bluuebunny/crossref_metadata_2025 huggingface dataset:
Interpretation of the Second Anodic Current Maximum on Polarization Curves of Sensitized Chromium Steels in 1N H2 SO4
Authors: ROCKEL M. B.
Published: February 2013

Some data on the occurrence of the second anodic current maximum observed on polarization curves of chromium steels in 1N H2SO4 are presented and used in a critical interpretation of the results of other investigators. It is shown that the second anodic current maximum observed on specimens with special prepolarization treatments, i.e., holding the specimen for a long time either at the open circuit potential or at a cathodic potential, results from artificially imposed surface effects and does not represent the bulk material. Recent investigations on iron-chromium electrodes which did not have a prepolarization treatment correlate the second anodic current maximum to preferential attack along α-γ phase boundaries. In the latter experiments, the second anodic current maximum is sensitive to heat treatment (degree of sensitization) and the effect is explained entirely on the chromium impoverishment theory. Supporting evidence is provided by microprobe analyses and critical model experiments.
Effect of Complex Cupric Ions on the Stress Corrosion Behavior of Copper-Germanium Solid Solutions
Authors: BHIDE G. , DODD R. A.
Published: February 2013

Cu2 At. % Ge and Cu8 At. % Ge alloys are susceptible to intergranular and transgranular stress corrosion cracking (SCC), respectively in 15N (NH3)aq preconcentrated with cupric complex ions. Cu2 At. % Ge cracks readily in electrolytes having high complex ion concentrations, which result in strongly adherent black tarnish films. Such films do not form on Cu8 At. % Ge. To a large extent, Cu-Ge behaves analogously to Cu-Zn, although a few significant points of difference exist.
Polarization of Copper in Acidic and Alkaline Solutions
Authors: KIM C P. , NOBE KEN
Published: February 2013

The polarization behavior of copper in acidic and alkaline solutions has been investigated. The cathodic Tafel slopes of copper in acidic solutions for hydrogen evolution by discharge of hydrogen ions were approximately 112 mv. The electrochemical reaction order for this reaction with respect to the concentration of hydrogen ions was one-half. For alkaline solutions, the Tafel slopes of the hydrogen evolution reaction were 180 mv and the rates of this reaction were independent of pH. The anodic Tafel slopes for copper dissolution in acidic solutions were 30 mv. The rate of anodic dissolution was increased by increasing the concentration of hydroxyl ions and the reaction order was about one-half. The pH dependence of the corrosion rate of copper in solutions of pH 0.35 to 5.8 was d log icorr/d PH = −0.4.
The Dezincification of Alpha and Beta Brasses
Authors: HEIDERSBACH ROBERT H. , VERINK ELLIS D.
Published: February 2013

The mechanisms of dezincification of single phase alpha and beta brasses were studied using X-ray diffraction, electron microprobe, metallographic, atomic absorption, and electrochemical techniques. The two mechanisms of dezincification which had been previously reported, (1) dissolution of both alloy constituents followed by redeposition of the more noble species, and (2) the selective removal of the less noble constituent, were found to be operative under certain conditions of potential and pH for both alpha and beta brasses. An electrochemical explanation of the circumstances under which dealloying can be expected to occur was developed based on the use of Pourbaix Diagrams.
Analysis of Cathodic Protection Criteria
Authors: JONES D. A.
Published: February 2013

The criterion of cathodic protection is that level of cathodic potential change (polarization) which is sufficient to give adequate protection for a given application. Ideally, it is preferred to polarize to the reversible potential of the anodic reaction, but this potential is often impossible to determine by experiment or to calculate from theory for complex corrosive electrolytes. Polarization to a specific potential (e.g., −0.85 volts) or to various potential changes (e.g., 100 to 300 mv) have also been proposed, but none have been universally accepted. Electrochemical kinetic theory has been very successful in predicting and correlating the corrosion behavior of metals. However, the theory has not been applied to cathodic protection until recently. It has been shown that the anodic Tafel constant determines the cathodic polarization necessary to effect a given reduction in corrosion rate. Thus, polarization required to obtain a given degree of protection can be predicted if the anodic Tafel constant is known. Determining the anodic Tafel constant may be difficult for complex structures in service. However, even an estimate from a small sample in the required corrosive would be very helpful in making the criterion of cathodic protection more quantitative.
A Correlation of Phase Change with Stress Corrosion Fracture in Alpha-Brass
Authors: SYLWESTROWICZ W. D.
Published: February 2013

Prestrained α-brass specimens, containing 1.9% lead, were exposed to stress corrosion at 30 and 90 C (86 and 194 F). It was found that at least 10% of prestraining was needed to fracture specimens in stress corrosion tests. It was also observed that in specimens strained more than 10% the face centered cubic (fee) structure of α-brass was transformed, inside of the specimen, to the hexagonal structure. It is postulated, that transformation of the fee structure to the hexagonal structural causes susceptibility of α-brass to the stress corrosion fracture.
Effect of Temperature and Some Inhibitors on Stress Corrosion Cracking of Carbon Steels in Nitrate and Alkaline Solutions
Authors: MAZILLE HENRY , UHLIG HERBERT H.
Published: February 2013

