bluuebunny/crossref_metadata_2025 huggingface dataset:
Nucleotide-Binding Oligomerization Domain 2 Signaling Promotes Hyperresponsive Macrophages and Colitis in IL-10–Deficient Mice
Authors: Jamontt Joanna , Petit Stephanie , Clark Natalie , Parkinson Scott J. , Smith Philip
Published: February 2013

IL-10 contributes to the maintenance of intestinal homeostasis via the regulation of inflammatory responses to enteric bacteria. Loss of IL-10 signaling results in spontaneous colitis in mice and early onset enterocolitis in humans. Nucleotide-binding oligomerization domain (NOD) 2 is an intracellular receptor of bacterial peptidoglycan products, and, although NOD2 mutations are associated with Crohn’s disease, the precise role of NOD2 in the development of intestinal inflammation remains undefined. To determine the role of NOD2 in the development of colitis on the clinically relevant genetic background of IL-10–deficient signaling, we generated mice lacking IL-10 and NOD2 (IL-10−/−NOD2−/−). Loss of NOD2 in IL-10−/− mice resulted in significant amelioration of chronic colitis, indicating that NOD2 signaling promotes the development of intestinal inflammation in IL-10−/− mice. Contrary to previous reports investigating immune function in NOD2−/− mice, T cell proliferative capacity and IL-2 production were not impaired, and immune polarization toward type 1 immunity was not affected. However, loss of NOD2 in IL-10–deficient macrophages reduced IL-6, TNF-α, and IL-12p40 production in response to bacterial stimulation. Further analysis of the intrinsic macrophage response before the onset of inflammation revealed that, in the absence of IL-10, synergistic signaling between various TLRs and NOD2 resulted in hyperresponsive, proinflammatory macrophages, thus providing the appropriate immune environment for the development of colitis. Data presented in this study demonstrate that NOD2 signaling contributes to intestinal inflammation that arises through loss of IL-10 and provides mechanistic insight into the development of colitis in inflammatory bowel disease patients with impaired IL-10 signaling.
Tolerant Anti-Insulin B Cells Are Effective APCs
Authors: Kendall Peggy L. , Case James B. , Sullivan Allison M. , Holderness Jeff S. , Wells K. Sam , Liu Edwin , Thomas James W.
Published: February 2013

Autoreactive B lymphocytes that are not culled by central tolerance in the bone marrow frequently enter the peripheral repertoire in a state of functional impairment, termed anergy. These cells are recognized as a liability for autoimmunity, but their contribution to disease is not well understood. Insulin-specific 125Tg B cells support T cell–mediated type 1 diabetes in NOD mice, despite being anergic to B cell mitogens and T cell–dependent immunization. Using this model, the potential of anergic, autoreactive B cells to present Ag and activate T cells was investigated. The data show that 1) insulin is captured and rapidly internalized by 125Tg BCRs, 2) these Ag-exposed B cells are competent to activate both experienced and naive CD4+ T cells, 3) anergic 125Tg B cells are more efficient than naive B cells at activating T cells when Ag is limiting, and 4) 125Tg B cells are competent to generate low-affinity insulin B chain epitopes necessary for activation of diabetogenic anti-insulin BDC12-4.1 T cells, indicating the pathological relevance of anergic B cells in type 1 diabetes. Thus, phenotypically tolerant B cells that are retained in the repertoire may promote autoimmunity by driving activation and expansion of autoaggressive T cells via Ag presentation.
Cytotoxic NKG2C+ CD4 T Cells Target Oligodendrocytes in Multiple Sclerosis
Authors: Zaguia Fatma , Saikali Philippe , Ludwin Samuel , Newcombe Jia , Beauseigle Diane , McCrea Ellie , Duquette Pierre , Prat Alexandre , Antel Jack P. , Arbour Nathalie
Published: February 2013

The mechanisms whereby immune cells infiltrating the CNS in multiple sclerosis patients contribute to tissue injury remain to be defined. CD4 T cells are key players of this inflammatory response. Myelin-specific CD4 T cells expressing CD56, a surrogate marker of NK cells, were shown to be cytotoxic to human oligodendrocytes. Our aim was to identify NK-associated molecules expressed by human CD4 T cells that confer this oligodendrocyte-directed cytotoxicity. We observed that myelin-reactive CD4 T cell lines, as well as short-term PHA-activated CD4 T cells, can express NKG2C, the activating receptor interacting with HLA-E, a nonclassical MHC class I molecule. These cells coexpress CD56 and NKG2D, have elevated levels of cytotoxic molecules FasL, granzyme B, and perforin compared with their NKG2C-negative counterparts, and mediate significant in vitro cytotoxicity toward human oligodendrocytes, which upregulated HLA-E upon inflammatory cytokine treatment. A significantly elevated proportion of ex vivo peripheral blood CD4 T cells, but not CD8 T cells or NK cells, from multiple sclerosis patients express NKG2C compared with controls. In addition, immunohistochemical analyses showed that multiple sclerosis brain tissues display HLA-E+ oligodendrocytes and NKG2C+ CD4 T cells. Our results implicate a novel mechanism through which infiltrating CD4 T cells contribute to tissue injury in multiple sclerosis.
Local control of extra-abdominal desmoid tumors: systematic review and meta-analysis
Authors: Wood Thomas J. , Quinn Kathleen M. , Farrokhyar Forough , Deheshi Ben , Corbett Tom , Ghert Michelle A.
Published: February 2013

