Dissertations / Theses on the topic 'Stress cracking'
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1
Gamboa, Erwin. "Stress corrosion cracking of rock bolts /." [St. Lucia, Qld.], 2004. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe18302.pdf.
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Attou, Abdelkader. "Cracking and stress corrosion cracking in glass fibre materials using acoustic emission." Thesis, Robert Gordon University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277702.
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Wells, David Brett. "Early stages of intergranular stress corrosion cracking." Thesis, University of Oxford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.256769.
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Mohammed, Farej Ahmed. "Stress corrosion cracking in duplex stainless steels." Thesis, University of Manchester, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.488331.
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Eccott, A. R. "Environmental stress cracking resistance of phenolic compounds." Thesis, Swansea University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636763.
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The environmental stress cracking (ESC) behaviour of a series of phenolics toughened with varying proportions of thermoplastic (0-35%), has been studied. Since these materials have been designed for applications in 'under-the-bonnet' automotive components, testing took place in serveral 'in-service' environments and in some of the constituent chemicals as well as in air. Initial screening of the materials using three point bend testing highlighted the most hostile environments for further study. Tensile testing of samples in air and in methanol and immersion of samples in various environments provided a further insight concerning the diffusion effects likely to be encountered. Creep tests were conducted in selected environments at 23oC, as well as at increased temperatures to provide more realistic 'under-the-bonnet' situations. The observed increase in creep rate in most hostile environments was related to crack initiation and growth. Within the range of added thermoplastic studied, two scales of morphology were seen to occur. In addition to a small scale morphology, only observed using TEM, there exists a large scale ribbon-like morphology. This was studied using light microscopy as well as SEM, on samples etched with permanganate and it was shown using X-ray microanalysis that the ribbons visible were thermoplastic rich regions. A good correlation was obtained between the amount of ribbon-like areas and the thermoplastic content of the sample. Samples, apparently prepared under identical conditions, vary slightly in colour. Further investigation revealed that these colour differences could be correlated with a variation in large scale morphology as well as considerable property differences. TEM, SEM and light microscopy were performed to relate the ESC behaviour with the material morphology. TEM investigations concerning the small scale morphology effect upon crack growth were inconclusive. However, from viewing etched samples subject to ESC via bend tests in methanol, using SEM and light microscopy, it was evident that the large scale morphology was responsible for deflecting microcracks.
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Kruska, Karen. "Understanding the mechanisms of stress corrosion cracking." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:94574eaf-4ae0-4093-bf20-3f4f4c559e7c.
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Austenitic stainless steels are frequently used in the cooling circuits of nuclear reactors. It has been found that cold-worked 304 stainless steels can be particularly susceptible to stress corrosion cracking at the operating conditions of such reactors. Despite more than 130 years of research underlying mechanisms are still not properly understood. For this reason, the effects of cold-work and applied stress on the oxidation behaviour of 304SS have been studied in this thesis. A set of samples with/without prior cold-work, and with/without stress applied during oxidation, were oxidized in autoclaves under simulated pressurised water reactor primary circuit conditions. Atom-probe tomography and analytical transmission electron microscopy were used to investigate the local chemistry and microstructure in the different samples tested. Regions containing grain boundaries, deformation bands, and matrix material in contact with the environment, were extracted from the coupon specimens with a focused ion beam machine. Cross-sections of crack tips were studied with secondary ion mass spectrometry and electron backscatter diffraction. The compositions of oxides grown along the surface and the different microstructural features were analysed. Fe-rich spinels were found at the surface and Cr-rich spinels were observed along fast diffusion paths. Ni-enrichment was found at the metal/oxide interfaces and a Ni-rich phase was detected in precipitates ahead of grain boundary oxides. Li was observed in all oxidised regions and B segregation, originating from impurities in the alloy, was observed in grain boundaries and crack tip oxides. Cavities and hydrogen associated with Ni-rich regions were found ahead of the bulk Cr-rich oxide in some of the samples. The implications of these findings for the understanding of SCC mechanisms are discussed. It is suggested that Ni precipitation as well as the presence of deformation bands may play an important role in controlling SCC susceptibility in 304 stainless steel. A modification of the film-rupture model including internal oxidation and fast diffusion along H-stabilised vacancies in strain fields at the crack front is proposed.
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Deshais, Gerald. "Stress corrosion cracking in Al based alloys." Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621509.
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Meisnar, Martina. "High-resolution characterisation of stress corrosion cracking." Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:6915e56d-d63b-43dc-af29-5257a21d1e4b.
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The degradation of reactor grade stainless steels and their susceptibility to stress corrosion cracking (SCC) when exposed to the pressurised water reactor (PWR) primary water environment has been a topic of intense research for many decades. Nevertheless, our understanding of the underlying mechanisms of SCC remains incomplete to date. It has been generally accepted that only high-resolution (electron) microscopy techniques are capable of revealing the yet unidentified processes involved in SCC crack propagation. For this reason, one of the main objectives of this project was to make new techniques with improved spatial resolution accessible to SCC research. While low-keV energy dispersive X-ray spectroscopy (EDX) was used for the preliminary analysis of SCC cracks, transmission Kikuchi diffraction (TKD) and atom probe tomography (APT) were used for high-resolution studies of the microstructure and chemistry near the crack tip. In particular, TKD proved very beneficial for revealing the extent of the strain concentration around the crack tip. For the application of APT to SCC research, a novel method for preparing APT needles containing entire SCC crack tips was developed. The method was then used for acquiring very localised compositional measurements of the crack tip and GB oxide chemistry with extraordinary accuracy. The second objective of this thesis was to understand the impact of the SCC test temperature on the crack growth rate (CGR) in SUS316 stainless steel. It was found that after steady growth with increasing temperature, a peak in the CGR occurred at ~ 320°C, followed by a substantial drop towards higher temperatures. The inhibition of the CGR with increasing temperature between 320° and 360°C and its impact on the microstructure were studied via analytical transmission electron microscopy (TEM) and TKD. Furthermore, the potential impact of thermally activated diffusion and mechanical response-based mechanisms was investigated. It appears that higher dislocation density and strain concentrations around the crack tips at lower temperature (i.e. 320°C) lead to possibly enhanced brittle-like fracture at the crack tip. An enhanced model for the ongoing processes involved in SCC crack propagation based on the experimental results is presented at the end of this work.
