In this study, a new modelling approach for aluminium weldments has been explored. In the approach, the microstructure data calculated from welding analysis are directly transferred to the deformation and damage analysis. With an interpolation equation between the properties of the base metal and the fully reverted heat affected zone (HAZ), the exact dimension and gradient of mechanical properties of the whole HAZ are automatically predicted. The overall effect of the microstructure evolution during welding, and the resulting deformation and damage capacity of the welded joint can then be analysed. This approach has been applied in two case studies, one cross weld tensile specimen, which is used for the parameter study, and one real T-joint from which test data are available. With a linear interpolation for the flow stress and ductile damage parameter, the finite element results based on this new approach are in good agreement with the test data.