Simultaneously improving tensile properties and stress corrosion cracking resistance of 7075-T6 aluminum alloy by USRP treatment

The effect of gradient nanostructure prepared by ultrasonic surface rolling on stress corrosion behavior of 7075-T6 aluminum alloy was studied. Results showed that gradient structure improved stress corrosion cracking (SCC) resistance-strength-ductility synergy. Grain refinement and dislocation proliferation offset strength reduction caused by the dissolution of precipitated phase. The superior SCC resistance was attributed to the reduction of surface roughness and the introduction of compressive residual stress. In addition, grain refinement, re-precipitation of coarse η phase at trigonal grain boundaries and the transformation of intracrystalline precipitated phase from GP zone to η' phase further enhanced SCC resistance.