Physically based constitutive analysis and microstructural evolution of AA7050 aluminum alloy during hot compression. (5th October 2016)

• Record Type: Journal Article
• Authors: Wang, S.; Luo, J.R.; Hou, L.G.; Zhang, J.S.; Zhuang, L.Z.
• Is Part Of: Materials & design. Volume 107(2016)
• Page Start: 277
• Page End: 289
• Publication Date: 2016-10-05
• Subjects: 7050 aluminum alloy -- Constitutive model -- Dynamic recrystallization -- Grain boundary sliding -- Dislocation creep; Materials -- Periodicals; Engineering design -- Periodicals; Matériaux -- Périodiques; Conception technique -- Périodiques; Electronic journals; 620.11
• DOI: 10.1016/j.matdes.2016.06.023
• Languages: English
• ISSNs: 0264-1275

Abstract

Abstract: The hot compression tests of AA7050 aluminum alloy were conducted under conditions of 603–693 K and 0.001–10 s − 1, and the related microstructures were observed. Physically based constitutive analysis was conducted to describe the flow behaviors, which can relate the microstructural evolution with flow behaviors for high stacking fault energy (SFE) and/or precipitation-strengthened alloys. A revised model considering the coupling effects of lattice diffusion and grain boundary diffusion was proposed to characterize the transition of diffusion mechanisms under different deformation conditions. The main diffusion mechanism is determined as lattice diffusion at 633–693 K and grain boundary diffusion at 603 K. The microstructural evolution can be reflected by the deviation of creep exponent n ' from the theoretical value ( n ' =5). The reasons for the creep exponent n ' > 5 could be related to the change of internal stress and creep rate by dynamic precipitates at lower temperatures. At higher strain rates, it could be related to the impediment of dislocations motion by defects and the change of rate controlling mechanism. The operation of grain boundary sliding (GBS) may lead to n ' < 5 at higher temperatures and lower strain rates. Moreover, the mechanisms of dynamic recrystallization under wide conditions and high-strain-rate superplasticity were discussed. Graphical abstract: Highlights: The physically based model could relate the flow behaviors with microstructural evolution for AA7050 aluminum alloy. The transition of diffusion mechanism under different deformation conditions was determined by constitutive analyses. The influences of microstructural evolution on the variation of creep exponent n ' were discussed. The mechanisms of dynamic recrystallization under wide conditions and high-strain-rate superplasticity were discussed.