bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Crystal Orientation on the Anodic Polarization and Passivity of Zinc
Authors: ASHTON RICHARD F. , HEPWORTH MALCOLM T.
Published: February 2013

Potentiostatic polarization measurements on exposed (0001), (1010), and (1120) faces of single crystals and on polycrystalline zinc were made in aqueous solutions of sodium hydroxide. Crystal orientation was observed to have a well defined effect on anodic polarization with overvoltages for active dissolution increasing with increasing density of crystal planar packing. Potentials for passivation were equal for (0001) and (1010) crystal specimens, which were both noble to potentials for (1120) specimens.
Stress Corrosion Cracking of Alpha Titanium Alloys at Room Temperature
Authors: POWELL D. T. , SCULLY J. C.
Published: February 2013

Transgranular stress corrosion cracks are formed in Ti-5Al-2.5Sn alloy immersed in a 3 percent NaCl aqueous solution when tensile specimens are dynamically strained over a narrow range of rates. Metallographic evidence suggests that the critical process during crack propagation is entry of hydrogen into the alloy at the crack tip immediately following creation of fresh metal surface. Fractographic examination reveals that cracks propagate by a discontinuous cleavage mechanism. As each incremental growth is arrested, the embrittlement process resumes. Ductile fracture is observed in specimens strained (a) at high tensile rates because there is insufficient time for embrittlement to occur, and (b) at low tensile strain rates because repassivation occurs more readily and hydrogen entry is substantially reduced. In methanolic solutions containing HCl, an identical cleavage crack propagation process is observed. In addition, a slow intergranular dissolution mechanism is found in alloys susceptible and nonsusceptible to cleavage-type failure. This is initiated in specimens that have regions of high residual stress, e.g., sheared edges and continues until the mechanical strength of the alloy is reduced to a very low value. During this process hydrogen is picked up by the metal. Clevage has been observed in specimens broken in air after exposure. Vacuum annealing substantially reduces but does not eliminate this slower form of attack by removing initiation sites. Anodic polarization at low current densities produces extremely severe intergranular attack. The significance of dislocation arrangements, mechanical properties, and electrochemical reactions at the crack tip are discussed in detail. In particular, it is suggested that cathodic polarization can prevent cracking by forming films which reduce the rate of hydrogen ingress. In 10N HCl solutions, cathodic polarization does not prevent cracking.
Mechanisms of Sensitization and Stablization of Incoloy Nickel-lron-Chromium Alloy 825
Authors: RAYMOND E. L.
Published: February 2013

Incoloy(1) nickel-iron-chromium Alloy 825 can become sensitive to intergranular attack by exposure to temperatures in the 1200–1400 F (649–760 C) range. Sensitivity to intergranular attack (as measured by the Huey test) can be correlated to the presence of a chromium-depleted area adjacent to the grain boundary. This area is caused by the cellular precipitation of chromium-rich M23C6 during sensitizing treatments. The chromium-depleted region is between the M23C6 cells, but because the carbides grow by boundary migration the depletion is not in the plane of the grain boundary. Incoloy Alloy 825 can be stablized against intergranular attack by eliminating the chromium-depleted area. The degree of stabiization is related to the amount of carbon remaining in solution after the stablizing treatment. The titanium content of the alloy helps to effect stabtization. Because it has a greater affinity for carbon than does chromium, the titanium reacts to form stable carbides and thus reduces chromium depletion. Maximum stabtization of Incoloy Alloy 825 cannot be obtained if titanium carbide is used as the sole stablizing mechanism. The principal mechanism of stablization for this alloy is that of precipitating the M23C5 at a temperature where the diffusion of chromium is sufficiently rapid to prevent chromium depletion. This occurs at temperatures in the 1700–1800 F (927–982 C) range.
Absorption of Hydrogen by Cathodically Protected Steel
Authors: HUDSON P. E. , SNAVELY E. S. , PAYNE J. S. , FIEL L. D. , HACKERMAN NORMAN
Published: February 2013

Rates of hydrogen evolution and hydrogen absorption were determined by use of membrane experiments in environments simulating soil conditions. The objective of this work was to determine the amount of hydrogen absorbed by steel under various conditions encountered by cathodically protected pipelines. The conditions investigated included a pH range of 3 to 9, absence of and saturation by oxygen, effects of cathode poisons, and metal-to-soil potentials. For a given pipe-to-soil potential, the rate of hydrogen penetration of steel is decreased by the presence of oxygen and arsenic, and increased by the presence of sulfide.
Some Effects of Nitrogen Content on the Stress Corrosion Susceptibility of AIS1 Type 304 Austenitic Stainless Steel
Authors: ECKEL J. F. , COX T. B.
Published: February 2013

The effects of nitrogen content on the susceptibility of AISI Type 304 stainless steel to stress corrosion cracking have been studied by exposing U-bend specimens of the alloy containing various amounts of nitrogen to boiling magnesium chloride solutions. It was found that nitrogen in solid solution in Type 304 stainless steel reduces the resistance of the alloy to stress corrosion. Increasing amounts of nitrogen cause shorter times to crack initiation and more rapid failures by increasing the rate of propagation. The susceptibility of Type 304 is further increased by thermally aging the stressed U-bend specimens at 154 C before exposing them to the corrosive medium. The observations from this investigation seem to support those past theories which suggested that the increased susceptibility of austenitic stainless steels with higher nitrogen contents was due to the formation of nitrogen-rich areas within the austenitic matrix.
Discussion of Scale Removal in HCl
Authors: HUDSON R. M. , WARNING C J.
Published: February 2013

