Study Of Alloy Phase Effect On Static Recrystallization Structure,Properties And Crystallographic Texture Of AA2099 Al-Li Alloy

In this paper,AA2099 Al-Li alloy as-rolled and annealed state is selected as the research object.By using XRD?EBSD?TEM and other analytical techniques,the evolution of the texture,the influence of second phases on static recrystallization process and the mechanical properties are systematically analyzed.The conclusions are as follows:?1?The static recrystallization of hot-rolled plates with??phase and T₂ phase is very sufficient,while the recrystallization degree of hot-rolled plates with T₁ phase is relatively low.The strong shear band formed by??phase promoting coplanar slip and dislocation ring formed by T₂ phase interacting with dislocation provide sufficient driving force for static recrystallization.The static recrystallization nucleation mechanism of hot rolled plate with??phase is mainly particle stimulated nucleation,which can also occur at the shear band.The static recrystallization nucleation mechanism of hot rolled plate with T₁ phase and T₂ phase is also particle stimulated nucleation.?2?The 30°NDCube is the main recrystallization texture component of AA2099aluminum lithium alloy after static recrystallization.The annealed rolling plates with T₂phase possess the highest content of 30°NDCube component,while the annealed rolling plates with T₁ phase possess the lowest content of 30°NDCube component.Q and{111}<110>texture components also meet this rule.The recrystallization texture of annealed rolling plates with T₂ phase also includes many M textures.There is a competitive relationship between the growth of grains in 30°NDCube orientation and P orientation.When the driving force of recrystallization decreases,P and M components get better growth opportunities,and the proportion of these components increases.The reduction in the driving force of recrystallization has little effect on the content of recrystallization Q components.?3?In AA2099 Al-Li alloy,the formation mechanism of 30°NDCube,P and{111}<110>components is oriented growth,and the main recrystallization mechanism of grains in 30°NDCube orientation is particle stimulated nucleation.The grains in30°NDCube and{111}<110>orientation can also nucleate at the shear band and the lamellar dislocation zone formed by T₂ phase.The strong shear bands make it difficult to maintain the long orientation gradient inside the sample,and inhibit the growth of dominant oriented grains to a certain extent.The less competitive oriented grains wouldmaintain and grow such as the Cube components.?4?After the static recrystallization of AA2099 Al-Li alloy which containing??phase,the anisotropy of the material has no obvious change,but the mechanical anisotropy of AA2099 Al-Li alloy which containing T₁ or T₂ phases increases after the static recrystallization,and the anisotropy of the material is aggravated by the long grain.After static recrystallization,the tensile strength of AA2099 Al-Li alloy with T₂ phase has no obvious change,but the tensile strength of AA2099 Al-Li alloy with??phase or T₁ phase decreases significantly after annealing.?5?The hardness of AA2099 Al-Li alloy with??phase is the highest,while that of AA2099 Al-Li alloy with T₁ phase is the lowest.After annealing at 540?for 1h,the hardness of AA2099 Al-Li alloy with??phase or T₁ phase decreases obviously,while that of AA2099 Al-Li alloy with T₂ phase changes little.In the process of recrystallization,the hardness of the material first decreased rapidly,then increased briefly,and then decreased gradually,which was related to the strong recovery at the beginning of the material and the subsequent change of recrystallization grain size.The hardness of Al-Li alloy annealed at540?for one hour is higher than that of the sample annealed at 300?for two hours,which is due to the growth of the second phase during the recovery process,while the material has strong solution strengthening during the annealing process.