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1
Raseroka, Mantsaye S. "Controlled chloride cracking of austenitic stainless steel." Pretoria : [s.n.], 2009. http://upetd.up.ac.za/thesis/available/etd-07032009-120615/.
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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.
3
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.
4
Sui, Gaoyi. "Some aspects of stress corrosion cracking of Type 316 stainless steel steam generator tubes." Thesis, University of Newcastle Upon Tyne, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.481644.
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Gulbrandsen, Stephani. "Stress corrosion cracking of 316L austenitic stainless steel in high temperature ethanol/water environments." Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/47815.
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There has been an increase in the production of bio-fuels. Organosolv delignification, high temperature ethanol/water environments, can be used to separate lignin, cellulose, and hemicelluloses in the bio-mass for bio-fuel production. These environments have been shown to induce stress corrosion cracking (SCC) in 316L stainless steel. Previous research has been done in mixed solvent environments at room temperature to understand SCC for stainless steels, but little is known about the behavior in high temperature environments. Simulated organosolv delignification environments were studied, varying water content, temperature, pHe, and Cl- content to understand how these constituents impact SCC. In order for SCC to occur in 316L, there needs to be between 10 and 90 volume % water and the environment needs to be at a temperature around 200°C. Once these two conditions are met, the environment needs to either have pHe < 4 or have more than 10 ppm Cl-. These threshold conditions are based on the organosolv delignification simulated environments tested. SCC severity was seen to increase as water content, temperature, and Cl- content increased and as pHe decreased. To prevent failure of industrial vessels encountering organosolv delignification environments, care needs to be taken to monitor and adjust the constituents to prevent SCC.
6
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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Brady, Michael P. "Evaluation of laser surface melting to mitigate chloride stress corrosion cracking in an austenitic stainless steel." Thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-03122009-040851/.
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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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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
10
Sapiro, David O. "The Effects of Alloy Chemistry on Localized Corrosion of Austenitic Stainless Steels." Research Showcase @ CMU, 2017. http://repository.cmu.edu/dissertations/1087.
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This study investigated localized corrosion behavior of austenitic stainless steels under stressed and unstressed conditions, as well as corrosion of metallic thin films. While austenitic stainless steels are widely used in corrosive environments, they are vulnerable to pitting and stress corrosion cracking (SCC), particularly in chloride-containing environments. The corrosion resistance of austenitic stainless steels is closely tied to the alloying elements chromium, nickel, and molybdenum. Polarization curves were measured for five commercially available austenitic stainless steels of varying chromium, nickel, and molybdenum content in 3.5 wt.% and 25 wt.% NaCl solutions. The alloys were also tested in tension at slow strain rates in air and in a chloride environment under different polarization conditions to explore the relationship between the extent of pitting corrosion and SCC over a range of alloy content and environment. The influence of alloy composition on corrosion resistance was found to be consistent with the pitting resistance equivalent number (PREN) under some conditions, but there were also conditions under which the model did not hold for certain commercial alloy compositions. Monotonic loading was used to generate SCC in in 300 series stainless steels, and it was possible to control the failure mode through adjusting environmental and polarization conditions. Metallic thin film systems of thickness 10-200 nm are being investigated for use as corrosion sensors and protective coatings, however the corrosion properties of ferrous thin films have not been widely studied. The effects of film thickness and substrate conductivity were examined using potentiodynamic polarization and scanning vibrating electrode technique (SVET) on iron thin films. Thicker films undergo more corrosion than thinner films in the same environment, though the corrosion mechanism is the same. Conductive substrates encourage general corrosion, similar to that of bulk iron, while insulating substrates supported only localized corrosion.
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Engelberg, Dirk Lars. "Grain boundary engineering for intergranular stress corrosion resistance in austenitic stainless steel." Thesis, University of Manchester, 2006. http://www.manchester.ac.uk/escholar/uk-ac-man-scw:207805.
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Austenitic stainless steels are frequently used for engineering applications in aggressive environments. Typical sources of component failures are associated with localized attack at grain boundaries, such as intergranular corrosion and stress corrosion cracking. To prevent premature failures, structural integrity assessments are carried out, with the aim of predicting the maximum likelihood of cracking that may develop. For accurate predictions it is of great importance to know the interaction of parameters involved in life-determining processes. This PhD thesis investigates the effect of microstructure and stress on intergranular stress corrosion cracking in Type 302 / Type 304 austenitic stainless steels. High-resolution X-ray tomography has been successfully applied to examine, for the first time in 3-dimensions, in-situ, the interaction between microstructure and crack propagation. The development and subsequent failure of crack bridging ligaments has been observed and correlated with regions of ductile tearing persistent on the fracture surface. These ductile regions were consistent with the morphology of low-energy, twin-type grain boundaries, and are believed to possess the capability of shielding the crack tip. Following this observation, a new grain bridging model has been developed, in order to quantify the effect of static stress and crack bridging on the maximum likely crack length. The model was compared and evaluated with in the literature available percolation-like models. Intergranular stress corrosion tests in tetrathionate solutions have been designed and carried out to validate the new model. The assessment comprised,(i) a thorough examination of the microstructure and analysis parameters employed,(ii) the determination of the degree of sensitisation with subsequent crack path investigations,(iii) the identification of a suitable test system with associated grain boundary susceptibility criteria,(iv) the application of Grain Boundary Engineering (GBE) for microstructure control,(v) statistical crack length assessments of calibrated IGSCC test specimens. The results of these tests showed that the new model successfully predicts the magnitude of stress and the effect of grain boundary engineering on the maximum crack lengths.