This brief note is a discussion of the paper “Effect of Inhibitors on Scale Removal in HCI Pickling Solutions” by O. L. Riggs, Jr. and R. M. Hurd. “Corrosion,” 24, p 45 (1968) February.
Oxidation of Zinc Single Crystals Under Ionic Bombardment
Authors: DEMARIA R. , SPINEDI P. , SUSI-DEMARIA E.
Published: February 2013

Controlled oxidation processes conducted on surfaces of zone refined zinc single crystals under a beam of different gases (pure oxygen, air, inert gases such as helium or argon, in the presence of small amounts of oxygen) have been studied with an electron emission microscope. Surface phenomena which take place under ionic bombardment appear to be the result of two competitive mechanisms, an activating one (introduction of defects into the surfacial layers) and a de-activating one, which can be observed expecially with inert gases (inclusion of gas atoms in the lattice). It has been ascertained that oxide nucleation is preceded by formation of an absorbed oxygen layer.
Corrosion and Mass Transfer With Chemical Reaction–The Dissolution of Magnesium in Hydrochloric Acid
Authors: MARANGOZIS JOHN
Published: February 2013

The purpose of this paper is to review the theory of mass transfer, with and without chemical reaction, and to show how it can be applied in the prediction of uniform corrosion rates. As an example, experimental data reported for the rate of dissolution of magnesium cylinders in hydrochloric acid solutions were analyzed. A mechanism for the reactions and the transport of ions to or from the metal surface was suggested, and the model was used in the prediction of data with considerable success. Application of this method in other corrosion systems is presently under investigation, in an effort to broaden its usefulness and to determine its limitations.
Dislocation Etch Pitting Studies on Tungsten Single Crystals Under Potentiostatic Conditions
Authors: MALOOF S. R.
Published: February 2013

Dislocation etch pitting of the (100) surface occurs in chloride as well as nitrate and sulfate solutions during anodic polarization in a well-defined potential range (+0.3 to +0.7v vs H2) where the current is relatively insensitive to changes in potential. In chloride solutions, increasing the chloride ion concentration or temperature results in an increase in the rate of pitting. This suggests that the chloride ion participates in the pitting process. A linear current-time law is obtained at constant potential. A pitting rate curve established for the (100) surface in 0.5M NaCl is Gaussian in shape with an apparent maximum at a potential of +0.48v. The potential at which the maximum occurs appears invariant with composition or temperature, suggesting that the same chemical species adsorbs on the surface prior to pitting. The decrease in the pitting rate above this potential is explained by the desorption of the chemical species, considered to be WO2−, as a result of further oxidation at more positive anode potentials to the species WO4=. The inability to etch pit the (110) surface under the same conditions is attributed to the direct formation of the doubly charged monotungstate ion WO4= during anodic dissolution and its subsequent adsorption at all positive anode potentials up to as high at 10v. The specificity of etch pitting solutions is explained in terms of a “critical” potential range for pitting.
Influence of Alloying Elements on the Stress Corrosion Behavior of Austenitic Stainless Steel
Authors: LOGINOW A. W. , BATES J. F.
Published: February 2013

In certain applications, stress corrosion cracking of austenitic stainless steels has occurred when these steels are subjected to tension stresses (residual and applied) and are exposed to hot chloride solutions. Although stress corrosion cracking can be prevented by treatments to relieve residual stresses and by control of the environment, such procedures are expensive and not always reliable. An extensive study was therefore undertaken to develop a steel that would-be inherently resistant to stress corrosion cracking. The results of the study, conducted on stressed specimens of experimental steels immersed in a boiling 42% magnesium chloride solution, showed that carbon and nickel improved the stress corrosion resistance of annealed steels, and? nickel and silicon increased the resistance of cold-worked steels. It was also found that nitrogen decreased the resistance of annealed steels whereas phosphorus and molybdenum decreased the resistance of cold-worked steels. Manganese, copper, chromium, sulfur, and aluminum had little or no effect on stress corrosion resistance. This study resulted in the formulation of a steel composition containing 18% chromium, 18% nickel, 2% silicon, and 0.06% carbon, with low phosphorus and molybdenum contents. This steel was melted in an electric furnace; and1 its, stress corrosion, corrosion, and mechanical properties were determined. Test results show that the new steel (called USS 18-18-2 stainless steel) is much more resistant to stress; corrosion cracking than currently available austenitic stainless steels. Furthermore, the resistance of this steel is better than that of a 20% chromium, 34% nickel alloy that is being marketed; for its resistance to stress corrosion cracking.
Rates of Reaction of Dissolved Oxygen With Scavengers in Sweet and Sour Brines
Authors: SNAVELY E. S. , BLOUNT F. E.
Published: February 2013

Rates of reaction of dissolved oxygen with H2S were measured in a laboratory apparatus using a polarographic type instrument for the measurement of oxygen concentrations. Results show that oxidation occurs only at high pH in the absence of catalytic species. The reaction is catalyzed by transition metal ions in the order Ni++>Co ++>Mn++>Cu++>Fe++. In all cases, the reaction rate increases with pH and is at first complex but becomes zero-order with respect to oxygen after a brief induction period. Some natural waters contain sufficient catalysts that additional amounts are not required for scavenging O2 with SO2 or Na2SO3. Sour waters cannot be scavenged with SO2 or Na2SO3 because of ineffectiveness of catalysts.
The Mechanism of Stress Corrosion Fracture of a Copper-Beryllium Alloy
Authors: SYLWESTROWICZ W. D.
Published: February 2013