The local control of desmoid tumors constitutes a continuing treatment dilemma due to its high recurrence rates. The purpose of this systematic review was to critically examine the current treatment of these rare tumors and to specifically evaluate the local failure and response rates of surgery, radiation and systemic therapy. We comprehensively searched the literature for relevant studies across Cinahl, Embase, Medline and the Cochrane databases. Articles were categorized as surgery, radiation, surgery + radiation and systemic therapy (including cytotoxic and non cytotoxic). Methodological quality of included studies was assessed using the Newcastle-Ottawa Scale. Pooled odd ratios (OR) for comparative studies and weighted proportions with 95% confidence intervals (CI) are reported. Thirty-five articles were included in the final analysis. Weighted mean local failure rates were 22% [95% CI (16–28%)], 35% [95% CI (26–44%)] and 28% [95% CI (18–39%)] for radiation alone, surgery alone and surgery + radiation respectively. In the analysis of comparative studies, surgery and radiation in combination had lower local failure rates than radiation alone [OR 0.7 (0.4, 1.2)] and surgery alone [OR 0.7 (0.4, 1.0)]. Weighted mean stable disease rates were 91% [95% CI (85–96%)] and 52% [95% CI (38–65%)] for non cytotoxic and cytotoxic chemotherapy respectively.

The current evidence suggests that surgery alone has a consistently high rate of local recurrence in managing extra-abdominal desmoid tumors. Radiation therapy in combination with surgery improves local control rates. However, the limited data on systemic therapy for this rare tumor suggests the benefit of using both cytotoxic and non cytotoxic chemotherapy to achieve stable disease.
Compensation for Regulatory Takings with a Redistributive Government
Authors: Pecorino Paul
Published: February 2013

Richard Epstein has argued that governments should pay compensation for regulatory actions that impose costs on a subset of society. I develop a model in which there are two groups, one of whom benefits from a regulation, and one of whom bears the costs. A potentially biased government sets the level of the regulation and also redistributes income across the two social groups via the tax system. When taxes are nondistortionary, the government chooses the efficient level of the regulation to maximize wealth and then uses the tax system to distribute this wealth according to its preferences. If the government is forced to pay compensation for the costs of the regulation, it simply undoes this via the tax and transfer system. When taxes are distortionary, societal wealth is monotonically decreasing in the degree of compensation to be paid, so that the optimal level of compensation is zero.
Laboratory Investigation of Water-Side Scale And Corrosion in the Presence Of High Process-Side Temperatures
Authors: KERST HERMAN
Published: February 2013

A laboratory method of testing water-side corrosion and scale deposition in the presence of high process side temperatures has been developed. Two types of specimens are used: (1) a hairpin of ¼ inch seamless steel tubing mounted on a pipe plug and inserted in the circulating water system, and (2) a miniature heat exchanger made of ½ inch seamless tubing and standard pipe parts.

In studies on corrosion rates, and on calcium phosphate scale deposition under conditions of 130 F water temperature and 350–395 F hot-side temperatures, it was shown that corrosion rates may be increased up to 8 times over the rates on immersed coupons at 130 F. A possible method of calculating water-side skin temperatures is indicated.

It was shown that the use of polyphosphate treatments, at residual levels high enough to give corrosion protection, leads to the deposition of calcium phosphate scale. The use of chromate in combination treatments reduces the amount of this scale deposited, and also appears to reduce the amount of carbonate scale. 4.6.1
Effect of Iron, Aluminum and Cadmium Additions On the Performance of Zinc Anodes in Sea Water
Authors: WALDRON L. J. , PETERSON M. H.
Published: February 2013

Standard hull-mounting zinc anodes of various chemical compositions were immersed in water at the Norfolk Reserve Fleet site and supplied current continuously to a large steel sea wall for 36 weeks. The current was monitored daily during the initial week and 3–4 times weekly thereafter. At the conclusion of the test, the anodes were cleaned, weighed, and analyzed chemically. Electrochemical efficiencies and current outputs were determined.

Data are presented showing the performance of all anodes with graphical representation of typical specimens. Zinc anodes containing iron up to 0.006 percent and small additions of aluminum (to 0.5 percent) and cadmium (to 0.10 percent) out-performed the high-purity zinc anodes (0.0014 percent iron). There was some evidence that the addition of 0.1 percent aluminum without cadmium improves the performance of high-purity zinc. All anodes containing iron up to a maximum of 0.006 percent and aluminum and cadmium in any proportion within the limits of composition tested performed equally well. Minimum contents of 0.025 percent cadmium and 0.1 percent aluminum were indicated. 5.2.2
Selective Removal of Chromium From Type 304 Stainless Steel By Air-Contaminated Lithium
Authors: SEEBOLD R. E. , BIRKS L. S. , BROOKS E. J.
Published: February 2013

The corrosive action of high-purity and air-contaminated lithium on Type 304 stainless steel has been studied in non-isothermal closed systems in which maximum and minimum temperatures were 1500 F and 800 F. Chromium is selectively removed to depths of 10 microns from the surface of stainless steel by air-contaminated lithium at 1500 F and remains dissolved in the lithium where it is soluble to the extent of at least 25 percent. The other steel constituents are mass transferred in their original relative proportions and deposited as strongly magnetic dendrites. The preferential leaching of chromium is proposed as the initial step in the corrosion of stainless steel by aii-contaminated lithium. 6.25
Coupling Shift and Hydrogen Overvoltage In the Protection of Steel by Tin
Authors: KOEHLER E. L.
Published: February 2013

