Yoon-Seok Choi, F. Farelas, L. Paolinelli, S. Nešić, A. Z. Abas, A. Nor, M. Suhor
The effect of H2S on the aqueous corrosion behavior of mild steel was evaluated at high pressure and high temperature (HPHT) conditions at a partial pressure of CO2 of 12 MPa and a temperature of 160°C. The corrosion rate of steel samples was determined by electrochemical and weight loss measurements. The surface and cross-sectional morphology and the composition of the corrosion product layers were analyzed by using surface analytical techniques (SEM, EDS, and XRD). Results showed that the corrosion rate decreased with time and no significant difference was observed in the presence of 1000 and 2000 ppm of H2S at HPHT CO2 conditions. Surface and cross-sectional analyses revealed that the corrosion process was governed by the formation of FeCO3 regardless of the presence of H2S. Furthermore, the corrosion behavior of mild steel in these conditions did not depend significantly on flow velocity.
{"title":"Effect of H2S on CO2 Corrosion of Mild Steel in High Temperature Supercritical CO2 Condition","authors":"Yoon-Seok Choi, F. Farelas, L. Paolinelli, S. Nešić, A. Z. Abas, A. Nor, M. Suhor","doi":"10.5006/4355","DOIUrl":"https://doi.org/10.5006/4355","url":null,"abstract":"The effect of H2S on the aqueous corrosion behavior of mild steel was evaluated at high pressure and high temperature (HPHT) conditions at a partial pressure of CO2 of 12 MPa and a temperature of 160°C. The corrosion rate of steel samples was determined by electrochemical and weight loss measurements. The surface and cross-sectional morphology and the composition of the corrosion product layers were analyzed by using surface analytical techniques (SEM, EDS, and XRD). Results showed that the corrosion rate decreased with time and no significant difference was observed in the presence of 1000 and 2000 ppm of H2S at HPHT CO2 conditions. Surface and cross-sectional analyses revealed that the corrosion process was governed by the formation of FeCO3 regardless of the presence of H2S. Furthermore, the corrosion behavior of mild steel in these conditions did not depend significantly on flow velocity.","PeriodicalId":10717,"journal":{"name":"Corrosion","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45792671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Istemi F. Ozkan, N. Ebrahimi, Jieying Zhang, Dario Markovinovic, H. Shirkhani
Protection against atmospheric corrosion of steel infrastructure and its components requires assessment and prediction of corrosion rates using quantitative and reliable modelling of the environmental parameters that impact the corrosion process. This has become even more critical in the context of climate change. This study demonstrates the feasibility of using ISO Dose-response Functions (DRFs) to classify atmospheric corrosivity in Canada to improve the current qualitative approach to the corrosion design of carbon steel infrastructure, especially bridges. The DRF predictions for first-year corrosion rates were first confirmed using a set of historical field data collected from different locations across Canada. Further examination has revealed a dramatic change in atmospheric corrosivity at many locations in Canada since the last systematic effort in field data collection in the 1950-60s. it is believed that this was caused by significant drop in in sulfur dioxide levels in the atmosphere. A projection of future corrosivity in various Canadian cities with differing climates was also presented by considering the projected impacts of climate change on the temperature and relative humidity. This study has shown a promising precursor for the development of a corrosivity map in Canada to better guide the corrosion design and protection of steel infrastructure. Furthermore, this study has demonstrated an acute need to understand the current chloride deposition conditions of steel bridges, including the increased local exposure of roadways to corrosivity by the use of de-icing salts.
