Comparison of experimental AA6063 extrusion trials to 3D numerical simulations, using a general solute-dependent constitutive model

In this paper, laboratory scale extrusion experiments carried out on AA6063 billets are compared to numerical simulations. The numerical simulations a re performed with a general solute-dependent elasto-viscoplastic constituti ve model based on a hyperbolic sine law, allowing for the quantification of pressure levels, strain rates and stresses. The parameters for the materia l model were determined with compression tests. The extrusion trials were p erformed isothermally at temperatures of 623 and 723 K and with two distinc t material conditions. The results of the numerical simulations show good a greement with the experimental results. It turns out that local high strain rates (> 40 s(-1)) have a significant influence on the extrusion pressure. However adequate test methods to provide constitutive data at these strain rates are very limited. At high temperatures the difference between materi al conditions had a considerably smaller influence on the extrusion experim ents compared to the simulations. It is argued that this effect can be attr ibuted to dynamic precipitation that occurred during the experiments under high temperature, high strain rate conditions. (C) 2000 Elsevier Science B. V. All rights reserved.