Predicting Residual Thermal Stresses in Friction Stir Welding

Abstract

Sequentially coupled finite element models of the friction stir welding process have been proposed to study the residual stresses caused by the thermal cycles during friction stir welding of metals. This is a two step simulation process. In the first step, the thermal history is predicted from an input torque based thermal model. The temperature history generated by the thermal model is then sequentially coupled to a mechanical model that predicts the residual stresses. The model does not deal with the severe plastic deformations within the weld nugget and the thermo-mechanically affected regions, a fact that may cause modeled results to deviate from experimentally measured residual stresses. The model is three dimensional and uses temperature dependent material and thermophysical properties.