A Constitutive Description of Aluminum-1% Magnesium Alloy Deformed Under Hot-Working Conditions

Abstract

A constitutive description of the deformation of commercial aluminum-1% magnesium alloy (AA5005) under hot working conditions has been formulated on a rational basis. The strain dependence of the flow stress is described by means of the evolution law earlier advanced by Sah et al. The optimization procedure of the experimental stress-strain data allowed the determination the extrapolated values of the initial flow stress and saturation stress which were subsequently correlated with temperature and strain rate by means of the kinetic model proposed by Kocks. It is shown that the initial work-hardening rate of this alloy is strongly dependent both on temperature and strain rate and that the temperature dependence is much more significant than that explained by the temperature dependence of the shear modulus of aluminum. The best description of the experimental flow stress data is obtained by expressing the initial work-hardening rate as a function of the effective strain rate, in terms of a simple parametric relationship, rather than considering a constant value for this parameter, independent of temperature and strain rate. The accuracy of the constitutive description proposed, regarding the reproduction of both the experimental flow stress and work-hardening rate, makes it reliable for its use in the analysis of hot-working processes involving this material.