, automobile, marine, and other industries. In the present study, two different aluminum alloys AA5083-O and AA6082-T6 having 2 mm thickness were used. This research presents the multi-responses optimization of process parameters, i.e., rotation speed (R), travel speed (T), and shoulder diameter (S) in the FSW process using response surface methodology (RSM) based on gray relational analysis (GRA) coupled with principal component analysis (PCA) technique. For the optimization of the process, the face-centered central composite design technique with minimal design was used to get the optimum level of the parameter. The objective of this paper is to find out the optimum level of the process parameters which yields the maximum responses, i.e., ultimate tensile strength, total elongation, yield strength, dome height, and microhardness value. ANOVA technique was used to ensure the significant contribution of the individual and the combination of process parameters. The confirmatory run analyzed the optimized process parameters, and the experimental result was observed within 2.6% of error agreement with predicted values. GRA determined the optimum value of the input parameter with the PCA technique, a hybrid approach. The optimum value of R, T, and S was found at 1900 rpm, 40 mm/min, 12 mm, respectively. The microstructural study of variation in grain structure across the different zones of the FSW region was examined and tested by scanning electron microscope. The microhardness and formability tests for the optimized parameters were carried out. This research reveals that the multi-response optimization problem can be easily solved through RSM based GRA-PCA approach.