Showing papers in "Corrosion in 1979"
TL;DR: The susceptibility of Cu-Ni alloys to accelerated corrosion in sea water containing low sulfide concentrations has been investigated in this paper, and test alloys included wrought 90/10, 70/30, and wrought 30/30 CuNi.
Abstract: The susceptibility of Cu-Ni alloys to accelerated corrosion in sea water containing low sulfide concentrations has been investigated. Test alloys included wrought 90/10 Cu-Ni, 70/30 Cu-Ni ...
80 citations
TL;DR: In this paper, the corrosion of 90:10 Cu:Ni and 70:30 Cu: Ni alloys in sulfide polluted flowing sea water was studied as a function of sulfide concentration, and it was shown that the presence of sulfides induces a loss in passivity of the alloy surface due to the formation of cuprous sulfide as the principal corrosion product.
Abstract: The corrosion of 90:10 Cu:Ni and 70:30 Cu:Ni alloys in sulfide polluted flowing sea water has been studied as a function of sulfide concentration. The experimental techniques used include small amplitude cyclic voltammetry, AC impedance measurements, large amplitude cyclic voltammetry, and extensive surface examination by scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis, X-ray diffraction, and Auger electron spectrometry (AES). It is shown that the presence of sulfide induces a loss in passivity of the alloy surface due to the formation of cuprous sulfide as the principal corrosion product. Furthermore, accelerated corrosion of these materials in sulfide polluted sea water appears to arise from a shift in the corrosion potential to sufficiently active values that hydrogen evolution becomes a viable cathodic process.
79 citations
TL;DR: The lattice constants of hydride phases are larger by about 5% when charging of austenitic stainless steels with hydrogen evolved electrolytically from promoter containing acid solutions.
Abstract: Electrolytic charging of austenitic stainless steels with hydrogen induces formation of two distinct alloy hydride phases, both being unstable under normal atmospheric conditions. One of the new phases denoted Hγ, has the same Bravais lattice as austenite (fcc), whereas another, denoted Hϵ, exhibits an hcp structure. Compared with hydrogen-free austenite and ϵ-martensite, respectively, the lattice constants of hydride phases are larger by about 5%. During charging of austenitic stainless steels with hydrogen evolved electrolytically from promoter containing acid solutions, these hydrides form a hard and brittle surface layer, several μm thick with numerous microcracks, and it is probable that these hydride phases play an important role during stress corrosion cracking (SCC) of austenitic stainless steels.
69 citations
TL;DR: In this paper, the equation relating current to voltage for an electrode under charge-transfer control has been solved for a sinusoidal modulation of the electrode potential, so as to derive its value as a function of the Tafel parameter and of the amplitude of the modulating voltage, as well as of average electrode potential.
Abstract: The equation relating current to voltage for an electrode under charge-transfer control has been solved for a sinusoidal modulation of the electrode potential. The rectified Faradaic component has been obtained, so as to derive its value as a function of the Tafel parameter and of the amplitude of the modulating voltage, as well as of average electrode potential. The case where one electrode reaction is under diffusion control also has been treated. The amplitude and phase characteristics of the harmonic components have been derived, and their use for determining the kinetic properties of the electrode have been discussed. The capacitative current generated by the alternating voltage also has been investigated, and the conditions under which it can be separated from the Faradaic current have been given. The implications of these results on the corrosion due to AC leakage have been examined.
64 citations
TL;DR: In this paper, the thickness of surface films were analyzed by infrared multiple reflectance spectroscopy and scanning electron microscopy, and the results indicated that the protectiveness of the surface films was dependent on the pretreatment temperature.
