Showing papers in "Corrosion in 1974"
TL;DR: In this article, a strain aging type of reversible hydrogen embrittlement has been demonstrated for a high strength aluminum alloy in a 3% NaCl environment, and the evidence is quite consistent with a mechanism of stress corrosion cracking (SCC) involving absorption of hydrogen leading to lattice dissolved hydrogen.
Abstract: A strain aging type of reversible hydrogen embrittlement has been demonstrated for a high strength aluminum alloy in a 3% NaCl environment. Permeation of hydrogen was related to SCC under cathodic polarization as well as anodic conditions. Internal friction and lattice parameter measurements relate directly to lattice dissolved hydrogen arising from the environment. It is concluded that the evidence is quite consistent with a mechanism of stress corrosion cracking (SCC) involving absorption of hydrogen leading to lattice dissolved hydrogen and embrittlement.
164 citations
TL;DR: In this paper, an alloy of Fe-28% Cr-4% Mo with carbon not exceeding 0.010% and nitrogen below 0.020% (C+N < 0.025%).
Abstract: Because of the resistance of iron-chromium stainless steels to chloride stress corrosion, this alloy system was used as a base for developing superior resistance to various forms of corrosion by means of alloying with molybdenum, nickel, and the six metals of the platinum group. The effects of these alloying elements were evaluated by accelerated laboratory tests for pitting, intergranular, general, and stress corrosion. The optimum ductility and resistance to pitting, intergranular, and stress corrosion were found for an alloy of Fe-28% Cr-4% Mo with carbon not exceeding 0.010% and nitrogen below 0.020% (C+N <0.025%). This alloy resists pitting and crevice corrosion in 10% FeCl3-6H2O at 50 C (122 F) with six crevices on the specimen surfaces, and it resists all intergranular attack on a welded specimen in the boiling ferric sulfate-50% H2SO4 test. Addition of 2% Ni to this alloy extends its general corrosion resistance in oxidizing and organic acids to boiling 10% H2SO4 and 1% HCI, in which it i...
91 citations
TL;DR: In this article, the effects of Mo and other supplementary alloying additions on the pit initiation resistance of wholly austenitic stainless steel containing nominally 18% Cr have been evaluated using temperature as a pitting criterion.
Abstract: Using temperature as a pitting criterion, the effects of Mo and other supplementary alloying additions on the pit initiation resistance of wholly austenitic stainless steel containing nominally 18% Cr have been evaluated. Quantitative results for Mo, Cu, Ni, Mn, N, and Si alloy additions are presented and empirical relationships are given which describe the pitting resistance of several families of alloys. Both experimental and commercial alloys have been evaluated.
80 citations
TL;DR: Galvanic interaction between the Al alloys 1100, 2024, 2219, 6061, 7075, and Ag, Cu, Ni, Sn, Cd, Zn, the stainless steels 301, 304L, 347, A286, PH13-8Mo, Steel 4130, Inconel 718, Haynes 188 and Ti-6AI-4V has been studied in air saturated 3.5% NaCl by weight loss measurements and continuous monitoring of the galvanic current in 24 hour tests as discussed by the authors.
Abstract: Galvanic interaction between the Al alloys 1100, 2024, 2219, 6061, 7075, and Ag, Cu, Ni, Sn, Cd, Zn, the stainless steels 301, 304L, 347, A286, PH13-8Mo, Steel 4130, Inconel 718, Haynes 188 and Ti-6AI-4V has been studied in air saturated 3.5% NaCl by weight loss measurements and continuous monitoring of the galvanic current in 24 hour tests. Results show that the potential difference of uncoupled dissimilar metals, while in most cases accurately predicting the direction of current flow, is a poor indicator of the extent (rate) of galvanic corrosion of coupled dissimilar materials. The values of the average galvanic current density agree well with the increase of dissolution rates due to galvanic coupling. In general, galvanic corrosion of Al alloys coupled to dissimilar metals decreases in the order Ag > Cu > steel 4130 ≫ stainless steels ≈ Ni > Inconel 718 ≫ Ti-6AI-4V ≈ Haynes 188 >Sn > Cd. Coupling to zinc does not result in cathodic protection for all Al alloys studied, but can lead to increas...
