A microstructural work hardening model based on three internal state variables

A new model to predict the flow curves of aluminum alloys at elevated tempe ratures is introduced. In the model three dislocation densities are conside red. As the model has been developed for cell forming metals these are disl ocations stored either in cell walls or in cell interiors and the mobile di slocations, carrying the plastic deformation. For each of this three disloc ation densities an evolution law is set up. These rate equations account fo r dislocation generation, annihilation and storage and are coupled with eac h other. For the given temperature and microstructure the Orowan equation i s then used as kinetic equation of state to calculate the required stress t o comply with the externally imposed strain rate, Model predictions for the temperature dependence of the flow stress of pure aluminum will be compare d with experimental results. The substitution of empirical constitutive rel ations with the presented model in FEM simulations will be discussed. (C) 2 001 Elsevier Science B.V. All rights reserved.