On the Mechanism of the Corrosion of Steel in Saline Water

Cleary, H. J.

doi:10.1007/bf03355630

Cited by 6 publications

(8 citation statements)

References 21 publications

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“…Concerning gas phase hydrogen permeation experiments, Huffine and Williams (8) as well as Cochran (9) noted order of magnitude decreases in hydrogen permeation when a film was formed on the stainless steel, Fe-Cr-A1 alloy, or aluminum alloys studied in these tests. Huffine and.Williams ascribed the observed decrease in hydrogen permeation to the slow diffusion of the hydrogen through the oxide, while Cochran ascribed the decrease to the enhanced catalysis of the hydrogen recombination reaction by the surface films.…”

Section: Discussionmentioning

confidence: 97%

The Influence of Strain on Hydrogen Entry and Transport in a High Strength Steel in Sodium Chloride Solution

Scully

Moran

1988

J. Electrochem. Soc.

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The influences of mechanical strain on hydrogen entry and transport are reported for a high strength steel alloy (AISI 4340) under cathodic polarization in aqueous sodium chloride solution. The overall rate of hydrogen permeation and the quantity of hydrogen absorbed are shown to be particularly low in alkaline chloride at low cathodic current densities if the charging surface has been contaminated by slight corrosion. Evidence is presented that illustrates the role of mechanical strain in promoting enhanced hydrogen absorption as a result of film rupture. In addition to the conventional Devanathan-Stachurski method, results from plastic straining of a cylindrical annular Devanathan-Stachurski sample confirm the film rupture concept. Film removal is shown to enhance the overall rate of hydrogen entry by increasing the hydrogen surface coverage and possibly the adsorption-absorption rate constant on the bare surfaces formed. This increases the mobile hydrogen concentration in the metal lattice. The presence of the intact metastable film modifies the kinetics of the hydrogen evolution reaction, lowering the cathodic hydrogen overpotential at a given cathodic current density. This, consequently, is shown to lower hydrogen absorption for a given cathodic current density. The net effect of film rupture is to promote an increase in the hydrogen permeation rate independent of changes in the diffusion coefficient. Additional information indicates that long range enhanced diffusion of hydrogen by dislocation transport is not observed. Further evidence suggests that for sharp cracks, the rate of hydrogen accumulation at a position a distance from the crack tip where the crack initiates is an absorption controlled transport process. These findings provide additional insight on the rate limiting steps controlling the "time dependent" hydrogen assisted failure process of high strength steels in sodium chloride solution.Classical treatments describing the stress corrosion cracking behavior of metals in aqueous media typically incorporate surface film rupture as a necessary stage in the *Electrochemical Society Active Member. **Electrochemical Society Student Member. 1Present address: Sandia National Laboratories, Mechanical Metallurgy Division, Albuquerque, New Mexico 87185. overall process. For example, criteria for stress corrosion cracking susceptibility in metals usually place emphasis on the amount of corrosion occurring after film rupture before repassivation occurs (1-5). Less generally acknowledged is the role of surface film rupture in the environmental hydrogen assisted cracking of high strength steels in aqueous environments where atomic hydrogen is clearly ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 134.117.10.200 Downloaded on 2015-06-24 to IP Experimentol ProceduresMaterials and specimen preparation.--Specirnens were produced from a single heat of AISI 4340 steel (UNS no~ G43400), which had been heat-treated to form tempered marten...

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Section: Discussionmentioning

confidence: 97%

The Influence of Strain on Hydrogen Entry and Transport in a High Strength Steel in Sodium Chloride Solution

Scully

Moran

1988

J. Electrochem. Soc.

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“…The major corrosion product is again FeC03 with some Fe30a present. There also appear to be traces of 6 …”

