bluuebunny/crossref_metadata_2025 huggingface dataset:
Corrosion of Gold-Palladium, Nickel and Type 347 Stainless Steel in Molten Alkali Carbonates
Authors: JANZ G. J. , CONTE A.
Published: February 2013

Further to previously reported studies of corrosion of noble metals and refractories in molten alkali carbonates,1 similar studies were made on gold-20 percent palladium, nickel and Type 347 stainless steel at 600–700 C (1112–1292 F).

Type 347 stainless steel was found highly resistant to attack, possibly due to passivation by a film of LiFeO2. Nickel was embrittled at 600–700 C with the intergranular formation of NiO. The small but finite attack of the gold-20 percent palladium was accompanied by formation of sodium palladiate.
Hydrogen Absorption by and Dissolution Rate Of Low-Carbon Steel In Sulfuric, Hydrochloric, Phosphoric and Nitric Acids
Authors: HUDSON R. M.
Published: February 2013

The dissolution rate of steel in 2 N and 10 N solutions of nitric acid at 100 F (38 C) was much faster than for the same concentrations of the other acids studied, although for 0.05 N and 0.5 N solutions the rate was not significantly different than that for sulfuric acid. Dissolution in H2SO4 solutions of 0.5 N and 2 N at 100 F was more rapid than dissolution in hydrochloric acid, but for 10 N acid the rate in HCI was greater than for H2SO4. Dissolution rates in phosphoric acid solutions at 100 F were slower over the entire concentration: range than for other acids at comparable concentrations. The dissolution rates in 2 N acid solutions increased with an increase in temperature.

The amount of hydrogen introduced into the steel during dissolution in HNO3 solutions was much lower than for the other acids. Although the dissolution rates at 100 F differ between H2SO4, HCI and H3PO4 solutions at the various concentration levels, the percentage of theoretically available hydrogen absorbed by the steel after a given weight loss did not differ significantly between these three acids. For each acid, particularly when the weight loss was low, the amount of hydrogen absorbed at a given weight loss decreased with increase in temperature.
Oxidation of 80Ni–20Cr Alloys In Carbon Monoxide at High Temperatures
Authors: OSTHAGEN K.
Published: February 2013

Thermodynamic calculations were made of the reaction of Nimonic 75 with CO at 750, 900 and 1000 C (1382, 1652 and 1832F). The reaction was studied at gas pressures ranging from 760 to 10−2 mm Hg. The thermodynamic calculations were compared to experimental work by P. Kofstad and K. Piene at the Central Institute for Industrial Research in Oslo, Norway. This experimental work includes thermo-gravimetric reaction rate measurements, characterization of reaction products by X-ray diffraction and metallographic studies of reacted specimens.

From existing partial molar free energy values for the solution of Cr in Ni-Cr alloys critical CO pressures of 0.7 and 9 mm Hg at 900 and 1000 C (1652 and 1832 F) were calculated. Below the critical pressures a weight loss is expected for the reaction in CO. Above the critical pressures, however, a weight increase due to the formation of Cr2O3 and Cr7C3 on the surface is expected at 900 and 1000 C

At 750 C no weight loss is expected. The reaction products at this temperature are expected to be Cr2O3, Cr7C3 or free carbon.
Stress Corrosion Cracking Susceptibility Of Stainless Steels and Nickel-Base Alloys In Polythionic Acids and Acid Copper Sulfate Solution
Authors: SAMANS C. H.
Published: February 2013

Intergranular cracking tendencies of fourteen stainless steels and two high-nickel alloys have been evaluated by exposing numerous specimens to polythionic acid and standard acid copper sulfate solutions. The sensitization curves for solution-annealed wrought stainless steels, which had been held for varying times at temperatures from 800 to 1700 F (427 to 927 C), had the same lower temperature limit for both solutions. The higher temperature limit for acid copper sulfate was significantly higher than for polythionic acid so the more standard acid copper sulfate test can be used for control. Decreasing the carbon content shifted the sensitization curve to longer times. Times in excess of 1000 to 4000 hours were required to sensitize steels stabilized with columbium or titanium. Molybdenum additions decrease the sensitization range, but the higher-carbon molybdenum-bearing stainless steels had an unexplained sensitization zone from 900 to 1000 F (482 to 538 C) for holding times exceeding 200 hours. The 25 percent Cr-Ni materials became sensitized over a narrower range of temperature than the plain 18 percent Cr-Ni alloys and, for a given carbon content, were more stable. If 1200 F (649 C) sensitizing followed thermal stabilization, the low-carbon Type 310 and Types 347 and 321 steels were sensitized the least. Two high-nickel alloys and a cast stainless steel failed when sensitized for 4 hours at 1200 F.
Sodium Nitrite as a Corrosion Inhibitor for Mild Steel
Authors: LEGAULT R. A. , WALKER M. S.
Published: February 2013

The effect of sodium nitrite on the corrosion rate of mild steel in chloride and sulfate media has been investigated. The results obtained support the view that passivity in these systems results from an oxide film maintained in a state of dynamic equilibrium, with protection dependent upon the rate of protective oxide film formation exceeding the rate of film deterioration. The data also indicate that the basic function of sodium nitrite is to assist the cathodic process and thereby provide that current necessary to form a protective oxide film, or expressed differently, to provide that current necessary to polarize above the critical potential for passivity.
Study of Aromatic Amine Inhibitors by Nuclear Magnetic Resonance
Authors: COX P. F. , EVERY R. L. , RIGGS O. L.
Published: February 2013

Every and Riggs1,2 have reported the inhibitive properties of aniline and several of its derivatives. They found that the relative inhibitor effectiveness of these compounds was determined by the nature of the substituent group and its position in the aromatic ring. Some of the substituted anilines gave better than 95 percent protection to 1020 mild steel in 10 percent hydrochloric acid; a few of the substituted anilines accelerated the corrosion rate by as much as a factor of two. Differences in molecular area of these compounds were small. The observed corrosion rate could not be attributed to differences in surface area of the metal covered per molecule. No significant relationship was noted between the inhibitive properties and solubility, molecular weight or dipole moment.

