Comparative study of the stress corrosion behavior of a multiuse bainite steel in the simulated tropical marine atmosphere and seawater environments

Abstract

Stress corrosion cracking (SCC) behavior of a multiuse high-strength low-alloy (HSLA) bainite steel was comparatively studied in the simulated seawater and marine atmosphere environments using electrochemical measurements, static load SCC and slow strain rate tensile (SSRT) tests. The difference in SCC behavior was characterized in detail by morphology observation via scanning electron microscopy (SEM) and corrosion product analysis via X-ray diffraction (XRD) and energy dispersion spectrum (EDS) techniques. The results indicate that the HSLA bainite steel is very sensitive to SCC in the simulated tropical marine atmosphere, mainly due to the thin and uneven electrolyte film, which is characterized by a fast oxygen transportation rate on the steel surface. The rust layer also plays an important role in determining SCC behavior in the simulated marine atmosphere, as it restrains the electrochemically anodic process and promotes the cathodic process, particularly the hydrogen evolution reaction, resulting in the nucleation and transgranular-mode propagation of SCC microcracks at the bottoms of pits. As a result, both localized anodic dissolution (AD) and hydrogen embrittlement (HE) effects are promoted, contributing to the significant increase in the susceptibility of HSLA bainite steel to SCC.