Thermal modeling of overlap Friction Stir Welding for Al-alloys

This paper presents a thermal model for overlap joints produced through Friction Stir Welding (FSW) process and comparison of the model with experimental results for 5454-O Al-Alloy. A comprehensive 3-D thermal model based on a finite element analysis is proposed to predict temperature distribution during overlap friction stir welding process. The model accounts for moving heat generation caused by the rotation and linear traverse of the shoulder and pin as well as the convective/diffusive heat transfer caused by the plastic flow of the material in the vicinity of the shoulder and the pin. The moving heat source includes heat generation due to friction at the interface between the tool shoulder and the work piece as well as the interface between the pin and the work piece. The contact pressure distribution and consequently the surface conductance at the contact surface between the sheets is modeled as varying with the highest pressure being applied directly underneath the shoulder area. Temperature dependent properties of the weld-material have been used for the numerical modeling. A reasonably good match was demonstrated between the simulated temperature profiles and experimental data obtained through 3-D measurement of temperatures during real overlap FSW process. Some parametric analyses based on the present model are also presented.