Surface Roughness and the Metastable Pitting of Stainless Steel in Chloride Solutions

Burstein, G.T.; Pistorius, Petrus Christiaan

doi:10.5006/1.3293603

Cited by 214 publications

(136 citation statements)

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“…On the rougher surfaces, the grooves trap the corrosion products, which results in more pitting [13]. In a smooth surface the frequency of metastable pitting is reduced because of the number of available metastable pit sites is reduced and consequently the corrosion rate is decreased [17]. Also, in a smooth surfaces weak points are less " activate " than on rough surfaces and the formation of stable passive film on smooth surfaces is more likely to occur.…”

Section: Discussionmentioning

confidence: 99%

The effect of different surface topographies on the corrosion behaviour of nickel

Toloei

Stoilov

Northwood

2013

WIT Transactions on Engineering Sciences

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The electrochemical and corrosion behaviour of a surface is extremely complicated and depends on various chemical, physical and mechanical factors. In this study the effect of different surface roughnesses on the corrosion resistance of nickel in 0.5 M sulphuric acid was investigated. Open circuit potential, corrosion current density, polarization resistance and corrosion rate were measured for surfaces polished with different grits (120, 240, 400, 600 and 1200) of silicon carbide papers. The surface roughness was measured using a profilometry method both before and after corrosion testing. SEM images were taken and compared for all of the samples before and after corrosion tests. The results showed that surface roughness and surface morphology can considerably change corrosion and corrosion rate. A higher corrosion resistance is obtained for surfaces with lower roughnesses. Finally, the results were compared with specimens where a specific surface patterning was obtained using a laser ablation method.

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Section: Discussionmentioning

confidence: 99%

The effect of different surface topographies on the corrosion behaviour of nickel

Toloei

Stoilov

Northwood

2013

WIT Transactions on Engineering Sciences

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“…The value for I pit /r pit is simply 6.5 times the one-dimensional xi value due to geometry. Numeric values for the critical value of xi have been established for a range of metals and alloys, 4,[29][30][31] and the concept has been validated in its ability to predict the transition of pits from metastable to stable. 3,4 The pit stability criterion can be understood as representing a threshold current required to be generated by a pit of a given radius to produce sufficient metallic cations for hydrolysis to maintain a sufficiently low pH against the action of diffusional dilution.…”

Section: -27mentioning

confidence: 99%

Computational Modeling of Bounding Conditions for Pit Size on Stainless Steel in Atmospheric Environments

Chen¹,

Kelly²

2010

J. Electrochem. Soc.

118

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This paper presents analytic expressions for calculating bounding conditions for pitting under atmospheric conditions. These expressions allow the prediction of the maximum pit size that can develop under known atmospheric conditions by considering the factors that can control the inherent galvanic coupling between a circular pit under a thin electrolyte layer surrounded by a concentric cathodic area. Expressions are developed for the maximum cathodic current and the minimum anodic current required for pit stability. An analytic expression for the maximum cathodic current that the surrounding area can supply to the pit is developed and validated by comparison to calculations using the finite element method. The effects of the controlling environmental parameters ͑deposition density and relative humidity͒ on the cathode bounding parameters are explored, as is the effect of the size of the pit. The analytical expression for the maximum cathodic current is then coupled to the Galvele pit stability product to estimate the maximum pit size that could develop for a given set of environmental conditions. Those results are then compared to data available in the literature from outdoor exposures of stainless steels for up to 26 years. Corrosion resistant alloys such as stainless steels rely on their passive films for the maintenance of their characteristically low dissolution rates. Under most conditions, this film provides outstanding protection against uniform corrosion. Corrosion resistant alloys do suffer from localized corrosion when discrete locations lose this protection. It is generally accepted that such local loss of protection occurs spontaneously in the presence of aggressive ions, although in most cases, the alloy surface is able to repassivate the failed oxide film, thereby limiting the damage. These metastable events have been the subject of many investigations 1-4 to understand the underlying processes that lead to the more damaging, stable pits. Models have been constructed that relate the frequency of metastable pitting to the likelihood of stable pitting. [1][2][3]5 Such models are of use for predicting the likelihood of corrosion damage occurring in service if the material and exposure conditions are known, although they generally do not predict the extent of damage, although there are exceptions.5 In many applications of corrosion resistant alloys, only stable pitting creates sufficient damage to be of concern. Others have fit exposure data to develop empirical power laws for pit propagationwhere d pit is the maximum pit depth measured, t is the exposure time, and A and n are constants that depend on the material and environment. While useful for the environments and materials used in the exposure testing, such approaches are difficult to extend to other material/environment systems as the underlying factors controlling pit size are usually not clearly delineated.In applications where the intended service life is very long, it may be considered unwise to extrapolate empirical power laws to times orde...

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“…It was sometimes difficult to initiate pitting for 316 L samples, given their relatively high pitting resistance and small diameter which results in a lower density of surface inhomogenities that are precursors to pit nucleation. 52 This difficulty in initiating pitting, particularly on sequence cycling, may present an experimental challenge, especially when the technique is applied towards studying the effects of pitting inhibitors 50,53,54 or highly corrosion-resistant materials. 7,33,55 Ohmic compensation of the linear polarization scan would permit Tafel analysis in the potential range in which dissolution is no longer limited by diffusion under a salt film (i.e., where the salt film is not present).…”

Section: Limitations Of Proposed Technique-mentioning

confidence: 99%

A High-Throughput Artificial Pit Technique to Measure Kinetic Parameters for Pitting Stability

Srinivasan

McGrath

Kelly

2015

J. Electrochem. Soc.

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A cyclic electrochemical technique was developed which enables rapid, high-throughput extraction of important kinetic parameters from one-dimensional artificial pit (lead-in-pencil) electrode experiments. This approach combined methods for pit initiation and propagation with kinetic measurements at a series of pit depths to measure two key kinetic parameters -the pit stability product under a salt film (i·x) saltfilm and the repassivation potential E rp -from a single experiment. The entire sequence was cycled and automated for efficient, high-volume data collection and analysis for the case of stainless steel in neutral chloride solution. This method offered advantages in the extraction and interpretation of data from a wide range of pit depths, permitting statistical analysis of the kinetic parameters required for determining the critical conditions for pit stability and repassivation.

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Surface Roughness and the Metastable Pitting of Stainless Steel in Chloride Solutions

Cited by 214 publications

References 0 publications

The effect of different surface topographies on the corrosion behaviour of nickel

The effect of different surface topographies on the corrosion behaviour of nickel

Computational Modeling of Bounding Conditions for Pit Size on Stainless Steel in Atmospheric Environments

A High-Throughput Artificial Pit Technique to Measure Kinetic Parameters for Pitting Stability

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