Strain Compensation of the Constitutive Equation for High Temperature Flow Stress of a Al-Cu-Li Alloy

In order to study the workability of a Al-Cu-Li alloy, isothermal hot compressive deformation was investigated in the temperature range of 350-500 A degrees C at strain rates in the range of 0.01-10/s up to a true strain of 0.9 on Gleeble-1500 mechanical testing machine. The flow stress increased rapidly to a peak value. The peak stress decreased with increasing deformation temperature and decreasing strain rate. The effects of strain rate and temperature on hot deformation behavior can be represented by a Zener-Hollomon parameter including an Arrhenius term. The influence of the strain has also been incorporated in the constitutive equation and four material constants alpha, n, A, and the activation energy Q were calculated by compensation of strain. The proposed constitutive equation (considering the compensation of strain) gives an accurate description for the flow stress of the Al-Cu-Li alloy.