Research On Hot Deformation Structure And Anneal Softening Mechanism Of AA2195 Al-Li Alloy

Al-li alloys have become a hot material in the aerospace industry because of their excellent performance while achieving lightweight requirements,so it is important to explore their broader practical applications.This article takes AA2195 Al-li alloy as the research object,explores the evolution of microstructure and deformation texture of AA2195 Al-li alloy during hot deformation,and studies the annealing softening mechanism of typical deformed samples.The hot deformed structure of the alloy was characterized by EBSD technology,and the correlation between its microstructure and deformation temperature,strain rate,deformation and lnz value was studied.The analysis shows that with the decrease of strain rate,the dynamic recrystallization ability of the AA2195 Al-li alloy gradually increases,and the dynamic recrystallization grains also grow to a certain extent,but the dynamic recovery still dominates the softening process of the alloy.At high strain rates,a small amount of geometric recrystallization occurs;at low strain rates,it is a distinct continuous dynamic recrystallization feature.The effect of deformation temperature on AA2195 Al-li alloy is obvious.Under the strain rate of 0.01s-1,as the deformation temperature increases,the dynamic recrystallization behavior gradually increases,and the softening mechanism of the alloy changes from dynamic recovery to dynamic recovery and Coexistence of dynamic recrystallization.The effect of the amount of deformation on the microstructure is also very significant.As the amount of deformation increases,the dynamic recovery and dynamic recrystallization capabilities of the alloy gradually increase.By analyzing the relationship between the Z value and the microstructure and deformation texture of the alloy,it is found that the Z value can be used as a characteristic reference value for whether dynamic recrystallization occurs during the thermal deformation of the alloy.The lower the Z value,the easier the dynamic recrystallization of the alloy is;the higher the Z value is,the harder the dynamic recrystallization of the alloy is.The main softening mechanism is dynamic recovery.There is no obvious linear correlation between the deformation texture type and strength of the alloy and the Z value.Texture analysis shows that the alloy will form four typical rolling textures(strong Brass,S,Copper texture and weak Goss texture)during the plane hot compression process,and there are also weak Cube textures.Brass and Cube textures are not sensitive to changes in strain rate.S and Copper textures are more sensitive and negatively related to changes in strain rate.Goss textures are positively related to strain rate.Deformation textures are more likely to form at low strain rates,and Each type of texture is insensitive to changes in deformation temperature.Deformation texture has differences in the surface layer and the center layer of the material: Brass,Copper,and S textures are more uniformly distributed in the surface layer and the center layer,while the Goss texture is easily formed on the surface layer and the Cube texture is easily formed on the center layer.Through the microhardness test of the samples,it was found that there are differences in microhardness under different deformation conditions,but the subsequent annealing softening rules are consistent,at 400 ? The hardness is the lowest at 500 °C and the highest at 500 ° C.Comprehensive analysis shows that the softening of the alloy during annealing is mainly due to the complex changes of the second phase and the effect of recrystallization softening is quite limited.