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Showing papers in "Corrosion in 2007"


Journal ArticleDOI
TL;DR: The effects of irradiation on stress corrosion cracking occur through changes in the water chemistry and in the alloy microstructure as discussed by the authors, which can be expressed as a form of radiolysis.
Abstract: The effects of irradiation on stress corrosion cracking occur through changes in the water chemistry and in the alloy microstructure. Considerable reactor experience has shown that a high-temperature water environment and a radiation field combine to produce irradiation-assisted stress corrosion cracking (IASCC) in core components of light water reactors. The principal effect of irradiation on water chemistry is through radiolysis, which results in an increase in the corrosion potential through the formation of radiolytic species consisting of radicals and molecules that can be oxidizing or reducing. In addition, profound effects of irradiation on the microchemistry and alloy microstructure create numerous pathways for IGSCC to occur. Radiation-induced segregation, the formation of a dislocation loop microstructure, irradiation hardening, and irradiation creep all occur simultaneously in space and time. Unfolding these various effects to determine the primary factors governing the observed effect...

98 citations


Journal ArticleDOI
TL;DR: In this article, the corrosion behavior of mild steel in the presence of acetic acid (CH3COOH) and carbon dioxide (CO2) has been investigated using electrochemical techniques and weight-loss measurements.
Abstract: The corrosion behavior of mild steel in the presence of acetic acid (CH3COOH) and carbon dioxide (CO2) has been investigated using electrochemical techniques and weight-loss measurements. Electrochemical measurements have shown that the presence of acetic acid affects predominantly the cathodic reaction. The acetic acid effect is much more pronounced at elevated temperatures when catastrophic corrosion rates may be encountered at high concentrations. The undissociated form of acetic acid, present at lower pH, is responsible for the increases seen in the corrosion rate.

96 citations


Journal ArticleDOI
TL;DR: In this article, the rate of stress corrosion cracking (SCC) was measured for nonsensitized, cold-worked Type 316 (UNS S31600) and Type 304 (Uns S30400) in both hydrogenated pressurized water reactor (PWR) and PWR.
Abstract: The rate of stress corrosion cracking (SCC) was measured for nonsensitized, cold-worked Type 316 (UNS S31600) and Type 304 (UNS S30400) in both hydrogenated pressurized water reactor (PWR)...

84 citations



Journal ArticleDOI
J. Smith1, Zack Qin, Fraser King, L. Werme1, D.W. Shoesmith1 
TL;DR: The mechanism and kinetics of Cu corrosion in anoxic aqueous chloride solutions containing sulfide (10−3 mol/L) have been investigated electrochemically and under natural corrosion conditi... as discussed by the authors.
Abstract: The mechanism and kinetics of Cu corrosion in anoxic aqueous chloride solutions containing sulfide (10−3 mol/L) have been investigated electrochemically and under natural corrosion conditi...

80 citations



Journal ArticleDOI
TL;DR: In this article, the corrosion behavior of two commercial, nickel-based Inconel alloys, 625 and 718, has been evaluated after exposure to supercritical water (SCW) at 500°C and 600°C for periods of up to 1,026 h.
Abstract: The corrosion behavior of two commercial, nickel-based Inconel alloys, 625 (UNS N06625) and 718 (UNS N07718), has been evaluated after exposure to supercritical water (SCW) at 500°C and 600°C for periods of up to 1,026 h. The 500°C tests were performed in deaerated and 2 ppm dissolved oxygen SCW, while the 600°C tests were performed only in deaerated SCW. Evaluation of corrosion has been performed using weight-change measurements, scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS), x-ray diffraction (XRD), Auger electron spectroscopy (AES), and a surface profilometer. Surface oxidation and pitting were the principal corrosion mechanisms for both alloys at 500°C; however, intergranular corrosion was also observed in the Alloy 625 sample exposed to deaerated oxygen SCW at 600°C for prolonged durations. Oxidation was more dominant compared to pitting for the samples exposed to higher oxygen content or higher temperature SCW. The oxide thickness was lower for the higher ch...

