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Exfoliation Corrosion Susceptibility And Mechanisms Of Al Li 2060 T8e30 Aluminum Lithium Alloy In Acidic Media
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Book Synopsis Exfoliation Corrosion Susceptibility and Mechanisms of Al-Li 2060 T8E30 Aluminum Lithium Alloy in Acidic Media by : Ahmad Ivan Karayan
Download or read book Exfoliation Corrosion Susceptibility and Mechanisms of Al-Li 2060 T8E30 Aluminum Lithium Alloy in Acidic Media written by Ahmad Ivan Karayan and published by . This book was released on 2015 with total page 197 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Al-Li 2060 aluminum lithium alloy was first launched in 2011. This alloy is a potential candidate for the use at wing/fuselage forgings, lower wing, and fuselage/pressure cabin. However, since its first launching, the corrosion properties of this alloy has not been extensively explored. There are three common laboratory tests for assessing the exfoliation corrosion (EFC) susceptibility of aluminum alloy 2XXX, namely EFC test in EXCO, modified EXCO and MASTMAASIS media. The objectives of this work is to study the susceptibility and mecahnism of corrosion of this alloy in EXCO, modified EXCO and MATSMAASIS media. These three media are acid. In the EXCO solution, this alloy suffers EFC after a 96-hour EFC test. The pH dramatically increases in the first 11 hours from 0.25 to 0.30. The pH then slightly increases and tends to remain constant at pH of 3.45 after 96 hours. The cyclic potentiodynamic polarization (CPP) test results show the presence of negative hysteresis and one breakdwon potential. This negative hysteresis suggests the absence of pitting corrosion due to the breakdown of passive film. The potentiostatic tests at potentials below and above the breakdown potential show an abrupt increase in potential in the first minutes and the presence of current transients. The scanning electron microscopy (SEM)-energy dispersive x-ray spectroscopy (EDS) examination confirms that the Al20Cu2Mn3 particles preferentially dissolve, leaving the pitting after a potentiostatic test below the breakdown potential. From the potentiostatic test at a potential above the breakdown potential and an SEM examination after this potentiostatic test, intergranular corrosion (IGC) was observed. The electrochemical impedance spectroscopy (EIS) test and mathematical modeling indicates that the adsorption of intermediates in reduction of hydrogen ions is dominant in the first hours of immersion. The two time constants are observed when EFC occurs. The video capture microscopy obviously reveals the contribution of corrosion product and hydrogen gas bubbles to the grain lifting during EFC. An XRD analysis on this corrosion product confirms that this is composed of aluminum hydroxide and hydrated aluminum oxide. Unlike the EXCO solution, the modified EXCO one has a higher initial pH. In the first fifteen hours, the pH increases from 3.43 at hour 1 to 3.47 at hour 15. The pH value then increases very slowly and tends to remain constant at 3.49 after 96 hours. The CPP curve has two breakdown potentials where the first one correspond to pitting corrosion and the second one is attributed to IGC. The positive hysteresis indicates this alloy experiences the localized breakdown of passive film that generates pitting corrosion. No indication of EFC was observed after a 96-hour EFC test in the modified EXCO solution. The Nyquist and phase angle plots only show one single time constant during the EFC test for 96 hours. Cyclic acidified salt fog MASTMAASIS testing is an accelerated test method that closely mimic the outdoor exposure. Therefore, the results of MASTMAASIS test predict the EFC susceptibility of aluminum alloy in the real applications more accurately. Our results show that this alloy suffers pitting corrosion only after a four-week MASTMAASIS test in the fog chamber.
