Abstract:Effect of pre-recovery solid solution-T652 treatment and solid solution-T652 treatment on microstructure and properties of Al-11.5Zn-3.5Mg-2.3Cu-0.24Zr-0.0025Sr aluminum alloy extrusion were studied by means of micro-hardness tester and electrical conductivity test, tensile test, intergranular and exfoliation corrosion experiment, scanning electron microscope (SEM) and electron back-scattered diffraction (EBSD). The results show that pre-recovery-annealing treatment can restrain recrystallization effectively, refine the grain size, and reduce the average angle of grain boundaries, increase the percentage of low angle grain boundaries significantly. Pre-annealing can improve the yield strength and the corrosion resistance performance, and maintain the same tensile strength. The increase of the yield strength is attributed to dislocation strengthening and low angel grain boundaries strengthening.