Evidence is presented to further substantiate the existence of a “coupling shift” for the tin-steel couple in weak acid media. By virtue of the shift, tin is able to sacrificially protect steel concurrent with a greatly diminished rate of hydrogen evolution. Since an explanation of the phenomenon does not seem possible on the basis of existing corrosion theory, additional experimental evidence was sought to elucidate the mechanism. Polarization curves were determined with automatic equipment, enabling this to be done more rapidly and reproducibly than is usually possible. Results indicate a mechanism in which corrosion rate and corrosion potential are determined entirely on the basis of hydrogen reactions occurring on the metal surface. Coupling shift is associated with an increased hydrogen over-voltage. 5.2.1, 3.6.8
Corrosion of Iron in an H2S-CO2-H2O System
Authors: GRECO EDWARD C. , WRIGHT WILLIAM B.
Published: February 2013

Corrosion studies of iron in an H2S-CO2-H2O System were made under static and dynamic conditions. The data indicated that there existed a certain hydrogen sulfide partial pressure, approximately 0.02 psia, above which hydrogen blistering occurred. Similar results with sulfide stress cracking were obtained. The hydrogen sulfide partial pressure at onset of cracking was 0.150 psia. Hydrogen sulfide became the controlling factor at very low partial pressures causing an initial drop in the corrosion rate. Apparently, the type of corrosion film formed controlled the corrosion rate. Changes in these films were observed to take place coincident with changes in corrosion rate and prevalence of hydrogen blisters. The relationship of these phenomena is discussed. 6.2.2, 8.4.3, 3.2.2, 3.5.8
High Temperature Corrosion By Catalytically Formed Hydrogen Sulfide
Authors: COUPER A. S. , DRAVNIEKS ANDREW
Published: February 2013

Organic sulfur compounds are known to be a major cause of high-temperature corrosion in refining processes. Chromium steels are widely used in such environments. The required chromium content for adequate resistance depends upon the chemical form of sulfur encountered.

Surfaces of corroding metals can act as catalysts in forming hydrogen sulfide, either from hydrogen and sulfur or by decomposition of organic sulfur compounds. Catalytically formed H2S is more corrosive than the same concentration of other H2S and can be corn-batted by adding chromium to the steel. Because corrosion is proportional to the concentration of H2S, a surface concentration of H2S is postulated as proportional to the catalytic activity of the surface.

Laboratory tests on sulfur vapor mixed with hydrogen and on amyl mercaptan mixed with nitrogen or hydrogen indicate that corrosion is proportional to the yield of catalytically formed H2S. Chromium additions to the steel, oxide scales on the metal surfaces, additions of chlorides to the stream, and increased velocity decreased both H2S yields and corrosion, whereas increased temperatures and addition of oxidizing agents caused increases. Further work should be done to develop practical methods to reduce the catalytic activity of corroding steel surfaces, thereby improving corrosion resistance to certain high-temperature streams that contain sulfur compounds.

3.4.2, 4.4.9, 3.5.9, 3.7.2, 8.4.3
Electrochemical Methods for Determining Passivation Properties of Paint Pigments
Authors: ROZENFELD I. L. , RUBINSHTEIN F. I. , YAKUBAVICH S. V. , KUSSKAYA A. G.
Published: February 2013

Several rapid methods are available for qualitative testing of the anticorrosion properties of paint coatings. In order to gain a better understanding of the mechanism of the corrosion process under coatings, however, quantitative electrochemical methods have been devised. One such method is based on electrode potential measurements in thin layers of water extracts of paint pigments. Another involves measurement of potential difference between painted and unpainted electrodes.

A method is also described in which capacity measurements are made on an electrical condenser consisting of the coating as the dielectric layer with the metal coated and a constant area metal plate placed over the coating as the outside layers.
Mechanism of Crevice Corrosion
Authors: ROSENFELD I. L. , MARSHAKOV I. K.
Published: February 2013

Failure of structures and of many types of automatic equipment is often due to crevice corrosion. Differential aeration was advanced some time ago as a major cause of such attack. The present investigation was made to demonstrate other factors in the mechanism of crevice corrosion.

Electrochemical methods were used to determine effects and relationships of polarization potentials and corrosion current densities in the main volume of electrolyte (which has free access to the open surface of the metal tested) and in the metal's crevices and clearances. Special laboratory apparatus was used with which crevice corrosion conditions could be simulated and in which “crevice” width was adjustable.

Iron, aluminum and stainless steels were tested in 0.5N NaCl. Iron was also exposed to a mixture of Na2SO4, NaCl and NaNO2, to 8.6N HNO3 and to 0.2N H2SO4. Observations were also made of linear selective type crevice corrosion at the metal-dielectric interface perimeter in acid and of comparative corrosion rates above, at, and below the water line of partly-immersed iron. (In the latter case, a “crevice” is considered to exist near the liquid's meniscus.)

It was concluded that much destruction of metal in clearances is due to peculiar electrochemical behavior which results in acceleration of the anodic metal ionization reaction and deceleration of the cathodic reaction. Insignificant differences in potential between metal on the open surface and that in the crevices initiate operation of corrosion cells.

Linear-selective dissolution of iron in acids, on the phase boundaries of the metal-dielectric-acid system, proceeds according to the crevice corrosion mechanism.