Abstract: Corrosion protection afforded by pretreating copper in aqueous benzotriazole solutions at temperatures ranging from 25 to 100 C were evaluated. Electrochemical characteristics of pretreated copper mirrors were monitored using rapid polarization techniques. Thickness of surface films were analyzed by infrared multiple reflectance spectroscopy. Topography of surface films prior to and subsequent to test exposures was examined by scanning electron microscopy. Defects in protective films on pretreated copper mirrors were detected by immersion in silver nitrate solutions. The resulting silver “decorations” identified both the location and density of active corrosion sites in the multilayer protective films. Exchange current densities, corrosion current densities, corrosion rates determined by chemical analyses, electrical double layer capacities, and the densities of active corrosion sites all showed similar dependencies on pretreatment temperatures. All techniques indicated that the protectiveness of...
60 citations
TL;DR: In this paper, the corrosion rates of copper alloys 706 (90:10 Cu:Ni) and 715 (70:30 Cu: Ni) were measured, using rotating cylinder specimens in sea water that contained oxygen, sulfide, sulfur, and polysulfide, either singly or in combination.
Abstract: The corrosion rates of copper alloys 706 (90:10 Cu:Ni) and 715 (70:30 Cu:Ni) were measured, using rotating cylinder specimens in sea water that contained oxygen, sulfide, sulfur, and polysulfide, either singly or in combination. In addition a control test was performed using unpolluted deaerated sea water. Corrosion rates were monitored for over 24 hours, using linear polarization and potential step techniques. The work has shown that copper-nickel alloys can corrode quite rapidly in deaerated sea water if these normally “passive” alloys are made active by the presence of sulfide, or if sulfur is available as an oxidant.
53 citations
TL;DR: In this article, the conditions under which cathodically impressed or galvanically induced currents can cause hydriding of titanium were discussed, and the oxide film that normally covers the surface of the titanium was discussed.
Abstract: This paper discusses the conditions under which cathodically impressed or galvanically induced currents can cause hydriding of titanium. The oxide film that normally covers the surface of ...
52 citations
TL;DR: The hydrated iron (III) oxide membranes with adsorbed divalent anions such as MoO42− ions are cation selective in monovalent electrolyte solutions even in the pH region lower than pHpis.
Abstract: Ion selectivity in precipitate films of hydrated iron (III) and iron (III) molybdate has been studied by measuring the membrane potential and polarization property as a function of solution pH and ion valency. The hydrated iron (III) oxide membrane is found to be anion selective in 1-1 electrolyte solutions in the pH region lower than a specific pH. Beyond this pH, the membrane turns to be cation selective. This specific pH, at which the membrane potential is identical to the liquid junction potential, is named the point of iso-selectivity pHpis, and is evaluated in KCI solutions to be 10.3. The hydrated iron (III) oxide membranes with adsorbed divalent anions such as MoO42− ions are cation selective in monovalent electrolyte solutions even in the pH region lower than pHpis. This cation selectivity can be attributed to the strong adsorption of the divalent anions forming the negative fixed charges on the membranes. Under an applied membrane potential, the ionic current is rectified through the bi...
49 citations
TL;DR: Stress corrosion studies have been conducted with Type 304 stainless steel using a variety of electrochemical techniques at elevated temperatures as mentioned in this paper, and the object of these studies was to determ...
Abstract: Stress corrosion studies have been conducted with Type 304 stainless steel using a variety of electrochemical techniques at elevated temperatures. The object of these studies was to determ...
48 citations
TL;DR: In this paper, the relationship between test methods, surface condition, and experimental procedure on both base and weld metal pitting potential measurements have been made by potentiostatic, potentiokinetic, and scratch test methods.
Abstract: Pitting potential measurements have been made by potentiostatic, potentiokinetic, and scratch test methods. Several surface conditions were tested to determine the relationship between test methods, surface condition, and experimental procedure on both base and weld metal. The results indicate the complex interrelationships between specimen mounting technique, exposed edge effects, test methods, and surface condition on pitting potential determination. It was found that base metal pitting potentials are a strong function of the above mentioned effects, while the duplex weld metal is independent of them. This is explained by the nature of the pit initiation sites which are the sulfide inclusions in the case of the base metal, and the austenite-residual delta ferrite in the weld metal case.
47 citations
TL;DR: In this article, an attempt has been made to improve the SCC performance of Inconel Alloy 600 steam generator tubing by modifying the grain boundary microstructure, which has been shown to increase the performance of the generator.