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Lakocy, Alexander J. "Experimental characterization of stress corrosion cracking sensitization in austenitic stainless steel using nonlinear ultrasonic Rayleigh waves." Thesis, Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54476.
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This thesis examines the use of nonlinear ultrasound to evaluate sensitization, a precursor to stress corrosion cracking in austenitic stainless steel. Ultrasonic Rayleigh surface waves are generated on a specimen; as these waves pass through sensitized material, second harmonic generation (SHG) increases. In austenitic stainless steel with oven-induced sensitization, this increase is due only to the formation of chromium carbide precipitates, key products of the sensitization process. Weld-induced sensitization specimens demonstrate additional increases in SHG, likely caused by increased residual stress and dislocation density as a result of uneven heating. Experimental data are used to calculate the acoustic nonlinearity parameter, which provides a single value directly related to the quantity of micro- and nano-scale damage present within any given sample. Using this procedure, the effects of weld- and oven-induced sensitization are compared. Results demonstrate the feasibility of using nonlinear Rayleigh waves to detect and monitor stress corrosion susceptibility of welded material.
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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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Alsarraf, Jalal. "Hydrogen embrittlement susceptibility of super duplex stainless steels." Thesis, Cranfield University, 2010. http://dspace.lib.cranfield.ac.uk/handle/1826/4562.
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This thesis describes the metallurgical and environmental factors that influence hydrogen embrittlement of super duplex stainless steels and presents a model to predict the rate at which embrittlement occurs. Super duplex stainless steel has an austenite and ferrite microstructure with an average fraction of each phase of approximately 50%. An investigation was carried out on the metallurgical and environmental factors that influence hydrogen embrittlement of super duplex stainless steels. Tensile specimens of super duplex stainless steel were pre-charged with hydrogen for two weeks in 3.5% NaCl solution at 50º C at a range of applied potentials to simulate the conditions that exist when subsea oilfield components are cathodically protected in seawater. The pre-charged specimens were then tested in a slow strain rate tensile test and their susceptibility to hydrogen embrittlement was assessed by the failure time, reduction in cross-sectional area and examination of the fracture surface. The ferrite and austenite in the duplex microstructures were identified by analysing their Cr, Ni, Mo and N contents in an electron microscope, as these elements partition in different concentrations in the two phases. It was shown that hydrogen embrittlement occurred in the ferrite phase, whereas the austenite failed in a ductile manner. An embrittled region existed around the circumference of each fracture surface and the depth of this embrittlement depended on the hydrogen charging time and the potential at which the charging had been carried out. The depth of embrittlement was shown to correlate with the rate of hydrogen diffusion in the alloy, which was measured electrochemically using hydrogen permeation and galvanostatic methods. A two-dimensional diffusion model was used to calculate the hydrogen distribution profiles for each experimental condition and the model could be employed to provide predictions of expected failure times in stressed engineering components.
15
Shapiro, Karen Naomi. "'The effect of residual stress and surface condition on the stress corrosion cracking of austenitic stainless steel'." Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.499863.
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Wright, David Marc. "The effect of cold rolling on the susceptibility of austenitic stainless steel to stress corrosion cracking in primary circuit pressurised water reactor environment." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/the-effect-of-cold-rolling-on-the-susceptibility-of-austenitic-stainless-steel-to-stress-corrosion-cracking-in-primary-circuit-pressurised-water-reactor-environment(43d9ea3e-e941-4412-90f6-907f715b78c5).html.
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The stress corrosion cracking (SCC) of components which are fabricated from austenitic stainless steel has been observed in the primary circuit of pressurised water reactors (PWR). In recent years it has become an increasing concern that cold work can induce susceptibility to SCC in these materials, even when exposed to good-quality flowing coolant. Laboratory studies which were launched in response to this observation have confirmed that SCC susceptibility is enhanced by cold work. The intention of this study is therefore to investigate the link between the effects of cold work on the material and the susceptibility to SCC. The investigation has been conducted on a grade 304 austenitic stainless steel. Characterisation of the microstructure and mechanical properties has been carried out in the annealed condition, and following cold rolling to a reduction in thickness of 20 %. The cold rolled material has then been subjected to SCC tests in simulated PWR primary circuit coolant. Two types of test were utilised: slow strain rate tests (SSRTs) were carried out in order to investigate the initiation of cracks from a smooth surface and constant load tests using pre-cracked specimens were used to investigate the crack propagation behaviour. In both types of test the SCC produced was predominantly intergranular. The SSRTs revealed that the most susceptible grain boundaries separated grains which had dissimilar deformation microstructures (one grain deformed heavily by planar bands, the other more homogenously). It was also observed that initiation could occur on a grain boundary which is adjacent to an annealing twin. In both microstructural configurations the susceptibility is likely to be due to the deformation incompatibility across the failed boundary, possible indicating that shear at the boundary is important for the initiation of cracking. The crack propagation behaviour of the rolled material was particularly anisotropic; regardless of the loading direction (specimens were manufactured to allow loading along the rolling, transverse and normal plate directions) cracking was observed to occur parallel to the rolling-transverse plane. The origin of this behaviour was explored in terms of preferential alignment of the deformation microstructure and the anisotropic mechanical properties of the rolled plate. Limited transgranular cracking was also observed, which occurred along oxidised deformation bands. The results overall indicate that heterogeneous deformation between different regions of the material, and preferential alignment of the deformation microstructure are important with respect to the SCC susceptibility of the rolled material.