Section: Experimental Procedures and Resultsmentioning

confidence: 92%

On the corrosion products of orthopedic implants

Cahoon

1973

J. Biomed. Mater. Res.

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“…No attemPt was made to monitor the solutions for changes in pH, ionic strength, or ion concentration. In a report on a long term study of the corrosion of refined iron in ambient temperature, aerated, quiescent 3% NaC1, no long range change in solution pH was observed, with 4 x 10 5M Fe +2 and no Fe +3 being detected in solution after 11 days of free corrosion (8). At the completion of these tests, the corrosion products were easily removed from the sample surface, usually requiring only a moderate flow of tap water to dislodge the relatively thick corrosion product layers, Some spots required minor abrasion but essentially all of the corrosion products were readily removed from each sample.…”

Section: Methodsmentioning

confidence: 97%

“…The authors also wish to express their appreciation to the reviewers for the comments which strengthened the manuscript and for directing us to the specific references of Cleary (8) and Stern (14).…”

Section: Acknowledgmentsmentioning

confidence: 99%

“…The authors are very thankful to both the Columbia Gas System Service Corporation and the Southern California Gas Company for sponsorship of a gas pipeline corrosion project of which this effort was a part. The authors also wish to express their appreciation to the reviewers for the comments which strengthened the manuscript and for directing us to the specific references of Cleary (8) and Stern (14).…”

Section: Acknowledgmentsmentioning

confidence: 99%

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Steel Corrosion Rate Studies Using Sample Area as a Variable

Murray

Moran

1988

J. Electrochem. Soc.

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Corrosion rate data are often considered to be independent of sample size if constant transport conditions can be maintained. The corrosion system of hypoeuteetoid sheet steel samples in aqueous sodium sulfate solution has been studied, and data are presented to show that smaller samples corrode at higher current densities relative to larger samples in the same environment. Corrosion current densities from the varied area samples via weight loss data or electrochemical impedance spectroscopy (EIS) measurements exhibit a 50 mV/decade anodic Tafel slope withouf the need for ohmic drop corrections to the corrosion potential measurements.For at least the particular case of low carbon steel and aqueous solution corrosion, the rate controlling step is 02 diffusion to the cathodic sites and the cathodic sites have been suggested previously by others as being at the periphery of sheet-or flag-style samples. In that the periphery to central area ratio increases as the overall sample area decreases, the anodic current density is increased as the sample areas are reduced. The variable sample areas approach with ohmic free corrosion potentials, should have applicability for corrosion studies in low conductivity electrolytes.The application of the Stern-Geary equation (i) for converting polarization resistance data to corrosion current densities requires some knowledge or assumptions of the anodie and cathodic Tafel slopes for the reaction being studied. Because the polarization resistance measurement is normally conducted over a small polarization range, typically less than • 50 mV and normally within • 20 mV from the corrosion potential, supplementary potentiodynamic scans are necessary to obtain Tafel slope data. This is especially important where Tafel slope values for the system in consideration are not available in the literature. The authors do acknowledge there are other methods for obtaining corrosion rates from polarization resistance values which do not require the use of Tafel slopes, but the interest here is in an alternative method for obtaining anodic Tafel slopes for a corroding metal.In low conductivity electrolytes such as dilute (less than 0.01M) solutions, distilled water or soils, the generation of proper polarization resistance and Tafel slope values is complicated because of the voltage drop correction made necessary by high electrolyte resistance values in most research cell designs.Several investigators (2, 3) have discussed the problems in polarization curves in low conductivity electrolytes which are mainly caused by insufficient IR correction being applied to the voltage measurements. Recently a novel approach involving a "chemical potentiostat" and a rotating disk electrode was reported which eliminates the need for IR voltage drop correction and was shown to be effective for evaluating the polarization behavior of 1020 carbon steel in artificial seawater diluted tenfold (4). In that study, the 02 concentration at the surface of a conventional rotating disk electrode (RDE) was adjusted by the use ...

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On the Mechanism of the Corrosion of Steel in Saline Water

Cited by 6 publications

References 21 publications

The Influence of Strain on Hydrogen Entry and Transport in a High Strength Steel in Sodium Chloride Solution

The Influence of Strain on Hydrogen Entry and Transport in a High Strength Steel in Sodium Chloride Solution

On the corrosion products of orthopedic implants

Steel Corrosion Rate Studies Using Sample Area as a Variable

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