57 citations
TL;DR: In this article, an explanation for this effect is given in terms of the erosive disruption of surface films which normally hinder the diffusion of oxygen to the corroding surface, and it is shown that the presence of the solids can bring about a sharp increase in the corrosion rate.
Abstract: Electrochemical techniques have been used to determine the corrosion component of the erosion-corrosion of steel pipe carrying sand, iron ore, potash, limestone, and coal slurries, at commercial concentrations and velocities. The tests have shown that the presence of the solids can bring about a sharp increase in the corrosion rate, and that the effect is dependent on the solids concentration and slurry velocity. An explanation for this effect is given in terms of the erosive disruption of surface films which normally hinder the diffusion of oxygen to the corroding surface.
54 citations
TL;DR: In this article, a study on the mechanism of pitting corrosion, a gas evolution in the pit has been observed, which has been gaschromatographically identified as hydrogen and the explanation of the evolution of hydrogen by the acidification of the pit electrolyte and the potential drop across the pit have been experimentally proved.
Abstract: In a study on the mechanism of pitting corrosion, a gas evolution in the pit has been observed. This gas has been gaschromatographically identified as hydrogen. The explanation of the evolution of hydrogen by the acidification of the pit electrolyte and the potential drop across the pit have been experimentally proved. By means of vacuum extraction experiments, the diffusion and dissolution of hydrogen in the metal has been shown. Experiments have been carried out to determine the effects of the dissolved hydrogen on the austenitic stainless steel. Replica techniques show that the hydrogen embrittles the metal around the pit. X-ray diffraction lines demonstrate that hydrogen causes phase transformations in the austenitic stainless steel. In the case of pitting corrosion, such transformations have not yet been confirmed. It is suggested that dissolved hydrogen can create new initiation places for pitting corrosion and in this way is responsible for the secondary pit initiation. The most important ...
47 citations
TL;DR: In this article, the authors described an instrumentation for obtaining current-time curves for new metal surfaces produced by fast fracture in electrolytes under potentiostatic conditions and showed that formation and growth of a salt film in the tip region would give a rapidly decaying current density moving away from the tip which would keep the tip sharp.
Abstract: Instrumentation is described for obtaining current-time curves for new metal surfaces produced by fast fracture in electrolytes under potentiostatic conditions. Measured anodic current densities for titanium specimens in acid solutions decayed about a million fold in a time of 10−4 to 103 seconds at which steady state was approached. Analysis of the experimental data indicate the actual initial current density for anodic dissolution is more than 10 A/cm2 in 3M HCl and may be orders of magnitude greater. Thus stress corrosion crack propagation by an anodic process in titanium cannot be ruled out. Formation of metal salt films would be predicted at high anodic current densities in cracks. Calculations show that formation and growth of a salt film in the tip region would give a rapidly decaying current density moving away from the tip which would keep the tip sharp. This phenomenon may be called the electrochemical knife.
43 citations
TL;DR: Using temperature as a crevice corrosion criterion, a number of commercial and experimental Mo-bearing 18% Cr austenitic stainless steels have been evaluated for crevice degradation.
Abstract: Using temperature as a crevice corrosion criterion, a number of commercial and experimental Mo-bearing 18% Cr austenitic stainless steels have been evaluated for crevice corrosion resistan...
36 citations
TL;DR: In this paper, the authors describe a research program aimed at optimizing the composition, heat treatment, and structure of ferritic stainless steels for use as condenser tube material in desalination plants.
Abstract: This paper describes a research program aimed at optimizing the composition, heat treatment, and structure of ferritic stainless steels for use as condenser tube material in desalination plants. The results of corrosion tests carried out in a desalination plant are reported and discussed in relation to laboratory tests performed on the same alloy compositions. The corrosion measurements are used to outline general methods for maximizing the resistance of ferritic stainless steels to pitting and crevice crack attack in hot saline environments.
35 citations
TL;DR: In this paper, the effect of strain rate on the stress corrosion cracking (SCC) of an austenitic stainless steel in MgCl2 solutions was investigated by using a constant strain rate method over the r...