71 citations


Journal ArticleDOI
Z. Zhang1, D. Hinkson1, Marc Singer1, Hongbin Wang1, Srdjan Nesic1 
TL;DR: In this paper, a mechanistic model is developed to predict the general corrosion rate at the top of a gas pipeline using the three main processes involved in the top-of-the-line corrosion phenomena: the dropwise condensation, the behavior of the chemistry in condensed water, and the corrosion at the steel surface.
Abstract: A mechanistic model is developed to predict the general cor- rosion rate at the top of a gas pipeline. This model covers the three main processes involved in the top-of-the-line corrosion (TLC) phenomena: the dropwise condensation, the behavior of the chemistry in the condensed water, and the corrosion at the steel surface. The dropwise condensation process is mod- eled based on the heat and mass-transfer theory and is used to predict the condensation rate. The breakdown of species concentrations in the droplet is established through the main thermodynamic and chemical equilibrium. The general corro- sion rate is predicted using the kinetics of the electrochemical reactions at the steel surface and by taking into account the mass-transfer and chemical reactions occurring inside the droplet. Finally, the accuracy of the predictions of the model is evaluated by comparison with experimental data.

61 citations


Journal ArticleDOI
TL;DR: In this article, the interpretation of impedance data for cylindrical and irregularly-shaped noncylindrical pores, and the transmission lines most frequently used in corrosion studies are discussed.
Abstract: The transmission lines most frequently used in corrosion studies are discussed. The interpretation of impedance data for cylindrical pores, and irregularly-shaped noncylindrical pores, fre...

60 citations


Journal ArticleDOI
TL;DR: Spinel coatings of Cu-Mn-O and Co-mns-O were obtained on UNS S43000 stainless steel by oxidation of electroplated metal coatings as mentioned in this paper.
Abstract: Spinel coatings of Cu-Mn-O and Co-Mn-O were obtained on UNS S43000 stainless steel by oxidation of electroplated metal coatings. It was demonstrated that the coatings can effectively provi...

57 citations


Journal ArticleDOI
TL;DR: In this paper, the effects of hydrocarbons on corrosion have been predicted based on the type of emulsion (i.e., water-in-oil or oil-inwater), wettability (oil-wet, waterwet or mixedwet), and corrosiveness of brine in the presence of hydro-carbons.
Abstract: Under certain conditions, hydrocarbons may alter the internal corrosion conditions of oil and gas pipelines. In this paper, the effects of hydrocarbons on corrosion have been predicted based on the type of emulsion (i.e., water-in-oil or oil-in-water), wettability (oil-wet, water-wet, or mixed-wet), and corrosiveness of brine in the presence of hydrocarbons. Laboratory methodologies have been developed to determine wettability and to identify the type of emulsion under pipeline operating conditions. Using these methodologies, the wettability and the type of emulsion have been determined for 14 hydrocarbons obtained from operating pipelines. The corrosiveness of brine in the presence of hydrocarbons also has been determined using rotating cage experiments.

Journal ArticleDOI
TL;DR: The chloride concentration in concrete required to compromise reinforcing steel passivity and initiate active corrosion, [Cl−]th, is an important service life determinant for reinforced co... as mentioned in this paper.
Abstract: The chloride concentration in concrete required to compromise reinforcing steel passivity and initiate active corrosion, [Cl−]th, is an important service life determinant for reinforced co...

