Study on hot compressive deformation behaviors and corresponding industrial extrusion of as-homogenized Al–7.82Zn–1.96Mg–2.35Cu–0.11Zr alloy

Abstract

Hot compression tests of an as-homogenized Al–7.82Zn–1.96Mg–2.35Cu–0.11Zr alloy were carried out on a Gleeble-3500 thermo-simulation machine at temperatures varying from 300 to 460 °C and strain rates ranging from 0.001 to 10 s−1. The true stress–strain curves exhibited four cases which represented the competition between work hardening and dynamic softening under different deformation conditions. Arrhenius-type constitutive equation was established to describe flow behaviors and provide the basis for calculating the industrial extrusion parameters. In this study, microstructure evolution of the studied alloy under different deformation temperatures, strain rates, and strains was observed by optical microscopy, transmission electron microscopy, and electron backscatter diffraction. Dynamic recovery, continuous dynamic recrystallization, and discontinuous dynamic recrystallization occurred at high deformation temperatures and low strain rates. Based on processing map, the optimal processing domain was in the strain rate within the limits of 0.001–0.1 s−1 and deformation temperature ranges of 400–450 °C. The industrial extrusion process of the studied alloy was carried out on an extruder with capacity of 3500T, and the results of industrial extrusion were in accordance with the conclusions of hot compression tests. After T6 heat treatment, the studied alloy shows ultimate tensile strength of 700 MPa with elongation of 8.9%.