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Showing papers in "Corrosion in 1985"


Journal ArticleDOI
Roy Johnsen1, Einar Bardal1
TL;DR: The cathodic properties of a number of stainless steels, which were exposed to natural seawater flowing at 0 to 2.5 m/s and polarized to potentials from −300 to −950 mV SCE, have been studied as discussed by the authors.
Abstract: The cathodic properties of a number of stainless steels, which were exposed to natural seawater flowing at 0 to 2.5 m/s and polarized to potentials from −300 to −950 mV SCE, have been studied. The current density development at constant potential and the free corrosion potential during the exposure time were recorded continuously. At the end of the exposure period, after approximately 28 to 36 days of exposure, polarization curves were determined. After one to three weeks of exposure, depending on the water velocity, microbiological activity on the surface caused an increase in the current density requirement of the specimen. An explanation for the mechanism behind the current density increase caused by slime production from marine bacteria may be increased exchange current density, i0. There was no measurable calcareous deposit on the stainless steel surfaces at the end of the exposure periods.

99 citations


Journal ArticleDOI
TL;DR: The water content of 12 paints on steel substrate, exposed to 0.1M sodium chloride at 25 C for 24 h, was calculated from impedance measurements and compared with gravimetric determinations.
Abstract: The water content of 12 paints on steel substrate, exposed to 0.1M sodium chloride at 25 C for 24 h, was calculated from impedance measurements and compared with gravimetric determinations...

89 citations


Journal ArticleDOI
TL;DR: In this article, the authors describe current understanding of the propagation of transgranular stress corrosion cracking (TGSCC) in engineering alloys, focusing on a new approach, the film-induced cleavage model.
Abstract: This paper describes current understanding of the propagation of transgranular stress corrosion cracking (TGSCC) in engineering alloys. In contrast to intergranular stress corrosion cracking (IGSCC), which proceeds by preferential anodic dissolution at the crack tip, TGSCC is considered to propagate by discontinuous brittle fracture (cleavage). First, the propagation process is described, outlining current knowledge of the crystallography of the cleavage surfaces and reviewing the evidence for the discontinuous nature of cracking. An evaluation follows of the models that are currently proposed to explain how interaction with the chemical environment induces brittle fracture in normally ductile alloys, focusing, in particular, on a new approach, the film-induced cleavage model. Finally, attention is directed to step formation between the parallel, but displaced, primary cleavage facets. It is suggested that step formation, which in face-centered cubic (fcc)alloys occurs by highly localized plastic...

88 citations


Journal ArticleDOI
TL;DR: In this article, the Stawstrom and Hillert model was used to calculate the time temperature sensitization (TTS) diagrams for AISI 304 stainless steels (SS), which indicated that nitrogen additions below 0.16 wt% retard the sensitization kinetics; one possible mechanism by which this is achieved is an increase in chromium concentration adjacent to the grain boundaries.
Abstract: Thermodynamic calculations have been used to construct time temperature sensitization (TTS) diagrams for AISI 304 stainless steels (SS). The quantitative Stawstrom and Hillert model, which is based on chromium diffusion control of sensitization, was used to calculate the TTS diagrams. Electrochemical potentiokinetic reactivation (EPR) tests were performed on these steels, with various nitrogen additions, to obtain the experimental TTS curves. The calculated and experimental TTS diagrams have been compared to better understand nitrogen addition effects on the sensitization kinetics of AISI 304 SS. These results indicate that nitrogen additions below 0.16 wt% retard the sensitization kinetics; one possible mechanism by which this is achieved is an increase in chromium concentration adjacent to the grain boundaries, which decreases the chromium concentration gradient between the austenite matrix and the grain boundaries and hence retards carbide growth.

85 citations


Journal ArticleDOI
TL;DR: Although benzotriazole and tolyltitriazole are well known as extremely effective inhibitors of copper corrosion, very little has been reported in the literature regarding their chemistry as discussed by the authors.
Abstract: Although benzotriazole and tolyltriazole are well known as extremely effective inhibitors of copper corrosion, very little has been reported in the literature regarding their chemistry, pa...