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Gammon, M. A. "Stress corrosion cracking of nuclear grade steels." Master's thesis, University of Cape Town, 1992. http://hdl.handle.net/11427/21956.
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A nuclear grade 316L stainless steel and a 508-111 quenched and tempered pressure vessel steel were studied for their stress corrosion cracking susceptibility. Cylindrical tensile specimens were subjected to slow strain rate testing at 75°C in aerated, aqueous solutions (distiled water with 1000ppm Cl⁻ or SO₄ = ions in solution) in a range of corrosion potentials. The 316L has been examined for sensitization and stress corrosion resistance. This study has shown that the peak degree of sensitization attainable in this material is well within the limits considered as safe by the nuclear power industry. This material is not susceptible to environmentally assisted cracking as long as the potential is kept below the pitting potential for the material. A single instance of intergranular stress corrosion cracking was noted when this material was tested in 1000ppm Cl⁻ solution at 440mV (SHE). Two casts of 508-111 have been examined: 508-A has been tested in the as quenched condition as well as after two tempering heat treatments, while 508-B has been tested in the fully tempered condition only. The mechanical properties of the 508 type materials are strongly influenced by the heat treated condition and mildly influenced by the service environment. In the quenched condition anodic intergranular stress corrosion cracking is severe in the chloride solution and it is argued that the absence of intergranular cracking in the sulphate solution is due to the over aggressiveness of this environment. In all three heat treated conditions loss of ductility is more pronounced in sulphate solutions than in chlorides. Transgranular cleavage is evident in strongly cathodic conditions and this is ascribed to the ingress of hydrogen. The transgranular hydrogen embrittlement seems to be independant of heat treated condition. Rising load tests on fatigue precracked specimens have indicated that environmentally enhanced crack growth of existing defects does not occur for the conditions tested.
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Harrigan, Paul A. "Stress corrosion cracking of Zirconium in nitric acid." Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.503652.
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Wong, T. M. "Stress corrosion cracking in a high strength steel." Thesis, University of Canterbury. Engineering, 1986. http://hdl.handle.net/10092/6429.
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This thesis falls into four fields of study.
The first is a survey of relevant literature concerning the many theories of stress corrosion cracking and hydrogen embritt1ement. This includes descriptions of the mechanisms of stress corrosion cracking (SCC) and outlines electromechanical processes and stress - sorption theory. Four widely accepted mechanisms for environment assisted cracking are also outlined. They are, 1) Embritt1ement resulting from accumulated hydrogen at embritt1ement sites, 2) Lowering of surface energy by adsorption of hydrogen, 3) Hydrogen interaction with dislocations, and 4) Lowering of the binding energy by interaction of hydrogen.
The literature survey is a significant part of this thesis. The overall objective of the survey is to review a series of current SCC tests on high strength steels. The principal findings from these previous studies are summarized, they provide concrete evidence for the conclusion that SCC of high strength steels is due to hydrogen embrittlement.
The second part of the project deals with the development of a stress corrosion loading clevis suitable for testing compact tension specimens. Three existing constant load rigs were developed, and equipment was designed for the successful operation of the rigs.
Corrosive environment was applied to the standard compact tension specimen using a novel circulation system based on a magnetic plate stirrer. Corrosive solution (3.5% NaCl) was stirred by the magnetic plate, and the vortex created by the magnetic stirrer was used to create a pumping head.
The third area of work dealt with the testing of compact tension specimens of ULTIMO 200 steel using the developed apparatus. The experimental procedures used are based on the application of linear elastic fracture mechanics to stress corrosion cracking.
The fourth area of work carried out was to perform slot length calibration experiments on CT specimens by using strain gauges.
The results indicated that the specimens pre-cracked in air with a higher dynamic load gave higher threshold stress intensities (KIscc ) than those pre-cracked in air with a lower dynamic load. An electron microscope study indicated evidence of a largely inter granular fatigue crack having occurred in the specimens pre-cracked with a high dynamic load.
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Rimoli, Julian Jose Ortiz Michael Ortiz Michael. "A computational model for intergranular stress corrosion cracking /." Diss., Pasadena, Calif. : California Institute of Technology, 2009. http://resolver.caltech.edu/CaltechETD:etd-05142009-135909.
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Saithala, Janardhan R. "Pitting and stress corrosion cracking of stainless steel." Thesis, Sheffield Hallam University, 2007. http://shura.shu.ac.uk/20311/.