The effect of temperature is reported on failure times and critical potentials of mild steel and 0.24% C low alloy steel in a nitrate test solution, and in concentrated NaOH solution. The inhibiting behavior of small additions of acetates or chlorides to the nitrate solution, and Quebracho extract to NaOH solutions are studied. Mechanism of failure appears to depend on adsorption of damaging ions on appropriate defect sites of the plastically deforming metal, followed by weakening of adjacent metal bonds.
Hydrogen Sulfide Stress Corrosion Cracking of High Strength Steel Wire
Authors: TOWNSEND H. E.
Published: February 2013

High strength (244,000 psi ultimate tensile strength) cold drawn carbon steel wire is susceptible to cracking in hydrogen sulfide solutions at room temperature at stress levels less than 15% of the ultimate strength. Failure occurs with an unusual tendency for cracks to form at 45 degrees to the direction of tensile stress. Time to failure is decreased by cathodic polarization and is increased by anodic polarization. Susceptibility reaches a maximum at near room temperature and decreases at both lower and higher temperature. These facts are consistent with a hydrogen embrittlement mechanism of failure. The buildup of large pressures of molecular hydrogen within hollow steel cylinders exposed to H2S solutions is found to be much greater at the higher temperatures at which cracking susceptibility abates. The latter observation is contrary to the predictions of a mechanism of hydrogen embrittlement based on molecular hydrogen pressure but it is shown to be consistent with those of an internal adsorption mechanism.
Effect of Chloride Ion Concentration on the Polarization Behavior of an Fe-25Ni Alloy
Authors: CONDIT DALE O.
Published: February 2013

The polarization behavior of a high purity Fe-25Ni was determined as a function of the chloride ion (Cl−) concentration in a 1N H2SO4 solution. The anodic Tafel slopes were increased while the cathodic Tafel slopes were unchanged by increases in the (Cl−) concentration. However, a parallel shift in the cathodic curve in the noble potential direction was noted. Except for the increase in the anodic Tafel slopes, the active portion of the polarization curves were unaffected by the presence of (Cl−). The passive state of the alloy was greatly affected by increases in the (Cl−) concentration. At concentrations between 300 and 400 ppm rapid changes in the passive current density were observed. At concentrations greater than about 400 ppm, the passive state was no longer exhibited; and dissolution of the alloy occurred continuously throughout the anodic polarization test.
A Critical Appraisal of Some Popular Laboratory Electrochemical Tests for Predicting the Localized Corrosion Resistance of Stainless Alloys in Sea Water
Authors: WILDE B. E.
Published: February 2013

Evidence is presented to demonstrate that although the critical pitting potential is qualitatively related to the resistance of a material to passivity breakdown by pit initiation, it is of questionable value in predicting the corrosion performance off a structure containing crevices. Experiments conducted on a 30Cr-3Mo-Fe alloy indicated total immunity to passivity breakdown by pit initiation during anodic polarization in 1M NaCl and under freely corroding conditions in acidified 10% FeCl3. However, on specimens containing an artificial crevice, passivity breakdown by crevice corrosion initiation was observed in the same two media. The long term implications of these data were confirmed by 16 month immersion tests in sea water, where severe crevice attack was noted equal in extent to that observed on A9SS Types 304 and 316 stainless steels whose pit initiation properties were considerably inferior to those of the 30Cr-3Mo-Fe alloy. The results of cyclic potentiodynamic anodic polarization experiments conducted on A8S1 Type 430 stainless steel are presented to demonstrate that the so called protection potential, Ep, is not a unique material parameter. It is shown that Ep varies in a semi logarithmic manner with the amount of localized attack induced by polarization; that is, with the chemistry changes in the growing pit caused by hydrolysis of corrosion products and chloride ion buildup in the pit cavities. On this basis, it is concluded that Ep data (however determined) cannot be used alone as a criteria for protection against the propagation of pre-existing pits or crevices in an engineering structure. Based on cyclic polarization procedures, a method of assessing the susceptibility and resistance of an alloy to crevice corrosion is suggested. It is shown that, for alloys which initiate pits during anodic polarization, the magnitude of the “difference potential” (Ec-Ep) is related to the crevice corrosion weight loss. For alloys that have no critical pitting potential, the presence of hysteresis during cyclic polarization with an artificial crevice indicates susceptibility to crevice corrosion.
Stress Corrosion Cracking of Carbon Steel in Carbonate Solutions
Authors: SUTCLIFFE J. M. , FESSLER R. R. , BOYD W. K. , PARKINS R. N.
Published: February 2013

From observations of the characteristics of nitrate and hydroxide solutions, known to promote stress corrosion cracking (SCC) in carbon steels, and from the form of potentiodynamic polarization curves and the structural dependence of the corrosive attack, it was predicted that carbonate solutions would also produce intergranular stress corrosion in carbon steels. Constant strain rate stress corrosion tests, with some supplementary constant strain and constant load tests, have shown that intergranular cracking can be made to occur in certain ranges of electrode potential in carbonate solutions over a wide range of concentrations and temperatures with NH4, Na, or K as the cation. The range of potentials for cracking, which varies with solution composition and temperature, is shown to coincide with that range in which polarization curves obtained at different sweep rates indicated marked anodic activity and strong passivating tendencies. At more negative potentials than those that promote intergranular cracking, superficial transgranular fissuring is first detected and then, as the potential is moved toward even more negative values, a progressive loss in ductility is observed due to hydrogen entry into the steel.
Hydrogen Evolution on Copper in H2 SO4 Containing Benzotriazole
Authors: ALTURA DAN , NOBE KEN
Published: February 2013

