bluuebunny/crossref_metadata_2025 huggingface dataset:
Polarization Studies of Aluminum Alloys In Water at 200 C and 300 C
Authors: GREENBLATT J. H. , McMILLAN A. F.
Published: February 2013

Specimens of commercial 2S aluminum and two special alloys containing iron and nickel were polarized anodically and cathodically at a number of different current densities at 200 C and 300 C. Weight gains were obtained and the potentials relative to the stainless steel autoclave were measured by an interrupter method. The weight gain data indicated that the polarizing current is being carried by electronic conduction.

The potential-time curves for anodic polarization indicate differences between 2S aluminum and the alloys in that greater polarization is obtained with the latter. These curves also indicate that the impressed current decreases the film resistance. In all cases the potential reached a plateau value with time and this time was shorter for the alloys.

The potential-time curves for cathodic polarization also show plateau values but the rise to a plateau value is in the opposite sense to the applied current. With increasing cathodic polarization the plateau values occur at more negative values of the potential. This latter trend is in the same direction as the applied polarizing current. This apparently is explained in terms of the build-up of the aluminum oxidation potential which acts in a sense opposite to the applied current. Again the time to reach plateau values was shorter for the alloys.

Voltage current curves were also obtained on specimens left overnight (approximately 17 hours) at two different anodic polarizing currents. These curves indicated differences between 2S aluminum and the alloys; these differences are discussed in terms of the semi-conducting properties of the oxide film.

The observations made on the differences in the properties of the oxide films on the materials examined as revealed by potential and polarization curves are discussed as to their significance in determining corrosion resistance.
Effect of CO2 on the Strength and Ductility of Type 304 Stainless Steel at Elevated Temperatures
Authors: MARTIN W. R. , McCOY H. E.
Published: February 2013

One of the important problems in determining the usefulness of stainless steels as cladding materials in high-temperature gas-cooled reactors is the effect of chemical reactions between clad and coolant on the cladding strength and ductility. The mechanism by which the coolant (CO2 in this investigation) affects the strength properties of Type 304 stainless steel are being investigated in the range 1300 to 1700 F (704–927 C). Creep- and stress-rupture results obtained on sheet materials in wet and dry CO2 and argon are compared. The effect of annealing in CO2 on the tensile strength and ductility is also reported.

The question of whether the strengthening observed in CO2 was due to oxidation or carburization was investigated. Experiments on the effect of various partial pressures of oxygen in argon showed that the creep rate was minimum at approximately 10 ppm. The creep rate in CO2 at equivalent stress and temperature was one-third the minimum rate observed in oxygen. Chemical analyses, metallography, and experiments with isotopic carbon showed that carburization occurred in pure flowing CO2 in the temperature range studied. From this evidence it was concluded that the strengthening observed in CO2 was primarily due to carburization.

The creep- and tensile-fracture strains were adversely affected by exposure to CO2 with the magnitude of the effect dependent on the time and temperature of exposure.
Effect of Platinum, Copper and Iron Ions On Corrosion and Passivity of Titanium In 15 Percent Hydrochloric Acid
Authors: TOMASHOV N. D. , AL'TOVSKII R. M.
Published: February 2013

An investigation has been made of the effect on corrosion rate of titanium in 15 percent hydrochloric acid of introducing cations of more noble metals, particularly Pt4+, Cu2+ and Fe3+. It was found that such ions cause a shift in metal potential in the positive direction, enhancing the cathodic process and resulting in anodic passivity of the titanium.

In addition to acting initially as cathodic depolarizers, the noble metals deposit galvanically, forming more effective cathodic areas and further accelerating cathodic depolarization. However, in concentrations lower than those required to attain passivity, the noble metal ions increase rather than decrease the corrosion rate of titanium in 15 percent hydrochloric acid.

In the presence of the fluoride ion, Pt4+ ions accelerate the corrosion rate of titanium in HCI with increases in their concentration, the opposite of the effect when concentrating Pt4+ ions before fluoride is introduced.
Linear Polarization Measurements In the Study of Corrosion Inhibition
Authors: LEGAULT R. A. , WALKER M. S.
Published: February 2013

A reliable and accurate method of determining metal dissolution rates in a relatively short time is much needed in studies of corrosion inhibition. Weight-loss determinations on specimens supply only average rate data over the interval of the test. Rate determinations by chemical analysis of the corrosive environment are also subject to this limitation. Both of these methods are subject to errors arising from intermittent removal of the sample from the environment.

Knowledge of corrosion rate changes during the period of exposure is valuable to understanding of the mechanism of the reaction involved. The linear polarization method has been found very rapid and convenient for studying rate changes and evaluating corrosion inhibitors. It has also made possbile observations of the synergistic effects that may exist between inhibitor and environment.
Effect of Metal Composition and Structure On Corrosion and Oxidation
Authors: UHLIG HERBERT H.
Published: February 2013

Metallurgical factors such as heat treatment and cold-work are not important when corrosion in aqueous media is controlled by diffusion of reactants, e.g. dissolved O2, from the environment. They become important when corrosion control is focused at the metal surface, e.g. steel in acids. In this instance, galvanic cells depend less on where or how metal atoms are placed in their lattice, and more on compositional differences along the metal surface produced by heat treatment or plastic deformation.