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An investigation has been performed to determine the pitting resistance of stainless steels and stress corrosion cracking of super duplex stainless steels in water containing chloride ions from 25 - 170°C. The steels studied are 12% Cr, FV520B, FV566, 304L, Uranus65, 2205, Ferallium Alloy 255, and Zeron 100. All these commercial materials used in very significant industrial applications and suffer from pitting and stress corrosion failures. The design of a new experimental setup using an autoclave enabled potentiodynamic polarisation experiments and slow strain rate tests in dilute environments to be conducted at elevated temperatures. The corrosion potentials were controlled using a three electrode cell with computer controlled potentiostat. The experimental programme to determine pitting potentials was designed to simulate the service conditions experienced in most industrial plants and develop mathematical model equations to help a design engineer in material selection decision. Stress corrosion resistance of recently developed Zeron100 was evaluated in dilute environments to propose a mechanism in chloride solutions at high' temperatures useful for the nuclear and power generation industry. Results have shown the significance of the composition of alloying elements across a wide range of stainless steels and its influence on pitting. Nitrogen and molybdenum added to modern duplex stainless steels was found to be unstable at higher temperatures. The fractographic results obtained using the scanning electron microscope (SEM) has given insight in the initiation of pitting in modem duplex and super duplex stainless steels. A mathematical model has been proposed to predict pitting in stainless steels based on the effect of environmental factors (temperature, chloride concentration, and chemical composition). An attempt has been made to identify the mechanism of SCC in Zeron100 super duplex stainless steel. The proposed empirical models have shown good correlation between predicted pitting potential values with experimental results. It has been shown that the SCC mechanism in Zeron100 supports the slip assisted anodic dissolution model of SCC. The relationship between pitting and stress corrosion in dilute environments is established and empirical equations have been proposed to determine the damage region for wide range of stainless steels.
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Razzaghi, Langroudi Javad. "Comparative study of cracking models in concrete structures." Thesis, Heriot-Watt University, 2001. http://hdl.handle.net/10399/498.
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MACHADO, VERONICA MIQUELIN. "EFFECT OF ELASTIC-PLASTIC STRESS IN THE DEFECT TOLERANCE UNDER STRESS CORROSION CRACKING." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2016. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=33679@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE EXCELENCIA ACADEMICA
Corrosão sob tensão (SCC), que consiste na iniciação e propagação de trincas devido ao efeito combinado de tensões mecânicas e o ambiente corrosivo, é um dano potencial para estruturas e componentes. Além do mais, SCC pode ser explicado por diferentes mecanismos dependendo do par material ambiente corrosivo considerado, o que dificulta o uso de um modelo geral para predizer o comportamento de trincas em SCC. Sendo assim, projetos frequentemente utilizam um critério conservativo que desqualifica materiais susceptíveis à SCC sem analisar de maneira apropriada a influência dos campos de tensão que a induzem. O objetivo deste trabalho é avaliar o efeito de tensões elastoplásticas na corrosão sob tensão. Esta abordagem mecânica considera que todos os efeitos corrosivos envolvidos na corrosão sob tensão podem ser apropriadamente quantificados pelas tradicionais resistências do material à iniciação e propagação de trincas para um ambiente corrosivo específico. Corpos de prova de flexão em Alumínio fragilizados por Gálio líquido serão utilizados para prever o efeito de tensões residuais induzidas por deformações plásticas na iniciação de trincas por corrosão sob tensão. Além disso, uma análise quantitativa baseada no comportamento de trincas não propagantes a partir de entalhes será usada para estimar a tensão necessária para iniciar e propagar trincas em corpos de prova entalhados em aço AISI 4140 sujeitos à corrosão por sulfeto de hidrogênio em ambiente aquoso. O comportamento de trincas curtas e a carga máxima suportada pelos corpos de prova entalhados são analisadas considerando campos de tensões lineares elástico e elastoplásticos através do modelo proposto que será validado através de dados experimentais.
Stress Corrosion Cracking (SCC), which consist in the initiation and propagation of cracks due to the combined attack of mechanical stresses and a corrosive environment is a potential danger for structures and components. Moreover, SCC can be explained by different mechanisms depending on the metal environmental pair, what makes difficult to create a generalized analytical approach to predict the crack behavior in SCC. Therefore, projects often use an over-conservative design criteria that disqualify a material susceptible to SCC without properly evaluate the influence of the stress fields that drive them. The aim of this work is to evaluate the effect of elastic-plastic stress in SCC. This mechanical approach assumes that all chemical effects involved in SCC problems can be appositely described and quantified by traditional material resistances to crack initiation and propagation at under specific environment. Aluminum bending specimens in Gallium environment are used to predict the effect of the residual stress induced by plastic deformation in the crack initiation under SCC conditions. Furthermore, a quantitative analysis based on the non-propagating crack behavior departing from notch tips are used to calculate the necessary stress to initiate and propagate SCC in AISI 4140 steel notched specimens under aqueous hydrogen sulfide environment. The non-propagating crack behavior and the maximum load supported by notched specimens are analyzed under linear elastic and elastic-plastic stress field through the proposed model that will be validated by experimental data.
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Iyer, Venkatramani S. "Effect of residual stress gradients in austenitic stainless steels on stress corrosion cracking." Thesis, Virginia Tech, 1991. http://hdl.handle.net/10919/42119.
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The effect of the residual stresses developed during simulated weld heat affected zone in
austenitic stainless steel specimen on the stress corrosion cracking susceptibility was studied.
Residual stresses was measured using X-ray diffraction technique. Boiling Magnesium
Chloride was used as corrosive environment. Compressive stresses developed in the HAZ of
the specimen and in regions away from the HAZ stress free values were obtained. The magnitude
of the stress gradient decreased as the peak temperature attained during simulated
welding decreased. Transgranular cracks were observed in the compressive stress gradient
region and time to cracking decreased with increasing stress gradient. Higher nickel content
alloys took longer to crack as opposed to lower nickel content alloys at approximately the
same stress gradient.
Master of Science
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Ghasemi, Rohollah. "Hydrogen-assisted stress corrosion cracking of high strength steel." Thesis, KTH, Skolan för kemivetenskap (CHE), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-50416.
