Field corrosion study of 690 MPa grade Sb-containing high strength bridge steel in tropical oceanic environment

Bridge steel is developing towards high strength, lightweight and high corrosion resistance. Sb element is re-ported to be able to improve the corrosion resistance of steel in marine environments. However, current research focuses on the corrosion behavior of low-strength or Cu/Ni/Cr-added bridge steel and pays little attention to Sb-containing high strength bridge steel. Thus, this paper examined the corrosion behavior of a new 690 MPa grade Sb-containing high strength bridge steel through field exposure in a tropical marine atmosphere. The corrosion rate of the steel was calculated by the weight loss method, and the corrosion characteristic and product prop-erties were investigated by SEM, LSCM, EDS and XRD. Results showed that the corrosion rate decreased from 68.69 to 54.88 mu m/y as the exposure time increased from 6 to 24 months. The decrease was due to the improvement of corrosion products and the weakening of acidification process. Specifically, the corrosion products became compact and electrochemically stable, and the gamma-FeOOH was transformed into Fe3O4 and alpha-FeOOH with the extension of exposure time. This paper reported for the first time the corrosion evolution process of the 690 MPa grade Sb-added high strength bridge steel in a real marine atmosphere, which is of great significance for the material selection and anti-corrosion design of bridges in the future.