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Gupta, Jyoti. "Intergranular stress corrosion cracking of ion irradiated 304L stainless steel in PWR environment." Thesis, Toulouse, INPT, 2016. http://www.theses.fr/2016INPT0031/document.
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L’IASCC est un mécanisme de fissuration intergranulaire par corrosion sous contrainte (IGCSC) induite par l'irradiation. C’est un phénomène complexe qui peut avoir une influence significative sur le temps et le coût de maintenance des composants internes du coeur des réacteurs à eau pressurisée (REP) et est donc un sujet d'intérêt. Des études récentes ont proposé d'utiliser l'irradiation aux ions (protons) comme une alternative à l'irradiation neutronique afin d’améliorer la compréhension du mécanisme. L'objectif de cette thèse est d’étudier la sensibilité à la fissuration de l’acier austénitique SA 304L irradié aux ions ainsi que les facteurs contribuant à cette fissuration. Deux types d’irradiations aux ions ont été menées (fer et aux protons). Ces deux irradiations ont générées des défauts ponctuels dans la microstructure représentatifs de ceux crées par les neutrons provoquant ainsi le durcissement de l’acier austénitique 304L. Matériel (non irradié et le fer irradié) n'a montré aucune sensibilité à la fissuration intergranulaire sur la soumission à un essai de traction lente SSRT (Slow Strain Rate Test) commencer avec une vitesse de déformation de 5 × 10-8 s-1 jusqu'à 4% de déformation plastique dans un environnement inerte. Il est montré que les deux types d’irradiation aux ions (fer et protons) augmentent la sensibilité à la fissuration intergranulaire du matériau après un essai de SSRT dans un environnement simulé de REP à 340 ° C. La corrélation entre la sensibilité de fissuration et le degré de localisation de la déformation plastique a été étudiée. L’impact de l'irradiation aux ions fer sur l'oxydation du 304L a été aussi étudié grâce à des essais effectués pendant 360 h dans un milieu REP à 340 ° C. Les résultats de cette thèse indiquent que la fissuration intergranulaire de l'acier inoxydable 304L en milieu REP peut être étudiée en utilisant l'irradiation Fe malgré sa faible profondeur de pénétration dans le matériau. Par ailleurs, il est montré que le comportement vis-à-vis de la fissuration est similaire entre une irradiation aux protons et au fer, et ceux malgré une localisation de la déformation moins importante pour ces derniers. Par conséquent, l’irradiation au fer est utilisée pour étudier l'impact de la préparation de surface et des chemins de déformation sur la sensibilité de la fissuration intergranulaire de l’acier 304LIASCC is irradiation – assisted enhancement of intergranular stress corrosion cracking susceptibility of austenitic stainless steel. It is a complex degrading phenomenon which can have a significant influence on maintenance time and cost of PWRs’ core internals and hence, is an issue of concern. Recent studies have proposed using ion irradiation (to be specific, proton irradiation) as an alternative of neutron irradiation to improve the current understanding of the mechanism. The objective of this study was to investigate the cracking susceptibility of irradiated SA 304L and factors contributing to cracking, using two different ion irradiations; iron and proton irradiations. Both resulted in generation of point defects in the microstructure and thereby causing hardening of the SA 304L. Material (unirradiated and iron irradiated) showed no susceptibility to intergranular cracking on subjection to SSRT with a strain rate of 5 × 10-8 s-1 up to 4 % plastic strain in inert environment. But, irradiation (iron and proton) was found to increase intergranular cracking severity of material on subjection to SSRT in simulated PWR primary water environment at 340 °C. Correlation between the cracking susceptibility and degree of localization was studied. Impact of iron irradiation on bulk oxidation of SA 304L was studied as well by conducting an oxidation test for 360 h in simulated PWR environment at 340 °C. The findings of this study indicate that the intergranular cracking of 304L stainless steel in PWR environment can be studied using Fe irradiation despite its small penetration depth in material. Furthermore, it has been shown that the cracking was similar in both iron and proton irradiated samples despite different degrees of localization. Lastly, on establishing iron irradiation as a successful tool, it was used to study the impact of surface finish and strain paths on intergranular cracking susceptibility of the material
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Wang, Danqi. "EFFECT OF LOW TEMPERATURE CARBURIZATION ON THE MECHANICAL BEHAVIOR OF GASEOUS HYDROGEN-CHARGED 316L STAINLESS STEEL." Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1297369701.
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Wu, Xiaozhu. "Mechanistic studies of stress corrosion cracking in austenitic stainless steels and in 70Cu-30Zn." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0022/NQ37386.pdf.
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Martin, Diaz Ulises. "STRESS CORROSION CRACKING OF AUSTENITIC STAINLESS STEEL REBAR IN SIMULATED CONCRETE PORE SOLUTION INFLUENCED BY STRAIN-INDUCED MARTENSITIC TRANSFORMATION." University of Akron / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron1626520184452948.
