Research On7075Aluminum Alloy Microstructure And Property Evolution Regularity During Equal Channal Angular Pressing

7075aluminum alloy belongs to Al-Zn-Mg-Cu alloy with the very high specificstrength, which is a kind of typical high strength deforming aluminum alloy. It is stillformed by thermoplastic forming process. And in the hot forming, it is with the change ofmicrostructure. Parts owing the fine grain microstructure have good comprehensivemechanical properties.7075aluminum alloy need continue to improve its performance, andfine-grain strengthening by SPD is one of the most efficient methods. Nevertheless, ECAPis a kind of SPD that can form dense, large, relatively uniform ultra-fine crystal materialand the process is relatively simple. Approximate ideal pure shear deformation will occurduring ECAP deformation process, and super plastic deformation can make microstructureto refine, so as to form sub-micron or nanoscale ultrafine grain. Owing to the influence ofgrain boundary of polycrystalline materials, microstructure mechanism of grain refinementduring the ECAP process and the change of the grain boundary have not settled yet. As aconsequence, fine crystal of7075aluminum alloy was prepared by ECAP, and it is greatsignificance to study7075aluminum alloy microstructure evolution, the grain refinementand performance evolution during ECAP. Specific work is as follows:(1) Design on my own and manufacture equal channal presents pressing die.(2) The process of7075aluminium alloy during ECAP is numerically simulated using afinite element software to predict the microstructure grain size. The method of thecombining application of finite element simulation and experimental analysis is explored toinvestigate the variation of microstructure grain size. The result demonstrates thephenomenological model can accurately predict the evolution trends of grain size by ECAPand grain size can refine clearly and uniformly after1pass ECAP, at the same timeplasticity and strength of materials can be improved after ECAP.(3) Finite element analysis and experimental analysis were done for7075aluminumalloy during ECAP to study the influence of pressing path and extruding pass, friction andtemperature on materials microstructure grain size and distribution.(4) With finite element method and theoretical calculation, the deformation behavior ofthe grain shape of7075aluminum alloy was predicted during ECAP of A path for manypasses to explore grain shape deformation behavior. The result shows that grain shapedeformation behavior for them is consistent in A path of many passes after ECAP. Therelationship between angle β and N is anastomotic in both the calculated result and the simulated result.