Abstract: An attempt has been made to improve the SCC performance of Inconel Alloy 600 steam generator tubing by modifying the grain boundary microstructure. Changes in the grain boundary microstruc...
TL;DR: In this paper, a series of amorphous Fe-Ni-Cr-P-B alloys of varying Cr content were evaluated to characterize their susceptibility to crevice corrosion.
Abstract: Experiments were performed with a series of amorphous Fe-Ni-Cr-P-B alloys of varying Cr content to characterize their susceptibility to crevice corrosion. Potentiodynamic and potentiostatic polarization of freely exposed specimens was performed in simulated crevice solutions (1M NaCI at pH 1–7, and 6% FeCI3 at PH 1.4). Crevice corrosion experiments were conducted in an artificial crevice cell. Polarization in the simulated crevice electrolytes indicated that alloys containing 2 to 16 At.% Cr can passivate in even 1M NaCI, pH 1, and they do not experience significant pitting at potentials active to that at which oxygen evolution occurs. In agreement with previously published results,1 only a few At.% Cr were needed to confer passivity; even the alloy containing 2% Cr achieved a passive current density of only 10−1 A/2 in 1 M NaCI at pH 1, and it did not pit below about 1.20 V(SCE). Results indicated, however, that the alloys meet certain requirements for susceptibility to crevice corrosion and occ...
TL;DR: In this paper, Potentiostatic and isothermal immersion tests have been used to investigate pitting corrosion in the weld metal of low carbon (<0.03%C) austenitic stainless steels.
Abstract: Potentiostatic and isothermal immersion tests have been used to investigate pitting corrosion in the weld metal of low carbon (<0.03%C) austenitic stainless steels. The experiments were co...
TL;DR: In this paper, acoustic emission measurements have been performed on unstressed Al alloys which were freely corroding or coupled to Cu, 4130 steel, Cd or Zn in 3,5% NaCI.
Abstract: Acoustic emission measurements have been performed on unstressed Al alloys which were freely corroding or coupled to Cu, 4130 steel, Cd or Zn in 3,5% NaCI. The rate of acoustic emission is in qualitative agreement with the observed corrosion rates. The acoustic emission is probably a result of hydrogen bubble evolution in the acidified pits. The rate of acoustic emission of 4130 steel in HCI also follows the corrosion behavior, decreasing significantly with addition of organic corrosion inhibitor. Stainless steel Type 304 was studied freely corroding or at applied constant anodic or cathodic currents. The highest rates of acoustic emission were determined at cathodic currents; when an anodic current was applied, the acoustic emission rate was higher than for a freely corroding sample and showed wide fluctuations which continued for some time when anodic polarization was discontinued. For localized corrosion of Al alloys and stainless steel, the acoustic emission process seems to reflect the stati...
TL;DR: In this paper, the variation in stress corrosion susceptibility and cracking morphology of sensitized Type 304 stainless steel in high purity water is reported as a function of combinations of oxygen (0.01 to 8 ppm) and temperature (75 to 288 C).
Abstract: The variation in stress corrosion susceptibility and cracking morphology of sensitized Type 304 stainless steel in high purity water is reported as a function of combinations of oxygen (0.01 to 8 ppm) and temperature (75 to 288 C). The results are discussed both in terms of the fundamental parameters involved in stress corrosion cracking (SCC), and the relevance of the data vis a vis the prevention of cracking in operaitonal BWR's.
TL;DR: Corrosion fatigue crack propagation rates for aluminum-7% magnesium in the cold worked and stabilized condition have been determined as a function of stress intensity amplitude in various... as discussed by the authors,...
Abstract: Corrosion fatigue crack propagation rates for aluminum-7% magnesium in the cold worked and stabilized condition have been determined as a function of stress intensity amplitude in various ...
TL;DR: A fractographic study has been carried out on intergranular and transgranular cracks produced in the commercial aluminum alloy 7075 in a 3% NaCI aqueous solution and in ionized hydrogen ga... as discussed by the authors.