The rate of hydrogen evolution on copper in acidic solutions containing benzotriazole has been investigated. The rate of hydrogen evolution decreased with an increase in concentration of benzotriazole up to about 7 mM. The reaction orders and the Tafel slopes were approximately the same for uninhibited and inhibited copper, indicating that the mechanism of hydrogen evolution was not changed by the presence of benzotriazole. Differential capacitances of uninhibited copper were about 28 μf/cm2, but capacitances of inhibited copper decreased with increasing inhibitor concentration approaching a limiting value of 1 μf/cm2. The adsorption of the organic inhibitor follows Langmuir adsorption behavior with an adsorption constant of 7.2 mM−1.
Effect of Ni Additions Upon the Stress Corrosion of Ferritic Steels in a Chloride Environment
Authors: POULSON B. S. , PARKINS R. N.
Published: February 2013

Although mild steels will not fail by stress corrosion cracking (SCC) in a boiling MgCl2 solution, the addition of only 1% Ni to such steels will promote a susceptibility that becomes more marked at higher Ni contents. Constant strain rate stress corrosion tests, together with fractographic examination of failed specimens and the determination of relevant polarization curves, have been employed in order to ascertain the roles of both Ni and Cl− in the cracking mechanism. It seems that failures of Ni containing “mild steels” in concentrated chloride solutions are most readily explicable in terms of Ni promoting Cl adsorption which subsequently inhibits anodic dissolution. The mechanism of crack propagation is thought to be dependent on dissolution processes, possibly aided by mechanical tearing.
Passivity of Zirconium In Sulfuric Acid Solutions–Effect of Cathodic Pretreatment
Authors: ELAYAPERUMAL K. , CHOUTHAI S. S. , BALACHANDRA J.
Published: February 2013

The effect of cathodic pretreatment at −1.3 V vs a saturated calomel electrode (SCE) on the passivity of Kroll zirconium in 5, 10, and 20 vol % H2SO4 solution at room temperature was determined through potentiostatic anodic polarization studies. The cathodic treatment made the attainment of passivity easier and reduced the passive currents considerably. Studies on potential vs time and active and passive currents vs time indicated a protective film formation during the cathodic treatment. The possibility of a zirconium oxide film formation due to cathodic polarization induced alkalinity at −1.3 V (SCE) is discussed.
Corrosion of Metals by Liquid Bismuth-Tellurium Solutions
Authors: KANNE W. R.
Published: February 2013

Corrosion of candidate materials of construction for stills to extract radioactive polonium-210 from bismuth by distillation at temperatures of 450 to 950 C (842 to 1742 F) was evaluated. Tellurium, being chemically similar to polonium, was used as a nonradioactive stand-in for polonium. Tantalum appears to be the most satisfactory material from the standpoint of long term corrosion and fabricability. Tantalum was corroded at rates up to 2 × 10−5 in/hr during the initial 100 to 200 hours exposure; the rate decreased to below 2 × 10−6 in/hr after 400 hours for concentrations of tellurium in bismuth of less than 30%. Graphite was not attacked chemically, but was penetrated through pores. TZM alloy exhibited average corrosion rates of less than 6 × 10−6 in/hr during 500 hours exposure in less than 20% tellurium in bismuth, but corroded rapidly (7.2 × 10−5 in/hr) in 50% tellurium. The stainless steels, particularly Type 430, might be used to approximately 550 K (276.85 C); but corrosion rates increased above 3 × 10−5 in/hr for a 15% solution of tellurium in bismuth at higher temperatures.
Electrochemical Measurements of Corrosion Processes in a Boiling Water Nuclear Reactor
Authors: COWAN R. L. , KAZNOFF A. I.
Published: February 2013

The results of an electrochemical investigation of the corrosion behavior of reactor structural materials determined both in and out of reactor are presented. Electrochemical kinetic measurements in and out of reactor were fairly difficult to obtain because of the high purity (and associated poor conductivity) of the electrolyte. Three methods were used to account for the high values of overpotential cause by IR effects. All three methods gave similar results. The kinetic data showed large regions of linear behavior (500 mV overpotential cathodic and 200 mV overpotential anodic) on the materials studied. No correlation was found between electrochemically calculated corrosion rates and descaled weight loss measurements on identical material. It was concluded that electrochemical reactions involving dissolved O2 and H2 were playing a dominant role and obscuring the contribution from metal oxidation. Selected potential measurements were made with a specially designed 0.01 N Ag/AgCI electrode which allowed determination of electrode potentials on the standard hydrogen scale at 266 and 288 C (510 and 550 F). A system designed to allow electrochemically controlled sustained load stress corrosion tests in high temperature electrolytes is described. The results from these tests agree with results from more conventional tests.
Temperature as a Crevice Corrosion Criterion
Authors: BRIGHAM R. J.
Published: February 2013

Using temperature as a crevice corrosion criterion, a number of commercial and experimental Mo-bearing 18% Cr austenitic stainless steels have been evaluated for crevice corrosion resistance. These data have been correlated with the effect of Mo content on the rate of active corrosion in the very aggressive acid solution expected in the crevice itself. Alloyed Mo has been found to play the dominant role in reducing the relative rate of crevice corrosion and in defining the go/no-go crevice corrosion behavior in terms of the crevice corrosion temperature (CCT) in oxidizing acid chloride solutions. For 18% Cr austenitic stainless steels the empirical relationship has been found.
Use of Galvanokinetic Methods for the Determination of Characteristic Potentials for Pitting Corrosion on Aluminum
Authors: BROLI AASMUND , HOLTAN HANS , PRESTRUD KRISTOFER L.
Published: February 2013