High resolution nuclear magnetic resonance spectra have been obtained for a group of these amine bases in cyclohexane solution. It was found that there is a linear correlation between the proton resonance frequency of the amine hydrogens and the observed inhibitor characteristics of these compounds.
Effect of Contaminants on Resistance To Stress Corrosion Cracking Of Ni-Cr Alloy 600 in Pressurized Water
Authors: COPSON H. R. , DEAN S. W.
Published: February 2013

Numerous tests have shown that Alloy 600, a 76 nickel-15 chromium-7 iron alloy, has excellent corrosion resist­ance in pressurized high temperature water. The present tests were undertaken to determine the influence of possible contaminants in 600 F (316 C) pressurized water on corrosion behavior, using both single and double U-bend specimens. The double U-bend provided a combined stress and crevice specimen. Contaminants were sodium fluoride, air, lead powder, lead oxide, a petroleum hydrocarbon, and a mixture of lead powder and the hydrocarbon. Contamination and aeration were much in excess of any condition likely to be encountered in pressurized water reactors. Under certain conditions, some contaminants induced stress corrosion cracking.
Corrosion of Tantalum and Tantalum-Tungsten Alloys in 20 Percent Hydrofluoric Acid
Authors: EBERTS R. E.
Published: February 2013

Experimental data reported show that tantalum and tantalum-tungsten alloys containing less than 22 percent tungsten are more susceptible to attack by 20 percent hydrofluoric acid than has been previously reported.
Kinetics, Microstructures and Mechanism of Internal Oxidation - Its Effect and Prevention in High Temperature Alloy Oxidation
Authors: RAPP ROBERT A.
Published: February 2013

A review and evaluation of the role of internal oxidation in the oxidation of alloys is presented and five alloy types represented by Ag-In, Cu-Be, Ni-Cr, Nb-Zr and Cu-Zn-Al are considered in detail.

Internal oxidation is a diffusion-controlled process for which the kinetics may be predicted from solutions of the diffusion equation. Except for oxidations involving the formation of extremely stable solute oxide precipitates or oxidations at temperatures allowing only minimal solute mobility, the experimentally measured kinetics are in agreement with the calculated rates. The radius of a spherical internal oxide precipitate is expected to vary directly with the depth at which the precipitate is formed and inversely with the oxygen solubility at the external surface. Upon exceeding a critical solute content in a given binary alloy system, the occurrence of internal oxidation of the solute is replaced by the formation of an external scale of the solute metal oxide. A reduction in the oxygen content at the surface or the introduction of deformation into the surface of the alloy can reduce the solute content required for the transition from internal to external oxidation. In most cases, the prevention of internal oxidation by the formation of a compact surface layer of the solute oxide will result in a reduction of the oxidation rate of an alloy. When internal oxidation of a solute occurs in combination with external scale formation, the morphology of the precipitates in the microstructure of the oxidized alloy is determined both by the precipitation conditions and the mode of external scale formation. Internal oxide precipitates can affect both the mechanism and kinetics of external scale formation.
Dissolution Kinetics and Polarization Of Iron Whiskers
Authors: SHEMENSKI R. M. , BECK F. H. , FONTANA M. G.
Published: February 2013

The dissolution kinetics of iron filamentary single crystals were found to obey a mechanistic analysis based on the terrace-ledge-kink surface model. At low undersaturations, dissolution-ledge propagation from edge sites of finite crystals controlled the process and the dissolution rate was found to be a linear function of the ferrous ion concentration in solution. Generation of ledges from spiral or screw dislocation sources was rate-controlling at moderate undersaturations, the rate being dependent upon the logarithm of the undersaturation ratio. A linear relationship was again followed at high undersaturations because the spacing of ledges emitted from spiral sources was small, which dictated evolution to a limiting linear case.

An anodic polarization curve for the dissolution of iron whiskers in 1 N sulfuric acid, obtained by varying potassium persulfate depolarizer additions in solution, agreed favorably with the literature. The Tafel curve in the active range bifurcated with increasing current density and showed a greater rate of dissolution perpendicular to {110} surfaces. As the dissolution rate was shown to depend on the logarithm of the interfacial free energy, the orientation-dependent dissolution phenomena were in accord with the mechanistic model for surface anisotropy, especially with respect to ledge-kink configurations.
Corrosion of Iron in an H2S-CO2-H2O System: Some Factors Affecting Hydrogen Penetration Rate Through 8640 Steel
Authors: BRICKELL W. F. , GRECO E. C , SARDISCO J. B.
Published: February 2013

