Three-dimensional modelling of coupled flow dynamics, heat transfer and residual stress generation in arc welding processes using the mesh-free SPH method

The SPH method is able to predict the long term thermo-mechanical responses, namely heat transfer and residual stresses in the welded joint during the cooling stage. The SPH solutions demonstrate non-uniform cooling rates and temperature fields in a workpiece, as exhibited in practical welding processes. The solutions also show the existence of high temperature gradients around the boundary of the weld, which causes rapid microstructural and phase transformations. The SPH method also incorporated the evaluation of thermal residual stresses in the workpiece. In the early stages of welding, the residual stress varies rapidly with time and subsequently changes gradually. The residual stress variation over the welded joint depends on the local temperature gradients. The residual stress is very high at the interface between the filler and parent material and decreases rapidly further away from it. The typical thermo-mechanical behaviour found in the present study conforms to the observations of real life arc welding processes.