Flow stress behavior and constitutive model of 7055 aluminum 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 10s-1 on Gleeble-3180 thermo-simulation machine. The stress exponent and activation energy were acquired with successive approximation method by regression analysis. On the basis of the relationship between other deformation parameters and strain by polynomial fitting, constitutive equation consisting of temperature, strain rate and strain 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 constitutive equation.