The rate of hydrogen penetration through 8640 steel exposed to an H2S-CO2-H2O environment was shown to depend on concentration of the hydrogen sulfide, structure of the steel and condition of the surface through which the emerging hydrogen passed. Greater penetration rate resulted from an increase in corrodent concentration and from a decrease in martensitic structure. Surfaces coated with iron sulfide film were found to retard penetration by hydrogen to a significantly greater extent than mechanically prepared surfaces.
Hydrogen Embrittlement Of Austenitic Stainless Steel
Authors: WHITEMAN M. B. , TROIANO A. R.
Published: February 2013

Type 310 stainless steel in thin sections was embrittled by hydrogen. The temperature and strain rate dependence of this embrittlement was almost analogous to that well-established for hydrogenated body-centered cubic (b.c.c.) metals, differing only in that at low temperatures and relatively high strain rates complete recovery in ductility was not achieved. The activation energy for recovery in ductility, determined by aging at several temperatures, was 10,900 cal/mole.
Emission Spectrographic Method For Quantitative Analysis Of Corrosion Products
Authors: SHIFLETT G. M. , LIEBERMAN M.
Published: February 2013

Corrosion studies of metals, piping systems, steam generators, etc., often require knowledge of chemical nature of corrosion products formed. As amounts of such products are sometimes very small, wet chemical analysis may be difficult. Therefore, a direct arc emission spectrographic method has been developed for quantitatively determining 13 elements, many of which are known to be present in water systems as the result of corrosion, scaling or fouling. Using high purity graphite as diluent, germanium dioxide as buffer, and barium carbonate as internal standard, it was found that an element concentration of 0.3 percent provided the spectral line densities suitable for quantitative analysis. The 13 elements yielding satisfactory results were aluminum, calcium, chromium, cobalt, iron, lead, magnesium, manganese, nickel, silicon, tin, titanium and vanadium. Method was applied to carbonates, oxides and silicates of these elements with results indicating accuracy of ±15 percent and precision of approximately 12 percent. Corrosion deposits, scales, slags and oxides can be analyzed routinely by this method.
Type 304 Stainless Steel vs Flowing CO2 At Atmospheric Pressure and 1100-1800F
Authors: McCOY H. E.
Published: February 2013

Oxidation characteristics of Type 304 stainless steel in CO2 were observed over the temperature range 1100–1800 F (593–982 C). Although in general oxidation rate curves were parabolic, several periods were observed in which they were approximately linear. These breaks were reproducible and thought to be associated with changes in rate-controlling step of the oxidation process. Carburization of Type 304 stainless steel during exposure to CO2 was observed. Several other alloys were studied, to determine earbiorization mechanism. These included Type 406 stainless steel, a British 20 Cr– 25 Ni, niobium-stabilized steel, Inconel, iron, Fe–1 Cr, Fe–3 Cr, and Fe–10 Cr. Correlation was found between carburization and chromium content, with low chromium favoring and higher chromium inhibiting this reaction. Mechanism was proposed based upon influence of chromium on type of surface oxide formed.
Stress Analysis Of Bent-Beam Stress Corrosion Specimens
Authors: HAAIJER G. , LOGINOW A. W.
Published: February 2013

Many types of specimens are available for determining stress corrosion properties of metals and alloys. The bent-beam specimen is particularly well suited for determining atmospheric stress corrosion properties of higher-strength sheet materials. It is relatively simple to prepare and has given satisfactory results in extensive programs. Mathematical analysis used to calculate appropriate specimen dimensions to obtain a desired stress and results of tests to verify the mathematical analysis are presented.

Elastic stresses in bent-beam stress corrosion specimens were determined by mathematical large-deflection analysis. Relationships were established between maximum stress and specimen and holder dimensions, as well as between maximum deflection and these dimensions. The relationships were verified experimentally by comparing measured with theoretical values calculated from the derived relationships. Agreement was good; most experimentally determined data were within 5 percent of calculated values.

Variation in stress across specimen width was measured by strain gages. Results of these tests indicated that the variation was within acceptable limits.
Intergranular Corrosion of Alpha-Brass And Some Effects of Stress
Authors: LYNES W.
Published: February 2013

Intergranular corrosion of α-brass was produced in both ammoniacal and non-ammoniacal solutions, and on both visually bare and filmed surfaces. Cracking of 70–30 brass under stress occurred only in solutions containing NH3. When the surface of the brass was visually bare, path of cracking was transgranular; when the surface was filmed, it was intergranular. Addition of NH4+ ion prevented trans-granular cracking. Addition of Cl− ion produced transgranular cracking on both visually bare and filmed surfaces. When NO3− was added, path of cracking was transgranular on visually bare surfaces, but on filmed surfaces there was no cracking.
Investigation of Inhibiting Properties Of the Pertechnetate Ion
Authors: SPITSIN V. I. , ROSENFELD I. L , PERSIANTSEVA V. P. , ZAMOSHNIKOVA N. N. , KUZINA A. F.
Published: February 2013

Corrosion of iron in an aggressive medium containing sulfate and chloride ions has been completely inhibited by addition of minute amounts of the pertechnetate ion. Its effectiveness on the basis of mol concentration required under similar conditions is much greater than that of such widely-used inhibitors as the nitrite, chromate and dichromate ions. The pertechnetate ion is capable of inhibiting corrosion caused by a mol concentration of aggressive ions higher than that of the inhibitor itself.