Book Synopsis Study of Localized Corrosion in Aluminum Alloys by the Scanning Reference Electrode Technique by : Merlin D. Danford
Download or read book Study of Localized Corrosion in Aluminum Alloys by the Scanning Reference Electrode Technique written by Merlin D. Danford and published by . This book was released on 1995 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Exfoliation Corrosion Testing of Aluminum-Lithium Alloys by : JJ. Thompson
Download or read book Exfoliation Corrosion Testing of Aluminum-Lithium Alloys written by JJ. Thompson and published by . This book was released on 1992 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: A study was performed comparing the corrosion resistance of new aluminum alloys in shipboard environments with accelerated laboratory corrosion test environments. The aluminum-lithium (Al-Li) alloys tested were 2020-T651, 2090-T8E41, and 8090-T851. For comparison, 7075 aluminum was tested in the exfoliation susceptible T651 temper and the resistant T7351 temper. Shipboard exposures were performed aboard aircraft carriers deployed to the Mediterranean Sea, and to the Indian Ocean during the monsoon season. Accelerated laboratory tests performed were EXCO (ASTM G 34-86), sulfur dioxide salt fog (ASTM G 85.A4-85), and MASTMAASIS (ASTM G 85.A2-85).
Book Synopsis Exfoliation Corrosion of Aluminum Alloys by : SJ. Ketcham
Download or read book Exfoliation Corrosion of Aluminum Alloys written by SJ. Ketcham and published by . This book was released on 1972 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper is a general review of the subject of exfoliation corrosion of aluminum alloys summarizing both published and unpublished work. Present thinking on mechanisms is presented. Susceptible alloys and the corrosive environments in which exfoliation occurs are discussed, as well as effect of varying degrees of exfoliation on static and dynamic fatigue strength of 7075-T6 and on life of an actual aircraft structure.
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781722362485 Total Pages :44 pages Book Rating :4.3/5 (624 download)
Book Synopsis Measurements and Mechanisms of Localized Aqueous Corrosion in Aluminum-Lithium Alloys by : National Aeronautics and Space Administration (NASA)
Download or read book Measurements and Mechanisms of Localized Aqueous Corrosion in Aluminum-Lithium Alloys written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-07 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: Like most heat treatable aluminum alloys, localized corrosion and stress corrosion of Al-Li-Cu alloys is strongly dependent on the nature and distribution of second phase particles. To develop a mechanistic understanding of the role of localized corrosion in the stress corrosion process, bulk samples of T(sub 1) (Al2CuLi) and a range of Al-Cu-Fe impurity phases were prepared for electrochemical experiments. Potentiodynamic polarization and galvanic couple experiments were performed in standard 0.6 M NaCl and in simulated crevice solutions to assess corrosion behavior of these particles with respect to the alpha-Al matrix. A comparison of time to failure versus applied potential using a constant load, smooth bar SCC test technique in Cl(-), Cl(-)/CrO4(2-), and Cl(-)/CO3(2-) environments shows that rapid failures are to be expected when applied potentials are more positive than the breakaway potential (E sub br) of T(sub 1) (crack tip) but less than E(sub br) of alpha-Al (crack walls). It is shown that this criterion is not satisfied in aerated Cl(-) solutions. Accordingly, SCC resistance is good. This criterion is satisfied, however, in an alkaline isolated fissure exposed to a CO2 containing atmosphere. Rapid failure induced by these fissures was recently termed preexposure embrittlement. Anodic polarization shows that the corrosion behavior of T(sub 1) is relatively unaffected in alkaline CO3(2-) environments but the alpha-Al phase is rapidly passivated. X ray diffraction of crevice walls from artificial crevices suggests that passivation of alpha-Al occurs as hydrotalcite-type compound (LiAl2(OH)6)2(+) - CO3(2-) - nH2O. Buchheit, Rudolph G., Jr. and Stoner, Glenn E. Unspecified Center ...
