| High strength aluminum alloy as the less studied material in current materials area, has its vast market value. Severe plastic deformation as the more mature research theory, is one of the most effective way to refine materials structure and improve the overall performance of materials. The SPD process does not change any composition of the materials, at the same time achieving the purpose of grain refinement. It can effectively improve the material strength and the toughness of plastic materials. With the further development of modern industry, the metal materials demanded higher performance, which is forcing materials faculty have a deeper research and development to the properties of metal materials. Through the research and control of materials texture, the materials have a further improvement on the basis of original excellent performance.This paper using 7005 aluminum alloy in 7XXX series high strength aluminum alloy as the research sample, by means of equal channel angular extrusion processing, then study the micro structure and mechanical properties of original samples, standard annealed samples and the extruded samples with five passes, analysis mechanism of mechanical properties improvement and grain refinement. Use X-ray diffraction analysis pole figure of texture, investigate texture evolution. Conclusions mainly according to the research and experimental data are as follows:(1) As the annealing temperature increase, the tensile strength and hardness of 7005 aluminum alloy decreased, elongation is as increasing trend linearly, and also contrary with the tensile strength variation. When reach a certain temperature, the mechanical properties are stabilized. At this time, aluminum has been completed recrystallization.450℃for the 7005 aluminum alloy is determined to be the recrystallization temperature.(2) After five passes of equal channel angular extrusion,7005 aluminum alloy refine the grain size, the average size from 100μm refined to 0.5μm. The mechanical properties of 7005 aluminum alloy has been significantly improved, with the increase of extrusion passes, 7005 aluminum alloy hardness, compressive yield strength and tensile strength gradually increased. According to the experimental data, we can see the tensile strength from 189MPa increased to 468MPa, yield strength from 174MPa increased to 456MPa, surface hardness of the sample X increased by the 83.6HV to 148.6HV.(3) The microstructure and tensile fracture surface analysis of 7005 aluminum alloy in the multi-pass ECAE process after extrusion, while there are the strengthening phase and the second phase MgZn2 precipitation of Fe element. Through the analysis of SEM images, with the room temperature tensile, study each process fracture surface of aluminum after processing by the composition of dimples and tearing edges, showing a ductile fracture characteristics, while the center of the dimple has the second significant phase particle morphology,which can determine the strengthening phase and second phase particles play a key role in improving the mechanical properties of materials.(4)Through XRD diffraction of 7005 aluminum alloy in the different passes, the diffraction peak after extrusion and texture of the pole figure were determined in the extrusion, texture performance is the {100}<110> rotated cube texture in early process, with the extrusion pass increases and also deformation, texture gradually transformed into a stable {211}<110> A texture and {111}<110> Z texture component.In summary, through study the 7005 aluminum alloy by ECAE method and we found that grain refinement of aluminum alloy 7005 has produced superplasticity, ECAE texture intensity at the same time reducing the performance to more evenly in all directions, it is a kind of aluminum and texture help to improve the effective way and greatly improve the deformation properties of aluminum, so aluminum extrusions, has structural parts to be more widely used. |
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