Showing papers on "Corrosion published in 1974"
TL;DR: Pits are initiated at sulphide inclusions (usually MnS) in both carbon steels and stainless steels as discussed by the authors, and the propagation of a pit is, in principle, the same in both types of steel and depends upon the formation of a concentration cell in which the pit solution has a higher salt content, a higher acid content and a lower oxygen content than the surrounding bulk of the solution.
402 citations
177 citations
01 Jan 1974
TL;DR: In this article, the authors proposed a model to explain the static fatigue of glass in which this reaction is enhanced by the concentration of stress at crack tips in the glass, leading to a sharpening of the crack tip, a still higher stress there, and ultimately failure when the theoretical cohesive stress of the glass is reached.
Abstract: The decrease in the strength of glass under load results from reaction of the glass with water in the surrounding atmosphere. Hillig and Charles have proposed a model to explain the static fatigue of glass in which this reaction is enhanced by the concentration of stress at crack tips in the glass. This stress-enhanced corrosion leads to a sharpening of the crack tip, a still higher stress there, and ultimately failure when the theoretical cohesive stress of the glass is reached. This theory can explain some experimental results on delayed failure in glass but other results, such as the effect of surface treatment on delayed failure, are inconsistent with the theory.
169 citations
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
103 citations
01 Jan 1974-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science
TL;DR: In this paper, a method is presented whereby type of corrosion attack or mechanical properties can be accurately predicted from the cooling curve and a C-curve for the alloy, regardless of the complexity of the cooling conditions.
Abstract: Rate of cooling from the solution treatment temperature has a pronounced effect on corrosion behavior and mechanical properties of precipitation-hardenable aluminum alloys. This effect is attributed to loss of vacancies and to precipitation of solute during the quench. Analysis of data for aluminum alloys indicates that precipitation rate is an explicit function of temperature and the amount of solute remaining in solution; consequently, precipitation during cooling is additive and can be evaluated by integrating this function. A method is presented whereby type of corrosion attack or mechanical properties can be accurately predicted from the cooling curve and a C-curve for the alloy. Because the actual cooling curve is considered, the method is applicable regardless of the complexity of the cooling conditions. Also presented is an improved method of accurately determining C-curves using either interrupted or continuous quenching techniques. C-curves describing type of corrosion attack in 2024-T4 sheet and loss in mechanical properties of 7075-T6 sheet are presented.
103 citations
TL;DR: In this article, the authors investigated the process of anodic passivation and corrosion behavior of titanium and binary titanium alloys in nonoxidising acids at elevated temperatures, when the alloy dissolution in the passive state proceeds at a certain rate.
98 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
90 citations
TL;DR: In this paper, the authors discuss deposition and corrosion in Gas Turbines, and propose a method to detect the presence of such defects in a Gas Turbinet.
Abstract: (1974). Deposition and Corrosion in Gas Turbines. British Corrosion Journal: Vol. 9, No. 1, pp. 2-3.
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.
TL;DR: In this paper, five Fe-Si alloys containing between 0·06 and 5·3 w/o have been oxidized in a gaseous mixture of 20 w /o oxygen in argon.
Journal Article•
TL;DR: In this paper, the relative time to corrosion of reinforcing steel embedded in concrete slabs that are fabricated from various mix designs and construction procedures and subject to periodic wetting with a 3 percent sodium chloride solution was determined.
Abstract: The purpose of this investigation is to provide administrators and designers with factual data on which to base decisions as to the type of protection to provide for bridge decks constructed in corrosive environments. The specific study objective is to determine the relative time to corrosion of reinforcing steel embedded in concrete slabs that are fabricated from various mix designs and construction procedures and subject to periodic wetting with a 3 percent sodium chloride solution. Constructed and tested were 124 reinforced concrete slabs 4 by 5 by 0.5 ft. Data obtained from tests of the effect of portland cement concrete mix design, concrete cover over the reinforcing steel, and consolidation of the fresh plastic concrete are discussed in this paper. A brief description of slab fabrication and testing procedures is also presented.
TL;DR: Using a metallographic technique to identify and count corrosion pits, the tendency for passive film breakdown has been studied under conditions that simulate a crevice and a combination of two different materials.
Abstract: Using a metallographic technique to identify and count corrosion pits, the tendency for passive film breakdown has been studied under conditions that simulate a crevice and a combination of two different materials. Potential corrosion couples were formed among: 316L stainless steel, cast CoCrMo alloy, wrought CoCrWNi alloy, Ti–6% Al–4% V alloy, a CoNiCrMo (multiphase) alloy and graphite. Only 316L stainless steel seems significantly prone to pitting corrosion in a crevice condition. Dissimilar metals in the crevice configuration did not seem to accelerate the corrosion of stainless steel.
