On the Role of Cr in the Passivity of Stainless Steel

Brooks, A. R.; Clayton, Clive R.; Doss, Kantesh; Lu, Yawei

doi:10.1149/1.2108450

Cited by 299 publications

(149 citation statements)

References 10 publications

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“…[28][29][30][31][32] Three main depassivation models have been proposed in the presence of aggressive anions. 33 The adsorption model 34,35 is associated with the absorption of aggressive anions on the passive film.…”

Section: Discussionmentioning

confidence: 99%

Effect of Hydrogen Sulfide Ions on the Passive Behavior of Type 316L Stainless Steel

Lee

Kitagawa

Nakanishi

et al. 2015

J. Electrochem. Soc.

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The effect of hydrogen sulfide ions (HS − ) on the passivity of type 316L stainless steel was investigated in pH 8.4 boric acid-borate buffer solution. Galvanostatic polarization of a silver microelectrode covered with Ag 2 S generated both OH − and HS − above the stainless steel surface. During potentiostatic polarization of the stainless steel, the passivity-maintaining current density increased with increase in the concentration of HS − in the vicinity of the surface. The impedance of the stainless steel at a constant frequency decreased during polarization in the presence of HS − , while it was sustained after dilution of HS − . Electrochemical impedance spectroscopy (EIS), Mott-Schottky (M-S) analysis and scanning electrochemical microscopy (SECM) showed that a defective and n-type semiconductive passive film was formed in the solution containing HS − . Auger electron spectroscopy (AES) revealed that metal cations and oxygen vacancies in the passive film on the stainless steel increased when it was formed in a HS − -containing solution. The series of changes in passive film properties is thought to be due to adsorption of HS -on the film surface during the polarization. Corrosion resistance of stainless steel is thought to be dependent on degradation of the passive film, which is important to understand a precursor process involved in localized corrosion such as pitting corrosion and to estimate the long-term performance of the material. Inclusions of sulfides such as manganese sulfide (MnS) are known to provide pitting corrosion sites of stainless steel. [1][2][3] As for the roles of MnS in pitting corrosion, it has been generally agreed that electrochemical and/or chemical reactions of MnS release S species (SO 4 2-, HSO 3 -, S 2 O 3 2-, S and S 2-). The released S species change the composition of the local solution contiguous to the inclusion and lead to a decrease of pH near the micro-area. The decrease in pH and the presence of aggressive S species result in transition of the passive surface to a transpassive state, causing exposure of the substrate to the solution, which is the initiation of pitting corrosion.1-5 Eklund suggested that the dissolution of MnS gives rise to acidification of the solution by producing sulfate ions:Solution acidification is also caused by production of thiosulfate ions:In both cases, elemental sulfur is finally formed. On the other hand, Wraglén proposed that elemental sulfur formed by MnS dissolution leads to further acidification as follows: Many possible explanations for the detrimental effects of various S species causing initiation and/or propagation of pitting corrosion on stainless steel have been presented. Most previous studies have focused on the overall processes, including destabilization of the passive film, removal of the film, and initiation and/or propagation of pits. Since degradation of the passive film is the initial process of pitting corrosion, it is important to contemplate the change in passivity or passive film until depassivation. When stainless st...

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Section: Discussionmentioning

confidence: 99%

Effect of Hydrogen Sulfide Ions on the Passive Behavior of Type 316L Stainless Steel

Lee

Kitagawa

Nakanishi

et al. 2015

J. Electrochem. Soc.

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“…Brooks et al 32 reported the incorporation of sulfate and chromate in the oxide film grown on stainless steel during anodic oxidation in sulfuric acid, and concluded that the incorporation of these anions impeded the ingress of chloride ions into the film. As a consequence of the incorporation of these anions, a coulombic barrier against chloride adsorption is formed, which leads to a high resistance to stable pit formation.…”

Section: Resultsmentioning

confidence: 99%

“…33 In the present work, the anodic oxidation of stainless steel with 1 wt.% H 2 SO 4 might have occurred similarly to the literature. 32,33 In an ethanol/water mixture, the maximum amount of NaCl that can be solubilized is close to 2.0 wt.%, 34 hence in the electrochemical measurements 1.70 wt.% NaCl was added to ensure complete salt dissolution (Table 2). No H 2 SO 4 was added since 1 wt.% of acid decreases the salt solubility in an ethanol/water/NaCl mixture.…”

Section: Resultsmentioning

confidence: 99%

Influence of ethanol, acidity and chloride concentration on the corrosion resistance of AISI 316L stainless steel