In water-line zone corrosion, the crevice corrosion mechanism is also in evidence, rate depending on whether the electrolyte is neutral, acid or alkaline. In inhibited media, metal potential near the water line becomes negative, due to difficulty of access of inhibitor, so that macrocells are activated.
Initiation of Stress Corrosion Cracking; Migration of Chloride in Oxide Films on Austenitic Stainless Steel
Authors: BERGEN C. R.
Published: February 2013

The mechanism of stress corrosion crack initiation can perhaps be understood by noticing the similarities among the several corrodent-crack susceptible alloy systems. In a number of such systems the specific ion responsible for cracking is relatively large. The corrosion product formed in a corroding medium containing such ions would imbibe them. Under appropriate conditions, due to their size, the larger ions would tend to diffuse to the region of the oxide film under highest tensile stress where local high tensile stress in the base alloy would be reflected. It is postulated that the appropriate conditions for diffusion are present in stress cracking systems and that the migration of the ion to which cracking is ascribed leads to high local concentrations in turn causing a local increase in corrosivity. Where the physical properties of the alloy are such that crack propagation can occur, stress corrosion cracking results.

Tests of the above hypothesis have been conducted with the chloride-austenitic stainless steel system. It was shown that chloride will migrate reversibly under the influence of tensile stress. It was also shown that the presence of nickel will inhibit the migration of chloride up a tensile gradient and the immunity to cracking of high nickel austenitic stainless alloys is attributed to this effect.
Polarization of Iron in H2S-NaHS Buffers
Authors: BOLMER P. W.
Published: February 2013

Effects of H2S concentration, pH, and buffer capacity on the hydrogen evolution reaction are reported. Over-all electrode reaction in the presence of H2S is:

The reaction is limited by H2S diffusion and by hydrogen overvoltage. Above the diffusion current, reaction is by decomposition of HS− or H2O.

Expressions are derived for calculating the pH at the electrode surface at, above and below the diffusion current. After correcting for pH changes, Tafel slopes of 115 mv are found in 10−3 M HS− and 55–70 mv for higher concentrations of HS− below the diffusion current.

Solutions of 10−1 and 10−2 M HS− develop protective films. Anodic polarization curves for these solutions show typical active-passive transitions, with very low residual currents in the passive region.
Morphology and Structure of Oxides Grown on Aluminum In Superheated Steam
Authors: HART R. K. , MAURIN J. K.
Published: February 2013

Four methods (light microscopy, electron microscopy, electron diffraction and X-ray diffraction) have been employed to identify and estimate the-products of reaction of pure aluminum with steam; in a few instances gravimetric measurements were also made. At temperatures between 400 and 450 C (752 and 842 F) and intermediate to high pressures aluminum disintegrated to a white powder product within 6 hours. This powder product was a mixture of α- and γ-alumina together with a small amount of aluminum. At higher temperatures and over the whole pressure range only γ-alumina was formed. The morphology of this material was threefold. A thin, highly resistant film rapidly grew to approximately 300 Å and drastically slowed down the reaction process. Outcropping from this film were oxide crystallites between 0.1 and 1.0 micron in size, as well as thin platelets which grew out from the surface as much as 10 microns. After reaction, specimen surfaces were found to contain numerous gas blisters as well as pits of various shapes and sizes. These pits ranged in size from less than 1 micron up to 300 microns and were located at grain boundaries as well as within metal grains.
Corrosion of Carbon Steel in Simulated Boiling Water and Superheat Reactor Enviroments
Authors: PEARL W. L. , WOZADLO G. P.
Published: February 2013

Results are reported for the continuation1 of extensive corrosion testing of carbon steel exposed in a dynamic test loop simulating the various environments found in a nuclear boiling-water-reactor system. Water and steam conditions were based on 20 ppm oxygen and 2.5 ppm hydrogen in the 546 F (285 C) saturated steam, a condition representative of the radiolytic water decomposition in boiling-water reactors. The pH of the high-purity water was neutral with no chemicals added to the water.

Tests were conducted to study the total corrosion and corrosion product released into the system from isothermal and heat-transfer surfaces as a function of operating conditions. Results of the investigation show that: (a) the corrosion of carbon steel in such an environment is characterized by an initially rapid filming period governed by nonlinear kinetics followed by an essentially linear corrosion rate, (b) once the system has been properly brought to the oxygen and hydrogen contents typical of BWR conditions, essentially no iron is lost to the system in further exposure to such conditions. A theory describing the formation of the protective oxide is proposed.

Additional test results are included for carbon steel exposed to superheated steam at temperatures up to 932 F (500 C).
Effect of Cr Content On Pitting Behavior of Fe-Cr Alloys
Authors: STEIGERWALD R. F.
Published: February 2013

Immersion and applied current studies are used to investigate the pitting behavior of binary Fe-Cr alloys formed both by conventional melting techniques and by diffusion of chromium into mild steel (chromizing). Experiments on both sets of materials show that a chromium content of 28–30 percent is critical for elimination of room-temperature pitting corrosion.

It is proposed that chromium acts to improve the pitting resistance of Fe-Cr alloys by stabilizing passivity, thus reducing pit initiation and slowing pit growth.

