Local Dissolution of MnS Inclusion and Microstructural Distribution of Absorbed Hydrogen in Carbon Steel

Shinozaki, Jun; Muto, Izumi; Omura, Tomohiko; Numata, Mitsuhiro; Hara, Nobuyoshi

doi:10.1149/1.3611405

Cited by 22 publications

(18 citation statements)

References 46 publications

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“…Those results suggests that the MnS inclusions accelerate the hydrogen absorption into the steel. 4) As seen in Fig. 2(a), no corrosion occurred on the area without the MnS inclusion in 0.1 M NaCl at pH 5.5.…”

Section: Resultsmentioning

confidence: 72%

“…Naoto SATO, 1) Tateru TAKAHASHI, 2) Izumi MUTO, 3) * Tomohiko OMURA, 4) Yu SUGAWARA 3) and Nobuyoshi HARA 3) …”

Section: A Microelectrochemical Approach To Understanding Hydrogen Abunclassified

“…3,4) MnS inclusion is also known as an initiation site for pitting corrosion of steels. A microelectrochemical cell is suitable for understanding the mechanisms of pitting at the inclusions.…”

Section: Introductionmentioning

confidence: 99%

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A Microelectrochemical Approach to Understanding Hydrogen Absorption into Steel during Pitting Corrosion

et al. 2016

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A small Devanathan-Stachurski cell was newly designed to ascertain the hydrogen absorption behavior into re-sulfurized carbon steel during pitting corrosion. In 0.1 M NaCl (pH 5.5), a pit was generated on a small area with MnS inclusions, the current of hydrogen permeation current increased sharply when the solution (capillary) was placed on the steel surface, and the current density returned to the background after the capillary was removed. On the other hand, no pitting was observed on the area without the inclusions, and no permeation current was also observed. The time variation of the permeation current density was measured in 0.1 M NaCl (pH 2.0) and boric-borate buffer with 1 mM NaCl (pH 5.5) solutions. The permeation current from a small area with MnS inclusions was large compared with that of an area without the inclusions. After the experiments, a deep pit was generated on the surface with the inclusions. MnS inclusions were likely to accelerate the steel dissolution and the hydrogen absorption into the steel.

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Section: Resultsmentioning

confidence: 72%

“…Naoto SATO, 1) Tateru TAKAHASHI, 2) Izumi MUTO, 3) * Tomohiko OMURA, 4) Yu SUGAWARA 3) and Nobuyoshi HARA 3) …”

Section: A Microelectrochemical Approach To Understanding Hydrogen Abunclassified

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A Microelectrochemical Approach to Understanding Hydrogen Absorption into Steel during Pitting Corrosion

et al. 2016

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“…Table 1 shows the chemical composition of the iron specimen. Because the sulfur concentration was lower than 0.001 mass%, the formation of sulfide inclusions such as MnS, which was reported to induce the hydrogen absorption, [35][36][37] was inhibited. The pure iron sheet was cut into 25 mm × 25 mm coupons.…”

Section: Specimen and Electrolytementioning

confidence: 99%

Detection of Hydrogen Distribution in Pure Iron Using WO<sub>3</sub> Thin Film

et al. 2018

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The usefulness of a new approach to detecting the distribution of hydrogen absorbed into pure iron utilizing a WO 3 thin film was demonstrated in this study. A WO 3 film with an electrochromic property was formed on the hydrogen detection side of iron sheet by reactive magnetron sputtering. After hydrogen was absorbed into the iron sheet by cathodic polarization on the hydrogen absorption side, the color of the WO 3 film corresponding to the electrode area changed from light blue to dark blue. The WO 3 film was found to reflect the distribution of hydrogen absorbed into the pure iron sheet. No color change occurred on the hydrogen detection side unless a Pd film was inserted between the WO 3 film and the iron specimen. The reflectance of the WO 3 film in the visible region was reduced by hydrogen charging, with a marked reduction in the RGB color values after the start of hydrogen charging. The results of an XPS analysis suggested that the phase transition from WO 3 to H x WO 3 resulted in the color change of the WO 3 film during hydrogen charging. Because of the simplicity of this approach to detecting hydrogen compared to other hydrogen detection methods, it is expected to have various applications.

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“…16,17 The development of this technique has led to significant advances in the understanding of pitting corrosion at non-metallic inclusions in stainless steels over the past twenty years. [18][19][20][21][22][23] Chiba et al developed a microelectrochemical system for in situ high-resolution optical microscopy that can be used for the morphological analysis of pitting at the very beginning of the initiation process. [24][25][26] The micro-electrochemical technique has also been used to investigate other alloy families such as aluminum alloys.…”

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confidence: 99%

Pitting Corrosion Resistance of Martensite of AISI 1045 Steel and the Beneficial Role of Interstitial Carbon

Kadowaki

Muto

Sugawara

et al. 2017

J. Electrochem. Soc.

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The pitting corrosion resistance of AISI 1045 carbon steel with as-quenched, tempered, and low-carbon martensitic microstructures was investigated in boric-borate buffer solutions with and without NaCl. Analysis by micro-scale polarization found that tempering and decarburizing treatments decreased the pitting corrosion resistance of as-quenched martensite. The high corrosion resistance of the as-quenched martensite was likely due to the large amount of interstitial carbon. The pitting corrosion resistances of asquenched martensite, primary ferrite, and pearlite were compared using micro-scale polarization measurements. It was determined that the pitting corrosion resistances of the typical steel structures were ordered as follows: (high) as-quenched martensite > tempered martensite ≈ primary ferrite > pearlite (low). The pitting corrosion resistance of steel was shown to depend on its microstructure. © The Author ( Background.-Quenched and tempered martensitic carbon steels are known for their high strength.1-5 The supersaturation of interstitial carbon and high dislocation density provide martensitic steels with their high strength. 4 However, the toughness of as-quenched martensitic steels is relatively low. To optimize the balance between strength and toughness, the steels are subjected to tempering.1 Tempering involves heating the steels so that the non-equilibrium microstructure can return to near-equilibrium conditions. 4 However, tempering also lowers the dislocation density due to the recovery and recrystallization processes.2-4 It has also been shown that the precipitation of carbides results in a decrease in the amount of interstitial carbon.1 While tempered martensitic carbon steels have excellent mechanical properties, the effect of tempering on the pitting corrosion behavior of carbon steels is unclear. While such steels can be successfully protected from corrosion by coating and/or painting, localized corrosion is readily initiated at cut edges and in coating defect areas in atmospheric environments. To prolong their service life and improve their reliability, it is necessary to elucidate the mechanism of pitting corrosion and assess the pitting corrosion resistance of as-quenched, and quenched and tempered martensitic steels.Fundamental research on the corrosion mechanisms of carbon steels started during the 1950s. Stern found that the addition of carbon (0.11 mass% C) increased the corrosion rate of pure iron in 4% NaCl at pH 1 and 2. 6 This increase in the corrosion rate was explained by the decrease in the hydrogen overvoltage due to the addition of carbon. It is known that iron carbides (Fe 3 C) act as cathodic sites.

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Local Dissolution of MnS Inclusion and Microstructural Distribution of Absorbed Hydrogen in Carbon Steel

Cited by 22 publications

References 46 publications

A Microelectrochemical Approach to Understanding Hydrogen Absorption into Steel during Pitting Corrosion

A Microelectrochemical Approach to Understanding Hydrogen Absorption into Steel during Pitting Corrosion

Detection of Hydrogen Distribution in Pure Iron Using WO<sub>3</sub> Thin Film

Pitting Corrosion Resistance of Martensite of AISI 1045 Steel and the Beneficial Role of Interstitial Carbon

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