The process of stress corrosion fracture was investigated in a copper-beryllium alloy specimen exposed to different ammonia environments. Two basically different stages occur in this process. First, reactions leading to the formation of a crack, then formation and propagation of the crack. In the first stage, dissolution is probably the main effect of the corrosive environment resulting in a preferential attack on grain boundaries or on crystallographic planes. The distribution of solutes determines the areas of preferential attack (grain boundaries or crystallographic planes) and it depends on the aging conditions of the specimens. Plastic deformation and applied stress are not important factors in this stage. In the second stage, during the formation and propagation of the crack, the amount of plastic deformation, the value of applied stress and distribution of solutes are important. The main effect of the corrosive environment, in this stage, consists in the decrease of the surface free energy by a sorption process. Based on these observations a mechanism of stress-corrosion fracture in a copper-beryllium alloy specimen is proposed.
The Effect of Oxygen on the Compatibility of Niobium With Potassium
Authors: KLUEH R. L.
Published: February 2013

Refractory metals are highly resistant to dissolutive corrosion attack by liquid and boiling alkali metals when the alkali metals and refractory metals are free of impurities. Dissolution increases drastically, however, when the alkali metals contain oxygen. This phenomenon has been attributed to the formation of ternary oxides containing atoms of the two metals. As an alternative to the ternary oxide hypothesis, we have examined the possibility that at equilibrium only two condensed phases are present and that the oxygen affects the solubility of the refractory metal by decreasing the activity coefficient of the refractory metal in the liquid. The interplay between solute species in refractory metal-oxygen-alkali metal systems can be characterized in terms of interaction parameters as developed by Wagner. This approach was evaluated using data from the niobium-oxygen-potassium system at 600 C (1112 F). The observed solubility of niobium as a function of the oxygen content in potassium was consistent with that expected on the basis of calculated interaction parameters. Analysis of the observed behavior in terms of the phase rule also indicated that only two condensed phases exist at equilibrium.
Protective Films and Structure Dependent Corrosion in Aluminum
Authors: ARORA O. P. , ISASI J. A. , METZGER M.
Published: February 2013

Specimens of high purity aluminum with a high temperature oxide film, or certain others, were compared in 16% HCl with polished and etched specimens. Pitting attack was initiated only at sites where the film had suffered mechanical damage during cooling. The structure-related distribution of these sites, associated with vacancy condensation voids or grain boundary shearing, could determine the distribution of attack overshadowing the intrinsic effects of substrate structure. The pitting parameters were correlated with corrosion kinetics. Previous work in this system was reviewed with regard to possible influences of initial surface condition on the results.
Some Limitations of the Linear Polarization Techniques in Evaluating Corrosion Behavior
Authors: INDIG M. E. , GROOT C.
Published: February 2013

Current, potential, and weight losses were measured on a system consisting of a stainless steel working electrode, a platinum black reference electrode and platinum auxiliary electrode. The electrolyte was slightly alkaline lithiated water containing 3 ppm hydrogen at 288 C (550 F) and at saturation pressure. Linear polarization measurements were made in the region 0–20 millivolts from the open circuit potential. A corrosion current was calculated from these measurements, using previously cited Tafel constants. The cathodic Tafel constant was also measured directly. The cathodic Tafel slope agreed well with previous values. The corrosion current, estimated by linear extrapolation of the log current vs. voltage curve to zero applied current, agreed well with the current calculated from linear polarization. However, the descaled weight loss of the corroded electrode was only tenth of that computed from the current, time and Faraday's Law. The deviation from the expected corrosion behavior is explained by another anodic half reaction. The steady state exchange current is an equilibrium between several oxidation reactions and several reduction reactions. Only when the corrosion potential is sufficiently removed from the equilibrium potentials of the anodic and cathodic half reactions that constitute the corrosion reaction can the other competing reactions be ignored.
The Role of the Strain Hardening Exponent in Stress Corrosion Cracking of a High Strength Steel
Authors: COLANGELO V. J. , FERGUSON M. S.
Published: February 2013

Stress corrosion testing of a vanadium modification of 4340 alloy was conducted using precracked specimens in a cantilever beam apparatus. Plastic zones at the crack tip were determined using optical interference measurements, and the effect of these plastic zones on the fracture paths was demonstrated. Crack propagation rates were measured for steels of varying yield strengths (140–205 ksi). Electron fractographs and photomicrographs associated with the fracture through plastic zone are presented. Crack propagation rates were shown to vary inversely with the yield strength of the steel with the overall failure time being related to both the propagation rate and the fracture toughness of the material.
An Automatic Polarization Apparatus for Electrochemical Corrosion Studies
Authors: HENRY W. D. , WILDE B. E.
Published: February 2013