At elevated temperatures, compositional gradients within a metal are less important. The rate depends instead on diffusion through thick corrosion product layers and on the tendency for spoiling to occur during temperature fluctuations. Metallurgical factors assume greatest importance during initial oxidation, or for thin film formation.
Electrodeposition of Iron from Aqueous Solutions Onto an Aluminum Alloy
Authors: COOK E. H. , McGEARY F. L
Published: February 2013

Heavy metal contaminants such as copper, nickel and cobalt have long been recognized as corrosion hazards in aqueous solutions because their reduction is a comparatively common electrochemical corrosion reaction. It has been known for many years that Fe (III) is corrosive to various metals if the ferric salt is soluble, that is, if the solution is sufficiently acid to maintain the Fe (III) ion in solution. Metals such as aluminum, zinc, cadmium, iron, etc., reduce Fe (III) to Fe (II). Furthermore, if dissolved oxygen is available, more corrosive conditions can result by the oxidation of Fe (II) to soluble Fe (III).

Recently a service situation was encountered where ferrous iron in solution was reduced to metallic iron as the result of electrochemical action in an aluminum alloy pipe handling a brine solution. This article describes the laboratory studies conducted to define the mechanism of iron electrodeposition on certain metal alloys from aqueous solutions. Methods to control or prevent such reduction are discussed.
Corrosion Characteristics Of the Rare Earth and Yttrium Metals
Authors: LEE LINDA , GREENE N. D.
Published: February 2013

The corrosion of rare earth metals in air, water, and aqueous solutions at different temperatures has been measured by conventional weight loss and weight gain tests. The metals oxidize slowly in air, corrode slowly in water and alkaline solutions, and are readily soluble in most acids.

Correlations of corrosion behavior with the electronic and physical properties of the rare earths are discussed.
Effect of Supplementary Alloying Elements On Pitting Corrosion Susceptibility Of 18Cr-14Ni Stainless Steel
Authors: TOMASHOV N. D. , CHERNOVA G. P. , MARCOVA O. N.
Published: February 2013

This investigation was conducted because the development of new alloys with increased resistance to pitting corrosion appears to be largely dependent on an understanding of the effects of various concentrations of alloying elements on the initiation and steady operation of localized pitting sites on the metal surface.

Corrosion tests in 0.5N FeCl3 and determinations of passivity breakdown potentials in 0.1 N NaCl were employed to study the pitting tendencies of 18 Cr-14Ni stainless steels to which alloying elements in various concentrations had been added. The alloying elements, chosen for their stability in solutions containing chloride ions and their solubility in austenite, were: Mo, Si, V, W, Ti, Ce, Nb, Ta, Zr and Re.

Mo, Si and V, respectively, at 5 percent concentration, had the most marked effect in increasing resistance to pitting. Re, even in concentrations below 1 percent, was also very effective. The other elements tested had either a negative influence or no effect.

Heat treatment in the dangerous temperature zone (650 C for 2 hours) greatly impaired the resistance of steel alloyed with 5 percent Mo, Si or V, which is not susceptible to pitting corrosion in the quenched state.
Morphology of Stress-Corrosion Cracks In Notched Specimens of Austenitic Stainless Steels
Authors: SCULLY J. C. , HOAR T. P.
Published: February 2013

The pattern of stress-corrosion cracking of notched specimens of an 18 Cr-8 Ni austenitic stainless steel stressed in 42 percent aqueous magnesium chloride solutions is described. It illustrates the action of both tensile and shear stresses in promoting fracture: cracks are nucleated along directions of maximum shear strain and their propagation paths are determined by these and the acting tensile stress.
Passivity of Chromium and Stainless Steel In Hydrofluoric Acid
Authors: SEASTROM C. C.
Published: February 2013

The anodic polarization of chromium and 18Cr-8Ni stainless steel has been investigated in 2 to 48 percent hydrofluoric acid, 40 percent sulfuric acid, and in a solution containing 5 percent hydrofluoric acid and 40 percent sulfuric acid. Chromium can be anodically protected in hydrofluoric acid. The corrosion rate of stainless steel in hydrofluoric acid can be reduced by anodic protection but less than is possible in sulfuric acid. The dissolution rate of passive stainless steel in 5 percent hydrofluoric acid plus 40 percent sulfuric acid is similar to the rate in 5 percent hydrofluoric acid. The breakdown of the passive film on stainless steel probably is accelerated by the formation of stable ferric fluoride complex ions.
Mechanism of Electrochemical Corrosion Of Metals Under Insulating Coatings. II. Kinetics of Cathodic Processes On Insulated Metals in Electrolytes
Authors: TOMASHOV N. D. , MIKHAILOVSKII YU N. , LEONOV V. V.
Published: February 2013

1. Investigations were made of the kinetics of the cathodic process on metal surfaces coated with thin insulating films. It was established that enhancement of the cathodic reaction on insulated electrodes at definite potential values is connected with the emergence of electronic conductivity of the film. Along with this, there can also be observed a nonreversible process of electrochemical perforation of the protective film by the active ions in the electric field.

2. Studies were made of the mechanism possibly involved in the corrosion of metals under porous insulating films. It was shown that on metals with a static potential in the region of emerging electronic conductivity in the film, the cathodic process is active not only on the metal surfaces exposed by the film pores but also on the very thin sections of the insulating film.
Minimizing Corrosion In Uranium Extraction Solutions By Application of Anodic Protection
Authors: ROBINSON F. P. A. , GOLANTE L.
Published: February 2013

Anodic protection was applied to certain special alloys following an investigation into their anodic polarization characteristics in 0.1 percent HNO3 + 5 percent HCOOH + 20 percent NH4F solution saturated with SO2. The effectiveness of this method of corrosion prevention was confirmed by the large reduction in corrosion rate. In addition, intercrystalline corrosion, knifeline attack and weld corrosion were appreciably reduced on application of this technique.
Sulfates in the Passive Iron Layer
Authors: RIGGS O. L.
Published: February 2013

Anodic polarization data were obtained on iron in 20 N H2SO4 at 25 C (77 F). Along the polarization curve, the potential was held constant at 20 mv increments and the current was recorded at the end of 60 minutes. Minimum currents, the average of four experiments, were noted at 260, 520, 810, 1060, 1320 and 1600 mv noble potential with reference to the saturated calomel electrode (S.C.E.).

