The Microstructure Evolution In The Multi-pass Hot Deformation And Solution Heat Treatment Process Of 7085 Aluminum Alloy

7085 aluminum alloy is chosen as the experimental material in this thesis. Gleeble hot deformation simulation, optical microscopy, scanning election microscopy and electron back-scattering diffraction were used comprehensively to study the flow behavior of 7085 aluminum alloy during hot deformation process. The matrix microstructure evolution during hot deformation and it’s subsequent solution heat treatment of 7085 alloy have been investigated by isothermal compression tests at deformation temperature ranging from 330 ℃ to 450 ℃, strain rate of 0.001 s-1 to 10 s-1,strain ranging from 0.5 to 1.6 and deformation pass of 1 to 4. Average grain size, recrystallization fraction and low angle boundary were quantificationally characterized. The results can provide theoretical guidance and experimental basis to accuracy control the matrix microstructure of the alloy.The flow behavior during isothermal compression process was studied. The deformation temperature and strain rate had a significant influence on flow stress of 7085 aluminum alloy. The flow stress increases with increasing strain rate shows that 7085 aluminum alloy was positive to strain rate. The characteristic constants of the alloy were calculated by liner regression method and the constitutive equation was established.The influence of deformation temperature and strain to matrix structure during 1-pass deformation process was investigated. After hot deformation, the grains of 7085 aluminum alloy became flat and elongated along deformation direction. In this paper studies parameter range, with the deformation temperature decreasing or increasing the strain, the average grain size reduced. The fraction of low angle boundary rose when the deformation temperature increased in the range between 330 ℃ and 420 ℃ or the strain decreased. With the deformation temperature enhancing in the range between 330 ℃ and 420 ℃ or reducing strain, the high angle boundary and the recrystallization fraction reduced.The influence of different deformation parameters (defined A, B, C and D as deformation temperature, deformation pass, strain and strain rate, respectively) to matrix structure was researched by orthogonal experimental. The results show that the influence of deformation parameters to as-deformed microstructure parameters follows the sequence: low angle boundary(C> D> A> B), high angle boundary(C> D> A> B), average grain size (D> C> A> B). To as-quenched microstructure parameters follows the sequence:low angle boundary(C> B> A> D), high angle boundary(C> B> A> D), average grain size(C> D> A>B).The influence of deformation pass to matrix structure was studied. In this paper studies parameter range, with the deformation pass decreasing, the fraction of low angle boundary rose. Decreasing the deformation pass was beneficial to reduce the average grain size, the high angle boundary and the recrystallization fraction.