Statistical alloy development programs in which electrochemical screening techniques are used require facilities to produce precision polarization data. Conventional equipment and techniques presently available for such programs are not entirely satisfactory. Therefore, modifications were made to readily available commercial equipment to significantly improve the attainable sensitivity and reproducibility. This paper describes in detail the procedures necessary to produce an apparatus that automatically measures and records anodic and cathodic polarization curves over an applied potential range of ±2.0 volts. Traverse rates between 2 × 10−3 and 3 × 104 volts per hour are attainable and can be used to polarize electrodes through zero volts (with respect to reference electrode) without the necessity of manual switching. A special mode switch is described in detail with which the basic electronic potentiostat can be used as a constant current or constant voltage source by manual selection. The results obtained from three typical polarization experiments: (1) potentiodynamic anodic polarization, (2) galvanodynamic cathodic polarization, and (3) galvanodynamic linear polarization of AISI Type 304 stainless steel in hydrogen saturated 1N H2SO4 at 25 C (77 F), showed the performance of the apparatus to be equal to or superior to that of conventional manual procedures.
Discussion: Role of the Anion in Passive Layer Formation
Authors: RIGGS O. L.
Published: February 2013

This brief note is a discussion of the paper “Optical Microscopy Studies of Anodic Dissolution of Iron in Sulfuric and Hydrochloric Acid Solutions” by L. Felloni and G. P. Cammarota, “Corrosion”, 24, 90 (1968) April.
The Role of Arsenic in Preventing the Dezincification of a-Brass
Authors: LANGENEGGER E. E. , ROBINSON F. P. A.
Published: February 2013

It is demonstrated by means of freely corroding total immersion tests and anodic and cathodic polarization experiments, that small amounts of arsenic in solid solution in α-brass, effectively prevent dezincification even in the most agressive media. On the other hand, the addition of relatively large amounts of arsenic ions to these corrosive solutions has little effect on the rate of dezincification of non-arsenical α-brass. Although a contribution towards a better understanding of the function of arsenic has been made, a clear-cut explanation of the mechanism appears to fall outside the scope of this experimentation.
Behavior of Fiber Reinforced Plastic Materials in Chemical Service
Authors: REGESTER R.F.
Published: February 2013

A study is made of the factors leading to the degradation in mechanical properties of glass reinforced polyester exposed to aggressive chemical environments such as H2SO4, HCl, and salt solutions at elevated temperatures. The penetration of water molecules, cations, and anions into the structure is described in terms of permeation rates as a function of time, temperature, pressure, glass content, resin type, and concentration of solutions. The permeation measure­ments are related to the diffusivity and solubility of the penetrating species in the structure and to the resultant degradation of mechanical properties.
An Investigation of the Mode of Failure of Copper Beryllium Alloy Specimens in Stress Corrosion Fracture
Authors: Sylwestrowicz W. D.
Published: February 2013

The mode of crack propagation was investigated in specimens of a copper-beryllium alloy which had failed by stress corrosion. The investigation was done by comparing the amount of plastic deformation on the side face and on the fractured face of the specimen. The amount of plastic deformation was measured by X-ray diffraction. Results indicate that an appreciable amount of plastic deformation occurred on the fractured face during the process of fracture. The presence of additional plastic deformation at the fracture face suggests that the specimen failed by the semi-brittle propagation of a crack.
Electrochemical and Corrosion Behavior of Fe-Ni Alloys in Sulfuric Acid
Authors: SAYANO R. R. , NOBE KEN
Published: February 2013

The anodic and cathodic polarization of pure iron and nickel, 20%, 40%, 60%, and 80% Fe-Ni alloys in de-aerated 1N H2SO4 has been investigated. The anodic Tafel slopes ranged from 41 to 50 mv. The cathodic Tafel slopes of the hydrogen evolution reaction were either 100 or 105 mv. The corrosion rates of the pure metals and alloys were determined by weight-loss, chemical analysis, and polarization methods. The corrosion rates determined by the three methods were in reasonable agreement. Weight-loss and chemical analysis methods indicated a minimum at 40% Fe. By the polarization method, a minimum was observed at 20% Fe. In addition, the differential capacitance attained a minimum at this same composition. It has been suggested that the minima at 20% Fe might be attributed to the possible existence of the ordered structure, FeNi3.
Corrosion of Cobalt and Cobalt Alloys
Authors: MORRAL F. R.
Published: February 2013

Investigations are reviewed of the composition and structures of corrosion films and scales found on cobalt and on simple and complex cobalt-base industrial alloys. The corrosion resistance of these films and scales depends on metal and alloy composition, environment (an atmosphere containing one or more of CO2, S, H2S, O2, H2O, SO2, V2O3, NaCl, etc.), pressure, temperature, and time. Additional factors, alone or in combination, such as surface preparation, stress, thermal shock, geometry of the part, velocity, density, and flow pattern of the corroding environment also have an effect. Data on oxidation, sulfidation, and hot corrosion (a combination of the first two) of cobalt and its alloys are summarized in some detail, as are the known characteristics of the films and scales that are formed. Only the work that used techniques permitting determination of composition and crystal structure of these films and scales was reviewed. The effect of impurities in metals and alloys may be as significant as that of added alloying elements; impurities may alter the scales' chemical and physical properties—increasing, decreasing, or neutralizing corrosion rates. Until data are available on the intereffect on diffusion of elements present in scales, films, and metal surfaces, the mechanisms of corrosion proposed are only hypotheses.
Environmental Effects of Sulfur and Sulfur Compounds on the Resistance to Stress Corrosion Cracking of AISI 4340 Steel in Aqueous Chloride Solutions
Authors: TIRMAN A. , HANEY E. G. , FUGASSI PAUL
Published: February 2013