Three different galvanokinetic methods have been used to determine the pitting potential (Ep) and the protection potential against pitting (Epp) for unalloyed aluminum in a deareated solution of 3% NaCI at 0 and 30 C (32 and 86 F). These three methods are (1) the continuous galvanokinetic, (2) the quasistationary galvanokinetic, and (3) the stationary galvanokinetic. From results of these investigations, determination of the potentials appears dependent on which of these three methods is used. It seems the quasistationary method gives the results with the best reproducibility. The results also supports the theory that aluminium does not have more than one characteristic potential for pitting corrosion under these special conditions. This theory was previously published by Broli and Holtan.1 The stationary method provides the possiblity for an approximation of the critical current density for aluminium dissolution.
Naval Brass Condenser Tube Corrosion
Authors: ALBAYA H. C. , BESSONE J. B. , TABERNER P. M. , COBO O. A.
Published: February 2013

Results of corrosion rates in brass tubes calculated from weight loss data obtained on equipment which simulates the operating conditions of a condenser are presented. These values are compared with electrochemical polarization measurements, and the applicability of the Stern and Geary equation is discussed.
Effect of Strain Rate on Stress Corrosion Cracking of Austenitic Stainless Steel in MgCl2 Solutions
Authors: TAKANO MICHINORI
Published: February 2013

The effect of strain rate on the stress corrosion cracking (SCC) of an austenitic stainless steel in MgCl2 solutions has been investigated by using a constant strain rate method over the range of strain rates from 4 x 10−3 mm/min to 6 mm/min. Crack propagation mode (intergranular vs transgranular) was a function of strain rate and temperature. At low strain rates, the rate determining step of the SCC corresponded to the formation of slip steps, but at higher strain rates, the rate determining step appeared to be a corrosion process on the slip steps. SCC was most prevalent when the formation rate of the slip steps was equal to the corrosion rate of the steps. The mechanism of SCC in this system has been discussed by considering both the formation rate of slip steps and the corrosion rate of these steps.
An Electrochemical Evaluation of 3003, 3004, and 5050 Aluminum Alloys for Desalination
Authors: BONEWITZ R. A.
Published: February 2013

Aluminum alloys 3003, 3004, and 5050 were evaluated for desalination applications by means of their anodic polarization curves determined in 1X synthetic sea water at 25 C (77 F) to 150 C (302 F). Pitting performance was established from the relative values of the corrosion potential and the breakdown and protection potentials, and general corrosion rates were calculated from corrosion currents determined by the slop-intercept method. Pitting is not anticipated for 3003 and 3004 alloys at temperatures to 150 C and for 5050 alloy to 125 C (257 F). General corrosion rates for these alloys were less than 1 mpy.
Relation Between Surface Slip Topography and Stress Corrosion Cracking in Ti-8 Wt % Al
Authors: BOYD J. D. , HOAGLAND R. G.
Published: February 2013

The deformation behavior of Ti-8 Wt % Al has been investigated in an inert environment (air), and an aggressive environment (salt water). Details of surface slip geometry were examined by high resolution surface replicas at various stages of deformation in both environments. Specimens aged to contain a fine dispersion of Ti3Al precipitates failed by subcritical crack growth in salt water, whereas specimens in the single phase condition showed no effects of environment on the yield or fracture characteristics. The Ti3Al precipitates produce little change in strength level or slip character compared to the single phase alloy, and there is no evidence of any effects of environment on the character of surface slip. Rather, the presence of trenches along slip bands on the surface of aged specimens suggest that the specific effect of the Ti3Al precipitates is to render the surface slip steps chemically active relative to the surrounding matrix by slip induced dissolution of the particles.
Effect of Alloy Structure, Hydroxide Concentration, and Temperature on the Caustic Stress Corrosion Cracking of Austenitic Stainless Steels
Authors: WILSON I. L. , PEMENT F. W. , ASPDEN R. G.
Published: February 2013

Caustic stress corrosion cracking (SCC) experiments have been conducted on Type 304, 304L, 316, 316L, and USS 18-18-2 stainless steels. The environments used were deoxygenated 50% NaOH solution at 316 and 371 C (600 and 700 F), deoxygenated 10% NaOH solution at 316 C and atmospheric boiling [~149 C (300 F)] 50% NaOH. The effect of grain size, cold work, and sensitization has been studied. Metallurgical structures were examined with light microscopy and the accelerated Strauss test. Exposed specimens were studied with the light microscope and the fracture surfaces were studied with the scanning electron microscope (SEM). Variations in crack morphology were observed with caustic concentration and alloy content. Certain sensitization treatments were the only conditions identified in Type 304 as beneficial in increasing the high temperature caustic stress corrosion resistance.
A Potentiostatic Method of Evaluating the Dezincification Tendencies of Brasses
Authors: COSTAS L. P.
Published: February 2013

Details of sample preparation, cell construction, and electrolyte composition are described. Metallographic examination of sample after running at 0 mV (SCE) for 24 hours is used to determine whether an alloy is susceptible to dezincification.
Stress Corrosion Cracking Behavior of Uranium Alloys
Authors: CZYRKLIS W. F. , LEVY M.
Published: February 2013