Experimental results indicate that the corrosion inhibiting power of the pertechnetate ion is the result of its adsorption on the metal surface, with resultant stifling of the anodic process of metal ionization. This is accomplished with a quantity of pertechnetate considerably smaller than that needed to produce a monomolecular layer on the metal surface; complete surface coverage is not required for complete inhibition.
Initial Stages Of Stress Corrosion Cracking In Austenitic Stainless Steels
Authors: LOUTHAN M. R.
Published: February 2013

Initial stages of stress corrosion cracking in Types 304 and 304L stainless steel were investigated with optical and electron microscopy techniques. Studies of U-bend samples and electron-transmission quality thin foils revealed that cracks initiated preferentially on the {111} family of planes and that formation of corrosion products accompanied both crack nucleation and propagation.

U-bend samples formed from metal-lographically polished strips were studied after exposures in 42 percent MgCl2 solutions at 154 C (309.2 F). Tiny corrosion pits were observed initially, then extension of corrosion formed linear traces of corrosion product on the sample surfaces. These traces lay parallel to the {ill} traces on grain surfaces and cracking was seen later in the corroded regions. Samples then had many small cracks which often formed Widmanstatten-like patterns in several grains. All the small cracks were in corroded regions and were on the {111} family of planes. Continued exposure caused the small cracks to propagate, interconnect and form characteristic trans-granular branching crack patterns.

Electron transmission studies of thin foils exposed to dilute chloride solutions revealed a similar sequence of crack initiation and propagation. Preferential pitting formed linear arrays along {111} traces on the foil surfaces.

Also, preferential attack occurred at stacking faults and dislocation arrays, producing crack-like voids in the foil.

Extent of preferential attack increased with increasing exposure time and temperature and corrosion products were observed in regions of attack. Foils exposed under similar conditions to deionized water and solutions of NaI did not contain the attacked regions, demonstrating importance of chloride ion in the stress corrosion process.

These results support the electrochemical mechanism of crack propagation by localized anodic dissolution and show that crystallographic defects provide the sites for such attack.
Oxidation Characteristics of Vapor-Plated Tungsten
Authors: NIEBERLEIN VERNON A.
Published: February 2013

Vapor-deposition is being used increasingly for fabricating complex shapes from tungsten. In contrast to conventional tungsten whose oxidation kinetics have been well explored, vapor-deposited material has never been investigated systematically with regard to oxidation.

Oxidation rates were run at 600–1000 C (1112–1832 F) in air using a recording balance. Activation energies were calculated and oxidation rates were compared to those of sheet tungsten prepared using powder metallurgy techniques. Humid air and dry air were compared as corroding media.
Observations on the Anodic Behavior off Nickel and Chromium: Surface Topography and Temperature Effect
Authors: MYERS J. R. , CROW W. B. , BECK F. H. , SAXER R. K.
Published: February 2013

Metallographic examination of anodically polarized nickel and chromium after long-time exposure at selected active, passive and transpassive potentials in H2-saturated, IN H2SO4 at 25 C (77 F) revealed significant differences in surface topography. Etch figures, present only in the trans-passive state, supported the belief that “active patches” are generated in passive films of these metals at potentials more noble than the passive region. The difference in nature of nickel surface in the early trans-passive region and visible oxygen evolution region is discussed.

Effect of temperature on passive nickel (i.e., nickel in passive potential region) over the range 25 to 95 C (77 to 203 F) was determined for H2-saturated 0.5, 1, 5 and ION H2SO4 (pH = 0.85 to −1.05). Apparent activation energies for dissolution of passive nickel were determined. Inflection temperature (Ti) above which “active patches” apparently are formed in passive film was dependent on acid concentration according to the expression 1/Ti × 103 = −0.11 pH+ 3.04 over the pH range investigated and was independent of the direction from which the temperature was approached. The change in apparent activation energy (ΔQ) was a function of direction from which the temperature was approached.

Measurements in which temperature was increased stepwise showed that ΔQ is related to pH by the expression ΔQ (kg - cal/mole) = 15,4 pH - 4.7 for acid concentrations studied. Because Ti and ΔQ are dependent on acid concentration, Seeger's activation energy for crystallization of a very thin pseudomorphic film and Kramer's exo-electron emission temperature which are independent of concentration cannot be used to explain fully generation of “active patches” in a passive film as proposed by previous investigators.
Using Radioactive Tracers to Study Chloride Stress Corrosion Cracking of Stainless Steels
Authors: OVERMAN R. F.
Published: February 2013

A combination of radioactive tracer and metallurgical techniques has made it possible to study some of the conditions necessary to produce chloride stress corrosion cracks in stainless steel The existence of charged areas on the surface of steel was demonstrated by autoradiography of samples exposed to solutions containing radioactive tracers. Charged areas on the surface may be created by a high concentration of small sulfide inclusions; the cracks that appeared were initiated within these charged areas. Seven nanograms of chloride on one charged area was sufficient to start corrosion and subsequent surface cracks in a surface of steel stressed by grinding.
Surface Disintegration of Zinc Hono-and Polycrystals Dissolving Anodically in Sodium Bromate Solutions and the Apparent Valency of Zinc Ions
Authors: STRAUMANIS M. E. , WANG Y.
Published: February 2013

Zinc, if dissolved anodically in an aqueous 3 percent NaBrO3 solution apparently deviates from Faraday's law in the sense that more Zn goes into solution than calculated. It can be proved that this disagreement is due to partial surface disintegration of the Zn anode while current is flowing. Very small particles of Zn are carried away from the anode when the surface oxide film detaches. The flakes are dark due to the presence of fine metallic particles. In moisture, the latter are oxidized quickly and turn white. The amount of disintegration (including the self-dissolution) is between 25 and 31 percent of the total Zn weight loss. Anodic disintegration decreases for Zn electrodes containing Au. The amount of disintegration is nearly independent of the crystallographic plane of the single Zn crystal and agrees with that of a polycrystal The reasons for and the mechanism of disintegration are discussed.
Boiling Mercury Corrosion of Certain Refractory Metals and Stainless Steels From 593–703C
Authors: FLEITMAN A. H. , ROMANO A. J. , KLAMUT C J.
Published: February 2013

