Modified Arrhenius constitutive model and simulation verification of 2A12-T4 aluminum alloy during hot compression

Abstract

An accurate constitutive model is imperative to describe the deformation behavior of aluminum alloy in numerical simulation of thermal plastic forming process. In this study, isothermal uniaxial compressions of 2A12-T4 aluminum alloy were conducted by Gleeble-3500 thermal-mechanical simulator under the temperature of 300–450 °C and strain rate of 0.01–10 s−1. Three different Arrhenius constitutive models, including strain compensation (SC), genetic algorithm (GA) and K-function modification (KM), were established basing on the double correction of the true stress–strain curve by considering the effect of temperature variation and interfacial friction. The prediction accuracy of three models were assessed by the correlation coefficient (R), average absolute relative error (AARE) and the logarithm of the mean square error (ln (MSE)). The results show that the newly KM constitutive model considering the coupling effect of temperature and strain rate showed excellent agreement with the experimental data and best prediction capability with lowest error. Hot processing map based on the Murty-Rao criterion shows that high temperature and low strain rate is suitable for stable forming. In order to verify the reliability of the proposed model in numerical simulation, the established KM Arrhenius constitutive equation is secondarily developed in DEFORM 3D software and used in the hot compression process under the stable forming conditions obtained from hot processing map. The simulated force–displacement curves and maximum load values under forming conditions were well match with the experiment trends, which proved the reliability of the KM constitutive equation in the finite element numerical simulation.