Hot tensile deformation behavior, fracture mechanism and microstructural evolution of 2195 Al-Li alloy

2195 Al-Li alloy is one of the most important structural materials in the aerospace industry in recent years because of its advantages, such as low density, high strength, good thermal stability and high corrosion resistance, which effectively improves the carrying capacity of spacecraft. In this study, isothermal tensile tests are conducted on a Gleeble-3500 thermo-mechanical simulator at temperatures of 380–470 °C and strain rates of 0.1–5 s−1 to explore the hot deformation and establish the processing map of 2195-O Al-Li alloy, and annealing temperature is 400 ℃. The changes in fracture micromorphology, grain size and microstructural evolution under different deformation parameters are analyzed through scanning electron microscope (SEM) and electron backscatter diffraction (EBSD) experiments of tensile specimens. show that the established constitutive equation can accurately predict the hot deformation behavior of the alloy. The fracture mechanism of the tensile specimens is ductile fracture at temperatures of 380–440 °C. When the temperature rises to 470 °C, the fracture mechanism of the specimens changes to brittle fracture and local overburning occurs on the fracture surface. Compared with the deformation temperature, the influence of deformation strain rate on the fracture morphology is not obvious. The average grain size of the specimens at temperatures of 380–440 °C increases with increasing temperature and the minimum grain size is 2.92 µm when the temperature is 440 °C. When the temperature rises to 470 °C, the grains begin to coarsen and the plasticity of 2195 is reduced. Based on the processing map, the optimal processing area is within 405–465 °C and 0.1–1 s−1.