{"title":"Atmospheric Corrosion of Steel Infrastructure in Canada under Climate Change","authors":"Istemi F. Ozkan, N. Ebrahimi, Jieying Zhang, Dario Markovinovic, H. Shirkhani","doi":"10.5006/4296","DOIUrl":"https://doi.org/10.5006/4296","url":null,"abstract":"Protection against atmospheric corrosion of steel infrastructure and its components requires assessment and prediction of corrosion rates using quantitative and reliable modelling of the environmental parameters that impact the corrosion process. This has become even more critical in the context of climate change. This study demonstrates the feasibility of using ISO Dose-response Functions (DRFs) to classify atmospheric corrosivity in Canada to improve the current qualitative approach to the corrosion design of carbon steel infrastructure, especially bridges. The DRF predictions for first-year corrosion rates were first confirmed using a set of historical field data collected from different locations across Canada. Further examination has revealed a dramatic change in atmospheric corrosivity at many locations in Canada since the last systematic effort in field data collection in the 1950-60s. it is believed that this was caused by significant drop in in sulfur dioxide levels in the atmosphere. A projection of future corrosivity in various Canadian cities with differing climates was also presented by considering the projected impacts of climate change on the temperature and relative humidity. This study has shown a promising precursor for the development of a corrosivity map in Canada to better guide the corrosion design and protection of steel infrastructure. Furthermore, this study has demonstrated an acute need to understand the current chloride deposition conditions of steel bridges, including the increased local exposure of roadways to corrosivity by the use of de-icing salts.","PeriodicalId":10717,"journal":{"name":"Corrosion","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47011168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Seyedeh Sajedeh Mousavi, M. Seyedi, M. Moayed, M. Mirjalili, I. Taji, Seyed Hossein Hosseini Mortazavi
In the present investigation, the potential effect of Nitrate ions' inhibition on pitting corrosion of 17-4 precipitation hardening stainless steel in different Chloride and Nitrate concentrations was investigated using potentiostatic and potentiodynamic examinations. Furthermore, metastable pitting was examined in depth to clarify Nitrate inhibition. The results demonstrate that adding Nitrate as an inhibitor to the Chloride containing solution decreases the metastable pit peak current, stability products, and pit radius. In contrast, no significant difference between metastable pit lifetime was observed in the presence and absence of Nitrate in the Chloride solution. It was also shown that introducing 17-4PH stainless steel to the high potential resulted in the repassivation of the surface, even if the Nitrate/Chloride concentration ratio was less than the critical value needed for Nitrate inhibition. Overall, Nitrate ions have an inhibition effect in the Chloride solution. Especially at very high potential, whether the Nitrate concentration was less than the critical value or not, Nitrate forces the surface to get repassivated.
{"title":"High potential inhibition of the 17-4 PH stainless steel in the presence of Nitrate and evolution of metastable pitting","authors":"Seyedeh Sajedeh Mousavi, M. Seyedi, M. Moayed, M. Mirjalili, I. Taji, Seyed Hossein Hosseini Mortazavi","doi":"10.5006/4281","DOIUrl":"https://doi.org/10.5006/4281","url":null,"abstract":"In the present investigation, the potential effect of Nitrate ions' inhibition on pitting corrosion of 17-4 precipitation hardening stainless steel in different Chloride and Nitrate concentrations was investigated using potentiostatic and potentiodynamic examinations. Furthermore, metastable pitting was examined in depth to clarify Nitrate inhibition. The results demonstrate that adding Nitrate as an inhibitor to the Chloride containing solution decreases the metastable pit peak current, stability products, and pit radius. In contrast, no significant difference between metastable pit lifetime was observed in the presence and absence of Nitrate in the Chloride solution. It was also shown that introducing 17-4PH stainless steel to the high potential resulted in the repassivation of the surface, even if the Nitrate/Chloride concentration ratio was less than the critical value needed for Nitrate inhibition. Overall, Nitrate ions have an inhibition effect in the Chloride solution. Especially at very high potential, whether the Nitrate concentration was less than the critical value or not, Nitrate forces the surface to get repassivated.","PeriodicalId":10717,"journal":{"name":"Corrosion","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44199681","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Z. Harris, Lara Ojha, J. Srinivasan, R. Kelly, J. Burns
The influence of crack-initiating feature on the environment-assisted cracking (EAC) behavior of sensitized AA5456-H116 exposed to marine environments is assessed via fracture mechanics-based testing. Specimens that contained either a traditional fatigue precrack or purposefully introduced intergranular corrosion fissures were immersed in 0.6 M NaCl and polarized to select electrochemical potentials while held at a constant force. The measured crack length versus time relationships from these experiments reveal that the two specimen geometries yield similar crack growth rates at -900 mVSCE and after the onset of accelerated crack propagation at -800 mVSCE. However, precorroded specimens exhibit significantly shorter times to failure than the precracked specimens at -800 mVSCE due to increased crack growth rates at the start of the experiment. The mechanical, environmental, and material factors that could contribute to the initially increased EAC susceptibility of the precorroded specimens are identified using a generalized model for EAC. Analysis of these possible causal factors suggests that the increased susceptibility is due to a residual, initially more deleterious crack chemistry at the occluded corrosion fissure tip from the aggressive galvanostatic polarizations used to accelerate fissure growth. The implications of these results on the efficacy of traditional fracture mechanics-based methods for quantifying EAC susceptibility are discussed.
