Abstract:Continuous, discontinuous, double-pass and multi-pass hot isothermal compression tests were conducted to understand the mechanical behavior and microstructure evolution of the Al-2.5wt%Cu-1.58wt%Li-0.3wt%Mn-0.12wt%Zr-0.06wt%Mg-0.05 wt%Ti alloy. The tests were conducted in the temperature of 420℃ and at strain rates of 0.001, 0.1 and 10s-1 on Gleeble-1500. EBSD and TEM were used to investigate microstructure evolution at different deformation stages of the alloy. Double-pass hot deformation results show that the extension of interval time between two passes is conductive to promoting static softening. It is possible to control the grain size in the test alloy by changing the strain rate at different deformation stage. During multi-pass hot deformation process, static softening between the deformation pass is beneficial to the dynamic softening, vice versa. Dynamic precipitation of T1 and θ′ phase is observed during the multi-pass deformation process(T=420℃, =0.1s-1). In the initial stage of multi-pass deformation, strain-induced dislocations provide the nucleation site for θ′ and T1 phase, promoting their precipitation and coarsening. With increasing of strain, the size of the precipitates T1 and θ′ phase decreased and then tend to be stable, the density of δ′ phase decreased. Flow stress of the test alloy during multi-pass hot deformation is influenced by dynamic softening, static softening and dynamic precipitation.