The Flow Softening Behavior and Deformation Mechanism of AA7050 Aluminum Alloy

Abstract

The flow softening behavior and deformation mechanism of AA7050 aluminium alloy are investigated though hot compressive tests using a Gleebe-1500 thermal simulator at strain rates of 0.01∼10 s⁻¹ and temperatures of 300∼450°C. The results show that the maximal relative softening transforms from 350°C to 450°C with increasing strain rate. Based on the processing maps and microstructure characterizations, dynamic recovery, dynamic precipitation and coarsening may be responsible for the softening behavior of AA7050 aluminium alloy at 350°C and 0.01 s⁻¹. With increasing strain rate and temperature, high level of the flow softening is associated with deformation heating, dynamic recovery and dynamic recrystallization. The superimposed processing map with various strains is established, indicating that the optimum hot workability domain is the temperature range of 390∼450°C and strain rate range of 0.1∼0.01 s⁻¹.

Fig. 6 Microstructures of AA7050 aluminum alloy under different deformation conditions: (a) 350°C, 10 s⁻¹, (b) 400°C, 10 s⁻¹, (c) 350°C, 0.01 s⁻¹, (d) 450°C, 0.01 s⁻¹.