The stress corrosion cracking (SCC) behavior of U-3/4% Ti, and uranium alloys 3/4% Quad, 1% Quad, and 1% Quint have been studied utilizing a linear elastic fracture mechanics approach. The threshold stress intensities for stress corrosion crack propagation for these alloys have been determined in distilled H2O and NaCl solutions containing 50 ppm Cl− and 21,000 ppm Cl−. All of the alloys studied may be classified as very susceptible to SCC in aqueous solutions since they exhibit SCC in distilled H2O (<1 ppm Cl−) and have low KIscc values in NaCl solutions. Crack extension in all of the alloys in all environments was transgranular and failure occurred by brittle quasicleavage fracture in NaCl solution.
Corrosivity of Pressurized Liquids in Aerosol Cans
Authors: SU L. S. , SHEPPARD E.
Published: February 2013

The complex corrosion mechanisms for pressurized aqueous solutions in contact with various aerosol containers were studied electrochemically. A pressurized corrosion cell consisting of an aerosol container serving as the working electrode, a platinum rod serving as a hybrid reference-counter electrode, and the pressurized liquids as the electrolyte was designed and fabricated. The correlation of the results between two accelerated electrochemical corrosion tests, namely the galvanostatic polarization test and a 24-hour accelerated constant polarization potential test, and a 10-week storage test, was excellent. It was found that the addition of 0.1%disodium phosphate (DSP) to the aqueous solutions pressurized with a 10% isobutane-propane propellent blend changed the color of the systems to colorless, produced an electrodeposition of colloidal particles, and shifted the site of the crevice corrosion from the bulk-stagnant interface towards the stagnant area. Three distinct and characteristic zones of the polarization potential responses were observed during the anodic galvanostatic polarization measurements, and their mechanisms are discussed.
Observations on the Stress Corrosion Cracking of an Al-5%Zn-2.5%Mg Ternary and Various Quaternary Alloys
Authors: GREEN J. A. S. , MONTAGUE W. G.
Published: February 2013

Studies were undertaken to test a concept of controlling stress corrosion crack propagation in Al-Zn-Mg alloys through the use of minor alloying additions of elements known to retard hydrogen ion recombination. Previous work suggested that the recombination of hydrogen ions governs the rate of anodic dissolution and, in turn, the rate of crack propagation in these alloys. Results indicated that the concept was invalid since the minor alloying additions themselves exerted a more profound influence on the grain boundary microstructure. Specifically, the microstructural features of grain boundary particle size and interparticle spacing were found to correlate with stress corrosion susceptibility. Auger electron spectroscope studies also revealed a correlation between the concentration of Zn and Mg within the precipitate-free zone and the susceptibility to cracking.
Laboratory Studies of Galvanic Corrosion I. Two-Metal Couples
Authors: MANSFELD F. , KENKEL J. V.
Published: February 2013

Galvanic interaction of stainless steel 304L, Ni 270, Cu, Ti-6AI-4V, Sn, 4130 steel, Cd, and Zn has been studied in 3.5% NaCl using galvanic current and weight loss measurements in 24-hour tests. Galvanic couples of 4130 steel and one of the Al alloys 1100, 2024, 2213, 6061, and 7075 have also been evaluated in tap water and distilled water. Galvanic current data can be used to assess both the effect of different dissimilar cathode materials as well as the relative susceptibility to galvanic corrosion of anode materials. For 3.5% NaCl, it has been found that the effect of the cathode material decreases in the order Cu > Ni > stainless steel >Ti-6Al-4V, while the relative susceptibility of anode materials decreases in the order Sn > Zn > 4130 steel > Cd. An analysis of data in various electrolytes shows that coupling of 4130 steel to Al alloys leads to cathodic protection of the steel in 3.5% NaCl, but to accelerated corrosion in tap water and distilled water.
Influence of Halides in Phosphoric Acid on the Corrosion Behavior of Stainless Steels
Authors: ALON A. , YAHALOM J. , SCHORR M.
Published: February 2013

The corrosion and electrochemical behavior of austenitic stainless steels in pure H3PO4, in the presence and absence of fluoride, chloride, and bromide, have been investigated in the 20 to 120 C (68 to 248 F) temperature range. Significant corrosive attack of Types 304 and 316 steels in pure H3PO4 starts to occur at about 60 C (140 F) and 90 C (194 F), repsectively. Up to these temperatures, these steels exhibit passivity, but with the increase of temperature, breakdown of passivity occurs, the potential becomes active, and an intense corrosive attack is established. The values of electrochemical parameters indicate corrosion, e.g., critical current density, change from system to system, in accordance with their respective corrosion rates. The presence of halide ions in H3PO4 affects the corrosion rate, the change in rate being dependent upon the free halide ion concentration, its chemical reactivity, and the ionic size. Values of the critical current density, passive current density, and corrosion potential change accordingly. The corrosion activity of halides in 30% and 50% H3PO4 follows the sequence: F− >Cl− >Br− and: Cl− > F− >Br− in 70% and 85% H3PO4.
Stress Corrosion Cracking of Mild and Low Alloy Steels in CO-CO2-H2O Environments
Authors: KOWAKA MASAMICHI , NAGATA SABURO
Published: February 2013

