Electrochemical properties of Fe and steel

Cleary, H. J.; Greene, N. D.

doi:10.1016/s0010-938x(69)80062-4

Cited by 50 publications

(19 citation statements)

References 19 publications

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“…The corrosion current density value of the deaerated system following the extrapolation of the Tafel slopes is 18.5 μA cm -2 . This value is consistent with those reported in the literature by both polarization curves (Tafel extrapolation) and weight loss methods [22].…”

Section: Effect Of Aeration On the Polarization Curves Of Carbon Steesupporting

confidence: 93%

Effect of aeration on Tafelian behavior of the carbon steel corrosion in acid sulfate medium

Sepúlveda

Vásquez

Gutiérrez

2017

Rev. Fac. Ing. Univ. Antioquia

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This study presents a corrosion analysis of carbon steel by electrochemical polarization tests on a rotating disk electrode at several aeration and hydrodynamic conditions in solution 0.2 mol L -1 K 2 SO 4 at pH 3. The reactions involved in the dissolution of the steel are analyzed by studying the Tafel regions of the polarization curves, confirming that the dissolved oxygen plays a predominant role in the corrosion of the metal. The corrosion rate was 35 times higher in natural aeration conditions than in the deaerated medium. Under natural aeration conditions, it is not possible to make a simple analysis of the corrosion of the steel from the extrapolation of the Tafel slopes since such slopes were not well defined due to the formation of rust in the anodic region and the influence of mass transport in the cathodic region. At cathodic polarization potentials and with natural aeration, there is an increase in polarization currents with respect to the deaerated system and the oxygen reduction reaction is controlled by the mass transport. Under deaerated conditions and at intermediate polarization potentials, there is a change in the dissolution mechanism of the steel. At high overpotential, the rate of dissolution of the steel tends to be equal in both systems, aerated and deaerated because the corrosion of the metal is controlled by the diffusion of species through corrosion products film. RESUMEN:Este estudio presenta un análisis de corrosión del acero al carbono mediante pruebas de polarización electroquímica en un electrodo de disco rotatorio en varias condiciones de aireación e hidrodinámicas en solución 0,2 mol L -1 K 2 SO 4 a pH 3. Las reacciones implicadas en la disolución del acero se analizan estudiando Tafel regiones de las curvas de polarización, lo que confirma que el oxígeno disuelto desempeña un papel predominante en la corrosión del metal. La velocidad de corrosión fue 35 veces mayor en condiciones de aireación natural que en el medio desaireado. Bajo condiciones de aireación natural no es posible realizar un análisis simple de la corrosión del acero a partir de la extrapolación de las pendientes de Tafel, ya que tales pendientes no están bien definidas debido a la formación de óxido en la región anódica y a la influencia del transporte de masa en la región catódica. En los potenciales de polarización catódica y con aireación natural, hay un aumento en las corrientes de polarización con respecto al sistema desaireado y la reacción de reducción de oxígeno es controlada por el transporte de masa. Bajo condiciones desaireadas y en potenciales de polarización intermedios, hay un cambio en el mecanismo de disolución del acero. A altos sobrepotenciales, la velocidad de disolución del acero tiende a ser igual en ambos sistemas (aireado y desaireado), porque la corrosión del metal es controlada por la difusión de especies a través de la película de productos de corrosión.

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Section: Effect Of Aeration On the Polarization Curves Of Carbon Steesupporting

confidence: 93%

Effect of aeration on Tafelian behavior of the carbon steel corrosion in acid sulfate medium

Sepúlveda

Vásquez

Gutiérrez

2017

Rev. Fac. Ing. Univ. Antioquia

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“…[13][14][15][16][17][18][19][20] Staicopolus clarified that hydrogen over-voltage on cementite is relatively low, and the cathodic reaction on cementite accelerates the anodic dissolution of ferrite.…”

Section: 10mentioning

confidence: 99%

“…12 Despite the lower dissolution rate of cementite, cementite seems to act as the cathodic site, and this accelerates the anodic dissolution of ferrite. [13][14][15][16][17][18][19][20] Staicopolus clarified that hydrogen over-voltage on cementite is relatively low, and the cathodic reaction on cementite accelerates the anodic dissolution of ferrite. 14 Hao et al revealed that ferrite dissolves more rapidly than cementite in chloride solutions, and the dissolution rate of ferrite increased with the amount of cementite at the open circuit potential (OCP) in NaCl solutions.…”

