Microstructural Evolution and Dynamic Softening Mechanisms of Al-Zn-Mg-Cu Alloy during Hot Compressive Deformation

Abstract

The hot deformation behavior and microstructural evolution of an Al-Zn-Mg-Cu (7150) alloy was studied during hot compression at various temperatures (300 to 450 °C) and strain rates (0.001 to 10 s−1). A decline ratio map of flow stresses was proposed and divided into five deformation domains, in which the flow stress behavior was correlated with different microstructures and dynamic softening mechanisms. The results reveal that the dynamic recovery is the sole softening mechanism at temperatures of 300 to 400 °C with various strain rates and at temperatures of 400 to 450 °C with strain rates between 1 and 10 s−1. The level of dynamic recovery increases with increasing temperature and with decreasing strain rate. At the high deformation temperature of 450 °C with strain rates of 0.001 to 0.1 s−1, a partially recrystallized microstructure was observed, and the dynamic recrystallization (DRX) provided an alternative softening mechanism. Two kinds of DRX might operate at the high temperature, in which discontinuous dynamic recrystallization was involved at higher strain rates and continuous dynamic recrystallization was implied at lower strain rates.

Effect of Zr, V and Ti on hot compression behavior of the Al–Si cast alloy for powertrain applications

“…Recently, CDRX was also reported in aluminum alloys [41]. This mechanism differs from that of DDRX, new grains are formed progressively within the deformed original low angle grains from a continuous increase of subgrains with low misorientations, as a result of the accumulation of dislocations in low angle boundaries [38][39][40][41].…”

“…The DDRX was observed in Al alloys, which involves development of high angle grain boundaries via nucleation and growth of new grains that typically initiate at original grain boundaries, boundaries of dynamically recrystallized grains and boundaries created during deformation [39]. Recently, CDRX was also reported in aluminum alloys [41]. This mechanism differs from that of DDRX, new grains are formed progressively within the deformed original low angle grains from a continuous increase of subgrains with low misorientations, as a result of the accumulation of dislocations in low angle boundaries [38][39][40][41].…”

Hot deformation behavior of 2060 alloy

“…Li [5] studied the deformation behaviors of Ag-containing 2519 aluminum alloy by isothermal compression and found DRX when the strain rate was 10 s -1 and the temperature was higher than 300 o C. Liu [6] reported that dynamic recrystallization of Al-Cu-Mg-Ag alloy occurred at low Z values and the tendency of dynamic recrystallization enhanced with decreasing Z value. Huang [7] [8,9].…”

Influence of Scandium Addition on Stress Corrosion Cracking Susceptibility of Al-Zn-Mg Alloy in Different Corrosive Environments

“…The age-hardenable 7xxx series Al alloys can be divided into medium strength Al-Zn-Mg system and high strength Al-Zn-Mg-Cu system [1][2][3][4][5][6]. Nowadays, 7xxx series alloys are being used in the aerospace and high-speed train system for structural components due to their high strength/weight ratio [7][8][9][10][11][12].…”