This paper is related to the new stress corrosion cracking phenomenon of mild and low alloy steels in a CO/CO2 environment. The incidents of cracking are described and these were reproduced by laboratory tests. The results obtained are as follows: (1) No stress corrosion cracking of mild steel was found to occur in water containing just CO or CO2. (2) The transgranular stress corrosion cracking occurred only in CO/CO2 environment with water. (3) Stress corrosion cracking occurred in a wide range of CO/CO2 ratios in water. (4) The susceptibility to stress corrosion cracking of mild steel decreases with increasing temperature. (5) No stress corrosion cracking was found to occur on 18Cr-10Ni stainless steel. (6) From the study of electrochemical measurements, the mechanism has been proposed that this form of cracking is stress corrosion cracking rather than hydrogen embrittlement. (7) Prevention of stress corrosion cracking in these environments is discussed.
A Versatile Polarization Cell System
Authors: GEISERT R. E. , GREENE N. D. , AGARWALA V. S.
Published: February 2013

Although numerous polarization cells have been designed for electrochemical measurements, many of them are complex in design and not easily modified for special experiments. There is a need for an adaptable polarization cell which can be employed for a wide variety of experiments. A new polarization cell system utilizing commercially available glass pipe and simple TFE parts has been developed to meet these needs. This system is simple and rugged and can be adapted, without fabricating special components, to perform: (1) multicompartment measurements; (2) multielectrode studies; (3) electrochemical measurements in large electrolyte volumes; (4) flow studies; (5) elevated temperature measurements; (6) optical studies of polarized electrodes; (7) electrochemical measurements in actual process streams; and (8) studies of stressed metal specimens.
Deformation of Iron Oxides Formed in Caustic Electrolyte
Authors: DIEGLE RONALD B. , VERMILYEA DAVID A.
Published: February 2013

Straining electrode experiments have shown that Fe3O4 grown on iron in NaOH electrolyte at 85 C fractures at strains ranging from less than about 3 × 10−4 to 3 × 10−3. Films less than 100 Å thick fracture at the smaller strain, whereas 1 μm films fracture at the larger value. Fracture strain is potential dependent, being least in the active-passive potential region of polarization behavior and increasing as the film growth potential becomes more anodic. These observations were used to interpret the potential dependence of caustic stress corrosion cracking (SCC) according to a film rupture model.
Triazole, Benzotriazole, and Naphthotriazole as Corrosion Inhibitors for Brass
Authors: WALKER R.
Published: February 2013

The use of triazole, benzotriazole, and naphthotriazole as corrosion inhibitors for brass is briefly reviewed. The corrosion of 70/30 brass immersed in a wide range of solutions is reported both with and without the inhibitors. The inhibitor efficiency of benzotriazole is given as a function of the solution pH and the concentration used. Triazole was only effective in mildly corrosive solutions and benzotriazole and naphthotriazole were much better. Generally naphthotriazole was better than benzotriazole but is much more expensive and a higher concentration of benzotriazole can give the same protection as naphthotriazole at a much lower cost.
Internal Hydrogen Embrittlement of Gamma-Stabilized Uranium Alloys
Authors: POWELL G. L. , KOGER J. W. , BENNETT R. K. , WILLIAMSON A. L. , HEMPERLY V. C.
Published: February 2013

Relationships between the tensile ductility and fracture characteristics of as-quenched, gamma-stabilized uranium alloys (uranium-10 Wt% molybdenum, uranium-8.5 Wt% niobium, uranium-10 Wt% niobium, and uranium-7.5 Wt% niobium-2.5 Wt% zirconium), the hydrogen content of the tensile specimens, and the hydrogen gas pressure during the annealing at 850 C of the tensile test blanks prior to quenching have been established. For these alloys, the tensile ductility decreases only slightly with increasing hydrogen content up to a critical hydrogen concentration above which the tensile ductility drops to nearly zero. The only alloy not displaying this sharp drop in tensile ductility was U-7.5 Nb-2.5 Zr, probably because sufficiently high hydrogen contents could not be achieved under our experimental arrangements. The critical hydrogen content for ductility loss increased with increasing hydrogen solubility in the alloy. Fracture surfaces produced by internal hydrogen embrittlement do not resemble those produced by stress corrosion cracking (SCC) in aqueous environments containing chloride ions.
Some Electrochemical Aspects of the Stress Corrosion Cracking of Steels in Liquid Ammonia Environments
Authors: DEEGAN D. C. , WILDE B. E. , STAEHLE R. W.
Published: February 2013

Some electrochemical aspects of the stress corrosion cracking (SCC) behavior of ASTM A517 Grade F steel in liquid ammonia environments at 25 C have been studied. Electrode potentials were measured during SCC tests by means of thallium/saturated thallous chloride/ammonia reference half cell. The effects of controlled additions of oxygen and nitrogen (species in combination known to cause SCC), as well as the inhibitive properties of water, were investigated. The test results indicate that an oxygen-bearing film forms on the metal surface after which passive-range potentials near +400 mV are observed. Under film-free conditions, potentials near −150 mV were measured. From coulometric measurements, film thicknesses were estimated at 3 to 5 monolayers coverage. SCC in this system can best be described by a film rupture model in which crack initiation occurs at local sites of film breakdown due to straining. The role of water as an inhibitor is to assist in the repassivation of the surface films, as indicated by the fact that water additions promote more noble potentials (+500 mV).
The Effect of Uncompensated IR-Drop on Polarization Resistance Measurements
Authors: MANSFELD FLORIAN
Published: February 2013