Mercury corrosion of the refractory metals W, Mo, Ta and Cb-1Zr was studied in natural circulation quartz loops with two-phase mercury at temperatures from 593 to 703 C (1095–1295 F). Three thousand hour tests on these materials indicate that Ta and W showed no attack or weight loss and could not be detected in the mercury. Mo and Cb-1Zr alloy were detected in trace amounts in the mercury.

Similar tests in quartz loops on Types 304 and 410 stainless steel also were completed. Effectiveness of small additions of Ti to the mercury in preventing corrosion was evaluated. Results indicate that Ti when added to mercury is effective in reducing mass transfer, of Type 410 stainless steel but appears to increase both the depth of corrosion and weight loss of Type 304.
Corrosion Behavior of Steels and Nickel Alloys in Superheated Steam
Authors: RUTHER W. E. , SCHLUETER R. R. , LEE R. H. , HART R. K.
Published: February 2013

Small amounts of a number of alloying materials were added to Type 304 stainless steel in an effort to improve its corrosion resistance to superheated steam at 650 C (1202 F), 42 kg/cm2. Aluminum and siliconwere valuable additions, but the amount of aluminum required to reduce the corrosion rate significantly embrittled the alloy. Type 304 containing about 3w/oSi appeared to be a practical alloy.

In a similar fashion, the addition of about 3w/oAl to Incoloy 800 greatly improved its resistance to static superheated steam.

Films stripped from samples corroded in steam with various prior surface preparations were examined by electron microscopy and chemical analysis in an attempt to clarify the reasons for differing corrosion behavior. It was concluded that the rapid diffusion of chromium into the corrosion films formed on mechanically worked surfaces is the key factor in the improved corrosion resistance of these surfaces.
Oxidation of Iron-Aluminum Alloys in the Range 500–1000 C
Authors: SAEGUSA F. , LEE L
Published: February 2013

Oxidation of 1 and 5 weight percent aluminum-iron base alloys has been investigated in oxygen at one atmosphere pressure over the temperature range 500–1000 C (932–1832 F). Effects of temperature and alloy composition on oxidation rate were determined by a gravimetric method. Oxide scales formed on alloy surfaces were examined by metallography, electron diffraction and electron microprobe analysis.

During the initial period of reaction the oxidation process obeyed a parabolic rate law. After prolonged exposure oxidation occurred at a constant rate. Several layers consisting of oxide mixtures were observed on oxidized specimens. The innermost layer was found to have a high aluminum content, whereas the outermost layer was found to be mainly iron oxide.
Surface Chemical Factors in the Stress-Corrosion Cracking off Alpha Brass
Authors: JOHNSON H. E. , LEJA J.
Published: February 2013

Stress corrosion cracking of alpha brass in ammonia solutions containing copper-ammonia complexes is most rapid in the pH range 6 to 7, where weight loss corrosion is insignificant, Linear relationships were found for (a) log 1/tc (tc = cracking time) vS log Cu++ (initial copper concentration) and (b) l/tc vs 1/T (T = absolute temperature). Oxygen appears necessary for general corrosion and cracking at pH values above 8.

Rapid cracking is interpreted in terms of a drastic surface free energy decrease caused by the adsorption of an intermediate copper-zinc- ammonia complex (not yet identified) which is catalytically formed at the brass/solution interface and is surface active. It is suggested also that linear relationships like (a) and (b) above may be distinguishing features of stress corrosion cracking mechanisms which involve surface energy lowering.
“Kansite” = Mackinawite, FeS
Authors: MILTON CHARLES
Published: February 2013

“Kansite” is mackinawite, FeS. References to recent publications establishing this and correctly describing this important corrosion compound are given. Besides appearing as a corrosion product, it occurs naturally in tidal sediments, where hydrogen sulfide reacts with iron or iron compounds and in most high temperature copper and nickel ore deposits. It also has been synthesized in the laboratory. Mackinawite has been observed repeatedly for nearly a century, but until 1963 was generally confused with a similar-appearing but much rarer ore mineral, valleriite, CuFeS2, and was described under that name.
An Investigation off the Utility off Instantaneous Corrosion Rate Measurements for Inhibitor Studies
Authors: ANNAND ROBERT
Published: February 2013