The relationship between polarization measurements and pitting is discussed. It is shown that in a simple immersion test pitting occurs at potentials quite different from the “critical” potentials predicted by polarization measurements.
Sulfurous Acid Corrosion of Low Carbon Steel at Ordinary Temperatures - I. Its Nature
Authors: McLEOD W. , ROGERS R. R.
Published: February 2013

Corrosion rate data are presented for low carbon steel in (1) a combination of sulfur dioxide, water vapor and air, and (2) aqueous solutions of sulfurous acid in the absence of air, at ordinary temperature. Information as to the nature of the corrosion products is presented and it is shown that this depends on the place in which the corrosion takes place to an important extent.
Effect of Grain Size on Stress Corrosion of Type 302 Austenitic Stainless Steel
Authors: BARNWELL V. L , MYERS J. R. , SAXER R. K.
Published: February 2013

Stress-corrosion cracking of Type 302 austenitic stainless steel exposed to boiling 42 w/o MgCl2 was determined to be grain-size dependent Decreased resistance to cracking observed for the larger grain-sized material was associated tentatively with a decreased incubation period. Incubation period was discussed in terms of a dislocation model for crack initiation. Possibility of a grain-size dependency for the propagation period was considered.
Sulfuric Corrosion of Chromel-Alumel Thermocouples
Authors: CREAMER E. L. , ROZALSKY I. , LOCHMANN W. J.
Published: February 2013

An investigation of premature, catastrophic failures of Chromel-Alumel thermocouples in petroleum refinery service disclosed that failures consisted of intergranular fractures of the Alumel wires caused by sulfidic corrosion. This type of failure was observed in the laboratory to occur in the 649–816 C (1200–1500 F) temperature range and in me presence of sulfides. Sulfur was detected by electron microprobe x-ray analysis in grain boundaries and cracks in failed Alumel wires. Intergranular sulfidic attack also was observed in progress by means of hot-stage metallography.

A mechanism for the observed type of attack is proposed: At temperatures in the 649 C (1200 F) range, sulfur diffuses into grain boundaries of Alumel and forms the nickel sulfide, Ni3S2±x and the eutectic, Ni-Ni3S2±x. Liquefaction of the eutectic above 645 C (1193 F) produces grain separations and wire failure. Above 810 C (1490 F), however, Ni3S2±x is unstable, hence, in this range Alumel corrosion is not limited to grain boundaries only and catastrophic failures do not occur.

The proposed corrosion mechanism may be applicable to other corrosion problems involving nickel and high-nickel alloys.
Anodic Behavior of Titanium and Commercial Alloys in Sulfuric Acid
Authors: LEVY MILTON
Published: February 2013

The anodic polarization behavior of commercially pure alpha titanium 75A (annealed), beta alloy 13V-llCr-3Al (annealed) and alpha-beta alloy 6Al-6V-2Sn (heat treated to strength levels of 140, 160 and 180 ksi) in hydrogen saturated 5, 12 and 20 percent sulfuric acid solutions was investigated at 20, 35, 50 and 65 ± 1 C, using a potentiostatic technique.

All specimens exhibited active to passive transition at temperatures above 20 C and acid concentrations greater than 5 percent Titanium alloy 13V-11Cr-3Al showed transpassive behavior which was attributed to the 11 percent chromium content Increasing acid concentration increased me critical current for passivity and shifted the critical potential for passivity in the noble direction. Increasing the temperature served only to increase the critical current for passivity.

Temperature coefficients and activation energies were the right order of magnitude for a reaction controlled by reactivity at the metal surface. For the alpha beta alloy 6Al–6V–2Sn the critical current for passivity increased as the ratio of amount of alpha to beta phase increased with increasing strength level. The dissolution is accelerated, probably, by the galvanic effects and the unfavorable area ratio. Ti 75A, a commercially pure metal and Ti 13V-11Cr-3Al, a homogeneous single phase alloy, had a smaller critical current for passivity values man did Ti 6Al-6V-2Sn, a multiphase alloy, which was expected.

The effect of Fe3+, Cu2+ and Cl− on polarization of Ti 6Al-6V-2Sn (180 ksi) was investigated also. Fe3+ and Cu3+ inhibited the anodic dissolution reaction and Cl− facilitated passivation.
Effect of the Polarization Technique on Dezincification Rates and the Physical Structure of Dezincified Zones
Authors: LANGENEGGER E. E. , ROBINSON F. P. A.
Published: February 2013

Accelerated dezincification has been produced by employing anodic polarization techniques. Polarizing currents were supplied either potentiostatically or by means of a constant voltage method. Extensive use of both techniques has been made; it was found that although rates of dezincification produced by the constant voltage method were slightly lower, there is less scatter of results. Furthermore, the constant voltage method proved to be the more suitable for research into the physical structure of dezincified areas, because anodically-produced dezincification was accompanied by less uniform corrosion and pitting.
Roles of Composition and Microstructure in Sulfide Cracking of Steel
Authors: SNAPE E.
Published: February 2013

The sulfide cracking behavior of a number of carbon and low alloy steels is described. Susceptibility to sulfide cracking is shown to depend primarily on microstructure. Steels with uniform, spheroidized carbides in a ferrite matrix have the greatest cracking resistance at any given strength level. The presence of untempered martensite in the microstructure drastically reduces cracking resistance. Lamellar carbides resulting from either normalizing and tempering or isothermal transformation give rise to cracking resistance intermediate between steels fully quenched and tempered and steels containing untempered martensite.
Improved Data Recording for Automatic Potentiodynamic Polarization Measurements
Authors: FRANCE W. D. , LIETZ R. W.
Published: February 2013

