Effect Of Rolling Process On Microstructure And Mechanical Properties Of AA2099 Aluminum-lithium Alloy

Aluminum-lithium alloy has low density,high specific strength,good ductility and is easy to process,and has been widely used in aerospace and other fields.With the advancement of science and technology and high-end manufacturing,higher requirements have been put forward for the comprehensive performance of aluminum-lithium alloys.In order to further improve the mechanical properties of the alloy and increase the production efficiency and yield rate of the plate,some new rolling processes have gradually replaced the traditional rolling process and begun to be applied to the aluminum alloy processing industry.In this paper,advanced aluminum alloy rolling processes such as cryogenic rolling and asymmetric rolling are selected as the research objects,and advanced analysis methods such as X-ray diffraction technology,electron backscatter diffraction technology,and transmission electron microscopy technology were used to study the effects of different rolling processes on the structure,texture and properties of the AA2099 alloy sheet.at the same time,the effect of different heating paths on the microstructure and properties of hot rolled alloy sheet was investigated.The main conclusions are as follows?After the AA2099 aluminum-lithium alloy is deformed by cryogenic rolling,high density straight shear bands are observed on the RD-ND plane of the specimen,which leads to the inhomogeneous mechanical response of the cryogenically rolled specimen with large strains.In the cryogenic rolling process,the shear band behavior is strongly promoted.The grain refinement in or near the shear zone is related to the temperature increase caused by the large strain localization at the shear zone.Cryogenic rolling improves the strength of the material and improves its plasticity.?Compared to asymmetric rolling and symmetric rolling,more shear bands are observed in asymmetric rolling samples,while symmetric rolling deformation is mainly concentrated on the surface.After annealing,the structure of the asymmetric rolling sample is more uniform,especially the recrystallization degree of the core structure reaches 74%,which is much higher than that of the conventional symmetric rolling sample.?Different heating paths affect the precipitation types,precipitation order and precipitation quantity of AA2099 aluminum-lithium alloy.After hot rolling,the types of precipitations have a significant influence on the structure.For samples containing ?'(Al3Li)phase,shear bands passing through multiple grains in the structure are observed,The sample structure with T1(Al2CuLi)phase as the main phase and part of T2(Al6CuLi3)phase is relatively uniform;Different types of precipitates significantly affect mechanical properties,after hot rolling,The order of strength improvement after hot rolling is samples dominated by ?'(Al3Li)phase>samples with the interaction of ?'(Al3Li)and T1(Al2CuLi)phases>samples of the interaction of T1(Al2CuLi)and T2(Al6CuLi3)phases>samples with T2(Al6CuLi3)phase;The order of elongation increasing is samples of the interaction of T1(Al2CuLi)and T2(Al6CuLi3)phases>samples with the interaction of ?'(Al3Li)and T1(Al2CuLi)phases>samples mainly composed of ?'Al3Li)phase.