Weathering Steel in Industrial-Marine-Urban Environment: Field Study

Abstract

In the present field study, we report the exposure of weathering steels in the industrial-marine-urban environment at Ennore, located near the east coast of India for 3 years. The Corrosion products viz., iron oxyhydroxides and oxides present in the rust layers were characterized using ATR-FTIR, XRD studies and quantified using TGA analysis. The specific surface area of the rust particles formed during the corrosion process were determined using N 2 adsorption isotherm studies. The morphology of the corrosion products were elucidated using SEM. ATR-FTIR and XRD studies showed that the corrosion products formed on the skyward surfaces were highly more crystalline than those on the the earthward surfaces. TGA showed that the iron oxyhydroxides were major corrosion products. N 2 adsorption-desorption studies confirmed the formation of compact inner rust layers with high specific surface area (SA). SEM analysis revealed that the skyward surface was smooth and compact while the earthward surface were cracked and porous. SEM images confirmed the formation of characteristic morphological structures such as sandy crystal (lepidocrocite), needle-like (goethite), cotton ball (goethite) and cigar shaped (akaganeite) structures. Further, it revealed the formation of goethite on the skyward surface as a major constituent phase in the rust layer, which was influenced by the presence of SO 2 content in the environment.

Comparative Study on the Corrosion Inhibitive Effect of 2-Mecraptobenzothiazole and Na2HPO4 on Industrial Conveying API 5L X42 Pipeline Steel

“…As mentioned before, these agglomerations are attributed to lepidocrocite, maghemite, and precursors of green rust (as magnetite) created in NaCl solution [15] and are not yet removed, due to the prolonged exposure process [3,63] (Figure 8a,b). Furthermore, miscellaneous laminas accreting in thorny three-dimensional structures [3] resemble hematite and goethite (sharper, more acicular) α phases with small aggregates of more globular lepidocrocite (or/and maghemite), which are precipitated during the submission together with tertiary phosphates [46,60,64] ( Figure 8c,d). As mentioned before, cracks with diameters of a few micrometers are considered to be due to the drying stage ( Figure 8b).…”

“…The surface SEM images of mild steel immersed in 3.5 wt % NaCl for 96 h in the presence of MBT (Steel-NaCl-MBT) are demonstrated in Figure 9. Characteristic laminar and eroded rosettes of green rust, lepidocrocite, and hematite consist of the three-dimensional structures (Figure 9a), while the ruptured inner layer (Figure 9c) indicates the inhibitor (MBT) interaction with the steel surface [29,64,65]. The EDS analysis of Figure 9b reveals elevated oxygen value concentrations compared to that of the Steel-blank sample due to the creation of the previously mentioned iron oxides along with the presence of sulfur that is assigned to the adsorbed organic MBT ( Table 3).…”

Influence of Fe3O4 particle size on corrosion of carbon steel under wet/dry cyclic conditions

“…The diffusion mobility of oxygen molecules also decreases due to interaction with water molecules that are strongly influenced by the Fe 3 O 4 surface. As a result, the reaction surface (pore) of fine Fe 3…”

“…The characteristics of these components are closely related to the structure and function of the rust layer. In particular, they are related to the compactness and ion selectivity of the rust layer, and thus strongly influence the corrosion resistance of the steel …”

“…In particular, they are related to the compactness and ion selectivity of the rust layer, and thus strongly influence the corrosion resistance of the steel. [1][2][3][4][5][6][7][8][9] The characteristics of rust components are known to be altered by alloy elements eluted from the steel. [10][11][12][13][14][15][16][17][18][19][20][21][22][23] For instance, a protective rust layer consisting of an X-rayamorphous substance is generated on a steel surface due to the influence of alloying elements.…”