Influence of pin profile on formability of friction stir welded aluminium tailor welded blanks: an experimental and finite element simulation analysis

In sheet metal forming processes, the forming limit diagram is frequently employed as a criterion for predicting necking initiation. This is one of the most useful and effective methods for the evaluation of the formability of tailor welded blanks. The goal of this study was to determine the formability of friction stir welded (FSW) AA6061-T6 and AA2017-T6 by employing five dissimilar tool pin profiles. To evaluate the limiting dome height, five different combinations of dissimilar blanks were used in experimental and simulation experiments. Material characteristics such as density, elastic modulus, and all multi-linear behavior of blanks were manually assigned for simulation from the test results of true stress vs true strain plots. The punch with die supports was considered as a rigid body, whereas the metallic blanks were considered as plastic material. To carry out the simulation, the entire blank was divided into three zones. The results obtained from the experimental and simulation results show that the straight square tool pin profile is the optimal tool pin profile for the formability of FSW AA6061-T6 and AA2017-T6. The tested height values obtained from the limiting dome height are 20.5mm and 20.9 mm in experimentation and simulation respectively. The straight cylindrical tool pin profile exhibited the worst formability properties in both experimentation and simulation.