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In this work, Slow Strain Rate Test (SSRT) testing, Light Optical Microscopy (LOM) and Scanning Electron Microscopy (SEM) were used to study the effect of micro-structure, corrosive environments and cathodic polarisation on stress corrosion cracking (SCC) of two grades of high strength steels, Type A and Type B. Type A is manufactured by quench and tempered (Q&T) method. Type B, a normalize steel was used as reference. This study also supports electrochemical polarisation resistance method as an effective testing technique for measuring the uniform corrosion rate. SSRT samples were chosen from base metal, weld metal and Heat Affected Zone (HAZ). SSRT tests were performed at room temperature under free corrosion potential and cathodic polarisation using 4 mA/cm2 in 1 wt% and 3.5 wt% NaCl solutions. From the obtained corrosion rate measurements performed in 1 wt% and 3.5 wt% NaCl solutions it was observed that increased chloride concentration and dissolved oxygen content enhanced the uniform corrosion for all tested materials. Moreover, the obtained results from SSRT tests demonstrate that both Q&T and normalized steels were not susceptible to SCC in certain strain rate(1×10-6s-1) in 1 wt% and 3.5 wt% NaCl solutions under free corrosion potential. It was con-firmed by a ductile fracture mode and high reduction in area. The weld metal of Type A with acicular ferrite (AF), pro-eutectoid (PF) and bainite microstructure showed higher susceptibility to hydrogen assisted stress corrosion cracking compared to base metal and HAZ. In addition, typical brittle intergranular cracking with small reduction in area was observed on the fracture surface of the Type A due to hydrogen charging.
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Xiao, Ming. "Mechanism of stress corrosion cracking of aluminum alloy 7079." Thesis, Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/19174.
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Salinas-Bravo, Victor Manuel. "Pitting and stress corrosion cracking of duplex stainless steels." Thesis, University of Manchester, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.493165.
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Smith, P. J. "Investigation into Environmental Stress Cracking in Processed Food Cans." Thesis, Imperial College London, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.520862.
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Yuan, Yudie. "Localised corrosion and stress cracking of aluminium-magnesium alloys." Thesis, University of Birmingham, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.433422.
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Singh, Preet Mohinder. "Stress corrosion cracking of carbon steel and inconel 600." Thesis, University of Newcastle Upon Tyne, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328104.
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Phan, Dan. "Atmospheric-Induced stress corrosion cracking of Austenitic Stainless Steels." Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.508598.
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Liu, Xiaodong. "Effects of stress on intergranular corrosion and intergranular stress corrosion cracking in AA2024-T3." Columbus, Ohio : Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1133313637.
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Jani, Shilesh Chandrakant. "A mechanistic study of transgranular stress corrosion cracking of austenitic stainless steels." Thesis, Georgia Institute of Technology, 1986. http://hdl.handle.net/1853/11236.
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Hepples, W. "Environment-sensitive cracking of 7000 series aluminium alloys." Thesis, University of Newcastle Upon Tyne, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375141.
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Bhattacharya, Ananya. "Stress corrosion cracking of duplex stainless steels in caustic solutions." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26491.
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Thesis (Ph.D)--Materials Science and Engineering, Georgia Institute of Technology, 2009.Committee Chair: Singh, Preet M.; Committee Member: Carter, W. Brent; Committee Member: Gokhale, Arun, M.; Committee Member: Neu, Richard; Committee Member: Sanders, Thomas H., Jr.. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Zhang, Jingyu Hsuan Grace. "Experimental study of stress cracking in high density polyethylene pipes /." Philadelphia, Pa. : Drexel University, 2006. http://dspace.library.drexel.edu/handle/1860/747.
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Andersen, Bistra. "Investigations on environmental stress cracking resistance of LDPE/EVA blends." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=972520481.
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Albores-Silva, Octavio E. "Atmospheric stress corrosion cracking and pitting of austenitic stainless steel." Thesis, University of Newcastle Upon Tyne, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.579513.
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The atmospherically-induced stress corrosion cracking (AISCC) of austenitic stainless steel type AISI 316L was investigated using a U-bend technique, under conditions relevant for storage of intermediate level radioactive waste drums. The specimens were obtained from an actual '500 litre' drum with a wet-bead blasted surface finish. Using MgCI2 as contaminant salt, it was found that at the characteristic equilibrium relative humidity a threshold deposition for AISCC occurrence is found above chloride-ion contamination levels of 10 and 25 µg cm-2 at 50 and 30 °C, respectively. Higher contamination levels were required to produce cracking at room temperature or with the increase of relative humidity to 60 %. The AISCC severity was related to the spatial characteristics of the electrolyte film. Above 100 µg cm-2, crack depth seems to be controlled by the electrolyte thickness as it determines the diffusion path of oxygen to the cathodic surface. Below 100 µg cm-2, crack depth is affected predominantly by the formation of a discontinuous electrolyte film which results in smaller anodic/cathodic domains. Transition from cracking to pitting corrosion with tunnel appearance was observed as test temperature was decreased from 30 °C to room temperature, except at high chloride deposition levels. The results indicate that AISCC occurrence can be limited by restriction of chloride deposition, control of RH away from the deliquescence point of relevant salts and control of temperature. Using an X-ray diffraction technique, it was found that the drum's surface residual stresses are compressive and would provide a degree of protection against AISCC. However, tensile residual stresses can be found in non-blasted areas and in sections of the drum welds. Exposure of corrosion coupons and U-bend specimens III an underground environment that potentially resembles a geological disposal facility did not cause any significant pitting or AISCC after 1.75 years of exposure. This was correlated to a low chloride deposition and a high average RH that would have maintained the hygroscopic deposits in a dilute condition.