Journal ArticleDOI
TL;DR: In this paper, the use of multi-coupled electrode arrays in various corrosion applications is discussed with the main goal of advancing the understanding of various corrosion phenomena both close-packed and far-spaced electrode configurations are discussed.
Abstract: The use of multi-coupled electrode arrays in various corrosion applications is discussed with the main goal of advancing the understanding of various corrosion phenomena Both close-packed and far-spaced electrode configurations are discussed Far-spaced electrode arrays are optimized for high-throughput experiments capable of elucidating the effects of various variables on corrosion properties For instance, the effects of a statistical distribution of flaws on corrosion properties can be examined Close-packed arrays enable unprecedented spatial and temporal information on the behavior of local anodes and cathodes Interactions between corrosion sites can trigger or inhibit corrosion phenomena and affect corrosion damage evolution

Journal Article
TL;DR: In this paper, a top-of-line corrosion prediction model for wet gas pipelines is presented. But the model assumes that the top of line corrosion is limited by the amount of iron which can be dissolved in the water condensing in the pipeline.
Abstract: Condensation of water in wet gas pipelines can cause top of line corrosion when the water condensation rate is high or acetic acid is present in the gas. For CO2 dominated systems the top of line corrosion is limited by the amount of iron which can be dissolved in the water condensing in the top of the pipeline. When acetic acid is present in the gas in addition to CO2 the solubility of iron in the condensed water is increased, and this increases the top of line corrosion. Fluid flow model simulations have shown that different approaches for pipeline insulation can give widely different water condensation rates. Application of a top of line corrosion prediction model has demonstrated that such variations in water condensation rates can have a much larger effect on the top of line corrosion rate than variation in the CO2 partial pressure.

Journal ArticleDOI
TL;DR: In this paper, field data for the corrosion of structural steel in the tidal and near-shore marine atmospheric zones taken from a variety of sources are reexamined and then interpreted in the light of a...
Abstract: Field data for the corrosion of structural steel in the tidal and near-shore marine atmospheric zones taken from a variety of sources are reexamined and then interpreted in the light of a ...

Journal ArticleDOI
TL;DR: In this article, the effect of the fluoride (F−) over the crevice corrosion induced by chloride ions is still not well established, but Alloy 22 is a Ni-Cr-Mo-W alloy highly resistant to localized corrosion.
Abstract: Alloy 22 (UNS N06022) is a Ni-Cr-Mo-W alloy highly resistant to localized corrosion. Alloy 22 may be susceptible to crevice corrosion in pure chloride (Cl−) solutions under aggressive environmental conditions. The effect of the fluoride (F−) over the crevice corrosion induced by chloride ions is still not well established. The objective of the present work was to explore the crevice corrosion resistance of this alloy to different mixtures of fluorides and chlorides. Cyclic potentiodynamic polarization (CPP) tests were conducted in deaerated aqueous solutions of pure halide ions and in different mixtures of chloride and fluoride at 90°C and pH 6. The range of chloride concentration [Cl−] was 0.001 M ≤ [Cl−] ≤ 10 M and the range of fluoride to chloride molar concentration ratio [F−]/[Cl−] was 0.1 ≤ [F−]/[Cl−] ≤ 10. Results show that Alloy 22 was susceptible to crevice corrosion in all the pure chloride solutions but was not in the pure fluoride solutions. Fluoride ions showed an inhibitor behavior ...

Journal ArticleDOI
TL;DR: In this article, the morphology and kinetics of localized corrosion of aluminum alloy (AA)2024-T3 (UNS A92024) at the open-circuit potential were investigated by in situ atomic force microscopy (AFM) s.
Abstract: The morphology and kinetics of the localized corrosion of aluminum alloy (AA)2024-T3 (UNS A92024) at the open-circuit potential were investigated by in situ atomic force microscopy (AFM) s...

Journal ArticleDOI
TL;DR: In this paper, the authors address the many modes of environmentally assisted cracking that have been identified while evaluating strength limitations of low-alloys steels and corrosion-resistant alloys with the intention of capturing the significant ideas and unresolved questions within the alloy development and testing framework.
Abstract: An evolution has occurred with low-alloy steels and corrosion-resistant alloys to address corrosive oil and gas production needs. This evolution occurred because of the extensive laboratory and on-site testing and the significant potential for economic and fitness-for-purpose gains. These alloys have evolved with primarily higher yield strengths than those used in the petrochemical industry. For many metals, a strength restriction arises if hydrogen sulfide (H2S) is present. The current uses of these alloys have resulted in pushing the limits of the use of low-alloy steels and the less heavily alloyed corrosion-resistant alloys. This paper addresses the many modes of environmentally assisted cracking that have been identified while evaluating strength limitations of low-alloys steels and corrosion-resistant alloys with the intention of capturing the significant ideas and unresolved questions within the alloy development and testing framework.

