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For providing a scientific basis for the applicability of weathering bridge steels in industrial atmospheric environments with different levels of pollution， the influence of industrial atmospheric environments on the corrosion behaviors of typical weathering bridge steels was simulated. The corrosion behaviors in industrial atmospheric environments of two kinds of weathering bridge steels， Q345qNH and Q420qNH， were studied through the periodic infiltration accelerated corrosion test. Furthermore， the applicability of these two kinds of weathering bridge steels in NaHSO3 solutions with different concentrations in simulated industrial atmospheric environments was investigated by weight loss method，electrochemical analysis and macroscopic morphology observation. Results showed that the corrosion resistance of Q420qNH weathering steel was better than Q345qNH in simulated industrial atmospheric environments. The corrosion rate of these two weathering bridge steels increased first and then decreased with the extension of the corrosion time，and the corrosion rate was the highest at 24 h. As the concentration of NaHSO3 solution increased，the corrosion rate increased. When the solution concentration reached 0.5%，the corrosion of the Q345qNH sample was continuously accelerated， indicating that the applicability of Q345qNH was limited in this case.

The corrosion behaviors of three bridge steels in a real tropical marine environment for 2 years were studied. One weathering steel (WS) was designed with higher levels of nickel, copper, and molybdenum compared to the other. These two kinds of WSs and one kind of ordinary high-strength low-alloy steel (Q345qe) were compared under two conditions (marine atmospheric zone and marine immersion zone at Sanya Marine Environmental Test Station). The morphology, corrosion rate, and corrosion product analysis of the steels were performed through SEM, XPS, FTIR and other characterization methods. The results demonstrated that weathering steels facilitate the densification of the corrosion product layer due to the addition of alloying elements Cr, Ni, and Cu, promoting rust nucleation and enhancing the compactness of the protective layer. However, in an immersion environment, the extensive erosion by chloride ions renders the benefits of WS ineffective. [ABSTRACT FROM AUTHOR]

The corrosion behaviors of two bridge steels (Q345q and Q500q) under simulated ultraviolet irradiation and a wet–dry alternating (UVWD) environment were studied. Weight loss measurement, stereomicroscope observation, SEM, XRD, and electrochemical impedance spectroscopy (EIS) were performed to investigate the influence of the coupled environment. The results revealed that the corrosion rates of Q345q and Q500q were significantly accelerated by the synergistic effect of UV light exposure and alternating wet–dry conditions. Numerous voids and cracks could be observed throughout the thickened rust layers, enabling the corrosive substances to easily penetrate through the rust layer. Q500q exhibited better corrosion resistance than Q345q due to the addition of Mo, Cr, and Ni as corrosion-resistant elements, which tended to transform the rust layer into α-FeOOH rather than γ-FeOOH during later stages of corrosion. [ABSTRACT FROM AUTHOR]