A Thermal Model of the Friction Stir Welding Process

A novel finite element method based 3-dimensional thermal model has been developed to study the temperature distributions during the friction stir welding process. The moving heat source generated by the rotation and linear traverse of the pin-tool has been correlated to input torque data obtained from experimental investigation of butt-welding of AA6061-T651. The moving heat source includes heat generation due to torques at the interface between the tool shoulder and the workpiece, the horizontal interface between the pin bottom and the workpiece, and the vertical interface between the cylindrical pin surface and the workpiece. Temperature-dependent properties of the weld-material have been used for the numerical modeling. Excellent conformity between simulated temperature profiles and experimental data has been demonstrated. The effects of various heat transfer conditions at the bottom surface of the workpiece, different thermal contact conductances at the interface between the workpiece and the backing plate, and different backing plate materials on the thermal profile in the weld material have also been investigated.