Hot deformation behavior of 2026 aluminum alloy during compression at elevated temperature

Hot compression tests of 2026 aluminum alloy were carried out on Gleeble-1500 system in the temperature range from 300 degrees C to 450 degrees C and at strain rate range from 0.01 s(-1) to 10 s(-1), and the associated microstructural evolution was studied by observations of metallographic and transmission electron microscope. The results show that the true stress-true strain curves exhibit a peak stress at critical strain, after which the flow stresses decrease monotonically until high strains, showing a dynamic flow softening. The peak stress level decreases with increasing deformation temperature and decreasing strain rate, which can be represented by the Zener-Hollomon parameter Z in the hyperbolic sine equation with the hot deformation activation energy of 340.98 kJ/mol. The hot deformed microstructure consists of a great amount of precipitate within subgrains in the elongating grains develops and may be associated with the Z value. At low Z value, the subgrains remain well formed with clean high-angle boundaries and coarse precipitates are distributed in the grain interior. At high Z value, a high dislocation density with poorly developed cellularity and considerable fine dynamic precipitates are observed. (C) 2009 Elsevier B.V. All rights reserved.