Insights into a weathering bridge steel with excellent corrosion resistance in high Cl − environments

Abstract

The low-temperature toughness and corrosion resistance of a novel weathering bridge steel were investigated through low-temperature Charpy impact tests and salt spray corrosion experiments. It was demonstrated that the experimental steel exhibits exceptional ultra-low-temperature toughness, achieving a maximum impact absorption energy of 53 J at −196 °C. The superior low-temperature performance originates from its refined grain structure, high proportion of high-angle grain boundaries, granular bainite microstructure with packet boundaries, and uniform dislocation distribution induced by recrystallization behavior. The enhanced corrosion resistance of the tested steel mainly arises from the cooperative interaction among Cu, Ni, and Mo. Mechanistically, CuFeO₂ and NiFe₂O₄ phases absorb Mo oxides, generating a composite protective film that stabilizes within the corrosion product layer. This unique mechanism enhances the rust layer's compactness, reduces electrochemical activity, modifies the ion-selective permeability of the oxide layer and mitigate the pitting corrosion behavior.