Microstructure evolution and Zener-Hollomon parameter analysis as-extruded 7005 aluminum alloy during hot deformation

Abstract

Isothermal compression tests were carried out on as-extruded 7005 aluminum alloy at a temperature range of 300–550 ℃, a strain rate ranging from 0.001 to 1 s−1, and a strain of 1.2. QFormUK was used to simulate the strain distribution during the high-temperature compression and investigating the microstructure evolution, it was found that the strain near the anvil was approximately 0.7, indicating a hard-to-deform area, the strain in the central region of the specimen reached 1.4, indicating a uniform deformation zone, and the strain near the side of the specimen was approximately 1.0, indicating a zone with free deformation. When the processing temperature ranged from 400 to 450 ℃, the main softening mechanism of the alloy was dynamic recovery (DRV), dynamic recrystallization (DRX) became the primary deformation mechanism at 500 ℃. It is worth noting that research into the relationship between lnZ value and microstructure evolution has shown that the grain structure with an lnZ value of 36.6 is mainly dynamic recovery. As the lnZ value decreases, the high-temperature softening mechanism of the alloy shifts from dynamic recovery to DRX. The lower the lnZ value, the more likely DRX is to occur. Furthermore, the lnZ parameter was introduced into a simulation software to analyze the microstructure and it was found to serve as an equivalent parameter for investigating microstructures in uniform deformation zones.