80 citations


Journal ArticleDOI
M. Landkof1, A.V. Levy1, D.H. Boone1, R. Gray1, E. Yaniv1 
TL;DR: In this paper, the influence of surface application of active elements on the composition, morphology, adherence, and growth rate of oxide scales formed during high temperature exposure has been investigated, and the active elements were applied as aqueous solutions of nitrate salts that were subsequently transformed into oxide.
Abstract: The influence of the surface application of active elements on the composition, morphology, adherence, and growth rate of oxide scales formed during high temperature exposure has been investigated. The active elements were applied as aqueous solutions of nitrate salts that were subsequently transformed into oxide. The active elements used were: Y, Ce, La, Hf, Ca, and Zr. The chromia-forming substrates used were AISI 304 and 310 stainless steels and IN 738, a nickel base alloy. To determine the effect of the minor alloying elements in stainless steels on the surface doping effect, Y was applied to three alloy modifications of AISI 304. The effect of the presence or absence of Mn and Si in the alloy on high temperature corrosion behavior was determined. Several different application techniques were used to determine which technique was most beneficial to the behavior of the oxide barrier scale. The application of Y, Ce, and La was found to enhance the oxidation resistance of the commercial stainles...

80 citations


Journal ArticleDOI
TL;DR: In this article, the authors examined the available information to give insight into the development of protective scales on alloy surfaces and causes of scale breakdown, and evaluated the effects of alloy and gas chemistry on corrosion of materials in coal gasification atmospheres.
Abstract: Extensive research has been performed over the past 10 years to evaluate the compatibility of engineering materials and model alloys in multicomponent gas environments that are relevant to various coal gasification schemes. This paper examines the available information to give insight into the development of protective scales on alloy surfaces and causes of scale breakdown. In addition, the available long-term kinetic data on sound-metal loss are examined to evaluate the effects of alloy and gas chemistry on corrosion of materials in coal gasification atmospheres.

76 citations


Journal ArticleDOI
TL;DR: A scratch test was used to study the pitting of an Fe-19Cr-10Ni alloy in a solution containing 0.25 molar (M) Na2SO4 and 0.025 M Na2S2O3.
Abstract: A scratch test was used to study the pitting of an Fe-19Cr-10Ni alloy in a solution containing 0.25 molar (M) Na2SO4 and 0.025 M Na2S2O3. Pitting was confined to a range of potentials from...

65 citations


Journal ArticleDOI
TL;DR: In this article, the anodic dissolution of nickel, electroless nickel deposits with 2.9 and 12.3 wt% P, and amorphous Ni81P19 alloy was examined in sodium hydroxide, sulfate, borate, and chloride solutions at 25 C.
Abstract: Anodic dissolution of nickel, electroless nickel deposits with 2.9 and 12.3 wt% P, and amorphous Ni81P19 alloy was examined in sodium hydroxide, sulfate, borate, and chloride solutions at 25 C. Phosphorus enhanced the anodic dissolution of nickel; however, the dissolution decreased as the phosphorus content rose from 2.9 to 12.3%. Auger electron spectroscopy (AES) analysis indicated that oxide-passivating films on the NiP materials were thinner than those on nickel, while scanning electron microscopy (SEM) and energy dispersive x-ray analysis (EDXA) examinations revealed the precipitation of phosphorus-containing corrosion products at the surface of the NiP materials. It is suggested that the detrimental effect of phosphorus on corrosion resistance of nickel is associated with lower protectiveness of the oxide film, whereas the inhibitive effect at the higher phosphorus contents can be associated with the formation of phosphates.

64 citations


Journal ArticleDOI
TL;DR: The effects of seawater contaminants such as ammonium and sulfide ions and trimethylamine on the corrosion behavior of copper base alloys have been studied as discussed by the authors, and the results show that sulfide contamination causes a...
Abstract: The effects of seawater contaminants such as ammonium and sulfide ions and trimethylamine on the corrosion behavior of copper base alloys have been studied. Sulfide contamination causes a ...