A theoretical analysis of the effect of uncompensated IR-drop on polarization resistance (Rp) measurements is given, which shows that it is not the absolute value of the solution plus surface film resistance (RΩ) which determines the error due to IR-drop, but the ratio (RΩ/Rp) An error is possible even in solutions of moderate to high conductivity, if corrosion rates are high. The experimentally determined polarization resistance (Rp) is the sum of the true polarization resistance (Rp) and the ohmic resistance (RΩ). If no corrections are made, polarization resistance values will be determined too high and consequently corrosion rates will be found too low. The effect of uncompensated IR-drop on measured polarization curves is shown. Experimental data with and without IR-drop compensation (“positive feedback”) confirm the theoretical considerations.
A Fractographic Analysis of Environmental Fatigue Crack Propagation in Ti-6AI-4V Sheet
Authors: WANHILL R. J. H.
Published: February 2013

A fractographic survey of environmental fatigue crack propagation in mill annealed Ti-6AI-4V sheet was carried out. The environments were dry argon, normal air, distilied water, and 3.5% aqueous NaCl. Test frequencies were 30 and 50 Hz. Fatigue striations were not observed for fractures in dry argon except at low growth rates. There was a striking difference between the fracture surfaces in gaseous and aqueous environments. A detailed explanation of the appearances of fractures in aqueous environments is given. Striation spacings were only in reasonable agreement with the macroscopic growth rate/cycle over a middle range in growth rates. The practical significance of these observations is discussed.
Hydrogen Diffusion Coefficients in Ferrovac 1020 and Cr-Mo Alloy Steels
Authors: ANGELES OLIMPIO F. , STUEBER RICHARD J. , GEIGER GORDON H.
Published: February 2013

Hydrogen diffusion coefficients were measured in Ferrovac 1020 and several Cr-Mo alloy steels at temperatures between 700 and 1150 F (370 and 620 C), using the time-lag method. Alloying was found to decrease the diffusion coefficient.
Stress Corrosion Cracking in Fe-Mn-Cr Alloys
Authors: SPEIDEL MARKUS O.
Published: February 2013

The stress corrosion resistance of austenitic chromium-maganese steels has been measured using fracture mechanics techniques. The resulting crack velocity-stress intensity curves resemble those observed with other material-environment combinations. High strength, nonmagnetic austenitic steels of the 18% Mn-5% Cr-0.5% C variety exhibit both intergranular and transgranular stress corrosion cracking (SCC) in distilled water at room temperature. Important mechanical and environmental effects on stress corrosion crack growth are measured and discussed.
Ellipsometric Studies on Iron Oxide Film Growth at 100 to 350 C
Authors: SZKLARSKA-SMIALOWSKA Z. , JUREK J.
Published: February 2013

Ellipsometric measurements of oxide film formed at 100 to 350 C in air were performed on a steel specimen. The complex indices of refraction of individual layers in the multilayer oxide film and their thicknesses were determined. The kinetics of oxide film formation was studied and the activation energy for film formation was calculated.
The Construction and Performance of a Silver/Silver Chloride Reference Electrode for High Temperature Aqueous Environments
Authors: MAGAR I. J. , MORRIS P. E.
Published: February 2013

A step-by-step procedure is described for constructing a single compartment, PTFE-contained silver/silver chloride reference electrode. Representative electrochemical measurements have shown that this reference electrode functions accurately at temperatures up to 316 C and test periods greater than two months.
The Effect of Boron on the Corrosion Resistance of Austenitic Stainless Steels
Authors: ROBINSON F. P. A. , SCURR W. G.
Published: February 2013

Two Type 304 stainless steels, one boron free and the other containing 4 ppm boron were investigated. Both steels were subjected to an identical series of corrosion tests and the results compared with one another. It was found (1) Boron had no detrimental effect on the potentiostatic characteristics, intergranular corrosion “resistance and pitting resistance of the steels in the “as-received” condition; (2) boron in solid solution had no detrimental effect on the potentiostatic characteristics and intergranular corrosion resistance of the steel, while boron in solution had a beneficial effect on the pitting resistance of the steel, and (3) boron retarded Cr23C6 precipitation and thus boron had marked beneficial effects on the intergranular corrosion resistance of the steels in a sensitized condition. In addition the potentiostatic characteristics and pitting resistance of such steels were improved slightly by the presence of boron.
Electrochemical and Corrosion Behavior of Iron in Presence of Substituted Benzotriazoles
Authors: ELDAKAR NADIA , NOBE KEN
Published: February 2013

The effect of benzotriazole (BTA), 5-methyl, 5-carboxy, 5-amino, 5-chloro, and a mixture of 5-carboxy and 4-carboxy benzotriazoles on iron corrosion and hydrogen evolution in H2SO4 was examined. At the concentrations of maximum inn bition, corrosion inhibition increased in the following order: NO2 - < Cl - < mixed COOH - < COOH - < BTA ≈ CH3 - < NH2 -. The results indicate that the COOH-BTA, and the mixed COOH-BTA were the most effective inhibitors on the basis of the quantity of organic required for maximum inhibition. An apparent linear free energy relationship was obtained for the corrosion rate at the concentrations of maximum inhibition.
The Influence of Contaminants on the Failure of Protective Organic Coatings on Steel
Authors: KOEHLER E. L
Published: February 2013

