MODELING THE EFFECT OF TOOL GEOMETRY ON FRICTION STIR 'Al' WELDS

Abstract

Friction stir welding (FSW) is a solid state welding process invented at The Welding Institute in 1991. FSW is an advancement of friction welding process. During the early days of FSW, it was used to weld only structural Al but now, FSW is used to weld SS, Mg, Ti, Cu, Zn alloys with varying degree of success. FSW has its applications in aerospace, astronautic, marine, road and rail transport etc. Friction stir welding is not unlike other industrial processes in that its primary development has been made via empirical observations. Much can be learned about a process, particularly in its nascent stages, through sometimes arbitrary adjustments to parameters and tooling. Past advancements in understanding of various other processes have been made with the aid of computational models. The overall aim of computational research in welding is to establish methods and models that are usable for control and design of welding process to obtain appropriate mechanical performance of welded component or structure. In the present work, the thermal effect of friction stir welding tool pin profile on welds is found. Also, a computational numerical model is developed for friction stir welding at its stationary state. A commercial CFD software Fluent was used for modeling. Validation of the model is done using the experimental data and the results were found to be in good agreement with each other. The experimental results have shown that a tapered cylindrical pin and trapezoidal pin generates more heat than the straight cylindrical pin profile.