Instantaneous corrosion rate measurements were evaluated under laboratory conditions to determine their utility, both in brine solutions and in two-phase brine/hydrocarbon systems containing nitrogen, air, H2S, CO2 and mixtures of these gases. Measurements are based on the “polarization resistance” equation first reported by Stern in 1958. Both 3-electrode and 2-electrode techniques were used. In the 3-electrode technique, one electrode serves as a reference and the use of a steel electrode identical to the test electrode was evaluated. Techniques were evaluated from two standpoints: (1) To determine that the data obtained corresponded to polarization characteristics of steel under conditions where a corrosion product layer accumulated; and (2) to establish that with sufficiently constant corrosion conditions measurements will correlate to weight loss. Analysis of the data produced the following conclusions: 1. Use of a never-polarized steel reference electrode is well founded; 2. Three-electrode measurements reliably measure the instantaneous corrosion rate of the test electrode; 3. Even with non-ideal curves, as long as the complex β's are reasonably constant, the Stern equation can be used to relate ΔI/AE to Icorr.; 4. There is reason to prefer anodic pulses because of the better shape of the anodic branches of the technique; 5. The 3-electrode technique is preferred because, although 2-electrode data are qualitatively related to the corrosion rate, the measurements exhibit variations which make them less reliably correlated to the corrosion rate of an identifiable electrode; 6. The measurements are uniquely suited for changing corrosion conditions, especially in nearly neutral saline solutions containing air, H2S or CO2; 7. The measurements should be useful in all practical solutions where the conductance is high enough to support electrochemical corrosion.
Stress Corrosion of Beryllium in Synthetic Sea Water
Authors: MILLER R. A. , MYERS J. R. , SAXER R. K.
Published: February 2013

Continuous total immersion testing of pickled beryllium sheet material in synthetic sea water revealed mat corrosion rate decreases asymptotically from about 21.5 to 2.0 mpy as exposure period increased from 5 to 150 days. Beryllium was observed to be susceptible to severe pitting attack. Testing established that beryllium is susceptible to stress-corrosion when exposed to synthetic sea water. Time-to-failure decreased from about 2340 to 40 hours as applied tensile stress was increased from 1220 to 40,000 psi. Electron fractography studies suggested that stress-corrosion failure occurred transgranularly.
Capacitance Measurements During Activation of Passive Nickel
Authors: SAYANO R. R. , NOBE KEN
Published: February 2013

Studies showed that length of Flade arrest increased by increasing duration of anodic passivation of Ni 270 in 1 N H2SO4. Capacitance behavior indicated electrode surface changes during activation.
Relationships Between Electrochemical Measurements and Stress Corrosion Cracking of Maraging Steel
Authors: GREEN J. A. S. , HANEY E. G.
Published: February 2013

Stress corrosion cracking of 18Ni maraging steel foil has been studied in deionized water solutions with the pH adjusted by NaOH additions over a range from 8 to 13. The full range of NaCl contents from saturated solutions to no addition was tested with specimens stressed to 75 percent of yield strength. For each variation in NaCl content, the specimen failure times go through a minimum with respect to pH. With increasing NaCl content, the minimum becomes more pronounced and its position shifts towards higher pH values. The position of each minimum is indicated by electrode potential measurements. Potentiostatic measurements as a function of pH confirm that maximum susceptibility to stress corrosion cracking occurs just prior to the onset of passivation.
Corrosion Resistance of Ti and a Ti-Pd Alloy in Hot, Concentrated Sodium Chloride Solutions
Authors: TAKAMURA AKIRA
Published: February 2013

Case histories are described concerning corrosion of titanium in hot concentrated chloride solutions and the results of the laboratory investigation on the corrosion behavior of titanium and titanium-palladium alloy in chloride environments reported. Although passivity of titanium was very stable in solutions of moderate concentration, this stability was found to decrease with increasing temperature, chloride and hydrogen ion concentration. In boiling concentrated chloride solutions, severe corrosion occurred locally in crevices such as interfaces between two titanium sheets or titanium and Teflon sheets which was identical to that encountered in field experience. In contrast to titanium, no crevice corrosion was observed to occur under the same conditions for titanium-palladium alloys. Superior corrosion resistance of the alloy was confirmed by field tests.
Adaptation of Linear Polarization Techniques for In-Situ Corrosion Measurements in Water Cooled Nuclear Reactor Environments
Authors: WILDE B. E.
Published: February 2013

Application of electrochemical polarization techniques to study corrosion of steels in aqueous environments at 289 C (554 F) and 1000 psi is described. A galvanostatic polarization circuit is discussed which permits determination of polarization parameters in-situ which are free of error due to resistance polarization in high purity water. Extended corrosion tests on plain carbon steel and Type 304 steel over 500 hours have shown that 99.6 percent correspondence can be achieved between electrochemical corrosion data and conventional weight-change techniques.

In de-oxygenated conditions, the steady-state corrosion rates of plain carbon steel and Type 304 stainless steel are 0.0015 and 0.0011 mg/cm2hr, respectively in water at 289 C. Cathodic and anodic Tafel constants for these steels under the above conditions have been determined and are shown to be independent of exposure time and corrosion rate.
High Temperature Corrosion and Evaporation of Haynes 25 and Hastelloy X-280
Authors: CHARLOT L. A. , WESTERMAN R. E.
Published: February 2013

The corrosion behavior of Hastelloy X-280 and Haynes 25 at 1120 C (2048 F) in atmospheres of oxygen, carbon monoxide, carbon dioxide, water vapor and methane has been investigated. Evaporation rates of the superalloys in vacuo have been determined to 1200 C (2192 F).

Oxidation rates generally were found to increase with increasing pressure in the range 0.04 to 760 torr. Oxidation rates in other oxidants were less than those in pure oxygen. Thermal cycling reduced the oxidation resistance of Haynes 25.

Both alloys carburize readily at 1120 C in a methane atmosphere. The carburization process can be reversed easily and ductility recovered by exposing material to oxidizing atmosphere at the same temperature.