{"title":"The effect of crack-initiating feature on the environment-assisted cracking behavior of sensitized AA5456-H116 in marine environments","authors":"Z. Harris, Lara Ojha, J. Srinivasan, R. Kelly, J. Burns","doi":"10.5006/4260","DOIUrl":"https://doi.org/10.5006/4260","url":null,"abstract":"The influence of crack-initiating feature on the environment-assisted cracking (EAC) behavior of sensitized AA5456-H116 exposed to marine environments is assessed via fracture mechanics-based testing. Specimens that contained either a traditional fatigue precrack or purposefully introduced intergranular corrosion fissures were immersed in 0.6 M NaCl and polarized to select electrochemical potentials while held at a constant force. The measured crack length versus time relationships from these experiments reveal that the two specimen geometries yield similar crack growth rates at -900 mV<sub>SCE</sub> and after the onset of accelerated crack propagation at -800 mV<sub>SCE</sub>. However, precorroded specimens exhibit significantly shorter times to failure than the precracked specimens at -800 mV<sub>SCE</sub> due to increased crack growth rates at the start of the experiment. The mechanical, environmental, and material factors that could contribute to the initially increased EAC susceptibility of the precorroded specimens are identified using a generalized model for EAC. Analysis of these possible causal factors suggests that the increased susceptibility is due to a residual, initially more deleterious crack chemistry at the occluded corrosion fissure tip from the aggressive galvanostatic polarizations used to accelerate fissure growth. The implications of these results on the efficacy of traditional fracture mechanics-based methods for quantifying EAC susceptibility are discussed.","PeriodicalId":10717,"journal":{"name":"Corrosion","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47267998","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Burnett, R. Euesden, C. Grant, M. Curd, A. Garner, Y. Aboura, Yichao Yao, Z. Barrett, C. Engel, N. Holroyd, P. Prangnell
Recent experience has shown that new-generation 7xxx-series alloys, that have a high Zn content and Zn/Mg ratios, have a greater susceptibility to Hydrogen-Environmental Induced Cracking (H-EIC) on exposure to humid air than more established materials, like AA7050. In this study we report new evidence of the EIC initiation and crack growth behaviour of two new generation alloys, AA7085 and AA7449, when exposed to 50% humidity. In-situ, time lapse, optical imaging over large areas has enabled the exact initiation sites to be identified and investigated with high-resolution fractographic studies, providing evidence for the sequence and mechanisms of initiation and transition to sustained cracking. A consistent behaviour was observed for both alloys. This has revealed that only minute-scale corrosion reactions, involving highly localised condensed water, are necessary for initiation. The preferred initiation sites are metal ligaments between surface-connected pore-clusters and/or intermetallic particles that are subjected to high stress concentration and undergo mechanical damage with associated higher levels of local oxidation. The growth of short proto-cracks from these sites is a distinct stage and displays intermittent arrest markings evidenced by localised corrosion. In contrast, in humid air environments, long cracks in these alloys exhibited relatively constant, higher velocity, with extremely limited corrosion commensurate with oxidation of a free surface in this environment resulting in ~5 nm oxide layer.
