Insights into atmospheric corrosion evolution of weathering steels with different nickel contents during simulated coastal atmospheric wet-dry cycling

• The kinetic evolution functions of three weathering steels were studied. • Distribution of corrosion products after varying corrosion cycles was determined. • Ni enhanced the ionic selectivity of rust layer, thereby inhibiting the ingress of Cl⁻. • Ni affected the relative content of α-FeOOH and β-FeOOH in the inner rust layer. This study investigates corrosion evolution of ordinary weathering steel (Q420NH) and super weathering steels with varying nickel contents (1 wt.% and 3 wt.%, named as 1Ni and 3Ni) under simulated coastal atmospheric wet-dry cycling conditions. Characterization of rust layers subjected to different corrosion cycles was conducted using indoor cyclic corrosion tests (CCT), X-ray diffraction (XRD), scanning electron microscopy (SEM), and Raman spectroscopy, thereby elucidating the transformation processes of corrosion products on the surfaces of Q420NH, 1Ni, and 3Ni steels. The results demonstrate that a higher nickel content significantly mitigates atmospheric corrosion in weathering steels and notably influences the compositional evolution of the internal rust layer. In the initial corrosion stages, the primary components of the internal rust layer for Q420NH and 1Ni steels are α -FeOOH, β -FeOOH, Fe 3 O 4 , and γ -Fe 2 O 3 , while the internal rust layer for 3Ni steel predominantly consists of α -FeOOH, Fe 3 O 4 , γ -Fe 2 O 3 , and ferrihydrite, with sporadic occurrences of β -FeOOH. In the later stages of corrosion, the relative contents of β -FeOOH and Fe 3 O 4 decrease in the internal rust layers of Q420NH and 1Ni steels, whereas the internal rust layer of 3Ni steel is primarily composed of α -FeOOH and ferrihydrites. Throughout the corrosion process, external rust layers of all three weathering steels consistently exhibit γ -FeOOH as main component. The presence of a high proportion of α -FeOOH contributes to enhanced density and stability of the rust layer of 3Ni steel, resulting in a significantly lower corrosion rate compared with both Q420NH and 1Ni steels.