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Krawczyk, Benjamin. "Elucidating the corrosion performance of type 316L stainless steel product storage cans." Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/elucidating-the-corrosion-performance-of-type-316l-stainless-steel-product-storage-cans(faa47d8a-65c4-443d-a00a-2ecf64898efd).html.
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Re-processed oxide fuel product from the Thermal Oxide Reprocessing Plant (THORP) is stored in Type 316L stainless steel, using a design of several nested cans, with the outer can providing the safety case containment barrier. The research reported in this PhD thesis aims to support the safety case related to these storage cans, by identifying and characterising susceptible microstructure sites and associated material surface conditions. The overarching goal of this project is to understand the propensity of THORP storage cans towards localised corrosion and Environment Assisted Cracking (EAC) in HCl and chloride-bearing atmospheric environments. The investigation focused on two possible corrosion cases: (1) understanding the effect of surface finishing on material performance in chloride-containing atmospheric environments, and (2) characterising the effects of the HCl aqueous solutions inside the can, with potential formation of HCl vapour. Microstructure investigations were carried out on surface-treated type 316L coupon specimens. The application of aqua blasting resulted in a deformed near-surface microstructure, containing compressive residual stresses to a depth of 100-120 micrometres. Subsequent laser engraving produced a recrystallized surface layer with tensile residual stresses reaching to a depth of 200 micrometres. Changes of surface roughness topography were accompanied by the development of a thick oxide/hydroxide film after laser engraving. Atmospheric exposure revealed similar corrosion attack for all samples, with laser engraving exhibiting the lowest number of corrosion sites, but with the largest average depth of attack. In addition, laser engraving led to atmospheric-induced stress corrosion cracking (AISCC) within two weeks of exposure to 386 ug/cm2 MgCl2-laden droplet deposits, with crack growth rates similar to ground U-bend samples. Strategies to reduce the likelihood of AISCC of laser-engraved components are discussed. The influence of HCl concentration and exposure temperature on the corrosion type and rate of annealed and cold rolled type 316L stainless steel has also been investigated. Cold rolling of up to 20 % reduction was introduced, with potentio-dynamic polarization measurements conducted in 0.01 - 3 M HCl aqueous solution. Results are compared to microstructures immersed under open circuit conditions, and to HCl-laden droplet deposits at temperatures up to 80C. Corrosion type diagrams are introduced to describe the transition between uniform corrosion, mixed-mode uniform with pitting corrosion, and pitting corrosion only, as a function of temperature, HCl concentration, and cold deformation. SCC tests of type 316L stainless steel have been carried out at 110C, by exposing U-Bend samples to HCl-laden droplets and HCl vapour. The humidity of the environment was controlled using defined volume fractions of H2O in a sealed environmental chamber. HCl-laden droplets with chloride deposition densities exceeding 1.5 ug/cm2 led to SCC after 90 minutes of exposure, whereas no corrosion attack was observed for samples with exposure to 0.15 ug/cm2 HCl. Increasing HCl concentrations resulted in fewer, but longer cracks, reaching up-to several hundreds of micrometres in length. HCl vapour exposure was carried out by adding various volumes of HCl solution in a beaker to the sealed test chambers. These HCl vapour tests confirmed a change of corrosion type with HCl concentration, from pitting corrosion with SCC, to the occurrence of uniform corrosion.
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Janin, Yin Jin. "Characterisation of residual stress and investigation of environmental effects on atmospheric-induced stress corrosion cracking of austenitic stainless steel nuclear waste containers." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/characterisation-of-residual-stress-and-investigation-of-environmental-effects-on-atmosphericinduced-stress-corrosion-cracking-of-austenitic-stainless-steel-nuclear-waste-containers(9b06d8fe-9395-4194-b276-73d698585e21).html.
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This research has investigated the conditions necessary for atmospheric-induced stress corrosion cracking to occur in material taken from an intermediate level nuclear waste storage container by means of experiments in a humidity chamber. It has also characterised the residual stresses associated with the container welds by modelling and measurement. Based on the work conducted in this research, the major findings can be summarised as follows:• Deliquescence of salt particles is dependent on relative humidity but independent of the quantity of salt present.• The time to initiate cracking may be sensitive to temperature, getting longer as the temperature decreases, but the timeframe of work as not long enough to establish this conclusively.• AISCC can occur at a stress (residual or applied) of 400MPa (0.2% strain) or more if the other necessary conditions are present. While AISCC was not observed when no stress was present, the threshold of stress below which AISCC will definitely not occur has not been determined in this work.
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Breimesser, Mathias Stefan [Verfasser], and Sannakaisa [Akademischer Betreuer] Virtanen. "Microelectrochemical approach towards the analysis of electrochemical noise signals related to intergranular stress corrosion cracking of austenitic stainless steel / Mathias Stefan Breimesser. Betreuer: Sannakaisa Virtanen." Erlangen : Universitätsbibliothek der Universität Erlangen-Nürnberg, 2012. http://d-nb.info/1028958692/34.
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Sterling, Colin J. "Effects of Friction Stir Processing on the Microstructure and Mechanical Properties of Fusion Welded 304L Stainless Steel." Diss., CLICK HERE for online access, 2004. http://contentdm.lib.byu.edu/ETD/image/etd440.pdf.