The various chemical compositions were identified with reproducible X-ray diffraction data. A technique involving an ethyl alcohol rinse permitted the X-ray study of the passive surface. The passive iron layer was identified as FeSO4.H2O, Fe2(SO4)3 H2O,FeSO4.4H2O and as FeSO4.7H2O at 260, 520, 810 and 1320 mv noble to S.C.E., respectively. The structures were reported to be responsible for the steady-state minimum currents. The X-ray diffraction values of the specimens held at 1060 and 1600 mv (S.C.E.) were not identified.

The anodic polarization curve was discussed in terms of specific electrochemical events.
Elevated Temperature Stress Corrosion Resistance of Titanium Alloys
Authors: NEWCOMER R. , TOURKAKIS H. C. , TURNER H. C.
Published: February 2013

A number of titanium alloys considered suitable for use in Mach II and III transports were tested for resistance to stress corrosion in the presence of chlorides. These included 4A1-3Mo-1V, 6A1-4V, 8A1-1M0-1V, 5A1-2.5Sn and RS-140. Samples were exposed stressed (smooth and fatigue pre-cracked) at 600, 700 and 800 F (316–427 C) 100 hours for smooth and 50 hours for precracked specimens. Welded and heat-treated specimens were among those tested.

All alloys were found susceptible to stress corrosion cracking. Welding appeared to increase susceptibility, but existing fatigue cracks did not seem to increase susceptibility.
Corrosion of Iron in an H2S-CO2-H2O System Composition and Protectiveness of the Sulfide Film as a Function off pH
Authors: SARDISCO J. B. , PITTS R. E.
Published: February 2013

Composition and protectiveness of the-iron sulfide film, formed as a result of the liquid phase H2S-CO2-H2O corrosion of Armco iron, have been related to the initial pH of the solution. Composition of the film was determined by electron diffraction analysis. Protectiveness of the film was determined by measuring the weight loss of iron specimens previously corroded and covered by sulfide films formed in H2S-CO2-H2O solutions of different pH values.

Composition and the protectiveness of the iron sulfide film were affected by the initial pH of the H2S-CO2-H2O solution. The film was least protective in the pH region of about 6.5 to 8.8. The film that was least protective contained essentially kansite, whereas the film that was most protective contained pyrite and troilite along with kansite.

Because the HS− anion is the predominant species in the pH region of about 6.5 to 8.8, it is indicated that the HS− was at least partially responsible for the film being less protective.
A Critical Survey off Possible Factors Contributing to Internal Boiler Corrosion
Authors: HOLMES D. R. , MANN G. M. W.
Published: February 2013

Main factors contributing to boiler corrosion are reviewed. Published data and work at authors' laboratories on the following causes of boiler pitting and corrosion are reviewed and discussed: Dissolved oxygen, copper deposition, concentration of sodium hydroxide, phosphate hideout, suspended solids, chlorides, thermal effects, thermogalvanic effects, breakdown of magnetite films from cyclic expansion and contraction, strain, weld and tube defects, compositional inhomogeneities.

Authors believe caustic and chloride attacks are mutually exclusive but that they may be found in combination with others. Changes in attitude about magnetite caused by recent discoveries indicate that radical concept changes can be expected.
Effect of Metallic Additives On Mercury Corrosion of Titanium
Authors: WANG JAMES Y. N.
Published: February 2013

Mass transfer of nickel to the hot leg (454 C, 850 F) of a mercury thermal convection loop in which titanium samples were exposed has been observed. This involved dissolution of nickel in mercury at 320 C (608 F), its transfer to the surface of the sample in the hot leg, and subsequent interdiffusion of nickel and titanium. Microprobe study of surface layers on the titanium sample indicated stratification of nickel. Outer layer contained two materials with compositions closely approximating those of TiNi and TiNi3, and an inner layer a material with nickel content close to the reported solubility limit for nickel in β-Ti, even though the reaction was conducted below α-β transformation temperature. Effects of other metallic additives are also discussed.
General Concepts of Gas-Metal Reactions
Authors: GULBRANSEN EARL A.
Published: February 2013

A metal in a gas atmosphere at high temperature is a complex chemical system. The metal usually is not pure but contains in addition to metallic impurities O, N, H, C, S, etc. The gas atmosphere also is usually complex, containing (in addition to O2) N2, H2, CO2, H2O, etc, A wide variety of chemical and physical phenomena occur in and on the metal surface in a typical gaseous environment at high temperature. The various phenomena are systematized into five zones of activity: metal, metal-oxide interface, oxide, oxide-gas interface, and gas.

