سجاد رسائی

The behavior of Al7075 during the hot compression in a wide range of temperatures, 623-773 K, and strain rates, 0.001-1 s-1, were investigated in this paper. Moreover, using the standard Arrhenius constitutive models, a mathematical equation was proposed for predicting the flow stress, and then the accuracy of the model was examined using standard verification methods. The increasing of temperature and strain rate, respectively, have a reverse and direct effect on the flow stress, which can be expressed using the Zener-Hollomon parameter with the activation energy of 304 kJ/mol. Since the potential dependence of the constants in the model has not been considered for any parameter, the accuracy of the standard model is low. It was found that the values of these constants depend on the strain, so for each of the constants, a relation was obtained in terms of strain to express this relation properly. The modified model not only precisely predicts the flow stress but also provides higher accuracy in predicting the trend of variation of stress due to the influence of metallurgical evolutions occurring during the process of hot deformation, such as dynamic recrystallization or softening and hardening.