A study of the hot formability of an Al-Cu-Mg-Zr alloy

The high-temperature plasticity of a Zr-stabilised 2014 aluminium alloy was investigated in a wide range of temperatures and strain rates. The microstructure of representative torsioned samples was analysed by transmission electron microscopy, and the characteristics of particle and precipitate distribution were quantitatively estimated. The strain-rate dependence on stress and temperature was analysed by means of the conventional constitutive equations used for describing hot-working behaviour as well as a modified form of the sinh equation, where the stress was substituted by an effective stress, i.e., by the difference between the stress and a threshold stress. This temperature-dependent threshold stress was found to be a fraction of the Orowan stress generated by precipitates increasing from 62 to 94% as temperature decreased from 773 to 573 K.