This work is part of a project dedicated to find accurate and reliable tools for prediction of welding and post weld heat treatment. In other parts of the project, a simulation method for combined welding and heat treatment simulations of the component was developed and different plastic/viscoplastic material models have been compared, these models included effects of phase changes. These simulations were made using an axisymmetric finite element model. The current paper presents welding and heat treatment simulations of the same aerospace component but now using a three-dimensional shell model. The results are compared with the previously used axisymmetric model. The simulations revealed that the two first welds have the greatest influents on a 'key dimension'. From the simulation, it can be concluded that the three-dimensional model give better prediction of the dimension based on measurement performed but not presented here. The simulation presented in this paper is part of an aerospace component called Turbine Exhaust Case which is a fabricated structure made of a martensitic stainless steel.