Temperature and Strain Rate Effects on the Dynamic Strain Ageing of Aluminium Alloy AA7030
The effects of temperature and strain rate on the mechanical properties of aluminium alloy AA7030 (Al-5.4Zn-1.2Mg) in naturally aged and peak aged condition are investigated, with emphasis on the relation to dynamic strain ageing. It is found that the naturally aged material shows more severe signs of dynamic strain ageing, including inverse strain rate and temperature dependence of flow stress, inverse temperature dependence of the ductility and serrated yielding. The peak aged material also shows signs of dynamic strain ageing, but to a lesser extent, most pronounced through serrated yielding. The observed effects can be qualitatively explained in terms of a thermal activation based model for dislocation glide. Furthermore, inhomogeneous deformation is observed on several size scales ranging from localized glide bands to surface deformation effects (orange peel surface) and macroscopic flow localization in shear bands.
W.J. Poole, M.A. Wells and D.J. Lloyd
M. Hörnqvist and B. Karlsson, "Temperature and Strain Rate Effects on the Dynamic Strain Ageing of Aluminium Alloy AA7030", Materials Science Forum, Vols. 519-521, pp. 883-888, 2006