Book Synopsis Exfoliation Corrosion Kinetics of High Strength Aluminum Alloys by : Xinyan Zhao
Download or read book Exfoliation Corrosion Kinetics of High Strength Aluminum Alloys written by Xinyan Zhao and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: The objective of this study was to quantitatively study localized corrosion, especially exfoliation corrosion (EFC) of high strength aluminum alloys and to investigate the mechanism of exfoliation corrosion with a focus on the effects of alloy temper, microstructure, relative humidity (RH) and mechanical stress. A new technique, Exfoliation of Slices in Humidity (ESH), was developed for the determination of exfoliation corrosion (EFC) susceptibility and quantification of EFC kinetics. This technique involves in exposing properly oriented and unconstrained samples to high humidity following an electrochemical pretreatment. The EFC kinetics was determined by measuring the width of the central unattacked region of the samples. The ESH results show the capability of the ESH test to discriminate between plates of varying susceptibility and to determine EFC rates quantitatively. Optical microscopy and analytical TEM were used to investigate the effects of microstructure and local chemistry at grain boundary on EFC susceptibility. Alloys with more elongated grain shape are more susceptible to EFC and a high Zn content in grain boundary precipitate free zone relates to a high susceptibility. The effects of RH, temper and applied stress on EFC kinetics of AA7178 were investigated by ESH tests. The critical RH for EFC propagation in AA7178 was found to be about 56% and the EFC kinetics increased with RH. ESH tests provide a quantitative description of the temper effect on EFC kinetics. The effects of applied compressive and tensile stresses on EFC kinetics were studied using a four-point bending jig. Compression accelerated EFC significantly and tension reduced kinetics. An equation describing the effects of RH, stress and time on EFC kinetics was developed based on the ESH results using Eyring model. In situ X-ray radiography was used to characterize intergranular and exfoliation corrosion in high strength Al alloys. The samples were either exposed to sodium chloride solution (NaCl) at a controlled potential or to high humidity after an electrochemical pretreatment in NaCl solution. In situ X-ray radiography of intergranular corrosion attack provides a wide range of IGC kinetics including the fastest growing sites. This method is a good approach for visualizing the EFC process.
Book Synopsis Modification of the EXCO Test Method for Exfoliation Corrosion Susceptibility in 7XXX, 2XXX, and Aluminum-Lithium Alloys by : S. Lee
Download or read book Modification of the EXCO Test Method for Exfoliation Corrosion Susceptibility in 7XXX, 2XXX, and Aluminum-Lithium Alloys written by S. Lee and published by . This book was released on 1992 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: The EXCO test (ASTM G 34) is widely used to predict long-term exfoliation corrosion of high strength aluminum alloys in seacoast and other service environments. Recent experience has shown that the EXCO test does not always accurately predict the resistance of 7X50 and 2024 products processed to different degrees of resistance to exfoliation. The test also severely underestimates resistance to exfoliation of 2090-T8 products.
Book Synopsis Stress-corrosion Behavior of Aluminum-lithium Alloys in Aqueous Environments by :
Download or read book Stress-corrosion Behavior of Aluminum-lithium Alloys in Aqueous Environments written by and published by . This book was released on 1983 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Mechanisms of Localized Aqueous Corrosion in Aluminum-lithium-copper Alloys by : Rudolph G. Buchheit
Download or read book Mechanisms of Localized Aqueous Corrosion in Aluminum-lithium-copper Alloys written by Rudolph G. Buchheit and published by . This book was released on 1991 with total page 558 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this dissertation is to determine the role of microstructural heterogeneity, the localized environment chemistry and unusual surface films in localized corrosion and stress corrosion cracking of an Al-3Cu-2Li alloy commercially designated as 2090.