Journal ArticleDOI
TL;DR: In situ identification of the films formed on alloys of Fe-13Cr-10Ni, Fe-5Cr- 10Ni, and Type 304 (UNS S30400) stainless steel immersed in high-temperature (288°C), high-purity water was per...
Abstract: In situ identification of the films formed on alloys of Fe-13Cr-10Ni, Fe-5Cr-10Ni, and Type 304 (UNS S30400) stainless steel immersed in high-temperature (288°C), high-purity water was per...

Journal ArticleDOI
TL;DR: In this article, a crack growth rate test on a compact tension specimen of Type 316 (UNS S31600) stainless steel was conducted in pure water under both subcritical and supercritical conditions.
Abstract: A crack growth rate test on a compact tension specimen of Type 316 (UNS S31600) stainless steel was conducted in pure water under both subcritical and supercritical conditions. The crack g...

Journal ArticleDOI
TL;DR: In this paper, seven kinds of corrosion tests were carried out on thirteen kinds of nickel-based alloys in subcritical and supercritical water containing 0.01 mol/kg sulfuric acid (H2SO4) and 800 ppm oxygen (O2) using a Ni-44Cr-1Mo autoclave.
Abstract: Seven kinds of corrosion tests were carried out on thirteen kinds of nickel-based alloys in subcritical and supercritical water containing 0.01 mol/kg sulfuric acid (H2SO4) and 800 ppm oxygen (O2) using a Ni-44Cr-1Mo autoclave. The obtained corrosion rates were significantly lower than the previous experiments performed under the same conditions using a titanium autoclave. A compact oxide scale was found on the specimens tested in the Ni-44Cr-1Mo autoclave. The chromium-rich oxide layer would originate from the autoclave material and provide a protective function against corrosion. The corrosion retardation phenomenon has been explained by dependencies of chromia (Cr2O3) solubility on the phase state of water and temperature.

Journal Article
TL;DR: In this paper, the scale removal tests were used to investigate the scale breakdown of the scale under flowing conditions, and the results showed that the scale can be partially removed by mechanical stresses, chemical dissolution or by both mechanisms acting simultaneously.
Abstract: Localized CO2 corrosion on mild steel is always associated with the partial breakdown of a protective corrosion product scale such as iron carbonate. The scale breakdown can happen for a variety of reasons many of them related to fluid flow. It is hypothesized that following the scale damage, a galvanic effect is established between the scale covered surface (cathode) and the scale free surface (anode) leading to propagation of localized attack. To test this hypothesis, in a series of laboratory experiments, an iron carbonate scale is formed by a repeatable process. Subsequently, in the so called “scale removal tests” the breakdown of the scale under flowing conditions is investigated. The results show that the iron carbonate scale can be partially removed by mechanical stresses, chemical dissolution or by both mechanisms acting simultaneously. In another series of experiments, a newly developed “artificial pit” test is used to investigate the propagation of localized CO2 corrosion via a galvanic coupling. The artificial pit is composed of a large cathode covered by protective iron carbonate scale, and a small bare steel anode. The two are electrically isolated and connected by a zero resistance ammeter to measure the galvanic current during the tests. The results have confirmed the galvanic mechanism for localized CO2 corrosion propagation. It has been demonstrated that pits will propagate only if the conditions are just right: the solution is neither undersaturated nor heavily supersaturated with respect to iron carbonate, i.e. they are in the so called “grey zone”.

Journal ArticleDOI
TL;DR: In this article, the authors identify the factors that cause a very small number of the NpHSCC cracks in pipelines, and then they determine the factors responsible for these cracks.
Abstract: One of the outstanding problems in understanding near-neutral pH stress corrosion cracking (NNpHSCC) in pipelines is the determination of the factors that cause a very small number of the ...

