A Comparative Assessment of Prediction Capabilities of Flow Stress Behavior by Various Constitutive Models for Hot Deformation of Aluminum Alloy AA2219

Abstract Constitutive models play a significant role in developing complex relationship between flow stress, strain, strain rate, and temperature during deformation. The predicted flow stress data obtained by constitutive models should be verified for accuracy before using it in numerical analysis. In the present study, a comparative evaluation of the prediction capabilities of flow stress behavior by three constitutive models: the modified Johnson-Cook (m-JC) model, the Arrhenius-type model, and the modified Zerilli-Armstrong (m-ZA) model, was carried out. Uniaxial hot compression tests were conducted on direct chill as-cast and homogenized aluminum alloy AA2219 in the deformation temperature range of 325 to 500 °C and strain rate range of 0.001 to 10 s−1. Average absolute relative error between the experimental and predicted flow stress values were evaluated to compare the prediction capability of these models. Contour maps of strain rate sensitivity were generated to validate the prediction accuracy, and it was found that Arrhenius-type model resulted in better predictability of flow behavior for the alloy over the other models. Material constants of all constitutive equation models were determined, and the activation energy for a true strain of 0.5 was computed as 161 kJ/mol, indicating the predominant softening mechanism to be dynamic recovery.