Book Synopsis Investigations Into the Corrosion Behavior of Aluminum-Lithium Alloys by : Christopher Shigeki Kumai
Download or read book Investigations Into the Corrosion Behavior of Aluminum-Lithium Alloys written by Christopher Shigeki Kumai and published by . This book was released on 1992 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Effect of Thermal-mechanical Processing of the Exfoliation Corrosion Resistance of an Aluminum-zinc-magnesium-copper Alloy by : James Lawrence Spehr
Download or read book The Effect of Thermal-mechanical Processing of the Exfoliation Corrosion Resistance of an Aluminum-zinc-magnesium-copper Alloy written by James Lawrence Spehr and published by . This book was released on 1969 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The objective of this investigation was to evaluate the effect of thermal-mechanical processing on the exfoliation corrosion resistance of an aluminum-zinc-magnesium-copper alloy. the aluminum alloy used was commercially available 7178 alloy in two thicknesses, 0.390 inch thick and 0.250 inch thick. this material was reduced 10, 25 and 40% in thickness in both the annealed and solution heat treated conditions. The material was then aged to a high strength condition, T6, or T8, in the case of the material reduced in the solution heat treated condition. The effect of the thermal-mechanical processing on the exfoliation corrosion resistance was then evaluated by exposing 3 by 6 inch specimens to both an intermittent acidified salt spray test and a salt spray plus sulfur dioxide gas test. Increasing amounts of mechanical deformation of material in the solution heat treated condition resulted in progressively lower resistance to exfoliation corrosion. As the amount of deformation of the annealed material increased to a point where recrystallization resulted during the subsequent solution heat treatment, the exfoliation corrosion resistance improved. The aging schedules developed for the T8 condition resulted in strengths equivalent to the high strength T6 condition without significant losses in ductility. It was also demonstrated that the salt spray plus sulfur dioxide test was a considerably more severe exfoliation test environment than the intermittent acidified salt spray test"--Abstract, leaf ii.
Book Synopsis Corrosion Behavior of Aluminum-Lithium Alloys by :
Download or read book Corrosion Behavior of Aluminum-Lithium Alloys written by and published by . This book was released on 1994 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: Corrosion behavior of three aluminum-lithium (Al-Li) alloys was investigated in aerated 0.5 M sodium sulfate (Na2SO4), deaerated 3.5% sodium chloride (NaCl), and aerated 3.5% NaCl. Corrosion behavior of the Aluminum Association (AA) alloys 2090-T8E41 (UNS A92090, sheet), AA 8090-T851 (UNS a98090, sheet), and AA 8090-T82551 (UNS A98090, bar) was compared to behavior of the conventional AA 7075T6 (UNS A97075, sheet). Uniform corrosion was the predominant form of attack in aerated Na2SO4, and deaerated NaCl, although some localized attack resulted from corrosion of intermetallics on specimen surfaces. Pitting was the main form of attack in aerated NaCl. In all three media, the sheet materials corroded at a similar rate, but the bar form of AA 8090 corroded at a lower rate. Pretreatment of the alloys by immersion in a cerium (Ce) solution inhibited pitting in aerated NaCl but only for a short period.
Book Synopsis Oil and Gas Pipelines by : R. Winston Revie
Download or read book Oil and Gas Pipelines written by R. Winston Revie and published by John Wiley & Sons. This book was released on 2015-04-20 with total page 868 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive and detailed reference guide on the integrity and safety of oil and gas pipelines, both onshore and offshore Covers a wide variety of topics, including design, pipe manufacture, pipeline welding, human factors, residual stresses, mechanical damage, fracture and corrosion, protection, inspection and monitoring, pipeline cleaning, direct assessment, repair, risk management, and abandonment Links modern and vintage practices to help integrity engineers better understand their system and apply up-to-date technology to older infrastructure Includes case histories with examples of solutions to complex problems related to pipeline integrity Includes chapters on stress-based and strain-based design, the latter being a novel type of design that has only recently been investigated by designer firms and regulators Provides information to help those who are responsible to establish procedures for ensuring pipeline integrity and safety
Book Synopsis Biomechanics of the Eye by : Cynthia J. Roberts
Download or read book Biomechanics of the Eye written by Cynthia J. Roberts and published by Kugler Publications. This book was released on 2018-04-20 with total page 546 pages. Available in PDF, EPUB and Kindle. Book excerpt: Covering all major components of the ocular system, this state-of-the-art text is essential for vision scientists, biomedical engineers, and advanced clinicians with an interest in the role of mechanics in ocular function, disease, therapeutics, and surgery. With every chapter, leading experts strengthen the arguments that biomechanics is an indispensable and rapidly evolving tool for understanding and managing ocular disease.