The general concepts are considered by setting down classification schemes of diverse observations and phenomena. Eight classification systems are given, then discussed. These are (1) type of reaction, (2) sign and magnitude of free energy change, (3) extent of reaction, (4) crystal structure, (5) empirical and theoretical rate laws, (6) physical and chemical properties of metal and oxide, (7) topology of metal and reaction product and (8) effect of reaction on metal or environment.
Stress Corrosion Behavior Of Maraging Nickel Steels In Natural Environments
Authors: DEAN S. W. , COPSON H. R.
Published: February 2013

Stress corrosion cracking behaviors of several laboratory and commercially produced heats of 18, 20 and 25 percent Ni maraging steels have been observed in marine and industrial atmospheres and in sea water. Resistance of 18 percent Ni maraging steels was strongly affected by their structure and thermal histories. In properly processed materials rate of growth of stress corrosion cracks was low in most environments tested, and many stressed specimens lasted more than 500 days. Lower-yield-strength 18 percent Ni maraging steels were more resistant to stress corrosion cracking than higher strength alloys, also more resistant to hydrogen cracking when cathodically protected in sea water. Composition affected behavior of maraging steels, 20 percent Ni materials having relatively poor resistance and 25 percent Ni maraging steels good resistance, particularly in anoveraged condition. Control specimens of AISI 4340 steel hardened to 240-ksi yield strength failed rapidly in all test environments and conditions.
Anodic Polarization Behavior Of Nickel-Chromium Alloys In Sulfuric Acid Solutions
Authors: MYERS J. R. , BECK F. H. , FONTANA M.G.
Published: February 2013

Anodic polarization behavior of annealed high-purity Ni, Cr and selected Ni-Cr alloys in hydrogen-saturated, 1, 5, 10 and 20N sulfuric acid solutions was investigated at 25 ± 1 C (77 F) using a potentiostatic technique. All specimens except pure Ni in 20N acid had an active-to-passive transition. Decreasing acid concentration increased passive potential range of pure Ni while acid concentration did not appreciably affect the passive region of pure Cr or the Ni-Cr alloys. Increasing acid concentration and decreasing chromium content increased the secondary passivation tendency in the transpassive region. No oxygen evolved in the transpassive region except for pure Ni and the higher nickel alloys. Tafel slopes for anodic dissolution, early transpassive region and oxygen evolution were determined.

Corrosion potentials for pure Ni and Ni-Cr alloys containing up to 90 w/o Cr behaved as a reversible hydrogen electrode over the pH range 1.63 to −0.44. This linear relationship did not exist for the higher acid concentrations. Slope dependence for pure Cr and the 99Cr-1Ni alloy was −0.110.

A minimum in critical current density versus percent Cr curves was established at 90 to 95 w/o Cr. Passivation potentials were determined. Passive current density decreased with increasing chromium content over the composition range 0 to 33 w/o Cr.

It was established that increased specimen purity decreases the magnitude of critical current density and shifts corrosion and passivation potentials in the noble potential direction.
Oxidation Of A Ni-2 Percent ThO2 Alloy And The Logarithmic Rate Law Of Oxidation
Authors: JONES D. A. , WESTERMAN R. E.
Published: February 2013

The oxidation of pure nickel containing a dispersion of submicron size ThO2 particles was investigated in the range 600 to 1000C (1112–1832 F). At 600 and 700 C oxidation was described by a parabolic equation. At 950 and 1000 C a mixed parabolic relationship (partial control by an interface reaction) applied. Logarithmic oxidation, concurrent with a minimum in the oxidation rate, occurred at intermediate temperatures of 800, 850 and 900 C. The partially controlling interface reaction at 95(3 and 1000 C is interpreted to be activated adsorption of oxygen at the oxygen-oxide interface. A logarithmic rate law for oxide film formation is derived by considering oxygen adsorption as the controlling process.
Corrosion Resistance of Ta to Mixture of Phosphoric Acid and Potassium Chloride at 120 C
Authors: ALON A. , SCHOR M. , VROMEN A.
Published: February 2013

Corrosion resistance of commercially pure tantalum to the system KCl - H3PO4 - H2O, initially containing 60–260 ppm fluoride, has been investigated at 120 C (248 F) and at atmospheric pressure. Effect of the environment on the metal has been determined by visual and microscopic examination, by weight increments and chemical analysis. Confirmation of results was obtained radiochemically using Ta182 as radiotracer. Formation of a passive film, 13,000 Å thick, following a logarithmic growth law was detected. Corrosion rates calculated are of the order of 6 – 20 × 10−3 mpy, indicating good resistance to the system.
Stress Corrosion and Hydrogen Cracking off 17-7 Stainless Steel
Authors: MATSUSHIMA I. , DEEGAN D. , UHLIG H. H.
Published: February 2013

Whether a stainless steel fails by stress corrosion cracking or by hydrogen cracking depends on its structure. A pure ferritic 18–8, body-centered cubic as quenched, fails by hydrogen cracking when cathodically polarized in dilute sulfuric acid containing arsenic trioxide. However, it is resistant to stress corrosion cracking in MgCl2 solution boiling at 154 C (310 F). A similar composition austenitic 18–8, face-centered cubic as quenched and tested similarly is resistant to hydrogen cracking but fails by stress corrosion cracking.

Type 301 austenitic 17–7 stainless steel, which transforms in part to ferrite on cold rolling, is resistant, therefore, to hydrogen cracking as annealed-quenched or slightly cold reduced. It fails within 10–30 minutes when cold reduced more than 20 percent even though it transforms only partially to ferrite.