The resistance to stress corrosion cracking of AISI 4340 steel foil in 0.6M aqueous sodium chloride, acidified to pH 1.5 with hydrochloric acid, is greatly decreased by prior treatment of the specimens for short periods of time with aqueous and nonaqueous solutions of sulfur, organic and inorganic sulfides, sulfur dioxides, and the inorganic salts of sulfurousand sulfuric acids. It is suggested that this prior treatment produces sulfided areas which are inhibitors of the combination of atomic hydrogen into molecular hydrogen. The decreased resistance to stress corrosion cracking is thus attributed to hydrogen embrittlement. If the stress corrosion cracking test is made in 0.6M aqueous sodium chloride, adjusted to an initial pH of 8, the effect of a prior sulfiding treatment is small. The formation of such sulfided areas in practice result from the exposure of 4340 steels to industrial atmospheres which may contain hydrogen sulfide, sulfur dioxide, and elemental sulfur.
Corrosion Inhibition of Zone-Refined Iron by Ring-Substituted Benzoic Acids
Authors: AKIYAMA A. , NOBE KEN
Published: February 2013

The corrosion inhibition of high purity zone-refined iron in 1N H2SO4 by hydroxybenzoic acids, aminobenzoic acids, and the parent compounds—benzoic acid, aniline and phenol—has been investigated. The aminobenzoic acids inhibited the corrosion of iron to the greatest extent. In addition, the open circuit capacitances of iron in the presence of the aminobenzoic acids were significantly lower than those of uninhibited iron in the entire potential range studied. The electrochemical behavior of iron in the presence of phenol, meta- and para-hydroxybenzoic acid indicated the oxidation of the hydroxyl group during corrosion. A comparison of the experimental results of inhibited zone-refined and Armco iron indicates that the corrosion inhibition characteristics are significantly affected by the impurities in the iron.
Electrochemical Behavior of Molybdenum in Acid Chloride Solutions
Authors: JOHNSON J. W. , LEE M. S. , JAMES W. J.
Published: February 2013

The anodic dissolution of Mo was studied in HCl-KCl solutions at 25 C (77 F). The apparent valences of Mo ions going into solution were approximately six. Slightly lower values were obtained in HCl solutions, the more pronounced changes occurring in the higher acid concentrations. The resultant ions in solution were Mo-VI. The Mo surface appears to be covered with an oxide whose approximate composition is Mo2O5. The anodic dissolution is controlled by the oxidation of this oxide to MoO3.
Corrosion of Resulfurized Free-Machining Stainless Steels
Authors: HENTHORNE MICHAEL
Published: February 2013

The influence of manganese (0.3 to 2.4%), sulfur (0.01 to 0.4%), sulfide composition, and heat treatment on the corrosion resistance of 13% chromium, 17% chromium and 18% chromium-9% nickel steels has been investigated. Corrosion in acid solutions, high humidity, and salt spray is dependent upon sulfide composition which in turn is determined by the manganese to sulfur ratio in the steel. Low manganese resulfurized stainless steels which contain chromium rich sulfides are inherently more corrosion resistant than high manganese steels containing manganese rich sulfides. The influence of heat treatment on the corrosion resistance of resulfurized steels is similar to that for residual sulfur grades. Sulfide composition also controls the behavior of these steels during nitric acid passivation treatments. Highly oxidizing solutions must be used to avoid attack during these treatments particularly for steels with high manganese to sulfur ratios. These solutions do not dissolve the commonly used tool steels (particles of which might be imbedded in the surface of a machined part) but can improve subsequent corrosion resistance by removing deleterious manganese rich sulfides. These improvements are most marked in the high manganese 13% chromium alloys. Passivation treatments can increase the corrosion susceptibility of cross section areas in low manganese resulfurized stainless steels.
Cathodic Hydrogen Absorption and Severe Embrittlement in a High Strength Steel
Authors: FARRELL K.
Published: February 2013

Hydrogen absorption and consequent embrittlement are studied in hardened low-alloy steel tensile specimens after electrolytic hydrogenation in an aqueous solution of 4% H2SO4 containing arsenic. A critical arsenic content greater than 0.5 mg/liter is needed to cause poisoning. Saturation with hydrogen at a level of 5 to 6 wt ppm is readiiy achieved but causes a reduction in true fracture stress from 385,000 psi to as low as 35,000 psi. Much of this embrittlement is recovered when the specimens are degassed, but some permanent damage remains in the form of near-surface cracks, many of which are associated with inclusions. These cracks develop during cathodic electrolysis. Hydrogen absorption is much more rapid than is degassing at room temperature. These effects are consistent with a picture of hydrogen migration and embrittlement involving entrapment of hydrogen gas at internal interfaces.
Effect of Heavy Metal Ions on Susceptibility of AISI 4340 Foil to Stress Corrosion Cracking in Dilute Aqueous Hydrochloric Acid Solutions
Authors: FUGASSI PAUL , HANEY E. G.
Published: February 2013

