Characterization of the Hot Deformation Behaviour of an As-Extruded Al-Cu-Li Alloy by Constitutive Analysis

The true stress-strain curves of an as-extruded state AA2099 were determined by uniaxial compression tests under various hot deformation regimes. Constitutive analysis of the curves allowed calculation of the hot deformation activation energy (Q(HW)). The microstructure of the as-compressed specimens were also characterized by electron back scatter diffraction (EBSD). EBSD data analyses showed that the major restoration mechanism corresponding to common industrial extrusion regimes was dynamic recovery. The precipitates in three states (T83, as-homogenized, and as-extruded) were characterized by X-ray diffraction (XRD) phase analyses and transmission electron microscopy. The results revealed that the Q(HW)was closely relevant to the precipitates strengthening. The finite element method simulation results and the microstructure of the extruded products confirmed that AA2099 in as-extruded state possessed good workability.