In MgCl2 solution, both the annealed-quenched and the cold-reduced alloy fail, cracking times being prolonged by cathodic polarization, characterizing the failures as stress corrosion cracking. Contrary to reactions observed in pure phase alloys, stainless steels containing mixtures of austenite and ferrite may fail either by hydrogen cracking or by stress corrosion cracking, depending on the environment.
Effectiveness of Nitroethane As a Hydrogen Diffusion inhibitor
Authors: DAUERMAN L , DENNY D. B. , SHANEFIELD D.
Published: February 2013

Tests using 1095 steel in 4.8 N HCl solution at 100 F (38 C) show nitro-ethane accelerates hydrogen diffusion and does not act as an inhibitor. A hypothesis is advanced for its effect in the tests.
Corrosion Rates off Mild Steel in Alkaline Lithium Bromide Solutions by the Polarization Resistance Method
Authors: COHEN ARTHUR , JELINEK ROBERT V.
Published: February 2013

This is an electrochemical evaluation of a chemical inhibitor on the corrosion behavior of mild steel (ASTM A-414) in solutions containing 54 percent lithium bromide and 0.2 percent lithium hydroxide at 25 C (77 F). Inhibiting effects of lithium chromate at concentrations up to 3000 ppm were studied Results are analyzed in terms of corrosion current determined from polarization resistance measurements and cathodic and anodic polarization slopes. These are compared with weight loss measurements.

The system inhibited with lithium chromate behaved as expected. Corrosion current, determined from polarization resistance, decreased steadily with increasing inhibitor concentration to a limiting value above 1000 ppm. Relative corrosion rates (ratio of corrosion rate of steel in the inhibited solution to that in the uninhibited solution) agree reasonably well with weight loss measurements.

Extrapolations of Tafel slopes from cathodic and anodic polarization curves to the corrosion potential suggest that in the lithium chromate inhibited system, the anodic reaction controls; whereas in the uninhibited solution, cathodic and anodic processes are equally important and lead to mixed control.

Severe pitting of the steel and gel formation have been observed in a number of experiments involving lithium chromate. Hence, proper chemistry involving inhibitor concentration and alkalinity control is very critical.
Inhibition of Aluminum Corrosion in Hydrochloric Acid by n-, Di-n- and Tri-n-Butylamines
Authors: UNNI V. K. V. , CHAR T. L. RAMA
Published: February 2013

Weight losses of aluminum in hydrochloric acid are diminished in the ranges 16–75 for n-; 40–90 for di-n~ and 50–98percent for tri-n-butylamine. Inhibitor efficiency increases with acid concentration up to 1.25 or 1.5 N, depending on the inhibitor and is practically constant thereafter. Efficiency increases with increased inhibitor concentration up to a certain value, then remains constant. Optimum inhibitor concentration depends on acid concentration and immersion period.

Experimental results indicate corrosion of pure aluminum in hydrochloric acid solutions is essentially under cathodic control and inhibition by amines is by adsorption on cathodic areas. A similar mechanism is indicated for aluminum alloyed with manganese.
Some Chemical Aspects of the Mercuric Nitrate Test Used for Copper Alloys
Authors: P.COSTAS L.
Published: February 2013

The chemical process involved in mercuric nitrate tests of copper alloys was studied from standpoint of electrode potential, solution composition and alloy composition. Pure copper was found to dissolve more readily than either brass or cupro nickel alloys, but no correlation to cracking tendency was noted. The electrode potential at higher mercury concentration was governed by the mercury-mercurous ion couple, not by the mercuric ion. At low mercury concentration, the electrode potential assumes the value for bare metal in contact with 1 M HNO3; mercury plays no part.

The cracking tendency of zinc-saturated mercury amalgam was shown to depend upon its environment in the case of 260 brass.
Ultrasonic-induced Cavitation Studies in Pb-Bi Alloy 500–1500 F
Authors: GARCIA R. , HAMMITT F. G.
Published: February 2013

Cavitation studies have been conducted in lead-bismuth alloy (70 percent lead-30 percent bismuth) at 500 and 1500 F (260–816 C) with a vibratory device utilizing a piezoelectric crystal transducer unit and high-temperature cavitation facility. Test materials subjected to the cavitation environment were Types 304 and 316 stainless steel, two tantalum alloys, Mo-1/2Ti and Cb-1Zr in two heat-treat conditions.

At 500 F tantalum alloys were most cavitation-resistant based on mean depth of penetration, although the Mo-1/2Ti and the two stainless steels were nearly as good.

At 1500 F both tantalum alloys were still the best, followed by Mo-1/2Ti, Cb-1Zr (cold-worked) and 316 stainless steel in that order. The Cb-1Zr (annealed) and 304 stainless steel were the least cavitation resistant. Thus, as expected, the relative advantage of the refractory alloys at high temperature is indicated. For all materials the cavitation damage at 1500 F was greater than that at 500 F, as expected.

Qualitative and quantitative correlations between the cavitation damage data and the mechanical properties of the materials are presented. Corrosion effects were negligible.
Cathodic Protection in Molten Fluoride Salts at 1200 F
Authors: MATSON L. K. , STEPHAN E. F. , MILLER P. D. , BOYD W. K. , MILFORD R. P.
Published: February 2013

Corrosion is a major problem in the Fluoride Volatility Process for recovery of nuclear fuel. Relatively large scale pilot plant developments are under way by the Chemical Technology Division of the Oak Ridge National Laboratory. In this process fuel is dissolved by hydrogen fluoride in a molten bath consisting of mixtures of such salts as NaF-LiF-ZrF4. Usual operating temperatures are near 1200 F (649 C). Because metals such as stainless steel and zirconium are to be dissolved in this process it is obvious that the salt mixture must be quite corrosive. This is particularly true because HF is sparged through the bath continuously. Experiments were carried out at Battelle on a laboratory scale to determine the feasibility of using cathodic protection to reduce the attack in process vessels.