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Mukahiwa, Kudzanai. "Microstructural characterisation of type 316 austenitic stainless steels : implications for corrosion fatigue behaviour in PWR primary coolant." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/microstructural-characterisation-of-type-316-austenitic-stainless-steels-implications-for-corrosion-fatigue-behaviour-in-pwr-primary-coolant(e8e04bc1-1413-4c59-bb04-7dd94bcbc78f).html.
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The environmentally-assisted fatigue crack growth behaviour of austenitic stainless steels in deoxygenated high temperature water at low strain rates has been reported to be greatly affected by the sulphur (S) content of the specimen, with high S specimens exhibiting significant reduced crack growth rates (retardation) when compared to low S specimens. To further the understanding of the mechanistic behaviour, fatigue crack growth experiments have been performed on high and low sulphur Type 316 austenitic stainless steel specimens tested in high temperature water and evaluated via microstructural characterisation techniques. At high strain rates the enhanced crack growth for both specimens appeared to be crystallographic and associated with slip localization. Furthermore, matching fracture surface analysis indicated discrepancy of the slip steps and micro-cleavage cracks between the matching surfaces, suggesting that slip steps and micro-cleavage cracking occurred after the crack-tip had advanced. It was also postulated that their formation may involve cathodically-produced hydrogen and shear deformation on the fracture surface. However, when the loading frequency was decreased, the high S specimens retarded the crack growth and the path was no longer crystallographic. Significant differences in the crack-tip opening displacements were observed in both materials, with blunt crack-tips in the high sulphur specimen and sharp tips in the low sulphur specimen when the strain rate was low. EBSD analysis at the crack-tips of both specimens showed that the strain was more localised at the crack-tip of the low sulphur specimen whist the strain ahead of the high sulphur specimen was more homogenous. It is thus postulated that retardation occurs when slip localisation is no longer the dominant factor. The localised deformation during enhancement is believed to have been caused by hydrogen enhanced localised plasticity (HELP) which causes the crack-tip to sharpen. The diffused strain distribution during crack growth retardation is believed to have been caused by hydrogen enhanced creep (HEC) which causes the crack-tip to blunt. It is also believed that both enhancement and retardation mechanisms are associated with contrasting effects deriving from hydrogen enhanced plasticity. Oxide induced crack closure was excluded as a mechanism responsible for retardation of fatigue crack growth when the stress ratio is high. Effects of hydrogen induced alpha' and ε martensite phases on oxidation behaviour of austenitic stainless steels in deoxygenated high temperature water have also been studied. Microstructural characterisation shows that hydrogen induced alpha' martensite enhances oxidation of austenitic stainless steels in deoxygenated high temperature water. The implications of this finding on environmentally assisted cracking of austenitic stainless steels in deoxygenated high temperature water is discussed.
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Clark, Tad Dee. "An Analysis of Microstructure and Corrosion Resistance in Underwater Friction Stir Welded 304L Stainless Steel." Diss., BYU ScholarsArchive, 2005. http://contentdm.lib.byu.edu/ETD/image/etd872.pdf.
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Ornek, Cem. "Performance characterisation of duplex stainless steel in nuclear waste storage environment." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/performance-characterisation-of-duplex-stainless-steel-in-nuclear-waste-storage-environment(4db73e9b-c87c-40a6-9778-0b823b1c499f).html.
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The majority of UK’s intermediate level radioactive waste is currently stored in 316L and 304L austenitic stainless steel containers in interim storage facilities for permanent disposal until a geological disposal facility has become available. The structural integrity of stainless steel canisters is required to persevere against environmental degradation for up to 500 years to assure a safe storage and disposal scheme. Hitherto existing severe localised corrosion observances on real waste storage containers after 10 years of exposure to an ambient atmosphere in an in-land warehouse in Culham at Oxfordshire, however, questioned the likelihood occurrence of stress corrosion cracking that may harm the canister’s functionality during long-term storage. The more corrosion resistant duplex stainless steel grade 2205, therefore, has been started to be manufactured as a replacement for the austenitic grades. Over decades, the threshold stress corrosion cracking temperature of austenitic stainless steels has been believed to be 50-60°C, but lab- and field-based research has shown that 304L and 316L may suffer from atmospheric stress corrosion cracking at ambient temperatures. Such an issue has not been reported to occur for the 2205 duplex steel, and its atmospheric stress corrosion cracking behaviour at low temperatures (40-50°C) has been sparsely studied which requires detailed investigations in this respect. Low temperature atmospheric stress corrosion cracking investigations on 2205 duplex stainless steel formed the framework of this PhD thesis with respect to the waste storage context. Long-term surface magnesium chloride deposition exposures at 50°C and 30% relative humidity for up to 15 months exhibited the occurrence of stress corrosion cracks, showing stress corrosion susceptibility of 2205 duplex stainless steel at 50°C.The amount of cold work increased the cracking susceptibility, with bending deformation being the most critical type of deformation mode among tensile and rolling type of cold work. The orientation of the microstructure deformation direction, i.e. whether the deformation occurred in transverse or rolling direction, played vital role in corrosion and cracking behaviour, as such that bending in transverse direction showed almost 3-times larger corrosion and stress corrosion cracking propensity. Welding simulation treatments by ageing processes at 750°C and 475°C exhibited substantial influences on the corrosion properties. It was shown that sensitisation ageing at 750°C can render the material enhanced susceptible to stress corrosion cracking at even low chloride deposition densities of ≤145 µm/cm². However, it could be shown that short-term heat treatments at 475°C can decrease corrosion and stress corrosion cracking susceptibility which may be used to improve the materials performance. Mechanistic understanding of stress corrosion cracking phenomena in light of a comprehensive microstructure characterisation was the main focus of this thesis.
