In the present work a detailed characterisation of a cold rolled and annealed AA3103-alloy has been carried out. The effect of different concentrations of Mn in supersaturated solid solution on the deformation and subsequent annealing behaviour has been studied in detail. A physically based microstructure model has been used to predict the evolution in microstructure and flow stress during annealing of the given alloy, with particular focus on the effect of concurrent precipitation on the softening behaviour.