Polarization curves were developed under simulated operating conditions for the materials of interest, i.e., Inor-8, Zircaloy and graphite. Polarization characteristics were obtained by use of a potentiostat using platinum as a reference electrode and graphite as an anode.

Experiments using rectangularly shaped coupons were carried out to determine the amount of protection furnished by the impressed current technique in the most corrosive salt composition.

Specimens were made cathodic at current densities ranging from 3 to 50 amp/ft2. Excellent protection was furnished to the submerged portions of the specimens. However, severe attack occurred at the interface at reasonable current densities.
Electrochemical Measurement of Low Corrosion Rates
Authors: JONES D. A. , GREENE N. D.
Published: February 2013

Materials with corrosion rates of 0.i mpy or less are required in many applications. In this investigation, application of linear polarization to measurement of low corrosion rates is examined, Also, two new electrochemical techniques are derived theoretically and verified experimentally. These methods can measure accurately corrosion rates less than 0.0005 mpy and require 20 minutes or less to perform.
Hydrogen Sulfide Cracking of Carbon and Alloy Steels
Authors: HUDGINS C. M. , McGLASSON R. L , MEHDlZADEH P. , ROSBOROUGH W. M.
Published: February 2013

The need for more adequate engineering data and a better theoretical understanding of sulfide cracking has led to a more thorough study of several variables involved in the sulfide cracking of carbon steel. Hardness, yield strength, stress and microstructure were the primary metallurgical variables studied; sulfide concentration and pH were the environmental factors considered. Both failure, no-failure and time-to-failure data were used as dependent variable, A number of alloy steels were tested.

In general, it was found that the time to failure increased with decreasing hardness, decreasing stress, decreasing H2S concentration and increasing pH. Failures occurred even down to 0.1 ppm H2S in solution Useful hardness limits for carbon steel for various stress and H2S concentrations were developed and used in field operations. However, it was found that excessive cold work can render almost any steel susceptible to sulfide cracking. K-Monel was the only alloy tested that remained immune to cracking failure at high load and at yield strength above 100,000 psia. It was postulated that the time to failure may be related to the time required for hydrogen to diffuse into the steel and reduce ductility sufficiently to allow crack propagation. Crack initiation may be due to the reduction in true fracture stress which accompanies hydrogen entry into steel.
Hydrogen Permeability in a Stable Austenitic Stainless Steel
Authors: SHIVELY J. H. , HEHEMANN R. F. , TROIANO A. R.
Published: February 2013

Tests at 21 C (69 F) show hydrogen enters and penetrates thin Type 310 stainless steel in H2SO4 solution under applied cathodic currents, first condition for hydrogen entry contributing to hydrogen embrittlement and stress corrosion cracking. When metal surface is passive permeation rate depends on applied current density; when active, rate depends on surface corrosion currents and applied current.
Resistance to Pitting of Types 202 and 321 Steels to Sulfuric Acid and Sodium Chloride Solutions
Authors: LEBET R. , PIOTROWSKI A.
Published: February 2013

Anodic potentiokinetic polarization measurements were made of pitting corrosion of two stainless steels in 1 N sulfuric acid and 1 N sodium chloride solutions to compare then-resistance to this type of corrosive attack. One steel was approximately of the same analyses as AISI Type 321 (H18N9), the second a substitutional steel with lower nickel content containing manganese and nitrogen approximately of the same analyses as AISI Type 202 (OH17N4G8). The steels were investigated both in as-cast state and after the plastic deformation.

Type H18N9 steel, in its passive potential region is somewhat less resistant to pitting, assuming that total corrosion volume is taken into account-However, the type of pits seems to be more dangerous in Type OH17N4G8 steel.

A similar situation is observed with respect to the structure effect. Rolled alloys exhibit greater total pitting corrosion losses while those tested as-cast suffers less extensive over-pitting. Pits in as-cast materials are, however, deeper and larger.
Oxidation of Fe-Ti Alloys in CO-CO2 Mixtures
Authors: GEIGER GORDON H. , WAGNER J. BRUCE
Published: February 2013

Oxidation of iron alloys containing 0.59 or 1.06 at.% titanium has been studied in the temperature range 800 to 1100 C (1472–2012 F) in CO2-CO mixtures. The kinetics are initially linear and the rate determining step is inferred to be the dissociation of CO2 into adsorbed oxygen atoms or ions and CO at the gas mixture-wustite interface.
Reaction Rate of Sulfur With Lead
Authors: FRADIN FRANK , WAGNER J. BRUCE
Published: February 2013

The rate of sulfidation of lead and lead alloyed with small amounts of bismuth, sodium or silver has been studied at 250, 275 and 300 C (482, 527 and 572 F). The rates decrease in the orders Sodium-doped lead, bismuth-doped or undoped lead and silver-doped lead. Only the silver-doped lead sulfidized with parabolic kinetics. The remainder sulfidized with linear kinetics because of the cracking of the sulfide layer on the lead.
Effects of Columbiumin Steel on Elevated Temperature Hydrogen Attack
Authors: BISARO R. E. , GEIGER G. H.
Published: February 2013

The effect of columbium on the elevated temperature hydrogen attack phenomenon was studied under dynamic conditions at temperatures in the range of 950 to 1075 F (510–580 C) and under gaseous hydrogen pressures of 1000 to 1400 psig. Test material used throughout this investigation was Ferrovac 1020 containing 0.22 weight percent columbium. Gas chromatography, gas permeability and metallographic techniques were utilized to study the hydrogen attack resistance of the columbium-treated steel. The thermodynamics of the attack reaction were considered and a mechanism of predicting the maximum depth of hydrogen attack was proposed.
An Electrochemical Study of Aluminum Corrosion in Boiling High Purity Water
Authors: LEGAULT R. A. , DRALEY J. E.
Published: February 2013

An equation relating current and electrochemical potential has been derived on the basis of a physical model of the corrosion process. In the model, the total potential drop from metal to solution is the sum of potential contributions arising from the interfacial reactions at the metal-oxide and oxide-solution interfaces and that which derives from the transport of charged species through the film.