01 Jun 1974-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science
TL;DR: In this article, the fracture kinetics of Al-5.5 Zn-2.5 Mg alloys submersed in 3 pct NaCl-H2O solutions were varied by heat treatment.
Abstract: The fracture kinetics of Al-5.5 Zn-2.5 Mg alloys submersed in 3 pct NaCl-H2O solutions were varied by heat treatment. The steady state velocity, on a plot of velocity vs stress intensity, was compared with microstructure and it was found to be inversely proportional to the volume of MgZn2 in the grain boundary. This behavior suggests that grain boundary precipitates can act as sacrificial anodes to retard intergranular stress corrosion cracking.
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.
02 Apr 1974
TL;DR: The principles of corrosion have been reviewed from two aspects: Thermodynamics and kinetics as mentioned in this paper, and three types of corrosion cells have also been mentioned: Galvanic, concentration and simple anodic.
Abstract: The principles of corrosion have been reviewed from two aspects: Thermodynamics and kinetics. Thermodynamic considerations yield the relative corrosion tendencies ofthe elements. Three types of corrosion cells have also been mentioned: Galvanic, concentration and simple anodic. Kinetics attempts to explain and predict the actual corrosion behavior of materials. The relative corrosion tendencies, the metallurgical aspects and the environmental conditions must all 'be considered. The environmental conditions of interest are normally temperature, relative humidity, applied electrical bias and ionic contamination. Examples of practical corrosion problems have been discussed. Corrosion is a difficult subject because each case is highly specific. Corrosion of IC devices is even more difficult because of the small sizes of components and because the local corrosion conditions within the IC packages are unknown Several examples of metallization corrosion have been briefly described, such as Mo-Au (galvanic), Al and NiCr (simple anodic), and Al in the presence of phosphorus and chlorine(ionic contamination). The function of failure analysis laboratories is to identify the corrosion mechanism and the Mfaterial causing corrosion. Then that source of corrosion must be related back to the device processing and fabrication stages in order to prevent future problems. There are two approaches to preventing corrosion failures: (1) Protect corrosion susceptible materials from the corrosive environment, as in applying oxide and nitride passivation coatinqs and in packaging finished devices in plas tic or hermetically sealed containers; (2) utilize corrosion resistant systems, such-as the (thus far suecesssful) .Ti/W/Au system.
01 Jan 1974
TL;DR: In this paper, the authors discuss corrosion of metals in organic solvents problems arise which have no parallel in the field of corrosion in aqueous media, and discuss the demands on the corrosion resistance of the materials used are immense.
Abstract: Developments in the chemical and petrochemical industries, advances in chemical engineering, the introduction of new products, advances in the technology of intermediates, and problems in energy conversion have created new corrosion problems, involving the failure of metallic materials under the influence of aggressive organic solvents. Failures of this type lead not only to a deterioration of the mechanical properties of structural material, but also to discoloration and unwanted changes of the solvent. Since organic solvents in most cases are poisonous, inflammable, and, in the presence of air, explosive, the demands on the corrosion resistance of the materials used are immense. Therefore, in discussing corrosion of metals in organic solvents problems arise which have no parallel in the field of corrosion in aqueous media.
TL;DR: The measurement of the polarization resistance using AC enables the corrosion losses to be determined with certain difficulties only, Despite that the AC methods are of technical interest because they allow the determination of corrosion rate/time curves without difficulties and enable potentiel fluctuation to be easily compensated; beyond that they offer certain advantages with respect to the construction of the measuring instruments as mentioned in this paper.
Abstract: The measurement of the polarization resistance using AC enables the corrosion losses to be determined with certain difficulties only, Despite that the AC methods are of technical interest because they allow the determination of corrosion rate/time curves without difficulties and enable potentiel fluctuation to be easily compensated; beyond that they offer certain advantages with respect to the construction of the measuring instruments.
TL;DR: The corrosion products NaCrO/sub 2/ and Na/sub 4/FeO/Sub 3/ were observed on the surfaces of chromium, iron, and stainless steel after exposure to liquid sodium at 600 deg C and above as discussed by the authors.