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Le, Millier Morgane. "Fragilisation des aciers inoxydables austénitiques sous irradiation : évolution de la microstructure et amorçage de la corrosion sous contrainte assistée par l'irradiation en milieu REP." Thesis, Paris, ENMP, 2014. http://www.theses.fr/2014ENMP0047/document.
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Cette étude porte sur l'évolution de la microstructure des aciers inoxydables austénitiques sous irradiation et les conséquences de cette évolution sur leur comportement en milieu REP. Un acier 304L a été irradié aux protons à 360°C à 5 et 10 dpa. Suite à ces irradiations, la sensibilité du matériau à l'IASCC a été étudiée en milieu primaire simulé à 350°C, avec suivi par microextensométrie des champs locaux de déformation. Parallèlement à ce travail, des lames minces ont été irradiées in situ aux ions Ni++ à 500°C jusqu'à 2 dpa avec implantation simultanée d'hélium. Ces expérimentations nous ont permis (i) grâce au couplage microstructure /champs mécaniques /fissuration de mieux comprendre les paramètres responsables de l'amorçage de l'IASCC en milieu réducteur (ii) de définir le rôle joué par l'hélium sur l'évolution des défauts d'irradiation. Il s'avère que, dans les conditions d'étude, l'implantation d'hélium n'a qu'un effet limité sur les populations de boucles de dislocation et de cavités pour des rapports inférieurs à 800 appm He/dpa. Des cavités ont été observées avec et sans implantation d'hélium, y compris dans les joints de grains ce qui pourrait être un facteur de fragilisation. L'ensemble des essais de corrosion sous contrainte ont validé que la densité de fissures augmente avec l'augmentation du taux de déformation et qu'un chargement séquentiel conduit à une plus grande ouverture et propagation en surface des fissures. Ces fissures se propagent en profondeur dans la couche irradiée notamment du fait de la surcontrainte générée par le fort gradient de propriétés entre la zone irradiée et non irradiée du matériau. Les mécanismes de déformation activés sont complexes et du maclage a été observé après 2 et 10% de déformation macroscopique. La déformation après irradiation est fortement localisée sous forme de bandes intragranulaires et autour de certains joints de grains, mais la déformation de ces joints ne semble pas constituer un critère d'amorçage. L'absence de transmission de la déformation de part et d'autre des joints fissurés est par contre systématiquement observée et la connaissance de l'état de contrainte local s'avère indispensable pour décrire l'amorçage de l'IASCC en milieu réducteur. Une méthodologie basée sur l'exploitation des résultats expérimentaux (champs d'orientation cristallographique, champs cinématique) appliquée à une simulation aux éléments finis permet d'estimer l'état local de contrainte, seul à même de discriminer un critère d'ouverture de fissureThis work deals with the microstructure evolution of austenitic stainless steels under irradiation and the consequences of this evolution on their behavior in PWR environment. 304L steel was proton-irradiated at 360°C to 5 and 10 dpa. Following these irradiations, IASCC was studied in a 350°C simulated primary water, with strain fields measurements using digital image correlation. In parallel, thin foils were irradiated in situ with Ni++ ions at 500°C up to 2 dpa with simultaneous helium implantation. These experiments allowed us (i) to have a better understanding of the key parameters responsible of the IASCC initiation in reducing environment thanks to the coupling between microstructure, mechanical fields and cracking (ii) to define the role of helium on the nucleation and evolution of radiation defects. It turns out that, in the studied conditions, the implantation of helium has only a limited effect on the dislocation loop and cavity populations for ratios lower than 800 appm He/dpa. Cavities were observed with and without helium, including in the grain boundaries which could be a factor of embrittlement. The stress corrosion cracking tests resulted in an increase of the crack density with the increase of the macroscopic deformation and in a bigger opening and on-surface propagation of cracks after a sequential loading. These cracks propagate deeply in the irradiated layer partly because of the overstress generated by the strong gradient of mechanical properties between the irradiated and non-irradiated zones of the material. The activated deformation mechanisms are complex and twinning was observed after 2 and 10% of macroscopic deformation. The deformation after irradiation is strongly localized in transgranular bands and around some grain boundaries, but it appears that the strong deformation around boundaries is not an initiation criterion. Deformation discontinuity on both sides of cracked boundaries is systematically observed and evaluation of the local stress state appears to be essential to describe IASCC initiation. This local stress state could be calculated by finite elements, taking into account the experimental results in terms of crystallographic orientation fields or Kinematics fields strong heterogeneity of local deformation quantified in this work
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Mariano, Neide Aparecida. "Corrosão sob tensão de um aço inoxidável austenítico em soluções aquosas contendo cloretos." Universidade de São Paulo, 1997. http://www.teses.usp.br/teses/disponiveis/18/18136/tde-03102017-142025/.