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Alkathafi, Maftah Hussien Abdulgader. "Modelling of carbonate-bicarbonate stress corrosion cracking of pipeline steels." Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.498675.
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This research work has been concerned with the physical and numerical modelling of the conditions developed under disbonded coatings on steel, with a view to understanding the processes responsible for the conditions that lead to carbonate-bicarbonate stress corrosion cracking. The physical model has used a polyethylene coating covering a crevice of controlled thickness, with a controlled gas connposition (air with 1% CO₂) on the exterior of the coating. An optical fibre chemical sensor was developed to monitor the pH at locations along the crevice, and the potential has been monitored at the same locations using salt-bridge to conventional reference electrodes. A mathematical model of the same system has been developed using a commercial finite element package. The model was based on a one-dimensional crevice and results have been obtained for a high and a low permeability of coating. The results showed that the permeability of the coating plays an important role in controlling the conditions at the end of the crevice. At a high h permeability of coating the gas transport through the coating creates more alkaline solution inside the crevice, the generation of hydroxyl ions due to the oxygen reduction reaction increasing the pH. With a low permeability coating, no gas diffusion through the coating occurs, and the solution inside the crevice becomes less alkaline where the iron dissolution reaction takes place. So the pH and potential inside the crevice with a high permeability coating were greater than with the low permeability coating. In addition, the carbonate and bicarbonate ion concentrations were also higher with the high permeability coating. The results of this model were in good agreement with the physical model and with mathematical models reported in the literature.
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Li, J. J. "Environmental stress cracking behaviour of cross-linked acrylic based resins." Thesis, Swansea University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.637899.
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The environmental stress cracking behaviour of several cross-linked acrylic based resins has been investigated under various testing conditions (bending, creep and constant strain rate tension.). Urethane methacrylate resins were found to undergo crazing in organic liquids only, and the critical strains and critical stresses for craze initiation can be related to the solubility of the liquid environments. PMMA resins with different EGDMA contents (and thus different cross-link densities) underwent crazing in all the environments tested. Small amounts of EGDMA, up to 3% were found to have little effect on critical strains, although in general, materials with higher cross-link densities had higher resistance to crazing. This capability tended to be reduced in aggressive agents. Environmental diffusion was found to play a very important role in determining the ESC behaviour of these resins. There was always competition between diffusion enhanced crack initiation and growth, and diffusion promoted crack blunting. Under most testing conditions, conventional ESC was the main failure mechanism for these materials since such an attack could come into effect over a wide range of liquid uptakes. However, strong environmental diffusion was also found to lead to crack blunting by the mechanisms of surface softening and compression. This occurred when a plasticised layer developed either on the specimen surface before crack nucleation, or ahead of the crack tip. The effects of cross-linking the chains were to restrict environmental liquid diffusion, to suppress craze initiation and to increase crack growth rate, although these effects were only significant at high levels of cross-linking A combination of these effects determined the overall ESC behaviour of cross-linked polymers Amongst them, restriction to environmental diffusion by cross-linking, appeared to be the most important factors.
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Mackay, F. G. "The application of the J-integral to stress corrosion cracking." Thesis, University of Newcastle Upon Tyne, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384084.
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Shushan, S. M. "The susceptibility of diffusion bonded joints to stress corrosion cracking." Thesis, University of Newcastle Upon Tyne, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295046.
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Zhang, Daxu. "Stress transfer, stiffness degradation and transverse cracking in composite laminates." Thesis, University of Leeds, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.436379.
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Nguyen, Olivier T. Ortiz Michael. "Cohesive models of fatigue crack growth and stress-corrosion cracking /." Diss., Pasadena, Calif. : California Institute of Technology, 2002. http://resolver.caltech.edu/CaltechETD:etd-12032004-161201.
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Seong, Jinwook. "Inhibition of Corrosion and Stress Corrosion Cracking of Sensitized AA5083." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1429701294.
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McNutt, Steven A. "Stress relief cracking in copper-precipitation strengthened HSLA-100 steel." Thesis, Monterey, California. Naval Postgraduate School, 1988. http://hdl.handle.net/10945/23410.
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Approved for public release; distribution is unlimitedThe US Navy is currently developing a new family of high-strength , low-alloy steels which derive a significant portion of their strength from copper precipitation. These highly weldable steels require little or no preheat. resulting in substantial cost savings. The first of these steels. HSLA-80, has been certified for ship construction, but recent studies have indicated some susceptibility to stress relief cracking in weldments. HSLA-100, a modification of HSLA-80, is now being considered for several higher-strength naval structures. Stress-relief cracking has not been studied previously in this steel and is the subject of investigation in this work. The steel weldments were loaded below their yield strength, heated to temperatures of 550°-650° C, and permitted to stress relieve for one hour. At all temperatures, the steel exhibited susceptibility to stress relief cracking in certain stress ranges. Optical and scanning electron microscopy exhibited intergranular cracking which always traversed the coarse-grained region of the heat-affected zone. Auger and transmission electron microscopy indicated high concentrations of alloying elements at the grain boundaries. Stress-relief cracking was associated with the diffusion of alloying elements to the prior austenite grain boundaries.
http://archive.org/details/stressreliefcrac00mcnu
Captain, Canadian Forces
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Hays, Richard A. "Surface residual stress effects on stress corrosion cracking/hydrogen embrittlement behavior of AISI 4340 steel." Thesis, Virginia Polytechnic Institute and State University, 1988. http://hdl.handle.net/10919/80148.