On the basis of some simplifying assumptions, the derived equation reduces to ΔE = IR + Ksℓn (1 + ID), where R and D are complex constants and Ks is equal to RT/αzF for the liberation of hydrogen at the surface of the protective layer. This equation has been fitted successfully to experimental data. Assigning the value usually attributed to α for the hydrogen reaction, 1/2, optimum values of the constants were found to vary reasonably with time. If a value of α is not assigned, the equation can be fitted to experimental data over a wide range of values for the three constants.

Polarization measurements alone are not sufficient to determine unequivocal values for the constants, hence a determination of the mechanism of the aqueous oxidation of aluminum will require additional independent measurements.
Effect of Organic Corrosion Inhibitors on Corrosion Fatigue
Authors: MEHDIZADEH PARVIZ , McGLASSON R. L. , LANDERS J. E.
Published: February 2013

The effect of organic inhibitors on corrosion fatigue performance of steel in a mixture of brine containing H2S-CO2 and diesel fuel is reported.

The inhibitor concentration required to give significant protection to steel under corrosion fatigue conditions is much higher than that for corrosion control. This is due to the fact that corrosion fatigue cracks initiated at incompletely protected spots on the material surface influence fatigue failure regardless of the degree of protection achieved on neighboring areas.

Effects of fatigue stress and concentration of corrosion inhibitors were investigated. Results were analyzed in terms of the proposed mechanism for corrosion inhibition in these environments.
Factors Affecting Water Content Needed to Passivate Titanium in Chlorine
Authors: MILLAWAY E. E. , KLEINMAN M.H.
Published: February 2013

Titanium generally is reactive to dry, gaseous chlorine. A small amount of water in gaseous chlorine will inhibit this reaction. A testing program showed the amount of water required for inhibition varied with exposure conditions from about 0.20 to 1.1 over the range of about 25 to 175 C (77–347 F). When water content in the gaseous chlorine is sufficient titanium can be considered passive.

Data were obtained mostly by scratching to expose fresh titanium surfaces to gaseous chlorine and observing reactions. Under some conditions a definite reaction sequence often took place, which could be observed from initiation to ignition of a specimen. Some data were obtained from exposure of undisturbed titanium specimens in gaseous chlorine.

The water content required to passivate titanium in chlorine gas was found to be dependent upon temperature, gas flow rate and chlorine pressure. It was affected also by titanium surface condition, some roughened surfaces showing increased reactivity. Under static conditions involving chlorine of high purity, water required was greater than under flow conditions in dried, crude Hooker cell chlorine. Undisturbed titanium surfaces exposed at 195 C (382 F) for over a year showed no reaction when chlorine water content was 1.5 percent or more.
Liquidus Curves and Corrosion of Fe, Cr, Ni, Co, V, Cb, Ta, Ti, Zr, in 500–750 C Mercury
Authors: WEEKS JOHN R.
Published: February 2013

Liquldus curves of Fe, Cr, Ni, Co, V, Cb, Ta, Ti and Zr with Hg have been investigated at temperatures from 500 to 750 C (932–1382 F). From the results, relative corrosion rates have been estimated for each of these pure metals at 600 C (1112 F) in Hg which is saturated at 500 C. Predicted corrosion rates increase in the sequence: Ta, Cb, Fe, Co, V, Cr, Zr, Ti, Ni„

A stress-sensitive penetration of grain boundaries of Cb-lZr by Hg was shown to be associated with selective leaching of Zr from the alloy. Annealing the alloy before stressing it reduced but did not eliminate this attack.
Reference Electrodes in Acid and Base Systems
Authors: EVERY RICHARD L. , BANKS WILLIAM P.
Published: February 2013

Several electrodes were screened for possible use as reference electrodes for anodic corrosion control systems. Mercury-mercury salts, noble metal-noble metal oxides and molybdenum-molybdenum oxide were examined extensively and found to be useful reference electrodes in sodium hydroxide and phosphoric acid. A chromium carbide electrode was found to be a useful reference electrode in sodium hydroxide. The emf of these electrodes as a function of concentration and of temperature is described. The emf behavior of the noble metal-noble metal oxides in chromic acid cleaning solution and the emf of stainless steel in nitric acid are described briefly.
Oxidation of Iron-Titanium Alloys at 1000 C in Air
Authors: GEIGER GORDON H. , WAGNER J. BRUCE
Published: February 2013

Iron alloys containing titanium oxidized in air at 1000 C (1832 F) at a rate diminishing as titanium content increased. Relative thicknesses of three oxide layers were markedly different from thicknesses measured on pure iron exposed under like conditions.
Destructive Accumulation of Nitrogen in 30 Cr 20 Ni Cast Furnace Tubes in Hydrocarbon Cracking Service at 1100 C
Authors: SCHLEY J. R. , BENNETT F. W.
Published: February 2013