{"title":"Mechanisms of environmentally induced crack initiation in humid air in new generation Al-Zn-Mg-Cu alloys","authors":"T. Burnett, R. Euesden, C. Grant, M. Curd, A. Garner, Y. Aboura, Yichao Yao, Z. Barrett, C. Engel, N. Holroyd, P. Prangnell","doi":"10.5006/4336","DOIUrl":"https://doi.org/10.5006/4336","url":null,"abstract":"Recent experience has shown that new-generation 7xxx-series alloys, that have a high Zn content and Zn/Mg ratios, have a greater susceptibility to Hydrogen-Environmental Induced Cracking (H-EIC) on exposure to humid air than more established materials, like AA7050. In this study we report new evidence of the EIC initiation and crack growth behaviour of two new generation alloys, AA7085 and AA7449, when exposed to 50% humidity. In-situ, time lapse, optical imaging over large areas has enabled the exact initiation sites to be identified and investigated with high-resolution fractographic studies, providing evidence for the sequence and mechanisms of initiation and transition to sustained cracking. A consistent behaviour was observed for both alloys. This has revealed that only minute-scale corrosion reactions, involving highly localised condensed water, are necessary for initiation. The preferred initiation sites are metal ligaments between surface-connected pore-clusters and/or intermetallic particles that are subjected to high stress concentration and undergo mechanical damage with associated higher levels of local oxidation. The growth of short proto-cracks from these sites is a distinct stage and displays intermittent arrest markings evidenced by localised corrosion. In contrast, in humid air environments, long cracks in these alloys exhibited relatively constant, higher velocity, with extremely limited corrosion commensurate with oxidation of a free surface in this environment resulting in ~5 nm oxide layer.","PeriodicalId":10717,"journal":{"name":"Corrosion","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41299101","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The corrosion risk for stainless steel components is not the same in all seawaters, with more failures generally reported in tropical seas. In this study, the influence of biofilm on electrochemical behavior and corrosion resistance of passive films of high-grade alloys was studied in different seawaters, including temperate seawater (France-Brest, North Atlantic Ocean), tropical seawater (Malaysia-Kelatan, Meridional China Sea), and intermediate conditions in terms of temperature (Brazil-Arraial do Cabo, South Atlantic Ocean). The stabilized open-circuit potentials and the polarization behavior of high-grade stainless steels were measured as function of temperature in all the tested field marine stations, providing quantified data and direct comparison on the biofilm-enhanced corrosion risks. Significant differences were measured in tropical and in temperate seawaters in heated conditions above 30°C. In parallel to the monitoring of biofilm-induced depolarization, crevice corrosion of 8 high grades passive alloys was studied with the use of crevice formers specifically developed for tube geometries. Duplex, super-duplex, hyper-duplex and 6Mo stainless steels tubes have been evaluated together with Ni-based alloys. The corrosion results are discussed regarding the monitored biofilm-induced depolarization measured in the different test conditions.
不锈钢部件在所有海水中的腐蚀风险并不相同，热带海域通常报告的故障较多。在本研究中，研究了生物膜对高档合金钝化膜电化学行为和耐蚀性的影响，包括温带海水(法国-布列斯特，北大西洋)，热带海水(马来西亚-克拉丹，中国经向海域)，以及温度方面的中间条件(巴西- arraial do Cabo，南大西洋)。在所有测试的现场海洋站中，测量了稳定开路电位和高级不锈钢的极化行为作为温度的函数，为生物膜增强腐蚀风险提供了量化数据和直接比较。在30°C以上的加热条件下，在热带和温带海水中测量到显著差异。在监测生物膜引起的去极化的同时，研究人员还利用专门为管道几何形状开发的裂缝形成器研究了8种高等级被动合金的裂缝腐蚀。双相、超双相、超双相和6Mo不锈钢管与镍基合金一起进行了评价。讨论了在不同试验条件下监测的生物膜诱导去极化腐蚀结果。
{"title":"Crevice Corrosion of High-Grade Stainless Steels in Seawater: A Comparison Between Temperate and Tropical Locations","authors":"N. Larché, C. Leballeur, E. Diler, D. Thierry","doi":"10.5006/4370","DOIUrl":"https://doi.org/10.5006/4370","url":null,"abstract":"The corrosion risk for stainless steel components is not the same in all seawaters, with more failures generally reported in tropical seas. In this study, the influence of biofilm on electrochemical behavior and corrosion resistance of passive films of high-grade alloys was studied in different seawaters, including temperate seawater (France-Brest, North Atlantic Ocean), tropical seawater (Malaysia-Kelatan, Meridional China Sea), and intermediate conditions in terms of temperature (Brazil-Arraial do Cabo, South Atlantic Ocean). The stabilized open-circuit potentials and the polarization behavior of high-grade stainless steels were measured as function of temperature in all the tested field marine stations, providing quantified data and direct comparison on the biofilm-enhanced corrosion risks. Significant differences were measured in tropical and in temperate seawaters in heated conditions above 30°C. In parallel to the monitoring of biofilm-induced depolarization, crevice corrosion of 8 high grades passive alloys was studied with the use of crevice formers specifically developed for tube geometries. Duplex, super-duplex, hyper-duplex and 6Mo stainless steels tubes have been evaluated together with Ni-based alloys. The corrosion results are discussed regarding the monitored biofilm-induced depolarization measured in the different test conditions.","PeriodicalId":10717,"journal":{"name":"Corrosion","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42040769","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