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A series of experiments was performed in an attempt to measure the effects of surface residual stresses on the stress corrosion cracking/hydrogen embrittlement (SCC/HE) behavior of AISI 4340 steel. Stress corrosion tests were performed under load control on cylindrical and notched tensile specimens in acidified 3.5% NaCl solution. The electrochemical potential of the specimens was maintained at -0.7 V versus a saturated calomel reference electrode. Time to failure for specimens tested at various applied and residual stress levels was measured. Stress relieved specimens as well as specimens containing mechanically induced residual stresses were tested. Residual stresses were estimated using Neuber's rule and were measured using an x-ray diffraction technique. In all cases, the sum of the applied and residual stresses was greater than zero.
Test results showed the initiation of SCC/HE cracks to be insensitive to the effects of surface residual stresses under the conditions evaluated. This is probably a result of the total time to failure criterion used to evaluate the SCC/HE tests. The extremely aggressive environment used in these experiments apparently led to rapid crack initiation, even in specimens containing compressive residual stresses. Another possible explanation of the insensitivity of this series of tests is crack initiation in the interior of the specimens below the depth of the mechanically induced residual stresses.Master of Science
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Yamada, Kazuo. "Stress corrosion cracking behavior of aluminum alloy 7079 in region II." Thesis, Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/19078.
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Scott, Brian E.-S. "THE ROLE OF STRESS IN THE CORROSION CRACKING OF ALUMINUM ALLOYS." Monterey, California. Naval Postgraduate School, 2013. http://hdl.handle.net/10945/32897.
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This work examines the effect of stress on the rate of sensitization, the rate of pitting corrosion and the rate of crack nucleation of aluminum alloy 5083-H116 aluminum. Stress corrosion cracking in aluminum superstructures of Naval vessels is a multibillion-dollar maintenance problem, which requires more scientific understanding to better predict and mitigate. To investigate the role of applied stress on these corrosion-related processes, rolled plate of AA5083 was placed under tensile stress through bending while being subject to elevated temperature and salt spray. Nitric acid mass loss tests quantified the amount of sensitization as a function of stress level. Optical micrographs were used to determine the rate of pitting corrosion and crack nucleation while under applied tensile stress. The effect of applied, elastic stress on the degree of sensitization was inconclusive. Applied stress did increase the rate of localized corrosion, in terms of both pitting and intergranular corrosion. Moreover, the orientation of the plate with respect to the applied tensile stress, strongly affected the type and amount of localized corrosion observed. When the tensile stress was applied across the rolling direction, more localized corrosion occurred and intergranular corrosion dominant over pitting.
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Kelly, D. J. "Exfoliation and stress corrosion cracking of the aluminium-lithium alloy 8090." Thesis, Cranfield University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302803.
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Barlow, D. "Stress relief cracking in A533B and A508C1 2 pressure vessel steels." Thesis, University of Leeds, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233221.
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Scatigno, Giuseppe Giovanni. "Chloride-induced transgranular stress corrosion cracking of austenitic stainless steel 304L." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/51506.
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Stress corrosion cracking (SCC) of austenitic stainless steels has been a known failure mode for more than 80 years and it continues to be a major cause of concern in the nuclear industry. The so-called nuclear grades, such as 304L, contain low levels of C and are therefore hard to sensitise, which is a major problem with high C grades, and these low C grades mainly fail by transgranular SCC. The effect of cold work (CW) has long been known to have a detrimental effect on SCC performance of a stainless steel component. CW is readily introduced in engineering components, through manufacturing history, or implementation, i.e. welding and hammering during fitting. The aim of this thesis is to systematically assess the role of CW in Cl-induced atmospheric SCC in 304L grade austenitic stainless steel. 304L is widely used in the nuclear industry, for both the primary cooling system of nuclear power plants and dry casks for interim storage of spent nuclear fuel. CW was applied in uniaxial tension to levels of 0, 0.5, 1, 2, 5 10, 20, and 40%. The specimens were loaded in a jig to produce a uniform stress of 60 MPa on the top surface and corroded under atmospheric conditions at 75°C, 70% relative humidity, using MgCl2, for 20 days. The role of applied stress (from 60-180 MPa), on SCC susceptibility was investigated at a fixed level of CW (chosen as 10% CW after preliminary experiments) using indicators such as crack density. Secondary and transmission electron microscopy, electron back-scattered diffraction, focused ion beam and secondary ion spectroscopy were the main characterisation techniques used. The maximum susceptibility to SCC was observed between 0.5-5% CW, while 20 and 40% CW did not exhibit cracking. The characterisation of the samples tested provided evidence that Cl is found ahead of the crack tip, whereas oxygen is not, which was never previously observed in the literature. Secondary ion mass spectroscopy and transmission electron microscopy were both used to observe and study the presence of Cl. Simulations such as SRIM and Casino 3.2 were used to confirm that the findings were not a technique artefact. Evidence of dealloying was also observed during the characterisation. Dealloying has long been deemed unlikely in Cl-SCC of austenitic stainless steel, but recent work showed that this may also be an available mechanism for SCC as more and more of the characteristics features of dealloying are observed. The dealloying signs observed were: nanoporosity, found on fracture surfaces; severe striations, heavy dissolution of slip planes; element migration (areas of light and dark contrast in back scattered electron images, dictated by the migration of Cr); cleavage failure; Cr and Ni migration around the crack. The role of salt loading was investigated. Different levels of salt deposition were tested in order to obtain an engineering threshold for salt deposition, namely: low ( < 5.70 x 10-3 g cm-2), medium (5.70 x 10-3–1.42 x 10-2 g cm-2) and high ( > 1.42 x 10-2 g cm-2). A linear relationship was observed between level of salt deposited and both crack density and corrosion area. However, more work is necessary to obtain a threshold.