Journal ArticleDOI
TL;DR: In this article, the authors examined three bridges in the Florida panhandle with ∼40 years in aggressive marine service and one newly constructed marine bridge utilizing concrete cylinder piles and found that the older marine bridges showed minimal corrosion distress despite a low design concrete cover over the steel hoop reinforcement (2 cm to 4 cm).
Abstract: Posttensioned concrete cylinder piles produced using a centrifugally cast, vibrated, roller-compacted process have shown promising corrosion resistance in marine environments. Three bridges in the Florida panhandle with ∼40 years in aggressive marine service and one newly constructed marine bridge utilizing concrete cylinder piles were examined. The older marine bridges showed minimal corrosion distress despite a low design concrete cover over the steel hoop reinforcement (2 cm to 4 cm). Typical concrete distress included minor rust staining (not necessarily indicating corrosion of reinforcement steel) and thin longitudinal cracks (likely caused by mechanical damage from pile driving). Chloride ion diffusivity was low, in the order of 1 × 10−9 cm2/s. Other measured parameters such as concrete resistivity, porosity, and water absorption indicate low permeability. Chloride analysis of cracked and uncracked concrete cores from the older bridges in this study did not show pronounced preferential chlo...

Journal ArticleDOI
TL;DR: In this article, an online corrosion rate monitor based on electrical resistance measurement as [O2] and flow velocity were used to determine the effects of water chemistry parameters on flow-assisted corrosion.
Abstract: Flow-assisted corrosion (FAC) often has caused serious damage to carbon steel piping in nuclear power plants. As a first stage of experiments to determine the effects of water chemistry parameters on FAC, corrosion rates of carbon steel were measured in 140°C pure water with an online corrosion rate monitor based on electrical resistance measurement as [O2] and flow velocity were changed. The data were compiled as a function of electrochemical corrosion potential (ECP) and flow velocity. It was concluded that the FAC rate was below the detectable limit in highly oxygenated conditions, where [O2] was >50 ppb and ECP was above −0.2 VSHE; and the effects of preoxidation treatment disappeared rapidly under deaerated conditions.

Journal ArticleDOI
TL;DR: In this paper, the corrosion inhibition of an aluminum alloy (UNS A96061) was evaluated in 3.5% sodium chloride (NaCl) solution for four different concentrations (250, 500, 750, and 1,000 ppm) of lanthanum chloride (LaCl3) and cerium chloride (CeCl3), with a maximum increase noticed for CeCl3.
Abstract: The corrosion inhibition of an aluminum alloy (UNS A96061) was evaluated in 3.5% sodium chloride (NaCl) solution for four different concentrations (250, 500, 750, and 1,000 ppm) of lanthanum chloride (LaCl3) and cerium chloride (CeCl3) inhibitors. The polarization resistance increased significantly with the addition of 1,000 ppm LaCl3 and CeCl3. The pitting nucleation resistance also increased with the addition of LaCl3 and CeCl3, with a maximum increase noticed for CeCl3. Electrochemical impedance spectroscopy studies showed that there was a significant increase in the overall resistance after the addition of 1,000 ppm LaCl3 and CeCl3, when compared to the case without inhibitor. It should be noted that both the film resistance as well as the resistance on the pitted regions increased after inhibitor addition, with the latter showing much improvement. Precipitates of oxides/hydroxides of lanthanum and cerium covered the imperfections on the surface and thereby reduced the corrosion rate.

Journal Article
TL;DR: In this paper, the authors investigated the effect of acid and CO2 corrosion on carbon steel specimens covered with iron carbonate (FeCO3) layers, and interpreted the results in terms of the scaling tendency concept.
Abstract: Acetic acid and CO2 corrosion was investigated on carbon steel specimens covered with iron carbonate (FeCO3) layers. The tests were carried out at 80 C, 0.5 bar CO2, using rotating cylinder electrodes. Protective iron carbonate layers did form in solutions with high FeCO3 supersaturation, both in presence and absence acetic acid. The protective effect of the FeCO3 layer failed with decreasing supersaturation. The results were interpreted in terms of the scaling tendency concept.

