Effect of Strain Rate on Hot Deformation Behavior and Softening Mechanism of Al–10.0zn–3.0mg–2.8cu Alloy

Abstract

Strain rates are important during the hot deformation of aluminum alloy because parameters regulation can change flow stress and softening mechanisms. In this study, different hot compression strain rates (0.001, 0.01, 0.1, and 1 s −1 ) and temperature (380 °C, 400 °C, 420 °C, 440 °C, and 460 °C) were designed to study the hot deformation behavior of Al-10.0Zn-3.0Mg-2.8Cu alloy. The Arrhenius model that considers strain compensation was established to reflect the flow stress. The prediction ability and accuracy of the modified Arrhenius model can reach 0.998. Meanwhile, the influence of strain rate on the softening mechanism was investigated. The complex recrystallization mechanisms, such as the particle stimulated nucleation, grain boundary bulging, and subgrain rotation, were demonstrated using the real-time EBSD-EDS detection technology at a strain rate of 0.001 s −1 . In addition, the fraction of the second phase particles was decreased with the strain rate increased from 0.001 to 0.1 s −1 . The second phase particles were refined by dislocation, which plays an important role to assist softening. With the strain rate increased to 1s -1 , the particles refinement was weakened, and the recovery and recrystallization became the dominant for softening.

Keywords: hot deformation, strain rate, particle stimulated nucleation, softening mechanism, recrystallization