The time required for the cracking of AISI 4340 steel foil in dilute aqueous hydrochloric acid solution, pH = 1.5, is greatly increased by the presence of small amounts of Cd++, Sn++, and Pb++ in concentrations as low as 10−4 molar. It is suggested that these heavy metals, whose sulfides have solubility products in the range, 10−29 to 10−26, form sulfides more insoluble at pH 1.5 than can be formed by certain areas present on the surface of the foil. Sulfided areas on the surface of the foil are assumed to accelerate the absorption of hydrogen by the foil.
Strain Electrometry Studies of Aluminum
Authors: LEIDHEISER HENRY , KELLERMAN ELSIE
Published: February 2013

The potential of aluminum wires immersed in an electrolyte was followed after abrupt straining of 1.5–12%. The maximum potential achieved after straining in 0.1M NaCl decreased with decrease in pH and the rate of decay to the initial steady-state value was independent of pH over the range of 1.5–6.5. The presence of dissolved oxygen in the solution increased the rate of decay to the steady-state value. The different potential behavior of untreated wires, wires heated in boiling water, and anodized wires was attributed to different mechanical properties of the oxide. The strain electrometry curves were identical in solutions of NaCl, Na2SO4, sodium tartrate, and Na2Cr2O7 of equal ionic strength. The pertinence of the results to the behavior of aluminum exposed at the tip of a growing stress corrosion crack is discussed.
Comparison of Fracture Mechanics and Nominal Stress Analyses in Stress Corrosion Cracking
Authors: NOVAK S. R. , ROLFE S. T.
Published: February 2013

Since the development of the fatigue cracked cantilever beam stress corrosion specimen, the fracture mechanics approach has been widely used to analyze the stress corrosion behavior of materials. However, there has been only limited experimental verification of the fact that propagation of flaws in corrosive environments is characterizec by the crack tip stress-intensity factor, KI, rather than by the nominal stress, σN. Therefore, an investigation was conducted to compare the fracture mechanics (KIc, KIscc) and nominal stress (σNf, σNscc) analyses of fatigue cracked cantilever beam specimens. The results indicate that both KIc and KIscc are material properties and independent of specimen size. However, the nominal stress counterparts to KIc and KIscc (σNf and σNscc) represent qualitative stress levels for the 18Ni (250) maraging-steel used in the investigation were 67 and 36 ksi √inch, respectively, regardless of specimen size. However, the (σNf and σNscc values varied by about a factor of 3 for the same order of magnitude change in specimen depth, W. Because the crack propagation rates for some materials in synthetic sea water may be very slow, high strength, highly alloyed steels should be tested for approximately 1000 hours under constant load conditions to measure KIscc values. In general, the results of this investigation have shown that the fracture mechanics approach is a quantitative method of assessing load thresholds, independent of specimen size, for the onset of fracture or of environmentally induced crack growth in notched specimens. Furthermore, KIc and KIscc values appear to be applicable for use in structural design and associated inspection because they properly account for the trade-off between design stress and flaw size.
Effect of Cold Work on Anodic Polarization of Iron in Sulfuric Acid
Authors: FINLEY T. C , MYERS J. R.
Published: February 2013

Effect of cold work on potentiostatic, anodic polarization behavior of commercial purity iron in hydrogen saturated, 1N sulfuric acid at 22 C (71.6 F) was determined. Cold work had no significant effect on the corrosion potential, Tafel constant for anodic dissolution in the active region, critical current density, potential associated with the initiation of the active-to-passive transition region, potential associated with the initiation of the transpassive region, or Tafel constant for visible oxygen evolution in the transpassive region. Potential associated with normal passive behavior was shifted in the noble direction by increasing amounts of cold work; major effect of cold work was to reduce the passive potential region.
Electrochemical Measurement of Corrosion
Authors: INDIG M. E. , GROOT C.
Published: February 2013

The results of electrochemical measurements on the corrosion of NiCrFe Alloy 600 and Zircaloy-2 in slightly alkaline lithiated water at 288 C (550 F) are presented. The study showed that, in the presence of dissolved hydrogen at the level of 35 Scc/kg-H2O, the electrochemical techniques could not be used to measure the corrosion rate of NiCrFe Alloy 600. However, the measurements on Zircaloy-2 were unaffected by the presence of hydrogen, and good agreement between the electrochemically determined weight gain and the directly measured weight gain resulted. The difference between the behavior of the two alloys is explained by the ease with which redox reactions involving hydrogen occur on the NiCrFe Alloy 600 surfaces.
Effects of Stress and Plastic Deformation on the Corrosion of Steel
Authors: FRANCE W. D.
Published: February 2013

The rate and type of corrosion exhibited by mild steel in the annealed, stressed, and plastically deformed state have been investigated. Precise electrochemical techniques provided potential and polarization data to supplement the results of chemical corrosion tests. Experiments were conducted in 0.6M NH4NO3 solutions in which steel exhibits active-passive dissolution behavior as well as localized corrosion. At active potentials, the anodic polarization curves for annealed and deformed specimens were nearly identical, with only slight increases in current densities for the deformed steel. Results at passive potentials demonstrated that increased plastic deformation can markedly decrease the passive potential range, the stability of passivity, and the ability to passivate. At certain passive potentials, the deformed steel exhibited current densities that were 400 times greater than those for annealed steel. The effects of pH, chloride ions, and crevices on the corrosion of deformed steel were examined in detail. The differences between the dissolution behavior of annealed and deformed steel were most distinctive in the approximate pH range of 3 to 6. This work is relevant to the understanding of the initiation of localized corrosion and to anodic protection.
Optical Microscopy Studies of Anodic Dissolution of Iron in Sulfuric and Hydrochloric Acid Solutions: Influence of Metal Purity, Structure, Heat Treatment
Authors: CAMMAROTA G. P. , FELLONI L. , PALOMBARINI G. , TRAVERSO S. SOSTERO
Published: February 2013

