Prediction of temperature distribution and thermal history during friction stir welding: input torque based model

A novel three-dimensional thermal model is proposed to study the transient temperature distributions during the ftiction stir welding of aluminium alloys. The moving heat source engendered by the rotation and linear traverse of the pin tool has been correlated with the actual machine power input. This power, obtained from experimental investigation, has been distributed to the different interfaces formed between the tool and the weldpiece based on the torques generated at different tool surfaces. Temperature dependent properties of the weld material have been used for the finite element based numerical modelling. Good agreement between the simulated temperature profiles and experimental data has been demonstrated. The effects of various heat transfer conditions at the bottom surface of the workpiece, thermal contact conductances at the interface between the workpiece and backing plate and different backing plate materials on the thermal profile in the weld material have also been investigated numerically. (C) 2003 IoM Communications Ltd. Published by Maney for the Institute of Materials, Minerals and Mining.