N. Holroyd, T. Burnett, J. Lewandowski, G. Scamans
The initiation of environment-induced cracking (EIC) in aluminum alloys typically dominates the total life during both service-life for structural applications and for smooth tensile test specimens subjected to conventional standard EIC testing. Experience and literature published over the past 70 years have been reviewed, and in some cases re-interpreted. The authors propose we are now well-positioned to use today’s advanced experimental techniques to properly elucidate the EIC initiation phenomena for aluminum alloys. EIC initiation typically involves at least three stages: incubation, intergranular cracking that may ‘arrest’ and a transition to propagating cracks where the mechanical driving force exceeds a threshold, KIEIC, and a surface feature has become a crack potentially propagating at mm/yr. Alloy developers, product designers and commercial users now need quantitative EIC initiation and growth data from accelerated laboratory testing that is directly relatable to actual surface conditions and the expected service conditions.
{"title":"Environment-Induced Crack Initiation in Aluminum Alloys – Experimental studies since the 1950’s and future opportunities","authors":"N. Holroyd, T. Burnett, J. Lewandowski, G. Scamans","doi":"10.5006/4320","DOIUrl":"https://doi.org/10.5006/4320","url":null,"abstract":"The initiation of environment-induced cracking (EIC) in aluminum alloys typically dominates the total life during both service-life for structural applications and for smooth tensile test specimens subjected to conventional standard EIC testing. Experience and literature published over the past 70 years have been reviewed, and in some cases re-interpreted. The authors propose we are now well-positioned to use today’s advanced experimental techniques to properly elucidate the EIC initiation phenomena for aluminum alloys. EIC initiation typically involves at least three stages: incubation, intergranular cracking that may ‘arrest’ and a transition to propagating cracks where the mechanical driving force exceeds a threshold, KIEIC, and a surface feature has become a crack potentially propagating at mm/yr. Alloy developers, product designers and commercial users now need quantitative EIC initiation and growth data from accelerated laboratory testing that is directly relatable to actual surface conditions and the expected service conditions.","PeriodicalId":10717,"journal":{"name":"Corrosion","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44849899","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Special Issue on Corrosion of Reinforced Concrete Structures (in Memoriam of Prof. Jose Antonio Gonzalez), Part II","authors":"D. Bastidas, N. Birbilis","doi":"10.5006/4394","DOIUrl":"https://doi.org/10.5006/4394","url":null,"abstract":"","PeriodicalId":10717,"journal":{"name":"Corrosion","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42736598","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Steel infrastructure in contact with particulate media is at risk of failure due to pitting corrosion. For reliability analysis it is important to understand the progression of pit depth with time and the associated extreme value statistics. An analysis was conducted on an extensive data set of pit depth observations, made on mild steel coupons buried in different particulate media and immersed in natural Pacific Ocean seawater. It showed that the trends for the deepest pits with time were consistent with the bimodal model, and that pitting was deepest under seawater and increased with particle size when under particulate media. Gumbel plots of the data showed that the deepest pits plotted as a straight line, indicating a good fit. The plots also showed small, regular deviations from this straight-line, and these permitted interpretations for pit depths developing in incremental steps. These step sizes were largest for surfaces under seawater and increased with increasing particle size under particulate media. These findings allowed for new conceptual models for the process of pit depth growth under rust and particulate media. They also allow for new insights into metastable pitting for steels. Opportunities for further research are also presented.