Ferreira¹,

Noce²,

Fugivara³

et al. 2013

J. Braz. Chem. Soc.

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A influência do etanol, ácido sulfúrico e cloreto na resistência à corrosão do aço 316L foi investigada por meio de curvas de polarização e medidas de espectroscopia de impedância eletroquímica. No intervalo estudado, o potencial de corrosão do aço foi independente das concentrações de H 2 SO 4 e NaCl em solução aquosa. Por outro lado, em solução contendo 65% (m/m) de etanol e 35% (m/m) de água, os potencias de corrosão foram mais altos do que os observados em solução aquosa. Além disso, o potencial de corrosão do aço foi alterado pela adição de H 2 SO 4 e NaCl em solução. Em soluções com e sem etanol, mais 0,35% (m/m) de NaCl, a presença de 1% (m/m) de H 2 SO 4 inibiu o aparecimento de corrosão puntiforme.The influence of ethanol, sulfuric acid and chloride on the corrosion resistance of 316L stainless steel was investigated by means of polarization curves and electrochemical impedance spectroscopy measurements. Over the studied range, the steel corrosion potential was independent of H 2 SO 4 and NaCl concentrations in aqueous solution. On the other hand, in solution containing 65 wt.% ethanol and 35 wt.% water, the corrosion potentials were higher than those obtained in aqueous solution. Besides, the steel corrosion potential was affected by the addition of H 2 SO 4 and NaCl in solution. In solutions with and without ethanol, plus 0.35 wt.% NaCl, the presence of 1 wt.% H 2 SO 4 inhibited the appearance of pitting corrosion.

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“…27,28 The degradation of a passive film has been discussed using three major models concerning the role of Cl − . (i) The adsorption model 29,30 is associated with the adsorption of Cl − on the passive film surface.…”

Section: Discussionmentioning

confidence: 99%

“…Alloying with Cr forms non-crystalline Cr 2 O 3 on stainless steel by a direct reaction of Cr with H 2 O and improves the resistance to localized corrosion. 2 Alloying with Mo enhances the protectiveness of a passive film to Cl − by increasing oxygen affinity of the stainless steel. 3 Alloying with W inhibits localized corrosion by dissolved WO 4 2− from the passive film to an aqueous electrolyte or by forming insoluble WO 3 , which enhances the stability of the passive film.…”

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confidence: 99%

Initiation of Localized Corrosion of Ferritic Stainless Steels by Using the Liquid-Phase Ion Gun Technique

Lee

Kawano²,

Ishii³

et al. 2016

J. Electrochem. Soc.

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The initiation of localized corrosion of types 430 and 443J1 ferritic stainless steels was evaluated in 0.15 mol dm −3 Na 2 SO 4 solution. A liquid-phase ion gun (LPIG), a silver microelectrode covered with a silver chloride layer, was cathodically polarized to generate Cl − in the vicinity of the stainless steel polarized at 0.4 V SSE . Contact of the stainless steel surface with the Cl − -concentrated environment by the LPIG operation induced a rapid increase in anodic current flow through the stainless steel electrode after the induction period t d and consumption of the cathodic electric charge Q d by the LPIG microelectrode. Numerical modeling using the LPIG microelectrode current for t d gave a critical Cl − concentration [Cl − ] d needed for the initiation of localized corrosion. These parameters obtained by LPIG tests showed that type 443J1 stainless steel was superior to type 430 stainless steel in localized corrosion resistance. AES depth profiling of the stainless steel surfaces after the LPIG operation revealed enrichment of Cl in the outermost oxide film as well as decreased film thickness. The mechanism of degradation of the stainless steel surface due to contact with the Cl − -concentrated solution is discussed. The adsorption of Cl − on the oxide surface is thought to be a trigger of the oxide degradation. Stainless steel, an Fe-based material with a minimum of 11 wt% Cr content, has corrosion resistance, which is attributed to the formation of Cr-and/or Fe-oxide films, so-called passive films, on the surface. The resistance is related to the chemical composition of the film, which is strongly dependent on the chemical composition of the substrate. The pitting resistance equivalent (PRE) number (= wt% Cr + 3.3 (wt% Mo + 0.5 wt% W) + 16 wt% N) has been used to determine the localized corrosion resistance of stainless steel.1 The larger the PRE number of stainless steel is, the greater is the resistance of the stainless steel to localized corrosion. The PRE number is related to the contribution of elements to the resistance of a passive film on stainless steel. Alloying with Cr forms non-crystalline Cr 2 O 3 on stainless steel by a direct reaction of Cr with H 2 O and improves the resistance to localized corrosion.2 Alloying with Mo enhances the protectiveness of a passive film to Cl − by increasing oxygen affinity of the stainless steel.3 Alloying with W inhibits localized corrosion by dissolved WO 4 2− from the passive film to an aqueous electrolyte or by forming insoluble WO 3 , which enhances the stability of the passive film.4 Alloying with N decreases local pH by decreasing acidity in pits due to NH 4 + formation and promotes repassivation. 5 For ferritic stainless steel, however, the effect of N is not quite satisfied and usage of the simple PRE number (= wt% Cr + 3.3 wt% Mo) is proposed.

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On the Role of Cr in the Passivity of Stainless Steel

Cited by 299 publications

References 10 publications

Effect of Hydrogen Sulfide Ions on the Passive Behavior of Type 316L Stainless Steel

Effect of Hydrogen Sulfide Ions on the Passive Behavior of Type 316L Stainless Steel

Influence of ethanol, acidity and chloride concentration on the corrosion resistance of AISI 316L stainless steel

Initiation of Localized Corrosion of Ferritic Stainless Steels by Using the Liquid-Phase Ion Gun Technique

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