Effect Of Thermal Deformation(Compression, ECAP)–Pre-Recovery On The Structure Properties And Anisotropy Of 7085 Aluminum Alloy

7085 aluminum alloy has received a wide range of applications in the weapon equipment, aerospace and others with a good comprehensive performance. Structure properties and anisotropy of 7085 aluminum alloy(Al- 7.0Zn- 1.41Mg- 1.50Cu-0.14Zr-0.023Sr) under thermal deformation(compression, ECAP)- pre-recovery were studied by metallographic structure, EBSD, XRD, hardness and electrical conductivity, tensile properties, intergranular corrosion and spalling corrosion test. Conclusions are as follows:(1) Structure properties and anisotropy of 7085 aluminum alloy under heat compression- solution- aging have been studied. The results show that, the alloy recrystallizes under heat compression- solution, different samples had obvious differences in the microstructure, the average grain size relationship is Y(transverse) < X(axial) < Z(compression direction); the low alloying degree of 7085 aluminum alloy promoted recrystallization and anisotropy of mechanical properties was not obvious, the tensile strength and yield strength under T6 and T76 aging were also small(under 10 MPa), and the strength of T76 aging is higher than that of T6, but the plasticity decreases. The corrosion resistance of the alloy is anisotropic, and the corrosion resistance of T76 is better than that of T6.(2) Structure properties and anisotropy of 7085 aluminum alloy under heat compression- pre-recovery- solution- aging have been studied. The results show that, the pre-recovery treatment before solution inhibited recrystallization, refined the average grain size(direction Y is only 10.650 ?m), increased the proportion of low angle grain boundary, improved the spheroidicity of grain. Compared with the heat compress- solution treatment, pre-recovery treatment significantly improved the alloy's hardness and decreased the conductivity and plastic, and had inferior effect on yield strength and tensile strength. However, the difference of hardness, conductivity and strength were lower, and the anisotropy of mechanical properties was not obvious in different directions of the alloys under different aging treatment. Compared with T6 aging treatment, T76 aging treatment significantly improved the tensile strength and yield strength, and reduced the plastic. Pre-recovery significantly increased the intergranular corrosion resistance, the corrosion level reached secondary level with the corrosion depth of only 19.65 ?m of direction Y under T76 aging treatment, the corrosion resistance of the alloy was also improved, and the corrosion resistance of the alloy is anisotropic.(3) Structure properties and anisotropy of 7085 aluminum alloy under heat compression-ECAP- pre-recovery- solution- aging have been studied. The results show that, ECAP processing promoted the recrystallization and grain growth of the alloy, the grain size distribution was more uniform, significantly improved the spheroidicity, eliminating the texture, and produced a lot of sub-grain, but reduced the proportion of small angle grain boundaries. With ECAP processing, the hardness of the alloy decreased, the electrical conductivity was improved, and the tensile strength and yield strength were increased significantly under the condition of keeping the plasticity unchanged at the same time. the tensile strength and yield strength under T76 aging were 544.83 MPa and 524.43 MPa. The intergranular corrosion resistance of the alloy was decreased, but the corrosion resistance of the alloy was improved, and the anisotropy of the corrosion resistance of 7085 aluminum alloy was controlled by ECAP.(4) Structure properties and anisotropy of 7085 aluminum alloy under heat compression-ECAP- heat compression- pre-recovery- solution- aging have been studied. The results show that, the recrystallization of the alloy was further promoted by the heat compression after ECAP, most of the dislocations and sub-grain after ECAP processing were eliminated, low angle grain boundary increased, and average grain size increased. Heat compression had little effect on the hardness and conductivity of the alloy, the tensile strength and yield strength decreased and the plastic change was not big, the anisotropy of the mechanical property become larger. The intergranular corrosion resistance and corrosion resistance were improved, but compared with heat compression- ECAP- pre-recovery- solution- aging the anisotropy of corrosion resistance was greatly increased.