Constitutive flow stress formulation, model validation and FE cutting simulation for AA7075-T6 aluminum alloy

Abstract

A consistent and reasonable description of the constitutive behavior of material under the coupled effect of strain, strain rate and temperature on the flow stress of the material is highly essential in current industrial practice to design and optimize the process parameters in manufacturing operations. In order to formulate a suitable constitutive model to predict the elevated-temperature deformation behavior in high strength aluminum alloy, AA7075-T6, isothermal uniaxial tensile tests over a practical range of deformation temperatures (300–623K) and strain rates (10−4–10−1s−1) were conducted. Two constitutive models, modified-Johnson Cook (m-JC) and modified-Zerilli–Armstrong (m-ZA) models are formulated considering the combined effects of strain, strain rate and temperature on flow stress. The prediction capability of these models is assessed in terms of statistical parameters, correlation coefficient and average absolute error between experimental and predicted flow stress data. In addition, finite element (FE) simulations have been carried out in order to validate the formulated model during orthogonal cutting processes. It was observed that both the models show a very high degree of linear dependence of fit as the value above 0.98. However, the m-ZA model can offer an accurate and precise estimate of the flow behavior for studied workmaterial over m-JC model. Further, the performance of developed model in FE cutting simulations is the most obvious for all moderate machining conditions and can provide relatively good prediction results for the AA7075-T6 machining process.