A microstructural work hardening model based on three internal state variables

A new model to predict the flow curves of aluminum alloys at elevated temperatures is introduced. In the model three dislocation densities are considered. As the model has been developed for cell forming metals these are dislocations stored either in cell walls or in cell interiors and the mobile dislocations, carrying the plastic deformation. For each of this three dislocation densities an evolution law is set up. These rate equations account for dislocation generation, annihilation and storage and are coupled with each other. For the given temperature and microstructure the Orowan equation is then used as kinetic equation of state to calculate the required stress to comply with the externally imposed strain rate. Model predictions for the temperature dependence of the flow stress of pure aluminum will be compared with experimental results. The substitution of empirical constitutive relations with the presented model in FEM simulations will be discussed.