Study On Hot Deformation Behavior And Microstructure Of 2195 Al-Li Alloy During Plane Strain Compression

In the present paper,plane strain compression（PSC）tests were conducted in the strain rate of 0.01 s^-1,0.1 s^-1,1 s^-1 and at the temperature of 350℃,400℃,450℃and500℃with 60%thickness reduction.Hot deformation behavior of the alloy was investigated and a constitutive equation was established,the microstructure was revealed by scanning electron microscopy（SEM）,electron backscatter diffraction（EBSD）,X-ray diffraction（XRD）and transmission electron microscopy（TEM）,besides,different types of dynamic recrystallization（DRX）during hot deformation were analyzed,main conclusions are as follow:（1）The flow stress increases with the increasing strain rate,but with the increase of temperature,the flow stress decreases,the peak strain and the critical strain for attaining steady state decrease,too.A constitutive equation was established,and the deformation activation energy was calculated to be 278.208 kJ/mol.（2）Dynamic recovery（DRV）is the basic softening of 2195 Al-Li alloy under hot deformation.The microstructure mainly contains fibrous deformed grains elongate along RD direction,which contains significant amounts of rolling texture.The microstructure is not homogeneous and shows flow localization,with the increase of the Zener-Hollomon parameter,the flow localization increases.（3）The DRX critical strain increases with increasing Z value,DRX is easier and more sufficient under lower Z value,discontinuous dynamic recrystallization（DDRX）is the primary type.（4）Both DDRX and continuous dynamic recrystallization（CDRX）are promoted in lower Z value.While because of the severe flow localization in high Z value,geometric dynamic recrystallization（GDRX）may take place in high Z value and increases with the further increase of Z value,the appearance of GDRX is accompanied by the increase of the number of DRX grains so that the DRX fraction slightly increases.