Abstract: The corrosion products NaCrO/sub 2/ and Na/sub 4/FeO/sub 3/ were observed on the surfaces of chromium, iron, and stainless steel after exposure to liquid sodium at 600 deg C and above. The products were identified by x-ray diffraction without the removal of the covering sodium layer. (8 figures) (auth)
TL;DR: In this paper, a polyphase alloys based on ordered Zr3Al (Ll2 type) have been deformed in tension at 20 to 600°C and exposed to moist air (300°C), pressurized water and atmospheric pressure steam (400°C).
01 Apr 1974
TL;DR: In this article, the surface conductivity of thermal SiO2 was measured as a function of relative humidity and temperature, and the authors investigated the factors which determine the rate of electrolytic corrosion of the Al metallization in plastic-encapsulated ICs.
Abstract: In an investigation of the factors which determine the rate of electrolytic corrosion of the Al metallization in plastic-encapsulated ICs operated in a moist atmosphere, the surface conductivity of thermal SiO2 was measured as a function of relative humidity and temperature. Electrolysis in the water film adsorbed at high relative humidity produces either protection of the Al metallization by anodization or destructive corrosion at the anode and/or cathode. The occurrence of protection or destructive corrosion is mainly determined by the nature and amount of ionic impurities present in the water film and by temperature.
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 ...
TL;DR: In this article, the use of the thin layer activation technique in measuring surface loss of materials due to wear and corrosion is described with particular reference to iron and steels, and the technique described is applicable to these materials and composites containing them, and to many other elements including silicon and hence glasses, enamels and abrasives.
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.
TL;DR: In this paper, galvanostatic measurements of the kinetics of hydrogen evolution with electrodic assessment of corrosion properties of the system, and volumetric measurement of the hydrogen evolution reflecting directly the rate of corrosion were investigated.
Abstract: Corrosion of pure and amalgamated zinc in pure concentrated solutions was investigated using two methods: (a) galvanostatic measurements of the kinetics of hydrogen evolution with electrodic assessment of corrosion properties of the system, and (b) volumetric measurement of the hydrogen evolution reflecting directly the rate of corrosion. The latter was followed as a function of time during 150 hr. It was found that the corrosion rate varies considerably with time and was suggested that different factors control the initial and the steady‐state corrosion. The initial corrosion rate increases with increasing concentration which is indicative of the chemical mechanism of hydrogen evolution. The change of the corrosion rate with time and the steady‐state corrosion rate can be explained in terms of formation of an impermeable film at the surface. In such a case the concentration dependence of the corrosion rate is inverse with time, which explains some results reported in literature. The amalgamated zinc surface gives complex galvanostatic transients which indicate a new phase formation in the process of initiation of hydrogen evolution, which could pertain to some solid potassium‐zinc‐mercury alloy.
Patent•
30 Dec 1974
TL;DR: In this paper, a process for scavenging hydrogen sulfide which frequently contaminates aqueous drilling fluids and a method of preventing metallic corrosion of iron drill pipe and the like by utilizing metal compounds which form insoluble sulfide compositions in aaqueous media, said compounds containing metals having an electromotive activity greater than that of iron.
Abstract: This invention relates to a process for scavenging hydrogen sulfide which frequently contaminates aqueous drilling fluids and to a method of preventing metallic corrosion of iron drill pipe and the like by utilizing metal compounds which form insoluble sulfide compositions in aqueous media, said compounds containing metals having an electromotive activity greater than that of iron. Said process consists of introducing said compounds into an aqueous drilling fluid and circulating said fluid in the well bore. The metal compounds may be prepared for subsequent addition to the drilling fluid or may be obtained by in situ reactions of materials and/or drilling fluid constituents. A preferred process utilizes metal compounds selected from the class consisting of zinc carbonate, basic zinc carbonate, and zinc hydroxide. An alternate preferred process utilizes a zinc compound which is reacted with an organic material to provide dispersion of the zinc compound, thus enhancing sulfide scavenging characteristics. The metal compounds utilized in the present invention will not adversely affect vital drilling fluid properties.
01 Jan 1974
TL;DR: In this paper, a laboratory study was conducted of several condenser tube alloys in flowing buffered sodium chloride solution, contaminated periodically with sulfide, and the results showed that alternate treatment with sulfides and air was much more aggressive than air alone or sulfide alone.
Abstract: Abstract Increasing sulfide pollution of harbors and river estuaries has markedly increased corrosion of surface condenser alloys using once through cooling water. A laboratory study was conducted of several condenser tube alloys in flowing buffered sodium chloride solution, contaminated periodically with sulfide. The results showed that alternate treatment with sulfide and air was much more aggressive than air alone or sulfide alone. Corrosion performance of the alloys is compared.