Abstract:Tensile properties, fracture characteristics and microstructures of 7055 aluminum alloy containing Ag in the T6, T73 and RRA conditions were investigated. The results of the investigations show that RRA treatment retains the strength of 7055-T6 with a higher electrical conductivity close to that of 7055-T73, but its elongation decreases greatly; SEM fractographs reveal that intergranular cracking and shear-type transgranular cracking were both present on the fracture appearance of 7055-T6 specimen. After T73 treatment, the fractographs consist of dimple-type transgranular cracking with minor intergranular cracking. With 7055-RRA specimen, intergranular cracking dominates with minor dimples distributed on the fracture surface. The types and volume fraction of precipitates, width of PFZ (Precipitate Free Zones ) and the ability of precipitates to impede dislocations varied with heat treatment regimes.