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Sandana, Daniel. "Stress corrosion cracking of pipeline steels in contaminated aqueous CO₂ environments." Thesis, University of Newcastle upon Tyne, 2016. http://hdl.handle.net/10443/3396.
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This work addresses the risk of Stress Corrosion Cracking (SCC) in CO₂transport pipelines. The susceptibility of X80 pipeline steels in aqueous CO₂environments in the presence of nitrates and sulphites is investigated using electrochemical potentiodynamic tests and Slow Strain Rate Tests (SSRT) at 23 and 75°C. The electrochemical measurements showed that in CO2-free and CO₂-saturated systems, the material presents an active-passive transition in bicarbonate/carbonate solutions with nitrate and sulphite. This indicated that SCC is possible in all the test environments. SCC occurred in bicarbonate/carbonate solutions with nitrates and sulphites at 75°C, both under CO₂-free and CO₂-saturated conditions. SCC severity declined as the potential moved towards the free corrosion potential. Cracking was still observed at +50 mV from Ecorr. The cracking mode in the active domain was transgranular for all the systems. In CO2-free systems, the severity and cracking mode in the HCO₃--CO₃² --H₂O and NaNO₃-HCO₃--CO₃² --H₂O systems was similar in the active-passive transition domain at 75°C. Crack growth was controlled by anodic dissolution and the crack mode was intergranular for both systems. At high pH ( > 9), the overall cracking mechanism remains dominated by the HCO₃--CO₃² --H₂O system even in the presence of nitrates. The addition of sulphites to bicarbonate/carbonate solutions however decreased the severity of cracking and shifted the cracking mode to transgranular. In CO₂-saturated systems, the SCC susceptibility in all test environments decreased with lower pH. Yet the highest susceptibility to cracking in the active-passive domain was identified in the nitrate-containing systems. With the drop in pH, nitrate SCC becomes the dominant mechanism when nitrates are present in the HCO₃--CO₃² --H₂O system. The addition of CO2 shifted the mode of cracking to transgranular in the active-passive domain in the pure bicarbonate/carbonate solution.
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PRECKER, Christian Eike. "Diffusion driven accelerated stress corrosion cracking in an acrylic polymer (PMMA)." Universidade Federal de Campina Grande, 2013. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/1939.
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Capes
A evolução dinâmica e o mecanismo da corrosão sob tensão fraturante acelerada (accelerated stress corrosion cracking – aSCC) em uma amostra de acrílico (PMMA – poly methyl 2-methylpropenoate) foi explorada quantitativamente na ausência de carga mecânica externa. Uma incomum e rápida propagação de trincas em amostras usinadas deste material foi induzida por solvente, onde estas foram monitoradas por imagens de vídeo de um microscópio. As trincas emanaram de canais fresados na amostra a partir de um breve contato do solvente acetona com a sua superfície. O período da propagação das trincas durou em torno de 1 minuto, compreendendo um comprimento final de 0,2 a 0,3 mm, e uma taxa de crescimento que decai de 5 2 10 para 6 10 m/s. A evolução temporal da trinca concorda com a difusão unidimensional do solvente ao longo da trinca, sobreposto por um campo de tensão residual. Através de birrefringência que foi oticamente registrada, bem como uma simulação da estrutura mecânica foi feita por meio de elementos finitos, identificamos tensão de tração residual (residual tensile stress) na zona da trinca como sendo uma força motriz. O fator de intensidade de tensão residual ΔK foi determinado em 1–2 MPa m1/2. A aSCC no material se origina de uma combinação de tensões residuais, induzida pela fresagem da superfície da amostra; stress que induz uma rápida difusão do solvente acetona no material e uma degradação associada com os parâmetros da estrutura mecânica.
The dynamic evolution and mechanism of accelerated stress corrosion cracking (aSCC) in an acrylic (PMMA–poly methyl 2-methylpropenoate) polymer sample have been exploited quantitatively, in absence of external mechanical load. Unusually fast propagation of solvent induced cracks in micro-machined sections of the material has been monitored by microscopic video imaging of a test device. Crack emanation from milled micro-channels was precisely triggered by brief surface wetting with acetone solvent. The crack propagation period persists over a time span of approximately 1 min, comprises a final crack length of 0.2–0.3 mm, and an associated crack growth rate that decreases from 5 2 10 to 6 10 m/s. The temporal crack evolution scales in accord with 1-dim solvent diffusion along the flaw, superimposed with the residual stress field. Optically recorded birefringence, as well as finite element structure mechanic simulation, identified residual tensile stress in the crack zone as the driving force. The residual stress intensity factor ΔK was determined to 1–2 MPa m1/2. The aSCC (accelerated stress corrosion cracking) in the material originates from a detrimental combination of residual stress, induced by surface milling; stress induced fast diffusion of the acetone solvent into the material and an associated degradation of structure-mechanic parameters.
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Lorho, Nina. "Stress corrosion cracking susceptibility in Alloy 600 with different strain histories." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/stress-corrosion-cracking-susceptibility-in-alloy-600-with-different-strain-histories(59eabd1d-b254-48bc-afca-e979f5d4e6c2).html.