While the ability of the organic coating to conduct corrosion currents may sometimes come into play, primarily the corrosive deterioration of protective organic coatings is brought above by the flow of corrosion currents through a film of electrolyte beneath the organic coating. Any of several specific mechanisms may be involved. The influences of contaminants lie in their abilities to: (1) draw water through the organic coating to establish a conductive film of moisture, (2) provide ions to carry the corrosion currents, and (3) provide ions of specific effect on underfilm corrosion mechanisms. Specific attention is given here to the effects of underfilm salt contaminants on atmospheric corrosion. Filiform corrosion observed is interpreted as a form of anodic undermining corrosion, which involves transport of the anion and the effect of the anion on the dissolution of metal from beneath the organic coating. Cathodic detachment, also observed, is interpreted in terms of cationic transport and the ability of the specific cation to form a strongly basic solution, resulting in loss of organic coating adhesion by water displacement.
An Intergranular Fracturing Technique for Grain Boundary Segregation Studies of Austenitic Stainless Steel
Authors: PARK J. Y. , DANYLUK S.
Published: February 2013

A creep-deformation, heat treatment impact-fracture technique that can be used to produce grain boundary surfaces is described. The technique is especially useful for exposing grain boundaries of austenitic stainless steels and can also be used with surface-sensitive analytical techniques. Intergranular fracture surfaces of Type 304 stainless steel have been produced using this technique. Auger electron spectroscopy analysis was performed on these fracture surfaces.
Reflectance Infrared Study of the Oxidation of Stainless Steels and Component Metals
Authors: MERTENS F. P.
Published: February 2013

Reflectance infrared studies of the oxidation of Types 304, 316, and 410 stainless steels, in oxygen at various temperatures, are described. Similar studies, directed toward the interpretation of the stainless steel oxide reflectance spectra, are presented for iron, nickel, molybdenum, and chromium. The value of the technique in providing a record of oxide compositional changes with time and temperature is demonstrated. It was concluded that Fe2O3 is the dominant constituent of oxide films formed on the three stainless steels at 400 to 500 C. At 850 C, chromia-iron oxide spinels, Fe2O3 and Cr2O3 were observed on Types 304 and 316 stainless steel, while chromia rich spinels or Cr2O3 formed on Type 410 stainless steel. Appreciable concentrations of nickel oxide on Types 304 and 316 stainless steel or molybdenum oxides on Type 316 stainless steel were not detected at temperatures up to 850 C. The formation of minor oxide constituents in both the stainless steel and component metal oxide films is discussed.
An Electrochemical Investigation of Fretting Corrosion of Surgical Implant Materials
Authors: SYRETT BARRY C. , WING SHARON S.
Published: February 2013

The fretting corrosion resistances of two alloys that are currently used in surgical implants (Type 316L stainless steel and cast Vitallium alloy) have been compared with the resistances of two high strength, highly ductile, metastable austenitic stainless steels (TRIP steels). The fretting corrosion apparatus used allowed control of the environmental composition, the vibrational amplitude, the vibrational frequency, and the stress between the two metal surfaces in fretting contact. The rate of corrosion of the contacting surfaces during fretting was significantly higher than the rate before or after the fretting period, and the corrosion rate during fretting generally increased with time. Corrosion rate data taken after 30 minutes of fretting indicated a linear dependence on amplitude, frequency, and contact stress. Cast Vitallium alloy appeared to have a somewhat higher resistance to fretting corrosion than the other three alloys. The available data suggests that fretting increases the corrosion rate because the passive surface film is repeatedly disrupted and repaired. However, the rate of corrosion appears to be controlled by the rate of oxygen transport from the bulk solution to the cathodic sites on the metal surface.
Effect of Alternating Current on Corrosion of Low Alloy and Carbon Steels
Authors: JONES D. A.
Published: February 2013

The corrosion rates of low alloy steel and carbon steel in 0.1 N NaCI were accelerated by factors of 4 to 6 when an alternating current density of 30 mA/cm2 (60 cps) was applied in dilute salt solutions purged with nitrogen. Tests with low frequency alternating anodic and cathodic current showed that both steels polarized more rapidly in the cathodic direction than in the anodic. Thus, the anodic half-cycle of AC did not have time to restore the potential to its original value after the preceding cathodic half-cycle. The result is a net cathodic polarization which accelerates or “depolarizes” the anodic metal-dissolution reaction by lowering the anodic Tafel slope. Depolarization of the anodic reaction was confirmed by polarization measurements in the presence of AC. Depolarization of the anodic reaction by AC was also observed in aerated solutions, but the corrosion rate was controlled by diffusion of dissolved oxygen, and no increase in corrosion rate was measured. Possible mechanisms of anodic depolarization are discussed.
Observation of Hydrogen Trapping in Fe-0.15 Wt% Ti Alloy by High Resolution Autoradiography
Authors: ASAOKA T. , LAPASSET G. , AUCOUTURIER M. , LACOMBE P.
Published: February 2013

The technique of microautoradiography at the electron microscope scale is used to describe the local repartition of hydrogen introduced by cathodic charging in an Fe-Ti alloy (0.15 Wt% Ti). The role of previous heat treatments of the alloy is studied. Different kinds of trapping sites for hydrogen are observed, mainly decorated dislocations, grain boundaries and interfaces between TiC precipitates and the matrix. A qualitative measurement of the quantity of trapped hydrogen and of the degassing rate leads to a classification of the traps with respect to their interaction energy with hydrogen. The consequence of carbon-hydrogen interactions on the further cracking sensitivity of the alloy, as influenced by the thermal history and carbide repartition, is discussed.