Atmospheric corrosion behavior of low-alloy steels in a tropical marine environment

The corrosion behavior of carbon steels and weathering steels was investigated in a tropical marine environment. And both exhibited similar corrosion weight-loss behavior in tropical marine environments. Corrosion weight loss (W) as a function of exposure time (t) can be calculated using the power function, W = Atⁿ. The values of the initial corrosion rate, A, and corrosion tendency, n, can be easily obtained by taking the logarithm of the power equation. However, the corrosion rust-layer structure of the two materials was quite different. The rust layer of carbon steel presents a single-layer structure. Meanwhile, the rust layer of weathering steel exhibits a single-layer structure after exposure for about 24 months and then gradually evolves into a double-layer structure. The main corrosion products of the steels are β-FeOOH, γ-FeOOH, and Fe₃O₄ in the initial stage of exposure. In the rust layers, α-FeOOH appeared after 12 months of exposure.