Measurement and simulation of temperature and residual stress distributions from friction stir welding AA2024 Al alloy

Abstract

Finite element (FE) models have been developed to predict residual stress distributions resulting from the friction stir welding (FSW) process. Plates 250 mm × 50 mm × 5 mm in dimension of an Aluminium alloy (AA2024-T4) were butt-joined through FSW. The thermal profiles were monitored in-situ during the welding process using thermocouples. Sequentially-coupled thermo-mechanical simulations have been performed using an instantaneous relative linear velocity based heat source. Post weld residual stress measurements have been obtained using the neutron diffraction technique and were used to verify the finite element results. The thermal profiles measured during welding have been simulated in the FE model. Increasing the tool traversal speed is found to reduce the peak temperatures experienced during welding for a given tool rotational speed. The general trends and magnitudes of the residual stress distributions measured along the weld line have been predicted by the FE model. The residual stress distributions measured and predicted are relatively symmetric and uninfluenced by the range of tool traversal speeds for the cases considered. Further refinement of the material and process model may be required to improve the predictions accuracy. However, effective predictions have been obtained in the FE model presented by treating the material as a continuum without additional complexities.