51 citations


Journal ArticleDOI
A. Garner1
TL;DR: In this article, it was found that thiosulfate contamination of white water can cause pitting in AISI 304 and CA-15 stainless steels (SS), and, by comparison, salts such as NaCl, Na2SO, and Al2(SO4)3 are much less corrosive.
Abstract: Potentiostatic, potentiodynamic, and immersion tests were conducted on a range of alloys used in paper-machine service. It was found that thiosulfate contamination of white water can cause pitting in AISI 304 and CA-15 stainless steels (SS), and, by comparison, salts such as NaCl, Na2SO, and Al2(SO4)3 are much less corrosive. For sensitized AISI 304, thiosulfate levels in the range of 3 to 75 ppm cause pitting, 5 to 20 ppm S2O3= being particularly aggressive. Thiosulfate pitting occurred in the absence of chlorides when sulfate was present at SO4=:S2O3= molar ratios from 1.6 to 58. Compared to AISI 304, significantly greater resistance to thiosulfate pitting was found in AISI 316 and 317 L, Ferralium 255, and cast duplex SS, KCR-A171 and Alloy 75.

Journal ArticleDOI
TL;DR: In this article, the authors describe the features of a recently developed high nitrogen-bearing, highly corrosion resistant stainless steel: tensile properties, stress corrosion characteristics in boiling magnesium chloride solution, effect of sensitizing heat treatment on the nature and extent of grain boundary attack, and electrochemical polarization behavior in sulfuric acid and low pH chloride solutions.
Abstract: This paper describes the following features of a recently developed high nitrogen-bearing, highly corrosion resistant stainless steel: tensile properties, stress corrosion characteristics in boiling magnesium chloride solution, effect of sensitizing heat treatment on the nature and extent of grain boundary attack, and electrochemical polarization behavior in sulfuric acid and low pH chloride solutions.

Journal ArticleDOI
TL;DR: In this paper, the authors measured hydrogen permeation transients for low-carbon iron and stainless steel at room temperature; pure nickel and 17Cr-12Ni austenitic stainless steel (SS) were electrochemically charged with hydrogen.
Abstract: Hydrogen permeation transients for low-carbon iron were measured at room temperature; pure nickel and 17Cr-12Ni austenitic stainless steel (SS) specimens were electrochemically charged with hydrogen. The results for unstrained specimens were compared with those obtained under conditions of continuous stretching. A slight increase in the permeation rate for iron was observed in the range of elastic deformation, with no change in effective diffusivity. Plastic deformation caused a substantial reduction of both the diffusivity and permeability of hydrogen. The magnitude of these effects depended on the amount of strain but was independent of the strain rate; this suggested they were caused by an enhanced trapping of hydrogen. Only a slight influence of plastic deformation on the effective diffusivity and permeability of hydrogen was observed in nickel and austenitic SS.


Journal ArticleDOI
J. A. Martin1, F. W. Valone1
TL;DR: In this article, Fourier transform infrared (FT-IR), carbon-13 nuclear magnetic reasonance (13C NMR), and ultraviolet (UV) spectroscopy were used to investigate the actual che
Abstract: Spectroscopic methods, i.e., Fourier transform infrared (FT-IR), carbon-13 nuclear magnetic reasonance (13C NMR), and ultraviolet (UV) spectroscopy, were used to investigate the actual che...

