Coupled thermal, metallurgical and mechanical models of multipass welding

Abstract: This thesis deals with modelling and simulation of thermo mechanical processes in multipass welding. The aim of the simulations is to predict the residual stresses and/or the deformations that occur after welding. These residual stresses and deformations are caused by the high temperature gradients due to the local heating. In most thermo mechanical simulations only temperature dependent material properties are used but here we also consider that the material properties are temperature history dependent. This is taken care of by calculation of microstructure evolution and assigning material properties to each phase. These properties are combined by mixture rules to give the macro material properties. All simulations have been carried out using the finite element method. The material properties are temperature dependent only in paper A. The microstructure evolution is computed from the given temperature history. The coupling between the thermal and mechanical field and the microstructure evolution is considered in paper B. This model is refined in paper C by including transformation plasticity and a more detailed modelling of the weldpasses.