Journal ArticleDOI
TL;DR: In this paper, an Fe-13Co-11Ni-3Cr-1Mo-0.2C steel alloy, processed for ultra-high strength and fracture toughness, exhibits three distinct hydrogen trap states in a complex precipitation-hardened martensitic microstructure and is susceptible to severe hydrogen embrittlement (HE) at threshold stress intensity levels as low as 20 MPa√m.
Abstract: An Fe-13Co-11Ni-3Cr-1Mo-0.2C steel alloy, processed for ultrahigh-strength and fracture toughness, exhibits three distinct hydrogen trap states in a complex precipitation-hardened martensitic microstructure and is susceptible to severe hydrogen embrittlement (HE) at threshold stress intensity levels as low as 20 MPa√m. The causes of HE susceptibility include very high crack-tip tensile stresses and a reservoir of diffusible hydrogen that is trapped reversibly with a binding energy, Eb, of 11.5±0.5 kJ/mol at (Fe,Cr,Mo)2C precipitates. This reversibly trapped hydrogen repartitions to interstitial sites proximate to the highly stressed crack tip and, subsequently, may retrap at martensitic lath interfaces to produce substantial local hydrogen concentrations and transgranular embrittlement. These results are pertinent to the control of HE in this modern ultrahigh-strength steel with a cadmium-plated coating and codeposited hydrogen (H). Thermal desorption spectroscopy demonstrates that 190°C baking r...

Journal Article
TL;DR: In this article, a study of the combined influence of partial pressure of H2S and the concentration of free acetic acid on the general and localized CO2 corrosion at the bottom of the line is presented.
Abstract: This research work presents a study of the combined influence of the partial pressure of H2S and the concentration of free acetic acid on the general and localized CO2 corrosion at the bottom of the line. Experiments were carried out during 21 days in three 4” internal diameter flow loops at 70oC with 2 bars of CO2. The flow regime was stratified for all of the experiments. It was found that trace amounts of H2S (from 0.004 to 0.13 bars) greatly retards the CO2 corrosion with general corrosion rates usually 10 to 100 times lower than their pure CO2 equivalent. However, the most protective conditions were observed at the lowest partial pressure of H2S as the corrosion increased when more H2S was added. The presence of a mackinawite film on the coupon surface seems to be the origin of this protectiveness. When acetic acid was added to the system (the tests were performed with 1000 ppm of free acetic acid), the general corrosion was multiplied by 2 in CO2 environment and by 10 to 50 in H2S/CO2 mixtures. Once again the lowest corrosivity is found at the lowest partial pressure of H2S. INTRODUCTION CO2 corrosion in the presence of acetic acid has been extensively studied in the literature by many different authors. Corrosion mechanisms are now very well defined and are already incorporated in prediction models. The influence of acetic acid on the FeCO3 film characteristics and formation may be one of the last areas where a widely accepted theory is not completed agreed upon. In summary, the different chemical and electrochemical reactions involved in CO2 corrosion in presence of acetic acid are described below: • Water dissociation − + + ⎯→ ← ) ( ) ( ) ( 2 aq aq l OH H O H • Carbon dioxide dissolution ) ( 2 ) ( 2 aq g CO CO ↔ • Carbon dioxide hydration (slow step) ) ( 3 2 ) ( 2 ) ( 2 aq l aq CO H O H CO ⎯→ ← +

Journal ArticleDOI
TL;DR: In this article, slow strain rate tests (SSRT) were used to investigate stress corrosion cracking behavior of an X-70 pipeline steel in a soil solution and NS-4 solution, both saturated with 5% carbo...
Abstract: Slow strain rate tests (SSRT) were used to investigate stress corrosion cracking (SCC) behavior of an X-70 pipeline steel in a soil solution and NS-4 solution, both saturated with 5% carbo...