Input torque based thermal model of friction stir welding of Al-6061

A novel thermal model of the Friction Stir Welding (FSW) process is presented. A finite element based 3-dimensional thermal model is used to predict the thermal history and temperature distribution during friction stir welding process. The moving heat source representing the heat generated by the rotation and linear traverse of the shoulder and pin has been correlated to the torque data obtained from experimental investigation of butt-welding of Al 6061-T651. The moving heat source includes heat generation due to torques at (i) the interface between the tool shoulder and the work piece, (ii) the horizontal interface between pin bottom and the work piece, and (iii) the vertical interface between the cylindrical pin surface and the work piece. Temperature-dependent properties of the weld-material have been used for the numerical modeling. Reasonably good match between the simulated temperature profiles and experimental data has been demonstrated. Investigation was also made to study the effect of backing plate and work-piece backing plate interface on the temperature distribution and history in the work-piece.