{"title":"Pitting corrosion of mild steel in long-term contact with particulate media in seawater","authors":"R. Petersen, R. Melchers","doi":"10.5006/4322","DOIUrl":"https://doi.org/10.5006/4322","url":null,"abstract":"Steel infrastructure in contact with particulate media is at risk of failure due to pitting corrosion. For reliability analysis it is important to understand the progression of pit depth with time and the associated extreme value statistics. An analysis was conducted on an extensive data set of pit depth observations, made on mild steel coupons buried in different particulate media and immersed in natural Pacific Ocean seawater. It showed that the trends for the deepest pits with time were consistent with the bimodal model, and that pitting was deepest under seawater and increased with particle size when under particulate media. Gumbel plots of the data showed that the deepest pits plotted as a straight line, indicating a good fit. The plots also showed small, regular deviations from this straight-line, and these permitted interpretations for pit depths developing in incremental steps. These step sizes were largest for surfaces under seawater and increased with increasing particle size under particulate media. These findings allowed for new conceptual models for the process of pit depth growth under rust and particulate media. They also allow for new insights into metastable pitting for steels. Opportunities for further research are also presented.","PeriodicalId":10717,"journal":{"name":"Corrosion","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43854668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
N. Larché, C. Leballeur, Sandra Le Manchet, Wenle He
Chlorination is widely used in seawater systems to avoid fouling. Free chlorine is a strong oxidizing agent that prevents the biofilm formation on immersed surfaces, when used above a certain content. However, the presence of residual chlorine associated with the high chloride content in seawater, significantly increases the risk of localized corrosion for most stainless steels. In the present study, a module initially developed to quantify the formation of electroactive biofilms on stainless steels has been used to assess the corrosivity of chlorinated seawater. Both the electrochemical potential and the cathodic current were measured on super-duplex stainless steel as a function of residual chlorine levels and seawater temperatures. In parallel, long term localized corrosion tests have been performed in simulated environments to assess the environmental limits for safe use of high-grade stainless steels in chlorinated seawater. It includes crevice corrosion exposure tests using adapted ISO18070:2015 crevice formers and internal tube pitting corrosion exposure tests in model tube heat exchangers simulating heat flux from 35°C to 170°C. The synergetic effect of residual chlorine content and temperature on the risk of localized corrosion has been quantified. Corrosion resistance properties are correlated to the electrochemical monitoring data, and the environmental limits of selected stainless steels have been established for duplex stainless steel UNS S32205, super-duplex stainless steel UNS S32750, hyper-duplex stainless steel UNS S32707 and the high-grade austenitic stainless steel UNS S31266.
{"title":"Localized Corrosion of High-Grade Stainless Steels in Chlorinated Seawater","authors":"N. Larché, C. Leballeur, Sandra Le Manchet, Wenle He","doi":"10.5006/4348","DOIUrl":"https://doi.org/10.5006/4348","url":null,"abstract":"Chlorination is widely used in seawater systems to avoid fouling. Free chlorine is a strong oxidizing agent that prevents the biofilm formation on immersed surfaces, when used above a certain content. However, the presence of residual chlorine associated with the high chloride content in seawater, significantly increases the risk of localized corrosion for most stainless steels. In the present study, a module initially developed to quantify the formation of electroactive biofilms on stainless steels has been used to assess the corrosivity of chlorinated seawater. Both the electrochemical potential and the cathodic current were measured on super-duplex stainless steel as a function of residual chlorine levels and seawater temperatures. In parallel, long term localized corrosion tests have been performed in simulated environments to assess the environmental limits for safe use of high-grade stainless steels in chlorinated seawater. It includes crevice corrosion exposure tests using adapted ISO18070:2015 crevice formers and internal tube pitting corrosion exposure tests in model tube heat exchangers simulating heat flux from 35°C to 170°C. The synergetic effect of residual chlorine content and temperature on the risk of localized corrosion has been quantified. Corrosion resistance properties are correlated to the electrochemical monitoring data, and the environmental limits of selected stainless steels have been established for duplex stainless steel UNS S32205, super-duplex stainless steel UNS S32750, hyper-duplex stainless steel UNS S32707 and the high-grade austenitic stainless steel UNS S31266.","PeriodicalId":10717,"journal":{"name":"Corrosion","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47622082","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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