Abstract: The effect of strain rate on the stress corrosion cracking (SCC) of an austenitic stainless steel in MgCl2 solutions has been investigated by using a constant strain rate method over the r...
35 citations
TL;DR: The effect of heat treatment on the microstructure and properties of 28Cr4Mo and 28Cr-4Mo-2Ni alloys with low carbon and nitrogen levels was investigated in this article.
Abstract: The effect of heat treatment on the microstructure and properties of 28Cr-4Mo and 28Cr-4Mo-2Ni alloys with low carbon and nitrogen levels was investigated. Sigma and chi phases form in these alloys in the range 1300 to 1700 F (704 to 927 C). The rate of formation is slow. Heating 1 hour at 1500 F (816 C) results in only a small amount of sigma phase at grain boundaries. This does not impair corrosion resistance. Annealing at 2000 F (1093 C) readily dissolves this sigma phase, and also much larger amounts of sigma and chi phases formed after heating 100 hours at 1500 F. These alloys are subject to embrittlement by hydrogen. It was shown that embrittlement produced in cold worked material by brief cathodic charging in 10% H2SO4 containing a sulfide can be eliminated by exposure to boiling water or aging at room temperature. Both compositions showed excellent resistance to crevice corrosion in a 9 month test in the ocean at the New Jersey shore. Resistance to caustic cracking was demonstrated by a t...
TL;DR: In this article, the errors due to the use of the approximation Icorr′ = B′ΔI, where B′ depends on anodic and cathodic Tafel slopes, in commercial corrosion current meters is shown to be due to nonlinearity of the currentpotential curve in the vicinity of the corrosion potential.
Abstract: The errors due to the use of the approximation Icorr′ = B′ΔI, where B′ depends on anodic and cathodic Tafel slopes, in commercial corrosion current meters is shown to be due to the nonlinearity of the current-potential curve in the vicinity of the corrosion potential. These errors are calculated for various combinations of Tafel slopes. It is proposed to use the relationship Icorr = κΔI, where κ depends on Tafel slopes, sign, and magnitude of polarization. The values of κ are tabulated for various combinations of Tafel slopes and polarization of +10 and −10 mV. The proposed procedure leads to correct values of corrosion currents independent of the degree of nonlinearity of the polarization curve.
TL;DR: The characteristics, advantages, and limitations of various methods for the detection of susceptibility to intergranular corrosion in austenitic stainless steels due to carbide precipitation are discussed in this article.
Abstract: The characteristics, advantages, and limitations of various methods for the detection of susceptibility to intergranular corrosion in austenitic stainless steels due to carbide precipitation are discussed. Information on corrosion rates and acceptance limits in nitric acid and ferric sulfate-sulfuric acid tests is presented and illustrated by statistical data from the evauation of approximately 10,000 samples representing commercial AISI 300 series stainless steels.
TL;DR: In this article, the effect of grain size, cold work, and sensitization has been studied on caustic stress corrosion cracking (SCC) experiments on Type 304, 304L, 316, 316L, and USS 18-18-2 stainless steels.
Abstract: Caustic stress corrosion cracking (SCC) experiments have been conducted on Type 304, 304L, 316, 316L, and USS 18-18-2 stainless steels. The environments used were deoxygenated 50% NaOH solution at 316 and 371 C (600 and 700 F), deoxygenated 10% NaOH solution at 316 C and atmospheric boiling [~149 C (300 F)] 50% NaOH. The effect of grain size, cold work, and sensitization has been studied. Metallurgical structures were examined with light microscopy and the accelerated Strauss test. Exposed specimens were studied with the light microscope and the fracture surfaces were studied with the scanning electron microscope (SEM). Variations in crack morphology were observed with caustic concentration and alloy content. Certain sensitization treatments were the only conditions identified in Type 304 as beneficial in increasing the high temperature caustic stress corrosion resistance.
TL;DR: In this paper, a series of experiments on the effect of oxygen on the kinetics of the hydrogen forming reaction was made to explain the commonly observed low degree of temperature dependence of the linear oxidation rate, which led to the concept of a hydride fracture mechanism for the rapid oxidation at near ambient temperature.
