Work hardening behavior of flow curves of aluminum alloy AA7075 under tensile and compressive loading at room temperature was addressed. The Kocks-Mecking (K-M) and Crussard-Jaoul (C-J) models were applied to analyze the work hardening behavior. Constitutive models, i.e., Hollomon, Ludwigson, Swift, Ludwik, and Voce, were used to predict the flow stresses during tensile/compressive loading. All models were validated, and the empirical parameters were determined by experimental data. The sum of squares of deviations of the prediction (Chi-square, χ2), coefficient of correlation (R2) and the mean absolute percentage error (MAPE) were calculated to validate simulated flow stresses. It was found that the flow curves exhibited a positive work hardening rate. The K-M plot (work hardening rate versus true stress) showed the work hardening of stage III with a single negative slope value. All models excellently predicted flow stresses with very low MAPE. Moreover, a piecewise regression was a meaningful method for accuracy improvement of the models.