Centrifugally cast furnace tubes of 30 Cr, 20 Ni, balance iron, exhibited certain unusual structural characteristics after failure in service at 1100 C. A common feature of these tubes is a relatively high nitrogen content. In one instance, weakening and rupture of the tube wall under normal operating conditions was associated with a nitrogen-rich phase in the alloy micro-structure. Other cases were noted in which porosity and actual blisters developed within the walls of high-nitrogen tubes under conditions of severe carburization and overheating. Similar phenomena were produced in laboratory experiments and a mechanism involving the evolution of molecular nitrogen gas within the alloy is postulated.
Intergranular Stress Corrosion Cracking of Austenitic Stainless Steels in Oxygenated High Temperature Water
Authors: ARMIJO J. S.
Published: February 2013

A bellows arrangement for controlled high temperature, high pressure, stress corrosion tests of thick specimens has been used to study the intergranular stress corrosion cracking of Type 304 stainless steel and Incoloy 800 in oxygenated (~ 100 ppm) 550 F (288 C) water. Complete intergranular fracture of sensitized Type 304 stainless steels occurs after 10.4 ± 4.4 hours exposure at stress levels of 14,000 to 17,000 psi. Cracking of Incoloy 800 requires longer exposures at higher stress. Crevices are not necessary to initiate cracking of sensitized alloys.
Effects of Composition on the Stress Corrosion Cracking of Ferritic Stainless Steels
Authors: BOND A. P. , DUNDAS H. J.
Published: February 2013

U-bend and axially loaded tensile-type specimens were used in stress corrosion tests performed in boiling 140 C (284 F) magnesium chloride solution. The experimental ferritic alloys tested contained 17 to 25% chromium, 0 to 4% nickel, 0 to 2% copper, and 0 to 5% molybdenum. Alloys essentially free of nickel and copper did not undergo stress corrosion cracking. (Tests on Types 430 and 434 stainless steels confirmed this behavior.) However, alloys containing more than 1% nickel or 0.5% copper were subject to transgi anular stress corrosion cracking in boiling magnesium chloride solution. Critical concentrations of copper and nickel that produce susceptibility to cracking were determined at various chromium and molybdenum levels. Experiments at controlled potentials indicated that cracking in boiling magnesium chloride was not the result of hydrogen embrittlement.
A Study of Sensitization in Types 304 and 304L Stainless Steels Using Mossbauer Spectroscopy
Authors: ALBRITTON O. W.
Published: February 2013

A relatively new research tool has been brought to bear on a relatively old problem. Mossbauer effect spectroscopy, in conjunction with X-ray diffraction techniques, were used to study the phenomenon of stainless steel sensitization. A ferromagnetic phase, thought to be pseudomartensite, has been found in sensitized Type 301. Stresses generated in the matrix by morphology changes of the precipitated carbides are deemed responsible for the creation of this phase. No such phase was detected in the Type 304L. It was confirmed that the precipitated carbides were of the complex type (Cr, Fe)2 3C6. Furthermore, it was established that these carbides are paramagnetic, In the presence of austenite, the mossbauer peak for the carbides is overshadowed
Interpretation of Passive Current Maxima During Polarization of Stainless Steels
Authors: FRANCE W. D. , GREENE N. D.
Published: February 2013

The occurrence of passive current maxima during the anodic polarization of stainless steel in sulfuric acid solutions has been investigated using electrochemical and electron microprobe techniques. This phenomenon is caused by nickel enrichment on the surfaces of electrodes during pre-polarization immersion. Tests with various samples of stainless steels show that passive current maxima are not caused by sensitizing heat treatments. Therefore, contrary to other interpretations, a suitable evaluation method for predicting intergranular corrosion susceptibility cannot be based on anodic polarization measurements.
Factors in Sulfide Corrosion Cracking of High Strength Steels
Authors: TRESEDER R. S. , SWANSON T. M.
Published: February 2013

Results of laboratory sulfide corrosion cracking tests on commercial steel alloys are presented. Emphasis is placed on effects of environmental factors, alloy composition and metallurgical variables. Environmental factors studied include pH in the range of 2 to 5, H2S partial pressures in the range 0.001 to 1.0 atmosphere and addition of sodium chloride. Twelve percent chromium stainless steels and low alloy steels containing more than 1 percent nickel, were found to have lower resistance to cracking at the same hardness level than low alloy steels normally used for oil field equipment. Plastic deformation of low alloy steels by cold rolling decreased the resistance to cracking.
Effect of Inhibitors on Scale Removal in HCl Pickling Solutions
Authors: RIGGS O. L. , HURD R. M.
Published: February 2013

Inhibitors are available which effectively reduce the loss of metal because of corrosion occurring in the hydrochloric acid pickling baths. Selection of these inhibitors, however, must take into consideration the effect the inhibitor will have on scale dissolution. The optimum concentration of inhibitor must consider the functional relationship between inhibitor concentration and the rate of scale removal. This relationship is not the same as that between inhibitor concentration and metal dissolution rate.

Data are shown on scale dissolution rates for two corrosion inhibitors in 10 percent by weight hydrochloric acid at temperatures of 55 through 85 C (131–185 F). Extrapolations to somewhat higher temperatures of some pickling operations can be made. However, it was observed that all corrosion inhibitor effects on scale removal became somewhat temperature-dependent at, or near, 80 C.

The experimental acid corrosion inhibitors (B and C) exhibit surfactant behavior between 55–75 C, removing scale more quickly than did the uninhibited acid.