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

Hot tensile deformation behavior of 2195 Al-Li alloy was investigated under the strain rate of 0.1 s(-1) in the temperature range of 440-500 degrees C, and the characteristics of microstructure evolution were discussed. At 440 degrees C, the degree of dynamic recrystallization (DRX) was relatively low at epsilon similar to 0.2 and 0.4. The fraction of high angle grain boundary (f(HAGB)) showed an increase with the increasing strain. Besides, large amounts of delta' and theta' phases dispersed in the matrix during the whole deformation. DRX was easier to develop and had dominated the dynamic softening at the same strain of 0.4 at 500 degrees C. The pinning effect of precipitation was not sensitive to the strain but to the temperature. The number of precipitations significantly decreased at 500 degrees C where only a few delta' phases remained. Consequently, the pinning effect of precipitations was weakened, while the driven force for the migration of dislocation and grain boundary increased. Thereby, more sufficient DRX could be activated at a smaller strain, and a significant growth of DRX grains at the large strain was present at 500 degrees C. The results in this article enable to provide useful guides for further developing the hot forming technology of 2195 Al-Li alloy.