Comparative study on stress corrosion resistance of 7150/7055/7A56 aluminum alloys

Abstract The effect of the alloying degree of 7xxx aluminum alloys on stress-corrosion resistance and microstructure was explored. The relationship between the microstructure characteristics and stress-corrosion performance of the three 7xxx aluminum alloys was analyzed. The results show that with an increase in alloying degree, the quantity of precipitated phases along grain boundaries notably increases, and the connectivity between precipitated phases is significantly enhanced, leading to an increased tendency for alloy dissolution. Anodic dissolution causes intergranular corrosion, making grain boundaries serve as channels for rapid crack propagation under tensile stress, thereby increasing the alloy’s stress-corrosion susceptibility. The stress-corrosion sensitivities of the three alloys are as follows: 7150 < 7055 < 7A56.