Improvements in instrumentation for automatically plotting potentiodynamic polarization curves by using a scanning potentiostat, a logarithmic converter, and an X-Y recorder are described. An accessory circuit permits uninterrupted recording of polarization currents from 10−2 to 107 μa and virtually eliminates operator attention. In addition, a low-pass filter reduces extraneous electrical noise in the electrochemical circuit and thereby provides smooth experimental curves.
The Relationship of Heat Treatment to the Corrosion Resistance of Stainless Alloys
Authors: BROWN M. H.
Published: February 2013

Information is presented on the response to sensitizing heat treatments of Incoloy 800, Incoloy 825, Carpenter 20 Cb-3, Inconel 600, Inconel 625, and Hastelloy G. None of the alloys investigated was found to be consistently immune to the development of susceptibility to intergranular corrosion as measured by nitric acid and ferric sulfate-sulfuric acid evaluation tests. In most cases the two test methods were in substantial agreement but the ferric sulfate-sulfuric acid test was less sensitive to thermal effects for Incoloy 825 and more sensitive for Hastelloy G. In general, variability in resistance to sensitization as a function of prior processing history appears to be more pronounced in the higher nickel alloys than in the 300 series stainless steels.
Thermal Stability of Hastelloy Alloy C-276
Authors: LEONARD R. B.
Published: February 2013

Hastelloy Alloy C has long been of major importance to the chemical process industry, but in many applications, vessels fabricated from Alloy C had to be solution heat treated to remove harmful weld heat affected zone precipitates which reduced corrosion resistance. Modification of the chemical composition produced Hastelloy Alloy C-276, which is more resistant to the precipitation of grain boundary particles than Alloy C. In order to fully utilize the improved alloy, and to understand its responses to fabrication techniques, it is helpful to understand the time-temperature-transformation characteristics. Grain boundary precipitates can form in Alloy C-276 when it is exposed to temperatures from 1200 to 2000 F (649 to 1093 C). The precipitation characteristics of Alloy C-276 compared to those of Alloy C can be shown through the use of a time-temperature-transformation curve (T-T-T). The precipitates have been identified as either “P” or Ni7Mo6-type phases. No M6C precipitate was found in Alloy C-276, whereas a considerable amount is normally found in Alloy C. The maximum precipitation occurs at 1600 F (871 C) with a sharp drop at higher and lower temperatures. However, the times required to form these precipitates are at least 30 times longer than those of Alloy C. When precipitates form in Alloy C-276, they decrease its corrosion resistance in both oxidizing and reducing environments. In a ferric sulfate-sulfuric acid environment, the greatest loss in corrosion resistance was found in material heat treated at 1600 F (871 C). This is the temperature of maximum precipitation and indicates an impoverishment of chromium in the areas surrounding the precipitate. When a hydrochloric acid test is used, maximum loss in corrosion resistance occurs in material heat treated at 1400 F (760 C). This indicates a difference in the precipitation phenomenon at this temperature when compared to higher temperatures, and is confirmed through electron microscopy. Impoverishment of molybdenum in the matrix areas surrounding the precipitate could account for the loss of corrosion resistance in this environment. Even though precipitation may occur under certain conditions, the alloy can be used in the as-fabricated condition without solution heat treatment if the time-temperature relationships used during fabrication are controlled to prevent precipitation. Heavy plate of Alloy C-276 has been welded without loss of corrosion resistance. Vessel “heads” made of heavy plate have been hot formed without loss of corrosion resistance using the best practice determined from the T-T-T diagram. Similarly brazing, stress relieving of clad composites, roll bonding and braze bonding can be successfully adapted to Alloy C-276.
Role of the Chloride Ion in Iron Corrosion
Authors: FOLEY R. T.
Published: February 2013

The role of the chloride ion in iron corrosion is assessed from the viewpoint of developing the concept that would lead to a general explanation. The experimental observations relating to such factors as the oxygen effect, concentration, cation, temperature, and pH dependence are reviewed. Some of the observations on the relative corrosion effects of various ions are described. These experimental factors are discussed in terms of oxide film theory (including colloidal films) and adsorption mechanisms. It is concluded that the anion effects can best be interpreted in terms of the complexes that are formed between Fe and the anion. In neutral chloride solutions, the complex is transitory unless it is “trapped” in a pit or crevice. In many acid solutions, halide complexes (compounds) are stable enough to inhibit corrosion.
Dissolution Behavior of Fe-Fe3 Structures as a Function of pH, Potential, and Anion – An Electron Microscopic Study
Authors: CRON C. J. , PAYER J. H. , STAEHLE R. W.
Published: February 2013

A phenomenological study of the dissolution behavior of an Fe-Fe3C structure was conducted using electron transmission microscopy as the primary investigative tool. Four distinct modes of attack were observed, i.e., carbide attack, matrix attack, general attack, and interface attack. The morphology of dissolution was found to depend upon pH, potential, and anion present. The results are rationalized in terms of: (1) thermodynamic calculations of the stability of carbides in aqueous environments, (2) known effects of pH, potential, and anion on dissolution kinetics, and (3) the influence of complexes formed with oxidized or reduced species. There were a number of significant results observed: (1) Iron carbide will dissolve at potentials in the range of –1000 mVH where Fe is thermodynamically stable. (2) The dissolution behavior of pearlite at pH 4 can shift modes between preferential attack at the ferrite, the carbide, and the interface as a result of changing only the anion. (3) Despite the general thermodynamic similarities for the stability of carbon and of iron carbide, their kinetic processes are greatly different. (4) The general patterns of dissolution behavior do not suggest any particular synergistic effects between the ferrite, carbide, and interface.
An Electrochemical Testing Method for Stress Corrosion Cracking by Separating Crack Anode from Cathode
Authors: SUZUKI TSUGUO , YAMABE MINORU , KITAMURA YOSHIHARU
Published: February 2013