Journal ArticleDOI
TL;DR: In this article, a rotating disk electrode system was used in the measurements with rotation rate varying from 500 to 6000 rpm, indicating a surface kinetic-controlleakage mechanism incorporating a soluble copper complex on the electrode surface.
Abstract: Electrochemical corrosion rates of Cu and Cu-Ni alloys have been measured in oxygenated 0.5M NaCl and in synthetic seawater using the Tafel extrapolation procedure. In addition, Cu corrosion has been measured with the linear polarization procedure. A rotating disk electrode system was used in the measurements with rotation rate varying from 500 to 6000 rpm. The corrosion characteristics of Cu and 90Cu-10Ni alloy in the two media, and 70Cu-30Ni alloy in 0.5M NaCl have been found to be similar. For these systems, the variation of corrosion current, corrosion potential, and anodic partial current with rotation rate of the electrode could be explained in terms of a convective diffusion controlled corrosion mechanism incorporating the generation of a soluble copper complex on the electrode surface. The 70-30 alloy in synthetic seawater behaved differently. Corrosion current, corrosion potential, and the anodic partial current were all constant with rotation rate, indicating a surface kinetic-controlle...

Journal ArticleDOI
TL;DR: In this article, the effects of various environmental factors on CO2 corrosion of 9 to 25% Cr steel, with emphasis on the finding that each alloy has application criteria based on critical temperatures and CO2 partial pressures in a CO2-Cl− environment.
Abstract: This paper reports the results of an investigation into the effects of various environmental factors on CO2 corrosion of 9 to 25% Cr steel, with emphasis on the finding that each alloy has application criteria based on critical temperatures and CO2 partial pressures in a CO2-Cl− environment. It is also shown that each alloy would be resistant even in two phase flow at flow rates of up to 26 m/s (in the respective critical conditions). The potential corrosion behaviors of 9Cr-1Mo, AISI 420 (13Cr), and 22 to 25% Cr duplex phase stainless steels in severely corrosive wells was investigated using a CO2-Cl− solution with a slight H2S contamination. In particular, the effects of H2S partial pressure and temperature on SCC and localized corrosion of these alloys are discussed.

Journal ArticleDOI
TL;DR: The polarization behavior of various pure zinc, Al-Zn, and Zn-Ni coatings was studied to evaluate electrochemical methods for use in testing the performance of such coatings on sheet steel as mentioned in this paper.
Abstract: The polarization behavior of various pure zinc, Al-Zn, and Zn-Ni coatings was studied to evaluate electrochemical methods for use in testing the performance of such coatings on sheet steel. Behavior in deaerated chloride solutions was found to simulate more nearly the good performance of pure zinc (galvanized) coatings in service. Al-Zn coatings exhibited low corrosion rates in both aerated and deaerated chloride solutions, yet they maintained active corrosion potentials and conferred galvanic cathodic protection to bare steel exposed in a scribe through the coating. The galvanic current, which provides cathodic protection for the steel in a scribe, was measured successfully using the polarization resistance technique.

Journal ArticleDOI
TL;DR: Mcorr is a better indicator of corrosive behavior than the time of exposure to sodium chloride solutions as discussed by the authors, which may give misleading results insofar as the mechanism by which steel goes from the passive to active state is concerned.
Abstract: Because of the variation in composition and steel surface conditions in steel-reinforced concrete samples immersed in sodium chloride solutions, Mcorr is a better indicator of corrosive behavior than the time of exposure. While it is true that for many samples, the longer the exposure time, the greater the probability of corrosion-product buildup, the corrosive behavior of individual samples selected on the basis of exposure time may give misleading results insofar as the mechanism by which steel goes from the passive to active state is concerned. Therefore, the value of Mcorr, when measured under the same conditions, is much more reflective of the corrosive behavior than the time of exposure to sodium chloride solutions.

Journal ArticleDOI
TL;DR: In this paper, the eta or zeta phase was present as the outermost layer of zinc coatings on steel and their electrochemical behavior was studied in a range of experiments.
Abstract: Well-characterized zinc coatings on steel have been prepared so that either the eta or zeta phase was present as the outermost layer. Their electrochemical behavior was studied in a range ...