Abstract: A fractographic study has been carried out on intergranular and transgranular cracks produced in the commercial aluminum alloy 7075 in a 3% NaCI aqueous solution and in ionized hydrogen ga...
TL;DR: Transmission electron microscopy (TEM) has been used to study intergranular corrosion of aged AI-4 Wt% Cu by direct observation of identical regions of grain boundary before and after imme...
Abstract: Transmission electron microscopy (TEM) has been used to study intergranular corrosion of aged AI-4 Wt% Cu by direct observation of identical regions of grain boundary before and after imme...
TL;DR: In this article, the polarization resistance of two copper-nickel alloys (90:10 Cu:Ni and 70:30 Cu: Ni) was monitored as a function of time in flowing sea water that contained 0.045, 0.85, 6.6, or 26.3 mg/dm3 dissolved oxygen.
Abstract: This work was stimulated by reports that electrochemical methods for measuring the polarization resistance of copper, nickel, or copper-nickel alloys in aqueous systems may lead to appreciable errors in the estimates of the corrosion rate. In the present work, the polarization resistance (Rp) of two copper-nickel alloys (90:10 Cu:Ni and 70:30 Cu:Ni) was monitored as a function of time in flowing sea water that contained 0.045, 0.85, 6.6, or 26.3 mg/dm3 dissolved oxygen. Rp values were obtained using the linear polarization, potential step, and AC impedance techniques. The total weight loss during the test period was calculated from the area under the 1/Rp versus time curve and compared with the measured weight loss. The experimental data support the validity of electrochemical methods for measuring corrosion rates of copper-nickel alloys in sea water, provided that a sufficient number of Rp measurements are made during the first 24 hours, and provided that proper consideration is given to the cap...
TL;DR: In this article, the susceptibility of 90/10 and 70/10 Cu-Ni alloys to sulfide induced corrosion was evaluated in sea water environments with as little as 0.007 mg/L sulfide.
Abstract: Experiments were performed to determine susceptibility of 90/10 and 70/10 Cu-Ni alloys to sulfide induced corrosion as related to sulfide concentration, sea water velocity, and duration of sulfide exposure. All exposures were conducted in fresh sea water, and the range of experimental variables included sulfide concentration (from sodium sulfide) from 0.007 to 0.25 mg/L, sea water velocity after sulfide exposure from 0.5 to 5.3 m/s, and sulfide exposure times from 1 to 90 days. Results showed that both alloys undergo localized attack in sea water environments with as little as 0.007 mg/L sulfide. The velocity dependence of active attack was minimal in the range tested. Duration of sulfide exposure, particularly at low sulfide concentrations, is a key factor in causing localized corrosion in these alloys and in the degree of attack experienced. On the basis of long term continuous low concentration sulfide exposure, 70/30 Cu-Ni appears to undergo less severe attack than that seen with 90/10 Cu-Ni.
TL;DR: Constant extension rate tests have been conducted on Type 304 stainless steel base metal specimens and on stainless steel weld metal specimens with ferrite contents of Ferrite Number 1, 3,... as mentioned in this paper.
Abstract: Constant extension rate tests have been conducted on Type 304 stainless steel base metal specimens and on stainless steel weld metal specimens with ferrite contents of Ferrite Number 1, 3,...
TL;DR: In this article, the influence of thermal treatment on the stress corrosion cracking (SCC) resistance of Inconel alloy 600 (I-600) in diferent test methods was evaluated.
Abstract: Electrochemically controlled test methods have been used to determine the influence of thermal treatment on the stress corrosion cracking (SCC) resistance of Inconel alloy 600 (I-600) in d...
TL;DR: Corrosion potentials and cyclic voltammograms were reported for AISI 1010 carbon steel, E-Brite 26-1 stainless steel, 316L stainless steel and Haynes Alloy 20 Mod, Carpenter 20 Cb-3.