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No presente trabalho foi estudado o comportamento de um aço inoxidável austenítico do sistema Fe-Cr-Mn-N, nas condições como recebido, solubilizado e sensitizado, quando submetidos à meios contendo cloretos. Para analisar a suscetibilidade à corrosão sob tensão foram utilizados corpos de prova dos tipos DCB (\"Double Cantilever Beam\") e C(T) (\"Compact- Tension\"), pré-trincados em fadiga, com entalhes laterais e carregados com cunhas. Os meios empregados foram as soluções aquosas 45% em peso de MgCl2 na temperatura de ebulição de 154°C, água do mar sintética na temperatura ambiente e de ebulição de 100°C e 3,5% em peso de NaCI na temperatura ambiente. A suscetibilidade à corrosão sob tensão foi avaliada em termos do fator limite de intensidade de tensão, KISCC, e foram caracterizados os aspectos fractográficos dos corpos de prova em que ocorreram propagação de trinca por corrosão sob tensão. Foi verificado que apenas os corpos de prova do aço E3949 nas condições como recebido e sensitizado, foram suscetíveis à corrosão sob tensão em solução aquosa de 45% em peso de MgCl2 na temperatura de ebulição. Também foi determinado o comportamento eletroquímico do material nas condições citadas acima com relação aos meios empregados. Os resultados das curvas de polarização obtidas mostraram que o material apresenta baixa resistência à corrosão, principalmente em meios de MgCl2.The present work studies the stress corrosion cracking behavior in austenitic Fe-Cr-Mn-N stainless steel, in as received, solubilized and sensitized conditions, when submited to several chlorides environments. To evalued the stress corrosion cracking susceptibility, DCB (\"Double Cantilcver Beam\") and C(T) (\"Compact- Tension\") specimens, fatigue precracked, side grooved and wedge loaded were used. The environments employed were boiling solution of 45 wt% of MgCl2 at 154ºC, synthetic sea water at room and 100°C temperatures, and a solution with 3,5 wt% of NaCI at room temperature. The susceptibility to stress corrosion cracking has been evaluated in terms of the threshold stress intensity factor, KISCC, and the fracture surface appearance of those specimens whose the crack propagation took place was characterized. The results showed that only the specimens in the as received and sensitized conditions, were suceptible to the stress corrosion cracking effect in the solution with 45 wt% of MgCl2 at the boilling temperature. Also, it has been verified the electrochemical behavior of this steel when submited in the above environments. The results of polarization curves showed that the material presents low corrosion strength, mainly in MgCl2 environments.
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Kaněra, Miloš. "Výroba odlitků z austeniticko-feritických hyperduplexních korozivzdorných ocelích." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-445174.
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The thesis deals with hyper duplex stainless austenitic-ferritic steels and their mechanical and castability properties. The evaluation of resistance to pitting corrosion is divided by PRE values. Steels with a PRE value higher than 48 belong to the group of hyper duplex steels. The theoretical part contains an introduction to the chemical composition, structure and properties of these steels. The practical part is focused on the conditions of tendency to crack castings during solidification and cooling. Furthermore, there is evaluated influence of intermetallic phases on mechanical properties.
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Campos, ClÃudio Valadares Farias. "Suscetibilidade à CorrosÃo Sob TensÃo Dos AÃos AISI 321 E 347 Em Meio De H2so4 + Cuso4." Universidade Federal do CearÃ, 2003. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=7323.
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Os aÃos inoxidÃveis austenÃticos tÃm sido bastante utilizados em equipamentos de utilidades de dessulfurizaÃÃo de petrÃleo devido à sua boa resistÃncia à corrosÃo em temperatura elevada.Contudo, esses materiais estÃo sujeitos a sensitizaÃÃo (deficiÃncia em cromo na regiÃo vizinha ao contorno de grÃo) quando expostos a temperaturas de 425 a 815ÂC, durante a operaÃÃo ou processos de fabricaÃÃo. A sensitizaÃÃo torna o equipamento suscetÃvel à corrosÃo sob tensÃo causada por aÃos politiÃnicos, formados pela interaÃÃo de compostos sulforoso, umidade e ar em temperatura ambiente. A resistÃncia à corrosÃo sob tensÃo de amostras de aÃo inoxidÃvel austenÃtico AISI 321 e 347, removidas de um tubo, foi investigada atravÃs do procedimento ASTM 262 Pr. E â ensaio alternativo e de execuÃÃo mais fÃcil do que a simulaÃÃo dos aÃos politiÃnicos. Os corpos de prova foram submetidos aos tratamentos tÃrmicos de estabilizaÃÃo (900ÂC, durante 75 minutos) e de sensitizaÃÃo (600ÂC, durante 20, 40, 80, 120 e 140 horas), apÃs o que foram expostos ao meio corrosivo de CuSO4 + H2SO4 durante 72 horas e depois dobradas, nÃo apresentando trincamento. A agressividade do meio utilizado no ensaio foi verificada atravÃs da utilizaÃÃo de amostras de aÃo AISI 304L sensitizadas (600ÂC, 24, 28 e 72 horas e 677ÂC durante 4, 45 e 72 horas). Neste caso, somente as amostras com acabamento superficial feito com lixa n 100 sofreram um intensivo processo corrosivo.Os aÃos inoxidÃveis austenÃticos tÃm sido bastante utilizados em equipamentos de utilidades de dessulfurizaÃÃo de petrÃleo devido à sua boa resistÃncia