Journal ArticleDOI
TL;DR: In this article, the crevice and pitting corrosion behavior of unalloyed titanium in chloride solutions at elevated temperatures (maximum 150 C) was studied using an electrochemical method.
Abstract: Electrochemical methods have been used to study the crevice and pitting corrosion behavior of unalloyed titanium in chloride solutions at elevated temperatures (maximum 150 C). The investi...

Journal ArticleDOI
TL;DR: In this article, the authors studied the stress corrosion cracking behavior of differently heat-treated specimens of Inconel 600 in 25 molal (m) NaOH solution at 140 C by using the slow strain rate technique (SSRT).
Abstract: The stress corrosion cracking (SCC) behavior of differently heat-treated specimens of Inconel 600 in 25 molal (m) NaOH solution at 140 C was studied as a function of potential by using the slow strain rate technique (SSRT). It was found that the cracking susceptibility and the failure mode (intergranular vs transgranular) depends heavily on potential, heat treatment, and grain size. In the mill-annealed condition, intergranular stress corrosion cracking (IGSCC) was obtained at potentials extending from the active peak (−900 mVSCE) to the secondary anodic peak (−400 mVSCE), while transgranular stress corrosion cracking (TGSCC) occurred at the open circuit potential (OCP), ∼−980 mVSCE, and at 0 mVSCE (secondary passive region). Solution-annealed material showed reduced IGSCC susceptibility with respect to the mill-annealed material, while almost complete IGSCC resistance was obtained by heat treatment at 700 C of both mill- and solution-annealed materials. Also, material with small grain size exhib...


Journal ArticleDOI
TL;DR: In this paper, the pit nucleation potential, Enp, was evaluated in two different concentrations of sodium chloride and cupric chloride, and the number and size of the pits increased with increasing concentrations of cupric and dissolved oxygen.
Abstract: Pitting corrosion of Inconel 600 was studied in aqueous sodium and cupric chloride solutions at 60 and 280 C. The pit nucleation potential, Enp, was evaluated in two different concentrations of sodium chloride. Enp decreased with increasing concentrations of the chloride ion and with temperature. On specimen surfaces exposed to cupric chloride solutions, pitting occurred at open circuit potentials nearly equal to or higher than the Enp determined by anodic polarization in 0.01 M NaCl solution. The number and size of the pits increased with increasing concentrations of cupric chloride and dissolved oxygen. On specimens partly covered with polytetrafluorethylene (PTFE) tape (i.e., in the presence of artificial crevices), pitting occurred more easily at low concentrations of CuCl2 (≤ 20 ppm CuCl2 in deaerated solutions at 280 C). Tubes covered with oxide films that formed during the operation of model boilers exhibited greater pitting resistance than tubes with clean surfaces at 280 C, but less resi...

Journal ArticleDOI
TL;DR: In this paper, a study of the effects of metallurgical and environment variables on stress corrosion cracking (SCC) propagation rates in NiCrMoV turbine disc steels was made.
Abstract: A study was made of the effects of metallurgical and environment variables on stress corrosion cracking (SCC) propagation rates in NiCrMoV turbine disc steels. Constant displacement tests, using wedge-opening-load (WOL) specimens, were performed on steels with yield strengths in the range of 627 to 1124 MPa. One steel was temper-embrittled to study the effect of phosphorus segregation on SCC growth rates. All tests were made at 157 C in either pure water environments, or environments containing common ionic turbine contaminants (NaCl and NaOH) and gaseous turbine contaminants (air, oxygen, and carbon dioxide). Crack growth occurred in all of these environments, although growth rates decreased with increasing environment purity. Estimated field crack growth rates were in close agreement with rates obtained in deaerated pure water. Crack growth was always intergranular, except in aerated pure water, when it was transgranular. Crack growth rates were found to increase with increasing yield strength....

