Study on Stress Corrosion Cracking Behavior of T Profiles of 7055 Aluminum Alloy

The stress corrosion cracking(SCC) performance of 7055 aluminum alloy were investigated by using tensile testing, C-ring stress corrosion experiment, metallographic observation, scanning electron microscope and transmission electron microscope. The results show that longitudinal test specimen of 7055 aluminum alloy had higher tensile strength, yield strength, elongation and reduction of area than those of the transverse specimen. The cracking time of longitudinal C-ring specimens was longer than that of transverse specimens under intermediate immersion and constant temperature and humidity environment. The deformation grains were mainly elongated in the longitudinal section. The crack of the transverse sample grew along the longitudinal direction. Once the crack was formed, it grew rapidly along the elongated grain boundary, the crack was straight and the cracking time short. The grains of transverse section were equiaxial, and the crack of longitudinal sample grew along the transverse direction. In the process of crack growth, deflection along the grain boundary occurred, and the cracking time was long. The stress corrosion mechanism of 7055 alloy consisted of hydrogen embrittlement and electrochemical theory.