Abstract: Oxidation kinetics of metallic uranium in moist gaseous media and its correlation to the surface morphology were studied by means of a gas chromatographic technique developed for this purpose. The results have substantiated the authors' earlier work which led to the concept of a hydride fracture mechanism for the rapid oxidation at near ambient temperature. Through a series of experiments on the effect of oxygen on the kinetics of the hydrogen forming reaction, an attempt was made to explain the commonly observed low degree of temperature dependence of the linear oxidation rate. Close examination of the morphology of the reaction product layers has indicated a sequence of successively occurring stages of different mechanisms. A speculation was made on the role of hydride formation and its fracture at the metal-to-oxide interface which leads the overall reaction to linearly time dependent kinetics, in which repetition of short segments of a diffusion controlled process is involved.
TL;DR: In this paper, the effects of environment and frequency on mechanics of crack growth were investigated in a Ti-2.5Cu sheet with dry argon, normal air, distilled water, and 3.5% aqueous NaCl.
Abstract: Environmental fatigue crack propagation at various frequencies is considered for Ti-2.5Cu (IMI 230) sheet. The environments were dry argon, normal air, distilled water, and 3.5% aqueous NaCl. The frequencies employed were 5, 29, 30, and 50 Hz. Crack propagation rate data are compared in terms of environment and frequency and also with rates predicted by a mechanical model suggested by Pelloux. Results of these comparisons are discussed together with fractographic observations in order to provide a rational for the effects of environment and frequency on mechanics of crack growth.
TL;DR: In this paper, the authors measured the susceptibility of iron to stress corrosion cracking (SCC) in nitrates, as a function of carbon, silicon, and germanium contents, and also for the binary alloys containing Ni, Cr, and Mo.
Abstract: Susceptibility of iron to stress corrosion cracking (SCC) in nitrates is measured as a function of carbon, silicon, and germanium contents, and also for the binary alloys containing Ni, Cr, and Mo. Effects of cold work and heat treatment are also studied. The results are related to crack-sensitive paths established by interstitial elements segregating along grain boundary regions.
TL;DR: In this article, three point bend L-T specimens of 2024-T3 and 7075-T6 aluminum alloy plate were fractured in liquid mercury and showed evidence for cleavage on {100, {110, and {111} planes.
Abstract: Three point bend L-T specimens of 2024-T3 and 7075-T6 aluminum alloy plate were fractured in liquid mercury. Fracture was predominantly transgranular in both materials. Fractography provided evidence for cleavage on {100}, {110}, and {111} planes.
TL;DR: The fractography of all transgranular stress corrosion cracking (SCC) failures of the Zircaloys is generally similar and consists of areas of cleavage separated by regions of ductile teari...
Abstract: The fractography of all transgranular stress corrosion cracking (SCC) failures of the Zircaloys is generally similar and consists of areas of cleavage separated by regions of ductile teari...
TL;DR: In this article, a variety of metal specimens of varying aluminum (6 to 16%), molybdenum (to 8%), chromium (to 2), chromium(to 2%), copper (to 3%), and nickel(to 3%) were exposed to ambient and boiling sea water.
Abstract: Wrought sheet corrosion specimens of varying aluminum (6 to 16%), molybdenum (to 8%), chromium (to 2%), copper (to 3%) and nickel (to 3%) were exposed to ambient and boiling sea water. Cor...
TL;DR: In this paper, various stress corrosion tests have been carried out on a 3CrMo steel in ammonium acetate solution and intergranular cracking has occurred at both the molar and 0.1 molar levels.
Abstract: Various stress corrosion tests have been carried out on a 3CrMo steel in ammonium acetate solution. Intergranular cracking has occurred at both the molar and 0.1 molar levels. Other acetat...
TL;DR: In this paper, both metal fluoride and metal corrosion products may deposit as the result of the interaction of molten fluoride salts and alloys in a temperature gradient system, and both types of deposits have been studied as they have occurred in iron base and nickel base thermal convection loops operating in the range 460 to 605 C (860 to 1121 F).