Evaporation of superalloys in vacuo at 1120 C can result in metal loss approximating that found under oxidizing conditions. Preformed oxide films are shown to be ineffective barriers to evaporation in an inert atmosphere (vacuum) at 1120 C.
Sulfide Stress Corrosion of Some Medium and Low Alloy Steels
Authors: SNAPE E.
Published: February 2013

A study made of factors influencing sulfide-stress corrosion of a number of low alloy and medium alloy steels showed that their delayed failures when exposed simultaneously to stress and the corrosive action of acidified brine-hydrogen sulfide solutions have most of the features of hydrogen induced, delayed brittle failures. Different steels subjected to the same exposure conditions showed varying degrees of embrittlement as measured by ductility loss in bend tests.

Ductility could be restored partially by room temperature storage. Ductility restoration was related to the amount of hydrogen removed after exposure.

Delayed failure under stress occurs when corrosion generated hydrogen is absorbed, and lowers fracture strain until it equals the strain under load.

A minimum applied stress was obtained for each steel below which failure did not occur. This “threshold” stress decreased as strength level increased and depended simultaneously on composition and microstructure.

Nickel had little effect on cracking behavior of a steel whereas carbon appeared to be detrimental. Twinned martensite was more susceptible than untwinned martensite. Steels containing austenite were more resistant than body-centered steels.
Effect of Temperature on Stress-Corrosion Fracture
Authors: SYLWESTROWICZ W. D.
Published: February 2013

Prestrained samples of copper-beryllium alloy (1.8 Be, 0.3 Co) were exposed to an ammonia atmosphere at −20, 30 and 90 C (−4, 86, 194 F). It was found that the effect of temperature is related to the amount of plastic deformation. Above a critical value of plastic prestrain, temperature effect reverses; a longer exposure is needed to fracture a sample at 90 than at 30 C. This temperature dependence is explained by considering the number and distribution of dislocations.
Experience With Alclad Aluminum in Deep Sea Buoyancy Sphere
Authors: WEI MAURICE W.
Published: February 2013

Blisters formed on Alclad 7072–7178 during exposure in sea water attributed to solid solution of zinc at interface between cladding and core which could lead to a zone with a high proportion of zinc to copper.
Influence of Alternating Current on Corrosion of Mild Steel: Behavior in 1 N Sulfuric Acid
Authors: YAMUNA A. R. , SUBRAMANYAN N.
Published: February 2013

Corrosion behavior of mild steel in 1 N sulfuric acid subject to alternating currents in the range 250 micro-amp to 100 mA cm−2 at frequencies varying from 30 to 1000 cps is reported. It was found that at low current values, the corrosion rate increases with frequencies up to 200 cps, but diminishes with frequencies above this rate. At relatively high current values, the corrosion rate decreases with increasing frequencies. A qualitative explanation of the observations is suggested.
Techniques for Investigating Hydrogen-Induced Cracking of Steels With High Yield Strength
Authors: KIM C D. , LOGINOW A. W.
Published: February 2013

As part of a Song range study to develop grades of steel with improved resistance to hydrogen-induced cracking, techniques for measuring hydrogen uptake and hydrogen permeability were investigated and these parameters were correlated with resistance to hydrogen-induced cracking at different strength levels. The steel used for these studies was a Ni-Cr-Mo steel heat treated to four yield strength values ranging from 95 ksi to 150 ksi. The environment studied was a hydrogen sulfide saturated aqueous solution of 3% sodium chloride and 0.5% acetic acid. The technique used to measure hydrogen permeability consisted of exposing one side of a steel specimen to the sulfide environment and electrochemically measuring the hydrogen permeating to the opposite side. Hydrogen uptake was measured by the vacuum extraction method with specimens exposed to the environment for various time periods. The results of this comparison Stowed that both the resistance to cracking and the apparent diffusivity of hydrogen decreased as the yield strength was increased. Hydrogen uptake increased with increasing yield strength but the steady state permeation rate was not affected by strength level. A concept of hydrogen trapping is proposed to explain the observed relationships among the parameters studied and the mechanical strength of the steel.
The Role of Interstitial and Substitutional Impurities in Stress Corrosion Cracking of Low Carbon Steel in Nitrate Solution
Authors: FLIS J. , SCULLY J. C
Published: February 2013

The metallurgical aspects of the stress corrosion cracking of Fe-0.025% C in 5N NH4NO3 at 75 C (167 F) have been investigated. Sites of preferential corrosion in the alloy [annealed at 925 C (1697 F) and aged at 250 C (482 F)] were examined by transmission electron microscopy, and the susceptibility of the alloy to stress corrosion cracking after varying heat treatment was examined in constant strain rate tests. From the experimental data and calculated rate of transfer of impurities to and from grain boundaries, it was concluded that the tendency of grain boundaries to preferential corrosion is determined primarily by segregated substitutional constituents, and not by C or N.
The Influence of Hydrogen, Oxygen, and Ammonia on the Corrosion Behavior of Plain Carbon Steel in High Temperature Water
Authors: WILDE B. E.
Published: February 2013

