Investigation of stress corrosion cracking of low-alloy steel in water

Abstract

For four low-alloy steels with a wide range of tensile strength, the dynamical processes of the nucleation and propagation of stress corrosion cracking (SCC) in water with various polarization conditions and in a 0.1 N K 2Cr 2O 7 solution were traced with an optical microscope. The results show that if the tensile strength of the steel is higher than a critical value that is different in different polarization conditions and K I K ISCC , the plastic zone in front of a loaded crack tip is enlarged with time i.e. the delayed plastic deformation occurs in all the environments used. The nucleation and propagation of SCR will proceed when this delayed plastic deformation develops to a critical condition. Neither anodic and cathodic polarization nor the inhibitor can change the feature of the delayed plasticity and the nucleation and propagation of SCC in water. In all the environments used, K ISCC is increased and da dt is decreased with the decrease in the strength of the steel. K ISCC is increased and da/ dt is decreased with the anodic polarization and the addition of the inhibitor, but the cathodic polarization has the opposite effect.