The Microstructure And Properties Of SPD And Annealed7075Aluminum Alloy

7000series aluminum alloys are important structural materials with excellentperformance and being widely used in many areas such as aerospace industry,automobile industry, construction manufacture industry. Many work have been done forimproving their properties such as strength, ductility and fracture performance. All thetime, research work focus on developing aluminum alloys’ properties. Severe plasticdeformation (SPD) is an effective mean to achieve the goals. In this paper, ECAP androlling were both used to produce ultrafine grained7075aluminum alloys and study thedeformed microstructure. Cold-rolled material was subsequently annealed andcharacterized. Besides, a X-ray diffracmeter was applied to investigate evolution ofmacro-texture during annealing. The conclusions are as follows:The solutionizing7075alloy was subjected to high speed ECAP with Bcroute，thepressed samples have large grains rather than ultrafine grains. Dynamic recrystallizationoccurred during deformation, both large and small grains were obtained. Precipitationdissolved in matrix with increasing pressing passes and the samples with strain of6.4have the least particles. The hardness of deformation samples increased significantlyafter1ECAPed pass, but changed little after further pressing.After many rolling passes, the7075alloy sheet deformed to ultrafine material withdeformation of95%. Then the deformed samples was annealed at100-500℃for an hour.When the temperature was below300℃, the microstructure were still ultrafined. Butthe grains grew up sharply and almost recrystallized after being annealed at350℃. Thegrains were much more uniform with increasing annealing temperature; more and moreequiaxed grains formed. There were many grains whose misorientation was (101)[-11-911](60°,45°，90°)when the annealed temperature was over350℃。After annealing at100°,200°,300℃for1h, the types and density of macro-textureshowed little changes. When the annealing temperature reached350℃, the textureschanged dramatically. There were two features from the ODFs, many random texturesappeared in the Φ=5°plane in the orientation space; there were many intensive texturein the Φ=45plane, while the varies from0°to15°and the related range.After annealing at350℃for different time, macro-texture didn’t change untilannealing time reached20min.,the texture had high density and transformed into {001}plane. With increasing holding time, the macro-texture had similar characters with samples annealed at400℃and500℃.Regarding the mechanical property, hardness decreased after annealing andminimized at350℃due to coarse grains. However, hardness increased after annealingat400℃,500℃and grain size became more uniform. The results showed that tensilestrength decreased while elongation increased after annealing.