Abstract: Hastelloy N (Ni-16% Mo-7% Cr-5% Fe) is quite compatible with pure fluoride salts and corrosion is difficult to detect. However, when impurities are present, both metal fluoride and metal corrosion products may deposit as the result of the interaction of molten fluoride salts and alloys in a temperature gradient system. Both types of deposits have been studied as they have occurred in iron base and nickel base thermal convection loops operating in the range 460 to 605 C (860 to 1121 F). In the iron base loop, metal deposits, consisting mainly of iron, resulted from extreme changes in the equilibrium constant of the corrosion reaction due to changes in temperature and from the highly oxidizing conditions of the salt. Metal-fluoride deposits also caused plugging in both the iron base and a nickel base loop and were mainly chromium fluorides. These were precipitated from the saturated salt. Under steady state (low corrosion rate) conditions, more of the least stable fluoride corrosion products (such ...
TL;DR: In this article, the advantages and limitations of the various ASTM intergranular tests for austenitic stainless, ferritic stainless, and nickel base alloys are reviewed, and guidelines for evaluating weldment corrosion are given, although it is recognized that there is no single best procedure for all situations.
Abstract: Weldments sometimes corrode preferentially in the weld metal itself or in the heat affected areas of the parent metal. The localized nature of the attack limits the usefulness of standard weight loss corrosion tests. Techniques for overcoming this limitation are discussed. The influence of specimen geometry and surface finish are dealt with as well as a variety of destructive and nondestructive methods for evaluating a corroded weldment. The advantages and limitations of the various ASTM intergranular tests for austenitic stainless, ferritic stainless, and nickel base alloys are reviewed. Guidelines for evaluating weldment corrosion are given, although it is recognized that there is no single best procedure for all situations. The use of sensitization treatments to simulate welding is discussed.
TL;DR: Three different galvanokinetic methods have been used to determine the pitting potential (Ep) and the protection potential against pitting (Epp) for unalloyed aluminum in a deareated solut...
Abstract: Three different galvanokinetic methods have been used to determine the pitting potential (Ep) and the protection potential against pitting (Epp) for unalloyed aluminum in a deareated solut...
TL;DR: In this article, the anodic polarization curves determined in 1X synthetic sea water at 25 C (77 F) to 150 C (302 F) were evaluated for desalination applications.
Abstract: Aluminum alloys 3003, 3004, and 5050 were evaluated for desalination applications by means of their anodic polarization curves determined in 1X synthetic sea water at 25 C (77 F) to 150 C (302 F). Pitting performance was established from the relative values of the corrosion potential and the breakdown and protection potentials, and general corrosion rates were calculated from corrosion currents determined by the slop-intercept method. Pitting is not anticipated for 3003 and 3004 alloys at temperatures to 150 C and for 5050 alloy to 125 C (257 F). General corrosion rates for these alloys were less than 1 mpy.
TL;DR: In this paper, the analytical method used for separation and identification of the corrosion products of copper specimens corroded by sulfide polluted sea water has been described, and many solvable problems have been identified.
Abstract: In this paper the analytical method used for separation and identification of the corrosion products of copper specimens corroded by sulfide polluted sea water has been described. Many sol...
TL;DR: In this article, the effects of environment on the fatigue behavior of a quenched and tempered medium carbon steel have been studied and the results are explained by consideration of the processes occurring at the tip of a growing fatigue crack where the freshly exposed clean metal surface interacts with the environment.
Abstract: The effects of environment on the fatigue behavior of a quenched and tempered medium carbon steel have been studied. Alternating tension, low cycle fatigue tests were performed at room temperature in humid and dry hydrogen, hydrogen sulfide, and argon, as well as in ambient air. With respect to behavior in air, humid hydrogen, and to a lesser extent, argon caused an increase in fatigue life, while hydrogen sulfide caused a decrease. These results are explained by consideration of the processes occurring at the tip of a growing fatigue crack where the freshly exposed clean metal surface interacts with the environment. In some cases, such as humid hydrogen, it is believed that the presence of a condensed water film can act as a shield to prevent reactions with hydrogen or oxygen which would otherwise increase crack growth rates. In the presence of hydrogen sulfide or dry hydrogen, however, chemical reactions are believed to occur leading to hydrogen embrittlement. The result is a change in the frac...