This paper describes the influence of metal purity, thermal treatment, cold rolling, grain orientation, and type of anion on dissolution kinetics of polycrystalline iron electrodes galvanostatically polarized in sulfuric and hydrochloric acid solutions. In 1N HCl solutions, Cl− adsorbed ions acted probably as anodic reaction inhibitors in the active region. This seemed to have been supported by corrosion behavior of differently oriented grains, ba high values, and depolarizing effects at current densities increasing with surface structural homogeneity. The Cl− adsorption, depending on pH, electrode potential, surface structure, grain orientation, and time, appears to have modified the chemisorption energy of the reactive species, changing the reaction mechanism. In 1N H2SO4 solutions, HSO4− may participate in the anodic process in the same way as OH− or H2O, e.g., following Evans' scheme (Reference 25). In the tests conducted in sulfuric solutions, the electrochemical data agreed with the Bockris' mechanism satisfactorily, but the corrosion morphology depended clearly on the surface structure.
Future Developments in Corrosion and Oxidation Research
Authors: WOOD G. C
Published: February 2013

The general problems confronting corrosion and oxidation research in the 1970's are outlined, and suggestions are made for dealing with some of them. Subjects discussed include ways of disseminating existing information, methods of organizing and performing research so that the broadly based, interdisciplinary approach may be maintained, and likely changes in corrosion education. More detailed suggestions are then made for research on the high temperature oxidation and corrosion of materials and on selected aspects of corrosion and protection at ambient temperatures.
Characteristics of Localized Corrosion of Steel in Chloride Solutions
Authors: POURBAIX ANTOINE
Published: February 2013

Pitting of steel in chloride solutions was studied in an experimental cell that permitted measurement of the pH and potential at active and passive areas as well as the current flowing between the areas. The potentials could be controlled potentiostatically. When the potentials of the active and passive areas were held at the same value, the corrosion rate at the active area was decreased by a factor of about 10, compared with the freely corroding rate. The kinetics of the processes in the active area were found to change rapidly with small variations of potential.
Electrochemical Behavior of High Purity Aluminum in Chloride Containing Solutions
Authors: DiBARI G. A. , READ H. J.
Published: February 2013

The electrochemical behavior of high purity aluminum has been studied to clarify the corrosion behavior of the metal when exposed to oxygen free and oxygen saturated saline solutions of varying pH. The mixed or corrosion potential, EM, of the electropolished high purity aluminum decreases as the pH is increased except in the intermediate pH range (4 to 8) where EM increases. A local maximum in the corrosion potential curve as a function of pH is thus observed. The potentiostatic polarization data and controlled potential weight loss data obtained at pH 4.0 suggest that the rate of dissolution of high purity aluminum is independent of electrode potential over a fairly wide range, relatively insensitive to the presence of dissolved oxygen in the electrolyte, and highly sensitive to changes in pH. Based on the potentiostatic data, a corrosion diagram believed to be approximately valid from pH 0 to pH 14 has been constructed. The corrosion diagram is consistent with the observed relation between EM and pH, and also yields estimates of the rate of dissolution of aluminum as a function of pH. The rate of dissolution of high purity aluminum increases slightly between pH 0 and 4, decreases between pH 4 and 8, and increases from pH 8 to 14. The minimum at pH 8 may be the point at which the rate of formation of aluminum hydroxide on the electrode surface equals the rate of formation of the aluminate ion.
Stress Corrosion Cracking Behavior of Maraging Steel Composites
Authors: FLOREEN S. , HAYDEN H. W. , KENYON N.
Published: February 2013

Laminated plate composites were prepared by hot roll bonding together plates of 18Ni(280) maraging steel and sheets of Armco iron. Composite welds of the same geometry were also prepared by successively depositing weld layers of these two materials. Plane strain stress corrosion tests of these two types of composites in aerated 3.5% NaCl solutions showed that stress corrosion crack propagation was stopped at stress intensities well above the KISCC values of the corresponding homogeneous maraging steel base plate and maraging steel weld metal. The results demonstrate that it is possible to retard stress corrosion crack propagation significantly in both base plate and weld structures by the use of a composite approach.
Mechanism of High Temperature Embrittlement and Loss of Corrosion Resistance in AISI Type 446 Stainless Steel
Authors: DEMO J. J.
Published: February 2013

The ferritic alloys, particularly AISI Type 446 steel with its high chromium content, have desirable properties of corrosion resistance, low raw material cost, and resistance to stress corrosion cracking (SCC); yet they are not widely used in construction work because of the damaging effects of high temperature exposures (such as welding) on their corrosion resistance and ductility. This work describes the causes for their loss of corrosion resistance and ductility, and defines changes in composition and heat treatment that would improve their material properties.
OBSERVATIONS AND THOUGHTS ON STRESS CORROSION MECHANISMS ASTM 1970 GILLETT MEMORIAL LECTURE
Authors: NIELSEN N. A.
Published: February 2013

