Hot compression tests of homogenized 7050 aluminum alloy were carried out on the Gleeble-1500 thermal simulation machine, and the associated microstructure was studied using electron back scattered diffraction technique and transmission electron microscopy. The results showed that the peak stress levels decreased with the increase of deformation temperatures or the decrease of strain rates, which can be represented by the Zener–Hollomon parameter in the exponent-type equation with the hot deformation activation energy of 160.3 kJ/mol. With the decrease of Z values, results showed a continuous decrease in very low angle boundaries, exhibiting a misorientation between 2° and 5°, associated to substructure, and a steady increase in the other higher angle boundaries, especially with the misorientation angles between 30° and 60°. And such an evolution is due to the increase of subgrain size with the decrease of Z values. At lower Z , the dislocations collected into more widely spaced and less dense tangles. As strain rose, the tangles reorganized into subgrains with walls that were more widely spaced and straighter; they had fewer, more regularly arranged dislocations. The main softening mechanism of homogenized 7050 aluminum alloy is dynamic recovery.

Hot deformation behavior and microstructural evolution of homogenized 7050 aluminum alloy during compression at elevated temperature

Isothermal compression tests of a new type Al–Zn–Mg–Er–Zr alloy are carried out on a Gleeble-3800 thermal simulator at temperatures varying from 300 to 460 °C and strain rates ranging from 0.001 to 10 s −1 . A comprehensive and scientific constitutive models based on the Arrhenius type equation have been developed from the experimentally measured data. The deformation temperature and strain rate have significant effect on flow stress and the material constants, such as α, β, n, ln  A and Q are the functions of the strain. The flow stress calculated by the developed constitutive equation shows a close agreement with the experimental value, which indicates that the proposed constitutive equation can precisely analyze the hot deformation behavior of the Al–Zn–Mg–Er–Zr alloy. Due to the presence of coherent L1 2 -structured Al 3 (Er,Zr) precipitates, the dominant softening mechanism is dynamic recovery during isothermal compression.

Hot deformation behavior and constitutive equation of a new type Al–Zn–Mg–Er–Zr alloy during isothermal compression

The isothermal deformation compression tests of AA7085 aluminum alloy were performed on Gleeble-1500 system in the temperature range from 250 °C to 450 °C and at strain rate range from 0.01 s −1 to 10 s −1 . The microstructure of samples was observed using optical microscopy (OM) and transmission electron microscopy (TEM) techniques. The results show that the peak stress levels decreased with the increase of deformation temperatures or the decrease of strain rate, which can be represented by the Zener–Hollomon parameter in the exponent-type equation with the hot deformation activation energy of 249.11 KJ/mol. Dynamic recrystallization more obviously occurred in the sample with higher Z value than in the sample with lower Z value. Dynamic recrystallization is sensitively dependent on the deformation temperature.

Hot deformation behavior of AA7085 aluminum alloy during isothermal compression at elevated temperature

Flow behavior modeling of the 7050 aluminum alloy at elevated temperatures considering the compensation of strain

Hot deformation characterization of duplex low-density steel through 3D processing map development

The hot deformation behavior of an Al–5.7 wt.%Mg alloy with erbium has been investigated. Compression tests are performed in the temperature range of 300–500 °C and in the strain rate ranging from 0.001 s−1 to 50 s−1 up to a true strain of 0.7. The processing maps are developed at different strains and the standard kinetic analysis has been applied to evaluate the rate controlling mechanisms. The processing maps have exhibited two domains of 350–450 °C at 0.001–0.03 s−1 and 450–500 °C at 0.01–1 s−1, representing dynamic recovery of Al–5.7 wt.%Mg with erbium. The apparent activation energies estimated in these two domains are 180 kJ/mol and 163 kJ/mol respectively, which suggests that cross-slip of dislocation and lattice self-diffusion are the deformation mechanisms. At strain rates higher than 10 s−1, the flow curves demonstrate flow softening behavior, and the flow instability regions reveal mixed microstructure of local deformation and dynamic recrystallization.

Gang Meng

Papers

Hot deformation and processing maps of an Al–5.7 wt.%Mg alloy with erbium