Abstract: Corrosion potentials and cyclic voltammograms are reported for AISI 1010 carbon steel, E-Brite 26-1 stainless steel, AISI 316L stainless steel, Haynes Alloy 20 Mod, Carpenter 20 Cb-3, Inco...
TL;DR: In this paper, the anodic polarization of mild steel in Na2SO4 solutions (pH 3-9) in the presence of a sinusoidal electric current was measured over a range of alternating current densities from 0 to 200 mA/c2 and AC frequencies from 20 to 6000 Hz.
Abstract: A study has been made of the anodic polarization of mild steel in Na2SO4 solutions (pH 3-9) in the presence of a sinusoidal electric current. The measurement was carried out over a range of alternating current (AC) densities from 0 to 200 mA/c2 and AC frequencies from 20 to 6000 Hz. It was found that the corrosion potential of mild steel shifted toward the active direction in the presence of AC. The magnitude of the potential shift increased with increasing AC densities, and decreased with AC frequencies. AC also increased the passivity current density in a way similar to the addition of chloride ions to the electrolyte. The phenomenon was explained with a time-averaging analysis of the mixed potential theory.
TL;DR: This paper showed that crevice corrosion generates basic conditions in the occluded region, but thermodynamic arguments indicate that the mechanism for intergranular stress corrosion cracking (IGSCC) of Alloy 600 in high purity water should differ from that for conventional caustic cracking.
Abstract: Small bore Inconel Alloy 600 tubing exhibits classical crevice behavior in an appropriate high temperature aqueous environment and is therefore useful for studying the crevice chemistry of this alloy in systems which are not readily amenable to crevice simulation by external electrochemical control. Experiments in high purity water at 288 C show that crevice corrosion generates mildly basic conditions in the occluded region, but thermodynamic arguments indicate that the mechanism for intergranular stress corrosion cracking (IGSCC) of Alloy 600 in high purity water should differ from that for conventional caustic cracking. The results also suggest that aqueous diffusion, rather than the kinetics of alloy dissolution, controls the rate of crevice corrosion, and that the film rupture theory of stress corrosion cracking (SCC) may not apply at high temperatures.
TL;DR: The composition and structure of the fuel elements of various PWR's were determined by SEM, EDAX, X-ray analysis, infrared spectroscopy, and thermomagnetic analysis.
Abstract: The composition and structure of “erud” taken from the fuel elements of various pressurized water reactors (PWR's) were determined by SEM, EDAX, X-ray analysis, infrared spectroscopy, and thermomagnetic analysis. The samples were taken from reactors varying in materials of construction from all stainless steel to mainly Inconel 600 and Zircaloy fuel cladding. It is shown that crud is essentially a nickel ferrite (NixFe3–xO4) with 0.45 < x < 0.75. Calibration of the lattice parameter versus x allows convenient determination of the main constituents of crud samples. Chromium also enters the inverse spinel lattice substitutionally to give a composition CryNixFe3–x–yO4. Aluminum, when present, generally formed amorphous compounds with silicon in the loose crud.
TL;DR: Putrid sea water results from the diagenesis of natural sea water due to the decomposition of plant and animal macroorganisms as discussed by the authors, resulting in a solution of low pH, high sulfide, and high to...
Abstract: Putrid sea water results from the diagenesis of natural sea water due to the decomposition of plant and animal macroorganisms. The result is a solution of low pH, high sulfide, and high to...
TL;DR: In this paper, an investigation of the iron-molybdenum binary system was undertaken to determine the effects of molybordenum on pitting and passive film behavior.
Abstract: An investigation of the iron-molybdenum binary system was undertaken to determine the effects of molybdenum on pitting and passive film behavior. Polarization curves, galvanostatically det...
TL;DR: A seeded growth method has been used to study the kinetics of crystallization of calcium sulfate dihydrate at various temperatures and at ionic strengths up to 0.6M as discussed by the authors.
Abstract: A seeded growth method has been used to study the kinetics of crystallization of calcium sulfate dihydrate at various temperatures and at ionic strengths up to 0.6M. Under all conditions, ...