Localized Corrosion of Iron and Steel

Matsushima, Iwao

doi:10.1002/9780470872864.ch47

Cited by 6 publications

(5 citation statements)

References 5 publications

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“…It can be seen from the metallographic structure analysis that the matrix structure of the flanges on both sides of the hydraulic valve is tempered sorbite. Improper heat treatment process will lead to a large number of Cr rich corrosion-resistant phases ((CrFe) 23C6) on the grain boundary of the material, which will lead to Cr poor regions in the grain boundary of the material [14][15][16][17]. The matrix structure of the valve cover is Tempered Martensite, and there is no Cr rich phase at the grain boundary.…”

Section: Discussionmentioning

confidence: 99%

Analysis on the Corrosion of the Inner Cavity of the Christmas Tree Hydraulic Valve in a Well in Western China

Kuang

Fan

2022

MSF

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In this paper, with the observing corrosion morphology of the inner cavity of the Christmas tree hydraulic valve and detecting the physical and chemical properties of the material (chemical composition, mechanical properties and metallographic structure),It is found that the main reason for the corrosion of the inner cavity of Yidong fan is that in the production process, due to improper heat treatment process, Cr element is accumulated in the metallographic structure of the hydraulic valve matrix, forming a grid like high Cr region, and the grid becomes a low Cr region, under the action of formation water containing CO2, the low Cr area is corroded, and large and deep corrosion pits are formed in the internal cavity of the hydraulic valve.

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Section: Discussionmentioning

confidence: 99%

Analysis on the Corrosion of the Inner Cavity of the Christmas Tree Hydraulic Valve in a Well in Western China

Kuang

Fan

2022

MSF

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“…Inhomogeneities in either composition or environment are well known to induce local cell corrosion in metals. 37 In the case of mechanism (i) in Fig. 8, the H 2 supply to some regions of PtO x is limited due to the presence of thicker ionomer over layers, which exist when there is a non-uniform distribution of the ionomer in the cathode CL.…”

Section: Effect Of Pt Oxidation State On Co 2 Generation In the H 2 -...mentioning

confidence: 98%

Degradation Mechanisms of Carbon Supports under Hydrogen Passivation Startup and Shutdown Process for PEFCs

Yamashita

Itami²,

Takano³

et al. 2017

J. Electrochem. Soc.

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The use of a hydrogen purge for startup and shutdown (H 2 -SU/SD) process of polymer electrolyte fuel cells has been proposed, which suppresses the generation of internal current during the SU/SD, process so-called "reverse current", and the severe carbon oxidation reaction (COR) in the cathode. However it was found that the COR was still caused during this H2-SU/SD process, even though it was less severe than that during the usual SU/SD process, i.e., the anode gas was successively cycled between air and H 2 . In order to clarify the mechanisms of the COR, we investigated (1) the effect of the presence of Pt catalyst, (2) the timing, and (3) the effect of Pt oxidation state. These results indicated that the COR was accelerated by the Pt catalyst in the cathode and was decelerated with increasing cathode potential during the H 2 -SU/SD process. We propose that the COR is caused by a shortage of protons associated with both the reduction of the Pt oxide and the oxygen reduction reaction at the reduced Pt. Polymer electrolyte fuel cells (PEFCs) convert chemical energy directly to electrical energy with low emissions and high energy efficiency and have shown promise to be an eco-friendly power source for fuel cell vehicles (FCVs) and residential co-generation systems. [1][2][3] Nevertheless, PEFCs still have several problems to be solved, such as limited lifetime and reliability and high cost, before large-scale commercialization can be realized. [4][5][6] The minimization of the PEFC cost can be achieved by improving the specific mass activity (MA) of the catalyst for the oxygen reduction reaction (ORR) at the cathode. The conventional cathode catalysts have consisted of Pt nanoparticles dispersed on high surface area carbon black supports (Pt/CB) to maximize the electrochemically active surface area (ECSA) for the ORR. 4 However, as is widely known, Pt/CB cathode catalysts are degraded under PEFC operating conditions such as load change cycles and startup/shutdown (SU/SD) cycles due to a combination of processes, which include ECSA loss due to the agglomeration or dissolution of Pt nanoparticles, [6][7][8][9][10][11][12] and the corrosion of the CB support material. 7,[11][12][13][14][15] During the SU/SD cycles, air and H 2 coexist transiently in the anode until the replacement of the former with the latter (or vice versa) is completed. Reiser et al. showed that this situation causes the cathode potential to climb to more than 1.5 V due to the so-called "reverse current mechanism", which significantly accelerates the degradation of the catalyst due to the oxidation of the CB and the agglomeration or dissolution of the Pt nanoparticles. 12 The latest papers on this topic have been reviewed. 13 Several approaches have been taken to both understand and mitigate the decrease of PEFC performance during operation.13 One approach to mitigate the decrease of the cell performance is to use transition metal oxide support materials, for example, titanium-based oxides [16][17][18][19][20] and tin-based oxides. [21][22][23][...

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“…Further, corrosion may develop under protective coatings (blisters) and perhaps advance rapidly while being difficult to detect, even when protective methods largely are in place [2,7,9]. For these reasons, it is imperative for vessel designers and operators to understand the likely corrosion degradation of ship hulls overall and in particular that at welded zones since these are known to be subject to more severe, preferential, corrosive attack [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

“…It has been demonstrated how severe localised corrosion can be considered in the design to produce a sufficiently safe asset with a more reliable long-term service life [18,24,25]. Also, the underlying causes of severe pitting corrosion of low-carbon mild steels located at or near the weld have been considered many times [11,12,18,[24][25][26][27] and is known to involve some degree of preferential corrosion but some uncertainty remains regarding the specific mechanism involved. Particular studies could be carried out in order to ascertain the level of effect for each of the aforementioned chemical, electrochemical or variation variables; however, herein the focus is long-term unbiased quantitative empirical data collection and interpretation.…”

Section: Introductionmentioning

confidence: 99%

Long-term marine immersion corrosion of welded ABS grade steels

Chaves

Melchers

Sterjovski

et al. 2021

Corrosion Engineering, Science and Technology

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Welded Joints long-term integrity is of particular importance to large vessels, such as frigates or bulk carriers. Downtime due to corrosion concerns can be onerous. Ship classification organisations, such as The American Bureau of Shipping (ABS), standardises processes and product approval programmes for materials manufacturers. High-strength steels are of particular interest due to their high strength to cost ratio for large marine vessel construction. The corrosion performance of such steels has been studied, but data on the specific degradation of such metals when welded and for the welds themselves are scarce. The present paper reports marine immersion corrosion pit depth data for several ABS steel grade weld permutations and exposed to different sites for up to 2.5 years. The implications of the presented results are discussed as well as the possible influence of alloying elements and microstructural differences on the underlying corrosion kinetics.

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Localized Corrosion of Iron and Steel

Cited by 6 publications

References 5 publications

Analysis on the Corrosion of the Inner Cavity of the Christmas Tree Hydraulic Valve in a Well in Western China

Analysis on the Corrosion of the Inner Cavity of the Christmas Tree Hydraulic Valve in a Well in Western China

Degradation Mechanisms of Carbon Supports under Hydrogen Passivation Startup and Shutdown Process for PEFCs

Long-term marine immersion corrosion of welded ABS grade steels

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