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Lifetime prediction of components in Alloy 600 is a major concern for nuclear power plants. Alloy 600 components have been shown to be susceptible to stress corrosion cracking (SCC). In the 1990’s, an engineering model was developed in order to predict the life time as a function of the main macroscopic parameters (stress, environment, material), based on laboratory results. This model has since been used to predict the ranking of various Alloy 600 components, using the knowledges of the manufacturing and service conditions for each component. It was applied successfully in the case of forged control rod drive mechanism (CRDM) nozzles. However, it was found necessary to improve this model to account for the strain history of the different components. Predictions using the model, investigated from an array of test results on Alloy 600 in laboratory primary water, have demonstrated that the time for initiation differed significantly according to the strain path applied to the specimen. The present work is dedicated to assess SCC results from samples with different strain paths and different level of cold work in order to better understand the manufacturing conditions on SCC. The samples are machined in three different directions and tested at different durations in order to model the time for transition (transition between slow and fast propagation) as a function of cold work, strain path and stress. Thermomechanical treatments are also applied on two different heats of Alloy 600: forged WF675 (very susceptible to SCC in as received conditions) and rolled 78456/337 (non susceptible to SCC in as-received conditions) in order to transform the forged microstructure into a microstructure close to the rolled microstructure and vice-versa. These microstructures are then tested in primary conditions and the results are compared to the results obtained on as-received material in order to get a better understanding of manufacturing process and microstructure parameters regarding SCC behaviour.
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Al-Rabie, Mohammed. "Observations of stress corrosion cracking behaviour in super duplex stainless steel." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/observations-of-stress-corrosion-cracking-behaviour-in-super-duplex-stainless-steel(51f53ed4-7bdc-469a-8ff7-7dfd9ff56339).html.
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The new generation of highly alloyed super duplex stainless steels such as Zeron 100 are preferable materials for industrial applications demanding high strength, toughness and superior corrosion resistance, especially against stress corrosion cracking (SCC). SCC is an environmentally assisted failure mechanism that occurs due to exposure to an aggressive environment while under a tensile stress. The mechanism by which SCC of duplex stainless steel is expected to suffer depends on the combination of electrochemical and the mechanical interaction between austenite and ferrite in the duplex alloys. The main aims of this work are to study the suitability of digital image correlation (DIC) to monitor the initiation and propagation of SCC and to understand how the microstructure of duplex stainless steel influences the kinetics of crack initiation and growth. The combined analysis of DIC, SEM and EBSD was used to study the relative crack propagation and the effect of interphase boundaries on crack growth as well. Cracking was initiated beneath saturated MgCl2 droplets in an atmospheric environment at 80°C and relative humidity of 30-33%. As-received and 10% cold rolled samples (with two orientations transverse and longitudinal to the loading direction) were subjected to an applied strain of 0.03 under displacement controlled tests. Regular optical observations were recorded of the droplets and their surrounding area. DIC analyses used the differentiation of the displacement fields to obtain the apparent surface strains used to detect crack initiation and propagation, and to measure crack opening displacements. It was found that DIC was efficiently observed the strain developments and the displacements in observed surfaces outside of the droplets but it could not identify or quantify the initiation of the cracks inside the droplets because of the mobility of the salt film and the high amount of the corrosion products formed which obscure the vision under the droplets. In addition, results showed that early stage microcracks were initiated in α phase and α/γ interfaces and propagated preferentially in the ferrite phase. Also, SCC initiation and propagation was accelerated by cold rolling and the grains orientations were of major effects on the retardation of crack propagation which was more severe in the transverse rolling direction. Also, there was no relation established between the strain level and the density of pitting in either phase.
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Yang, Di. "Cyclic stress effect on stress corrosion cracking of duplex stainless steel in chloride and caustic solutions." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42811.
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Duplex stainless steel (DSS) is a dual-phase material with approximately equal volume amount of austenite and ferrite. It has both great mechanical properties (good ductility and high tensile/fatigue strength) and excellent corrosion resistance due to the mixture of the two phases.
Cyclic loadings with high stress level and low frequency are experienced by many structures. However, the existing study on corrosion fatigue (CF) study of various metallic materials has mainly concentrated on relatively high frequency range. No systematic study has been done to understand the ultra-low frequency (10-5 Hz) cyclic loading effect on stress corrosion cracking (SCC) of DSSs.
In this study, the ultra-low frequency cyclic loading effect on SCC of DSS 2205 was studied in acidified sodium chloride and caustic white liquor (WL) solutions. The research work focused on the environmental effect on SCC of DSS 2205, the cyclic stress effect on strain accumulation behavior of DSS 2205, and the combined environmental and cyclic stress effect on the stress corrosion crack initiation of DSS 2205 in the above environments.
Potentiodynamic polarization tests were performed to investigate the electrochemical behavior of DSS 2205 in acidic NaCl solution. Series of slow strain rate tests (SSRTs) at different applied potential values were conducted to reveal the optimum applied potential value for SCC to happen. Room temperature static and cyclic creep tests were performed in air to illustrate the strain accumulation effect of cyclic stresses. Test results showed that cyclic loading could enhance strain accumulation in DSS 2205 compared to static loading. Moreover, the strain accumulation behavior of DSS 2205 was found to be controlled by the two phases of DSS 2205 with different crystal structures. The B.C.C. ferrite phase enhanced strain accumulation due to extensive cross-slips of the dislocations, whereas the F.C.C. austenite phase resisted strain accumulation due to cyclic strain hardening. Cyclic SSRTs were performed under the conditions that SCC occurs in sodium chloride and WL solutions. Test results show that cyclic stress facilitated crack initiations in DSS 2205. Stress corrosion cracks initiated from the intermetallic precipitates in acidic chloride environment, and the cracks initiated from austenite phase in WL environment. Cold-working has been found to retard the crack initiations induced by cyclic stresses.
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Williams, J. R. "Corrosion of aluminium-copper-magnesium metal matrix composites." Thesis, University of Nottingham, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239852.
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