The effect of stress in age-forming on corrosion behavior of high-strength aluminum alloy

Age-forming is a form of stress ageing that is widely used in modern aerospace industry. In this paper we investigated the effect of stress in the age-forming process on corrosion behavior of AA7050 in 3.5% NaCl solution and compared it to traditional ageing. Morphology analysis through optical profilometry and electrochemical impedance spectroscopy (EIS) measurement suggest that the age-formed samples exhibit more corroded attack. Stress in age-forming induced the precipitation (MgZn2) and precipitate free zone growth, which are anodic to the matrix. The bigger precipitates and wider precipitate free zone caused by age-forming result in decreased corrosion resistance of AA7050 in 3.5% NaCl solution. Additionally, stress during age-forming increases the grain aspect ratio, which is harmful to intergranular corrosion resistance. Therefore, the stress in age-forming reduces corrosion resistance of AA7050 in 3.5%) NaCl solution.