Effect of High-Temperature ECAP on Grain Coarsening and Refinement

Multi-pass equal-channel angular pressing (ECAP) experiments were carried out on extreme-cooled 7055 aluminium alloy at 400°C. The microstructure of 7055 aluminium alloy was characterised by X-ray diffraction (XRD), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM). The results reveal two distinct grain sizes: some coarsened grains exist in the microstructure, and most fine grains are distributed near and inside the coarse grains. The deformation texture is weakened, the recrystallisation texture is enhanced, and the recrystallisation texture {124} 〈211〉 (R) is more sensitive to strain. The refined grains are mainly mechanically refined by large shear deformation, the coarsened grains be formed by sub-grain merging and growth at high temperatures.