Relationship between boundary misorientation angle and true strain during high temperature deformation of 7050 aluminum alloy

Tensile tests of solid solution treated 7050 aluminum alloy were conducted to different strain degrees (0.1, 0.4, 0.6 and failure) at 460 °C with the strain rate of 1.0 × 10^-4-1.0 × 10^-1s^-1. The boundary misorientation angle evolution during hot deformation of the 7050 aluminum alloy was studied by EBSD technique and the fracture surfaces were observed using SEM. A linear relationship between the increase in the average boundary misorientation angle and the true strain at different strain rates is assumed when aluminum alloy is deformed at 460 °C. The increasing rate of average boundary misorientation angle is 15.1°, 15.7° and -0.75° corresponding to the strain rate of 1.0 × 10^-4, 1.0 × 10^-2 and 0.1 s^-1, respectively. The main softening mechanism is continuous dynamic recrystallization when the strain rates are 1.0 × 10^-4 and 1.0 × 10^-2 s^-1, and it is dynamic recovery when strain rate is 0.1 s^-1.