The corrosion behavior of plain carbon steel in high temperature water has been studied using electrochemical polarization techniques. The influence of oxygen, hydrogen, and ammonia on the corrosion behavior has been studied over the range < 0.1–100 ppm. Potentiostatic anodic polarization data indicate that only oxygen has any effect on the anodic dissolution kinetics of carbon steel at 289 C (552 F). Controlled potential corrosion experiments at highly noble potentials in oxygenated water did not produce any form of localized corrosion. Cathodic Tafel polarization data indicate that the primary cathodic partial process during corrosion on ammonia and hydrogenated solutions is the reduction of hydrogen ions. Reduced steady-state corrosion rates observed in ammoniated solutions are due to the severe reduction in the limiting diffusion rate of hydrogen ions because of a simple pH effect. In oxygenated solutions, over the range 0.1–50 ppm O2, the major reduction process is the reduction of H+. At 50–100 ppm O2 levels, however, the reduction process changes to O2 + 2H2O + 4e → 4OH−, with the formation of a protective oxide film and a reduction of the steady-state corrosion rate to 0.2 mdd. Linear polarization studies indicated that the steady-state corrosion rate of carbon steel on hydrogenated solutions is relatively independent of H2 content. The corrosion rate on ammoniated solutions decreased with NH3 content over the range 1–100 ppm NH3. Corrosion rates in oxygenated water over the range < 0.08–100 ppm increase through a maximum at approximately 50 ppm then decreases to a low value at 100 ppm. This behavior is interpreted by the formation of a protective oxide film which is dependent on oxygen content. X-ray diffraction studies indicate the presence of a duplex oxide film in high oxygen solutions consisting of γFe2O3 and Fe3O4. At lower oxygen levels, only αFe2O3 was observed and also in ammoniated solutions. In hydrogenated solutions, with the highers corrosion rates, only αFe2O3 was observed on the surface.
Effect of Impurities on the Defects in Oxides and Their Relationship to Oxidation of Metal
Authors: KOFSTAD PER
Published: February 2013

The defect structure of the oxygen-deficient oxides of Nb2O5, Ta2O5, and ZrO2 are discussed. It is suggested that the oxygen vacancies are probably the important defects, except possibly at the most oxygen deficient part of the homogeneity ranges where interstitial cations may predominate. At high oxygen pressures, (small deviations from stoichiometry) effects of impurities become important and, in reported studies, probably determine the point defect concentration. Oxidation of Nb, Ta, Zr, resulting in growth of compact scales of Nb2O5 Ta2O5, and ZrO2, is discussed on the basis of these considerations. It is shown that effects of impurities may explain apparent deviations from the simple behavior predicted by the Wagner theory. It is emphasized that analysis and control of impurities is essential in interpretation of defect structures of oxides and defect-controlled properties and reactions.
Influence of Silicon and Manganese on Corrosion Behavior of Austenitic Stainless Steels
Authors: WILDE B. E. , ARMIJO J. S.
Published: February 2013

The influence of silicon and manganese on the electrochemical and corrosion behavior of a high purity austenitic 14Cr/14Ni-balance Fe alloy has been studied. Over the composition range 50–41, 500 ppm Si, no effect was observed on the kinetics of the anodic or cathodic partial processes. Addition of manganese over the range 5–26,300 ppm accelerates the anodic dissolution kinetics in the active range of potentials and also the steady-state corrosion rate in 1N̄ H2SO4 due to its influence on the kinetics of the cathodic partial process. The nature of this effect is analyzed according to electrode kinetic concepts from which it is shown that manganese changes the value of the electrode process transmission coefficient. Alloys containing manganese and silicon over large concentration ranges are extremely resistant to stress corrosion cracking in boiling 42 w/o MgCl2.
Effect of Cold Working and Annealing on Oxidation Rates of Copper in Dry Air at Room Temperature
Authors: KRISHNAMOORTHY P. K. , SIRCAR S. C
Published: February 2013

The effect of plastic deformation and further annealing on the kinetics of growth of thin oxide films on copper at 30 C (86 F) has been investigated. Oxidation rate was found to decrease markedly with increasing deformation. Further annealing showed an increase in the rate, the most pronounced changes occurring during the recrystallization stage. Results are interpreted in the light of Cabrera-Mott theory of growth of very thin oxide films on metals. The change in rate has been related to the concentration of cation vacancies in the Cu2O semi-conductor, which is dependent on the lattice distortion and defect concentration of the substrate metal.
Studies of Galvanic Corrosion Couples in Liquid Fluorine
Authors: TOY S. M. , ENGLISH W. D. , CRANE W. E.
Published: February 2013

Galvanic corrosion couples of several metals and alloys were tested in liquid fluorine at −320 F (−196 C), and the corrosion rates of the alloys were determined. A relative galvanic corrosion series, based on the rates, was developed as a guide for selecting materials for missile components exposed to fluorine containing propellants for long term storage. Electrode potentials of Al 1100 and copper versus a platinum reference electrode in liquid fluorine verify the general arrangement of the galvanic series. Evidence of pitting was found on Al 2014-T6 and silver coupons exposed to liquid fluorine.
Observations on the Initiation of Stress Corrosion Cracking in Aluminum Alloy 7039
Authors: HELFRICH W. J.
Published: February 2013

The initiation of short-transverse stress corrosion cracking in aluminum alloy 7039-T64 was studied by optical microscopy. Aluminized-plastic replicas were taken from the transverse surface of smooth specimens prior to and periodically during the stress corrosion test. With this technique, it was possible to trace back in time the initiation and propagation of cracks in any given area of the specimen. Dissolution of stressed specimens began at constituent particles resulting in well-defined separations at the particle-matrix interface; in some instances mechanical rupture of the constituents occurred. Stress corrosion cracking started at these interfaces with crack propagation along grain boundaries adjacent to the constituents. It is suggested that the incubation time required to form an incipient stress corrosion crack must be associated with anodic dissolution at specific interfaces, i. e., adjacent to constituents which are cathodic with respect to the matrix.