Since the phenomena of stress corrosion cracking (of austenitic stainless steels) were first reported about 30 years ago, there has been a snowballing of costly failures in stainless steel equipment as well as in newer alloy systems, for example, titanium alloys, which were originally also thought to be immune to stress corrosion fracture. This has resulted in worldwide research on all aspects of stress corrosion phenomena. The incidence of failures can be controlled by judicious design, construction, operation, and maintenance of equipment, but complete understanding of stress corrosion cracking mechanisms remains to be achieved. It is believed, however, that from the cases of stress corrosion failures in aqueous chloride systems enough phenomenological information has been developed that a reasonably complete theoretical picture can be assembled. The main features of the suggested mechanism of corrosion cracking involve anodic dissolution, whereby nickel or another “noble” metal species is locally enriched, becoming sufficiently cathodic for hydrogen evolution to occur and embrittle the de-alloyed structure. The role of tensile stress in the system is to provide continuity and directionality to the local dissolution surface enrichment, hydrogen embrittlement (and mechanical rupture) process. Most all phenomenological features observed in alloys failed in chloride stress corrosion cracking systems can be worked into this model. The conclusion is made on the basis of a growing body of data being collected in many laboratories that the role of hydrogen as an embrittling agent may provide a possible unifying mechanism in stress corrosion and must be carefully reconsidered.
Stress Corrosion Properties of High Strength Precipitation Hardening Stainless Steels
Authors: CARTER C S. , FARWICK D. G. , ROSS A. M. , UCHIDA J. M.
Published: February 2013

The plane-strain fracture toughness KIC and stress corrosion threshold KISCC (in 3.5% aqueous sodium chloride solution) have been determined for the following high strength, precipitation hardening steels: 17-7 PH (RH 950, TH 1050), PH 15-7Mo (RH 950, TH 1050), AM 355 (SCT 850, SCT 1000), AM 362 (H 900, H 1000), AM 364 (H 850, H 950), 17-4 PH (H 900, H 1000), 15-5 PH air melted and vacuum melted (H 900, H 1000), PH 13-8Mo (H 950), and Custom 455 (H 950). Correlations of KISCC with service performance and smooth-specimen test data are discussed.
Review of Literature on Pitting Corrosion Published Since 1960
Authors: SZKLARSKA-SMIALOWSKA Z.
Published: February 2013

The effect of the following factors on the mechanism and rate of pitting corrosion is discussed: composition of the corrosive medium, composition and structure of the metal or alloy, temperature, pH, heat treatment, cold working, and structure of the oxide film on passivated metals. The kinetics of pit growth, sites susceptible to pitting, methods for studying the tendency to pitting and various theories of pitting corrosion also are discussed.
Ellipsometric-Potentiostatic Studies of Steel Corrosion: Oxide Film Development and Effects of Inhibitors
Authors: BORNONG B. J. , MARTIN P.
Published: February 2013

Simultaneous ellipsometric-potentiostatic measurements were used to study film development on mild steel in borate-boric acid buffer solutions at pH 7.4, with and without 0.005M and 0.0025M KCl. Effects of pre-adsorbed films of barium dinonylnaphthalene sulfonate were also determined. Coulometric and ellipsometric film thicknesses of the anodic films agreed reasonably well. Discrepancies increased when pitting occurred because of surface roughening. Chloride ion reduced the passive range and caused increased corrosion at a lower potential. Pre-adsorbed sulfonate films desorbed rapidly under anodic polarization, but were stable for 0.1 to 0.2 volt cathodic. The initial corrosion rate for the bare steel, determined by the Tafel extrapolation and linear polarization methods, was 4 mpy. The pre-adsorbed sulfonate film reduced the corrosion rate to 1 mpy.
Mechanism of Cracking of High Strength Martensltic Stainless Steels in Sodium Chloride Solutions
Authors: WILDE B. E.
Published: February 2013

This paper reviews previously proposed mechanisms for the environmentally induced cracking of high strength steels in sodium chloride. The electrochemical basis for the differentiation between hydrogen embrittlement and active path corrosion is examined along with the consequences of the recently demonstrated acidification that occurs in areas of localized geometry such as precracks, pits, and crevices. From electrochemical studies on a modified 12% chromium martensitic stainless steel, data are presented which indicate that hydrogen absorption occurs under conditions of exposure previously thought to preclude this possibility; that is, at applied bulk potentials noble to the reversible hydrogen potential. Data are also presented to show that the activation energy for crack growth at the corrosion potential and at cathodic and anodic applied potential is 9.5 Kcal/mole (±1); a value close to that reported previously for the cracking of cathodically embrittled steel. The experimental data are explained on the basis that an embrittlement process associated with hydrogen absorption is responsible for crack growth under all conditions of applied potential. With polarization at potentials active to the hydrogen reversible potential, hydrogen absorption results directly from the bulk cathodic discharge of protons. At the corrosion potential and more noble potentials, hydrogen absorption takes place from the cathodic discharge of protons occurring in the low pH conditions resulting from the hydrolysis of anodic dissolution products in pits. In the noble potential region, although active path anodic dissolution appears not to be the mechanism of crack growth, anodic dissolution is a prerequisite to crack growth by a hydrogen embrittlement mechanism. It is suggested that a similar mechanism can explain the cracking behavior of other high strength steels in sodium chloride solutions where conditions suitable for hydrolysis arise either by pitting or by crevice corrosion occurring in the presence of a mechanical precrack.