Flow stress behaviour and constitutive model of 7055 aluminium alloy during hot plastic deformation

In order to acquire flow characteristics in hot plastic deformation and establish the optimum hot formation processing parameters for 7055 aluminum alloy, the hot compressive flow stress behavior was studied at the temperatures from 300 to 450 and strain rates from 0.01 to 10 s(-1) on Gleeble-3180 thermo-simulation machine. The stress exponent and activation energy were acquired with successive approximation method by regression analysis. The relationship between material parameters in Arrhenius equation and strain was established by polynomial fitting and a modified Arrhenius constitutive equation considering strain compensation was established. The results show that 7055 aluminum alloy is positive strain rate sensitive material and the flow stress increases with the increase of strain rate and decreases with the increase of temperature. The experimental results agree with the predictive values according to the modified Arrhenius constitutive equation and the maximum error is 7.11%.