The accurate prediction of the residual stresses present in welded structures can be of great importance to the fracture assessment of such components. Therefore, a large amount of benefit can be gained from improving techniques for measuring and numerically analysing these stresses. In recent years many advances have been made in the field of analysing residual stresses using finite element methods. That said, very little work has been conducted on the accurate modelling of welded ferritic components. This is largely due to the added complication of phase transformations that occur during the heating and cooling of such steels. The objective of the work presented in this paper was to improve understanding of the effect that phase transformations have on residual stresses present within welded ferritic structures. This was conducted by simulating such welding processes using the finite element package SYSWELD. An investigation was conducted to determine how phase transformations, and therefore residual stresses, are affected by the welding process used. Phase transformation and material property data available within SYSWELD were used for this analysis. An autogenously welded beam provided a simple basis for this qualitative investigation. In the future the manufacture and measurement of suitable test-pieces will enable these simulations to be validated.