The initiation and propagation of stress corrosion cracking (SCC) of austenitic stainless steels in boiling 35% magnesium chloride solution, with the pH adjusted to 3.0, were investigated electrochemically by separating the crack anode from the cathode. The dissolution current accompanying crack propagation can be measured, by connecting the anode with the cathode through an external electric circuit, and as a result, the distinction between crack initiation and propagation becomes very clear. The passive-active cell of SCC, simulated by keeping the crack anode potential at the potential of the cathode using a potentiostat, prevents the coupled potential from falling during crack propagation step, accelerates the dissolution of crack anode, and reduces the time to failure. For materials and environments which have low susceptibility to SCC, it can clearly be determined whether SCC occurs or not, by comparing the critical potential for crack propagation, not for initiation, with the corrosion potential of the unstressed steel in the environment concerned. If the former is more active than the latter, SCC can occur. The present method was applied to predict SCC in some chemical equipment, and successful results were obtained.
Use of Charge Curve Analysis Technique for In Vivo Determination of Corrosion Rates
Authors: ARAGON P. J. , HULBERT S. F.
Published: February 2013

Type 316L stainless steel, commercially pure Ti (75A, TCA), and Ti-0.2Pd bone plates were attached to the femurs of adult New Zealand white rabbits using nylon screws. Corrosion rate-time determinations were conducted using linear polarization (LP) and charge curve analysis (CCA) techniques during 2160 hours following surgery. Of the materials tested, Ti-0.2Pd seems to be the most corrosion resistant and Type 316L stainless steel the least. At the end of the test period (90 days), corrosion rates (in mpy) were in the order of 0.02 for 316L SS, 0.005 for Ti and 0.001 for Ti-0.2Pd. Very good correlation was obtained between determinations made with LP and MCCA. Histopathologic examination of the bone plates and surrounding tissues were conducted. All plates were surrounded by a fibrous tissue capsule. Adverse tissue reaction was minimal.
Precipitation Reactions in Inconel Alloy 600 and Their Effect on Corrosion Behavior
Authors: SCARBERRY R. C. , PEARMAN S. C. , CRUM J. R.
Published: February 2013

Precipitation reactions that occur in Inconel Alloy 600 were studied and correlated with corrosion behavior in nitric acid and stress corrosion cracking (SCC) susceptibility in polythionic acid and sodium hydroxide. It was found that exposure of the alloy to times and temperatures near the boundaries of the precipitation region on the TTT diagram results in continuous grain boundary carbides with continuous chromium depleted areas near the boundaries. Such a sensitized condition leads to high corrosion rates in nitric acid. Exposure of the alloy to conditions well within the precipitation region results in intragranular carbide precipitation, restructuring of grain boundary films into discrete particles, and replenishment of chromium depleted areas. The alloy is then considerably less susceptible to intergranular corrosion in nitric acid. The sensitized condition can be either beneficial or detrimental to the alloy's resistance to SCC, depending on the environment involved. If the environment tends to cause true SCC and does not attack chromium depleted areas, the continuous grain boundary films of sensitized material may block the progress of a crack. However, if the environment corrodes chromium depleted areas, cracking could be accelerated by grain boundary films and consequent chromium depletion.
Analysis of Iron Corrosion Products Using Mössbauer Spectroscopy
Authors: GRAHAM M. J. , COHEN M.
Published: February 2013

A brief outline of Mössbauer spectroscopy is presented, and previous work on its application to the field of corrosion is summarized. Practical corrosion products formed under a variety of conditions are identified using the Mössbauer effect, and in some cases the Mössbauer data have been complemented by X-ray diffraction analysis. α-FeOOH, γ-FeOOH, γ-Fe2O3, and Fe3O4 are found in atmospheric corrosion products; Fe3O4, γ-Fe2O3, α-FeOOH, FeCO3, and perhaps γ-FeOOH on buried pipelines; Fe3O4, γ-Fe2O3, α-FeOOH, β-FeOOH, and perhaps γ-FeOOH on buried structures; Fe3O4 in boiler superheaters, and γ-Fe2O3, Fe3O4, α-FeOOH, and possibly γ-FeOOH on heat exchangers, and α-FeOOH, γ-FeOOH, γ-Fe2O3, Fe3O4, and sometimes ZnxFe3-xO4 in galvanized potable water pipe. The ability of the Mössbauer effect to distinguish these oxides and hydrated oxides provides the corrosion engineer with a valuable method for analyzing iron corrosion products.
A Short Duration Test Method for Prediction of Crevice Corrosion Rates on Stainless Steels
Authors: DRUGLI JOHN M. , BARDAL EINAR
Published: February 2013

The aim of the present work has been to develop a short duration test method by which it is possible to: (1) determine the necessary conditions for crevice corrosion, and (2) predict the corrosion rate in active crevices for different area ratios between free surface and crevice. The method consists of determination of cathodic and anodic polarization curves on separate cathode (free surface) and anode (crevice) specimens, respectively, by certain applied procedures. The results from short duration tests on three different stainless steels in chloride solutions have been compared with results from long duration tests, and fairly good agreement has been found. It is thought that the short duration method can be applied for determination of the most significant crevice corrosion properties. With minor adjustments, the method is also applicable for aluminum alloys in chloride solutions.
The Validity of Electrochemical Methods for Measuring Corrosion Rates of Copper-Nickel Alloys in Sea Water
Authors: SYRETT BARRY C. , MACDONALD DIGBY D.
Published: February 2013