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confidence: 99%

Real-Time Microelectrochemical Observations of Very Early Stage Pitting on Ferrite-Pearlite Steel in Chloride Solutions

Kadowaki

Muto

Sugawara

et al. 2017

J. Electrochem. Soc.

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The initiation site and morphology during the early stage of pitting on AISI 1045 carbon steel that has a microstructure of primary ferrite and pearlite were investigated in boric-borate buffer solutions with and without NaCl at pH 8.0. The pits initiated by micro-scale polarization were in the pearlite only and not in primary ferrite. In situ real-time observations during the micro-scale polarization of pearlite in a boric-borate buffer solution with 100 mM NaCl indicated that the pits were polygonal or rod-like in shape. In addition, it was found that the pit growth direction was the same as that of the pearlite lamellae that consisted of ferrite and cementite. Field-emission electron probe micro analysis detected segregated points of sulfur in the ferrite lamellae. On the basis of their etching behavior in 3% nital, the corrosion resistance of the cementite was estimated to be higher than that of the ferrite lamellar structure. Thus, pits readily initiated in the ferrite lamellae and proceeded along the ferrite lamellae. Ferrite-pearlite steel is widely used in the production of bars, plates, steel wires, etc.1-3 because of its high strength, ductility, toughness, wear resistance, and low cost.3-5 Pearlite has a lamellar structure that consists of ferrite and cementite (Fe 3 C) phases. A fine pearlite structure improves the mechanical properties of steels in terms of strength and ductility.6-8 While ferrite-pearlite steels exhibit excellent mechanical properties, their pitting corrosion resistance is relatively low. It is widely believed that the boundaries between the different phases act as initiation sites for localized corrosion in chloride environments. 9,10When ferrite-pearlite steel that does not undergo any surface treatment is exposed to chloride environments, the steel readily suffers from pitting corrosion. Although the steel is successfully protected from corrosion by coating and/or painting, to prolong their service life and improve their reliability, it is necessary to elucidate the initiation mechanism of pitting on ferrite-pearlite steel.The pitting corrosion process involves two stages: initiation and propagation.11 In chloride environments, pitting is initiated by a breakdown of the passive film on steel during a local active dissolution process that exposes the bare steel surface to the environment. This film-free dissolution involves the hydrolysis reaction of metal cations and results in acidification. Chloride ions migrate into the pit to maintain electrical neutrality, and the simultaneous accumulation of chloride ions combined with the high level of acidification accelerates the active dissolution inside the pit. There have been many reports about the propagation stage of pitting corrosion in ferrite-pearlite steels. A comparison of the active dissolution rates and the electrochemical properties of ferrite and cementite have been widely discussed. It is commonly believed that cementite has a lower dissolution rate than ferrite. Yumoto et al. synthesized stoichiometric Fe 3 C films with...

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“…In anoxic environments at near-neutral pH values (i.e., [5][6][7][8], the primary cathodic reaction is water reduction,…”

Section: Discussion Of Resultsmentioning

confidence: 99%

Corrosion Studies of A216 Grade WCA Steel in Hydrothermal Magnesium-Containing Brines

Haberman

Frydrych

1987

MRS Proc.

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The U.S. Department of Energy's Salt Repository Project (SRP) is investigating the general corrosion resistance of cast mild steel as a candidate material for waste package containers.Evaluation of this material is being performed at the Pacific Northwest Laboratory in environments simulating expected repository conditions.General corrosion studies of mild steel (ASTM A216 grade WCA) in the as-cast and normalized conditions were conducted in hydrothermal halitesaturated (saturated at ambient temperature) brine environments simulating a "dissolution" and an "inclusion" brine.Corrosion tests were also performed in brines similar to the inclusion brine but containing magnesium concentrations ranging from 1000 to 30,000 ppm to investigate the effect of magnesium on the corrosion behavior.Corrosion rates of the cast mild steel were found to increase with increasing temperature and with increasing magnesium concentration. Some possible mechanisms that explain the observed behavior are presented.

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Electrochemical properties of Fe and steel

Cited by 50 publications

References 19 publications

Effect of aeration on Tafelian behavior of the carbon steel corrosion in acid sulfate medium

Effect of aeration on Tafelian behavior of the carbon steel corrosion in acid sulfate medium

Real-Time Microelectrochemical Observations of Very Early Stage Pitting on Ferrite-Pearlite Steel in Chloride Solutions

Corrosion Studies of A216 Grade WCA Steel in Hydrothermal Magnesium-Containing Brines

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