Relationship between boundary misorientation angle and true strain during high temperature deformation of 7050 aluminum alloy
(School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China)
Abstract: 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 ℃ 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 ℃. 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.
Key words: boundary misorientation angle; aluminum alloy; electron backscatter diffraction(EBSD); high temperature deformation; microstructure