This work was stimulated by reports that electrochemical methods for measuring the polarization resistance of copper, nickel, or copper-nickel alloys in aqueous systems may lead to appreciable errors in the estimates of the corrosion rate. In the present work, the polarization resistance (Rp) of two copper-nickel alloys (90:10 Cu:Ni and 70:30 Cu:Ni) was monitored as a function of time in flowing sea water that contained 0.045, 0.85, 6.6, or 26.3 mg/dm3 dissolved oxygen. Rp values were obtained using the linear polarization, potential step, and AC impedance techniques. The total weight loss during the test period was calculated from the area under the 1/Rp versus time curve and compared with the measured weight loss. The experimental data support the validity of electrochemical methods for measuring corrosion rates of copper-nickel alloys in sea water, provided that a sufficient number of Rp measurements are made during the first 24 hours, and provided that proper consideration is given to the capacitive elements of the metal/solution interfacial impedance. Previous reports that electrochemical measurements may lead to underestimates of the corrosion rates are thought to have resulted primarily from undetected (and very high) corrosion rates at short exposure times. Reported overestimates of the corrosion rates are thought to have resulted from the use of a potential sweep rate that was too high (linear polarization technique), a time for current decay that was too short (potential step technique), or excitation frequencies that were insufficiently low (AC impedance technique).
Dependence of KISCC on Loading Rate and Crack Orientation in Ti-6AI-6V-2Sn
Authors: MOSKOVITZ J. A. , PELLOUX R. M.
Published: February 2013

The dependence of KISCC on loading rate was investigated for Ti-6AI-6V-2Sn in 3.5% NaCI for both the WR and RW orientations. Crack initiation was determined to occur when a spike in electrochemical potential was observed. The measured KISCC values were a minimum at an intermediate loading rate, which is indicative of hydrogen embrittlement through hydride formation. The strain rate at which minimum KISCC values were observed corresponded closely with the theoretical minimum strain rate for hydrogen transport by dislocations as Cottrell atmospheres. KISCC values were lower for RW specimens than for WR specimens due to a more favorable orientation of hydride habit planes with respect to the tensile axis.
The Effect of Oxygen Temperature Combinations on the Stress Corrosion Susceptibility of Sensitized Type 304 Stainless Steel in High Purity Water
Authors: FORD F. P. , POVICH M. J.
Published: February 2013

The variation in stress corrosion susceptibility and cracking morphology of sensitized Type 304 stainless steel in high purity water is reported as a function of combinations of oxygen (0.01 to 8 ppm) and temperature (75 to 288 C). The results are discussed both in terms of the fundamental parameters involved in stress corrosion cracking (SCC), and the relevance of the data vis a vis the prevention of cracking in operaitonal BWR's.
Localized Corrosion of Amorphous Fe-Ni-Cr-P-B Alloys
Authors: DIEGLE RONALD B.
Published: February 2013

Experiments were performed with a series of amorphous Fe-Ni-Cr-P-B alloys of varying Cr content to characterize their susceptibility to crevice corrosion. Potentiodynamic and potentiostatic polarization of freely exposed specimens was performed in simulated crevice solutions (1M NaCI at pH 1–7, and 6% FeCI3 at PH 1.4). Crevice corrosion experiments were conducted in an artificial crevice cell. Polarization in the simulated crevice electrolytes indicated that alloys containing 2 to 16 At.% Cr can passivate in even 1M NaCI, pH 1, and they do not experience significant pitting at potentials active to that at which oxygen evolution occurs. In agreement with previously published results,1 only a few At.% Cr were needed to confer passivity; even the alloy containing 2% Cr achieved a passive current density of only 10−1 A/2 in 1 M NaCI at pH 1, and it did not pit below about 1.20 V(SCE). Results indicated, however, that the alloys meet certain requirements for susceptibility to crevice corrosion and occluded cell corrosion in general; that is, they passivate at sufficiently anodic potentials, and the intensity of active dissolution increases with decreasing pH. The amorphous alloys were considerably more inert to corrosion than T304 and Incoloy 800 steels, suggesting a lesser susceptibility to crevice attack. Experiments with the artificial crevice cell confirmed that the amorphous alloys can indeed be forced to crevice corrode, but only at very anodic (transpassive) potentials. They are considerably more resistant to crevice attack than the crystalline Cr-containing alloys.
Effect of Physical Parameters on the Pitting Corrosion of Mild Steel in Low Total Dissolved Solids, Oxygen Bearing Waters: A Nonpassivating Metal/Environment System
Authors: TAIT W. S.
Published: February 2013

Potentiodynamic scanning was used to study the effects of solution temperature, test time, total dissolved solids (TDS) and local fluid velocities on pitting rates of AISI 1018 mild steel. Neutral, oxygen saturated waters of various TDS levels were utilized as corrosive fluids. Passivation of the steel did not occur in these fluids. The rate of pitting was found to be a very weak function of TDS levels. A semilog plot of temperature versus rate and a log-log plot of fluid velocity versus rate are straight lines. Temperature is the most dominant factor governing pitting rates in the systems studied.