Localized corrosion of carbon steel in marine media: Galvanic coupling and heterogeneity of the corrosion product layer

2016 ◽  
Vol 111 ◽  
pp. 583-595 ◽  
Author(s):  
Ph. Refait ◽  
A.-M. Grolleau ◽  
M. Jeannin ◽  
E. François ◽  
R. Sabot
CORROSION ◽  
10.5006/2505 ◽  
2017 ◽  
Vol 74 (1) ◽  
pp. 37-49 ◽  
Author(s):  
Saba Navabzadeh Esmaeely ◽  
Gheorghe Bota ◽  
Bruce Brown ◽  
Srdjan Nešić

As a result of the electrical conductivity of pyrrhotite, it was hypothesized that its presence in the corrosion product layer on a steel surface could lead to localized corrosion. Mild steel specimens (API 5L X65) were pretreated to form a pyrrhotite layer on the surface using high-temperature sulfidation in oil. The pretreated specimens were then exposed to a range of aqueous CO2 and H2S corrosion environments at 30°C and 60°C. X-ray diffraction data showed that the pyrrhotite layer changed during exposure; in an aqueous CO2 solution it underwent dissolution, while in a mixed CO2/H2S solution it partially transformed to troilite, with some mackinawite formation. Initiation of localized corrosion was observed in both cases. It was concluded that this was the result of a galvanic coupling between the pyrrhotite layer and the steel surface. The intensity of the observed localized corrosion varied with solution conductivity (NaCl concentration); a more conductive solution resulted in higher localized corrosion rates, consistent with the galvanic nature of the attack.


2020 ◽  
Vol 1 (1) ◽  
pp. 198-218
Author(s):  
Philippe Refait ◽  
Anne-Marie Grolleau ◽  
Marc Jeannin ◽  
Celine Rémazeilles ◽  
René Sabot

This article presents a synthesis of recent studies focused on the corrosion product layers forming on carbon steel in natural seawater and the link between the composition of these layers and the corrosion mechanisms. Additional new experimental results are also presented to enlighten some important points. First, the composition and stratification of the layers produced by uniform corrosion are described. A focus is made on the mechanism of formation of the sulfate green rust because this compound is the first solid phase to precipitate from the dissolved species produced by the corrosion of the steel surface. Secondly, localized corrosion processes are discussed. In any case, they involve galvanic couplings between anodic and cathodic zones of the metal surface and are often associated with heterogeneous corrosion product layers. The variations of the composition of these layers with the anodic/cathodic character of the underlying metal surface, and in particular the changes in magnetite content, are thoroughly described and analyzed to enlighten the self-sustaining ability of the process. Finally, corrosion product layers formed on permanently immersed steel surfaces were exposed to air. Their drying and oxidation induced the formation of akaganeite, a common product of marine atmospheric corrosion that was, however, not detected on the steel surface after the permanent immersion period.


2012 ◽  
Vol 61 (12) ◽  
pp. 483-494 ◽  
Author(s):  
Shigenobu Kainuma ◽  
Yuya Yamamoto ◽  
Yoshihiro Itoh ◽  
Hideyuki Hayashi ◽  
Wataru Oshikawa

1994 ◽  
Vol 353 ◽  
Author(s):  
Yoichi Kojima ◽  
Toshinobu Hioki ◽  
Shigeo Tsujikawa

AbstractThe use of bentonite as buffer and carbon steel as overpack material for the geological disposal of nuclear waste is under investigation. To better assess the long term integrity of the carbon steel overpack, a quantitative analysis of the corrosion behavior on the steel surface for time frames beyond that of feasible empirical determination is required. The state n years after disposal, consisting of Carbon Steel / Corrosion Products + Bentonite / Water, was simulated and the corrosion behavior of the carbon steel in this state investigated. The following facts became apparent. Both the corrosion rate and the non-uniformity of it increased with increase in the corrosion product content in the compacted bentonite. When the corrosion product layer was formed between the carbon steel and the bentonite, it ennobled the corrosion potential and increased the corrosion rate.


2015 ◽  
Vol 99 ◽  
pp. 55-65 ◽  
Author(s):  
Isabelle Lanneluc ◽  
Mikael Langumier ◽  
René Sabot ◽  
Marc Jeannin ◽  
Philippe Refait ◽  
...  

2015 ◽  
Vol 182 ◽  
pp. 1019-1028 ◽  
Author(s):  
Alexandre Romaine ◽  
Marc Jeannin ◽  
René Sabot ◽  
Sophia Necib ◽  
Philippe Refait

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3563
Author(s):  
Mathieu Robineau ◽  
Valérie Deydier ◽  
Didier Crusset ◽  
Alexandre Bellefleur ◽  
Delphine Neff ◽  
...  

Carbon steel coupons were buried in a specific low-pH cement grout designed for radioactive waste disposal and left 6 months in anoxic conditions at 80 °C. The corrosion product layers were analyzed by µ-Raman spectroscopy, XRD, and SEM. They proved to be mainly composed of iron sulfides, with magnetite as a minor phase, mixed with components of the grout. Average corrosion rates were estimated by weight loss measurements between 3 and 6 µm yr−1. Corrosion profiles revealed local degradations with a depth up to 10 µm. It is assumed that the heterogeneity of the corrosion product layer, mainly composed of conductive compounds (FeS, Fe3S4, and Fe3O4), promotes the persistence of corrosion cells that may lead to locally aggravated degradations of the metal. New cement grouts, characterized by a slightly higher pH and a lower sulfide concentration, should then be designed for the considered application.


CORROSION ◽  
1977 ◽  
Vol 33 (4) ◽  
pp. 117-128 ◽  
Author(s):  
R. H. HAUSLER

Abstract The linear polarization technique in principle is a convenient and rapid way for determining corrosion rates. In practice, one finds that it is often applied under conditions alien to the assumptions on the basis of which it was derived. This paper will present a series of comparative observations between linear polarization, resistance probe, and weight loss measurements in different systems. The systems studied were: (1) Hydrochloric acid containing acetylenic inhibitors, (2) a two phase system containing hydrocarbon and water saturated with H2S, and (3) tap water containing various inhibitors. An equation will be derived showing the effect of ohmic resistance due to corrosion product buildup. The effect of polarization on the properties of a corrosion product layer will be discussed qualitatively.


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