Abstract: Athermal compression experiment for AA7021 aluminum under a temperature ranging from 350—490 ℃ and a strain rate ranging from 0.01—10 s-1 was carried out by using gleeble-3500 thermal simulation test machine. A strain-based constitutive equation and a thermal processing diagram of the thermal deformation characteristic of the material was established and the microstructure of the safety zone and the instability zone in the thermal processing diagram was analyzed. The results show that the deformation induced precipitation effect is found in the safety zone. In the deformation instability zone, when the deformation temperature became lower and strain rate became high, the adiabatic shear zone is formed due to the effect of strain heat. In addition, in the region where the strain rate is greater than 1 s-1, the cause of deterioration of aluminum hot workability are found to be local rheology, large particle breakage, microcrack, etc. During the thermal deformation process, the dynamic softe-ning mechanism of aluminum changes from dynamic recovery to dynamic recrystallization as the temperature increase. AA7021 aluminum alloy coexists a variety of softening mechanism in the medium temperature and high temperature compression process, but dynamic recovery still dominates.
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2020, Vol. 34 