Journal ArticleDOI
TL;DR: In this article, it has been demonstrated with examples that, for the occurrence of stress corrosion cracking (SCC), time-dependent parameters as well as critical stress levels are highly important.
Abstract: It has been demonstrated with examples that, for the occurrence of stress corrosion cracking (SCC), time-dependent parameters as well as critical stress levels are highly important. Therefore, certain ideas that have developed concerning the differentiation between SCC and corrosion fatigue must be revised. When cyclic loading is involved, SCC, corrosion fatigue, and fatigue are successively encountered as the frequency or strain rate is increased, and such forms of material damage are therefore predominant in particular frequency ranges.

Journal ArticleDOI
TL;DR: In this article, the authors compared the performance of two methods, chemical analysis of corrosion products and instantaneous corrosion rate measurements, and concluded that the two methods are in good agnostic condition.
Abstract: Data on corrosion of metals are normally derived from two sources, namely, immersion/exposure tests and controlled electrochemical experiments. Because of inherent problems associated with the extrapolation of short-term measurements to long-term performance, many field workers are skeptical of the value of electrochemical data. In order to compare these two methods, corrosion rate data obtained for bronzes using (1) chemical analysis of corrosion products and (2) instantaneous corrosion rate measurements are presented. The material was examined after 170 years' immersion in tropical waters northwest of Western Australia where the American China Trader “Rapid” foundered in 1811. The nature of the corrosion products and the microenvironment will be discussed in terms of pH, oxygen access, Eh gradients, and the microstructure of the objects. Problems associated with non-uniform surfaces and slow rates of attaining a steady state will be discussed. Corrosion rates from the two methods are in good ag...

Journal ArticleDOI
TL;DR: A zirconia membrane electrode that responds to pH can serve admirably as a pH sensor in high temperature aqueous systems as mentioned in this paper, under conditions of known, stable pH.
Abstract: A zirconia membrane electrode that responds to pH can serve admirably as a pH sensor in high temperature aqueous systems. Alternatively, under conditions of known, stable pH, the sensor ma...

Journal ArticleDOI
TL;DR: In this article, an efficient method appears to be cathodic polarization within a certain potential range in unbuffered salt solutions of neutral pH, which leads to an appreciable improvement of the corrosion resistance of alloys in the 1000, 3000, and 6000 series.
Abstract: Corrosion of aluminum alloys is often closely related to the type, amount, and properties of intermetallic phases present in the matrix. The phases that contain iron as a component are especially detrimental to corrosion resistance. These phases can be dissolved preferentially, thereby achieving a relatively particle-free surface, by various chemical and electrochemical means. An efficient method appears to be cathodic polarization within a certain potential range in unbuffered salt solutions of neutral pH. It is shown that the method leads to an appreciable improvement of the corrosion resistance of alloys in the 1000, 3000, and 6000 series. The particles are removed physically as a result of crevice corrosion of the matrix adjacent to their surface. The rate of removal depends on the extent to which the cathodic reaction can be depolarized on the particles relative to the substrate. The mechanism is investigated by electrochemical and microanalytical means.

Journal ArticleDOI
TL;DR: In this article, the authors reported a study of stress corrosion cracking of Fe-3Ni and Fe-0.06P alloys in 9M NaOH and showed that the presence of carbon or carbides degrades the caustic cracking resistance of low alloy steels but that small additions of vanadium and chromium have little effect.
Abstract: This paper reports a study of stress corrosion cracking of Fe-3Ni, Fe-3Ni-0.5Mo, and Fe-3Ni-0.06P alloys in 9M NaOH. The samples were tested at 98 C and at −400 mVHg/HgO under constant load. The results show that Fe-3Ni is very resistant to caustic stress corrosion and that additions of 0.5Mo degrade this resistance only slightly. However, phosphorus segregation to grain boundaries significantly impairs caustic cracking resistance. Possible mechanisms for the effect of phosphorus and molybdenum on caustic stress corrosion cracking are considered. It will also be demonstrated by comparison of these data with those obtained on low alloy steels that the presence of carbon or carbides degrades the caustic cracking resistance of iron base alloys but that small additions of vanadium and chromium have little effect. Segregated sulfur also has no effect on the cracking process.