Fig. 1 Corrosion weight loss a, corrosion rate b, rust mass c versus time for the two experimental steels

Fig. 2 XRD patterns of the rust layers formed on the carbon a and weathering b steels surfaces after different corrosion times

Fig. 3 Quantitative analysis of different phases of the rust layers formed on the experimental steel surfaces after different corrosion times

Fig. 4 Corrosion weight gain of the samples with and without gold markers after different corrosion times

Fig. 5 Morphologies of the rust layers with gold markers of the weathering steel corrupted for 144 h a, 240 h b, 336 h c, without gold markers corrupted for 336 h d

Fig. 6 Morphologies of the rust layers with gold markers of the carbon steel corrupted for 144 h a, 240 h b, 336 h c, without gold markers corrupted for 336 h d

Fig. 7 Quantification of positions of gold markers in rust layers after different corrosion times

Fig. 8 Morphologies of the outer rust surface on the carbon a and weathering b steels without gold markers, and inner rust morphologies of the carbon c, the weathering d steels without gold markers corrupted for 336 h

Fig. 9 Raman spectroscopy in different locations of rust layers with gold markers of the carbon steel a, b and weathering steel c, d corrupted for 144 h a, c, 336 h b, d

Fig. 10 Cross-sectional morphologies and element distribution (line scanning of Cu element and area scanning of other elements) in the rust layers with gold markers a, without gold markers b formed on the weathering steel corrupted for 240 h

Fig. 11 Polarization curves of the rusted weathering steel (WS) and carbon steel (CS) without gold markers after different corrosion times