An elastic-viscoplastic constitutive model for the hot-forming of aluminumalloys

Under hot-forming conditions characterized by high homologous temperatures and strain-rates, metals usually exhibit rate-dependent inelastic behavior. An elastic-viscoplastic constitutive model is presented here to describe m etal behavior during hot-forming. The model uses an isotropic internal vari able to represent the resistance offered to plastic deformation by the micr ostructure. Evolution equations are developed for the inelastic strain and the deformation resistance based on experimental results. A methodology is presented for extracting model parameters from constant true strain-rate co mpression tests performed at different temperatures. Model parameters are d etermined for an Al-1Mn alloy and an Al-Mg-Si alloy, and the predictions of the model are shown to be in good agreement with the experimental data. (C ) 2000 Kluwer Academic Publishers.