The hot workability of homogenized 6069 Al alloy cast ingot was examined via hot compression tests. These tests were conducted using Gleeble-3500 thermal simulation machine within a temperature range of 300-550 °C and a strain rate range of 0.001-10 s−1. The compression data were then used to construct a processing map, through which a safe processing region was identified. The safe processing region could be divided into dynamic recovery and dynamic recrystallization domains. The variation in microstructure was related to the variation in efficiency of power dissipation, as indicated by microstructure observations. Dynamic recovery was observed in regions associated with the intermediate efficiency of power dissipation, whereas partial dynamic recrystallization occurred in regions with high efficiency. Flow instability was found to be related to flow localization. The strain rate sensitivity m map showed that flow localization occurred because of the deformation conditions with low m values. The kinetic analysis revealed a decrease in apparent activation energy with increased temperature in the partial dynamic recrystallization region.
- 6069 Al alloy
- dynamic recovery
- dynamic recrystallization
- efficiency of power dissipation
- processing map