Correction and Modeling of Flow Stress during Hot Deformation of 7055 Aluminum Alloy

This study aims to understand the flow behavior and processing properties of 7055 aluminum alloy. The hot compression tests with a strain rate range of 0.001-10 s(-1) and a deformation temperature of 250-450 degrees C are performed with the aid of a Gleeble-3500 thermomechanical simulation machine. The flow stress error caused by the frictional effect between the specimen and the thermal effect of deformation is corrected. Next, the modified Zerilli-Armstrong (MZA) model using friction-adiabatic corrected value as input is applied to predict the flow behavior of 7055 aluminum alloy. A hot processing map determines the safety and instability zone of 7055 aluminum alloy. The combined results are as follows: The influence of friction and adiabatic effect can not be ignored during the experiment. The maximum stress deviation after friction corrected and friction-adiabatic corrected was about 38 and 14 MPa, respectively. As the increasing strain rate or decreases of deformation temperature, friction and friction-adiabatic effect on stress gradually increase. The MZA model can predict the flow stress at different strains with relative accuracy (R = 98.74% and AARE = 12.74%). The hot processing map is drawn from real stress-strain curves. With the increase of true strain, the instability zone gradually expands toward the high strain rate, high-temperature range.