à corrosÃo em temperatura elevada.Contudo, esses materiais estÃo sujeitos a sensitizaÃÃo (deficiÃncia em cromo na regiÃo vizinha ao contorno de grÃo) quando expostos a temperaturas de 425 a 815ÂC, durante a operaÃÃo ou processos de fabricaÃÃo. A sensitizaÃÃo torna o equipamento suscetÃvel à corrosÃo sob tensÃo causada por aÃos politiÃnicos, formados pela interaÃÃo de compostos sulforoso, umidade e ar em temperatura ambiente. A resistÃncia à corrosÃo sob tensÃo de amostras de aÃo inoxidÃvel austenÃtico AISI 321 e 347, removidas de um tubo, foi investigada atravÃs do procedimento ASTM 262 Pr. E â ensaio alternativo e de execuÃÃo mais fÃcil do que a simulaÃÃo dos aÃos politiÃnicos. Os corpos de prova foram submetidos aos tratamentos tÃrmicos de estabilizaÃÃo (900ÂC, durante 75 minutos) e de sensitizaÃÃo (600ÂC, durante 20, 40, 80, 120 e 140 horas), apÃs o que foram expostos ao meio corrosivo de CuSO4 + H2SO4 durante 72 horas e depois dobradas, nÃo apresentando trincamento. A agressividade do meio utilizado no ensaio foi verificada atravÃs da utilizaÃÃo de amostras de aÃo AISI 304L sensitizadas (600ÂC, 24, 28 e 72 horas e 677ÂC durante 4, 45 e 72 horas). Neste caso, somente as amostras com acabamento superficial feito com lixa n 100 sofreram um intensivo processo corrosivo.
Because of their resistance to high temperature corrosion by hydrogen sulfide, austenitic stanless steels are commonly used for equipment in desulfurization process. However, these materials are subject to sensitization (chromium carbide precipitation) from exposure in the temperature range 425 to 815ÂC during fabrication or operation. Sensitization makes the equipment susceptible to failure from intergranular stress corrosion cracking caused by polythionic acid. Polythionic acid is formed by sulfur compounds, moisture, and air at ambient temperature. The main goal of the present work is to investigate the stress corrosion cracking susceptibility of stainless steels AISI 321 and 347 in polythionic acids using an alternative process that is to submit the samples to cooper-cooper sulfate-16% sulfuric acid test (ASTM A262 Pr.E). After the stabilization heat treatment at 900ÂC for 75 minutes, samples were heat treated at 600ÂC during 20, 40, 80, 120 and 140 hours and then exposed to boiling acidified copper sulfate solution for 72 hours. After exposure, the specimens were bent. The appearance of fissures or cracks was not observed in AISI 321 and 347 samples. The effectiveness of the solution has been made by submitting AISI 304L samples to the same environment . The AISI 304L samples with higher finishing have been cracked. The ones with fine-ground finishing have not been attacked.
Because of their resistance to high temperature corrosion by hydrogen sulfide, austenitic stanless steels are commonly used for equipment in desulfurization process. However, these materials are subject to sensitization (chromium carbide precipitation) from exposure in the temperature range 425 to 815ÂC during fabrication or operation. Sensitization makes the equipment susceptible to failure from intergranular stress corrosion cracking caused by polythionic acid. Polythionic acid is formed by sulfur compounds, moisture, and air at ambient temperature. The main goal of the present work is to investigate the stress corrosion cracking susceptibility of stainless steels AISI 321 and 347 in polythionic acids using an alternative process that is to submit the samples to cooper-cooper sulfate-16% sulfuric acid test (ASTM A262 Pr.E). After the stabilization heat treatment at 900ÂC for 75 minutes, samples were heat treated at 600ÂC during 20, 40, 80, 120 and 140 hours and then exposed to boiling acidified copper sulfate solution for 72 hours. After exposure, the specimens were bent. The appearance of fissures or cracks was not observed in AISI 321 and 347 samples. The effectiveness of the solution has been made by submitting AISI 304L samples to the same environment . The AISI 304L samples with higher finishing have been cracked. The ones with fine-ground finishing have not been attacked.
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Gao, Yuan. "Un essai robuste et fiable pour la recette de produits d’apport en soudage d’aciers inoxydables." Thesis, Lorient, 2017. http://www.theses.fr/2017LORIS461/document.
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Le matériau principal de cette étude est l’acier inoxydable austénitique 316L(N) (X2CrNiMo17-12-2 à teneur en azote contrôlée) envisagé dans la conception de la cuve et des structures du circuit primaire des futurs réacteurs de quatrième génération refroidis au sodium. Pour assembler des composants de forte épaisseur, il faut réaliser des soudages multipasses avec métal d'apport. Lors du soudage, il a parfois été constaté des défauts de fissuration à chaud de solidification au refroidissement dans la zone pâteuse, près du bain de fusion. Ces fissures sont des décohésions du matériau apparaissant à haut température le long des joints de grains lorsque la déformation dépasse un seuil critique. Il est donc nécessaire de prévenir ce risque en utilisant un critère de fissuration à chaud. L'approche utilisée dans cette étude est double : développer un essai de fissuration à chaud à chargement extérieur, puis simuler numériquement ces expériences pour déterminer un seuil critique en déformation en utilisant un critère proposé par Kerrouault. Une version améliorée d’un essai de fissuration à chaud (Controlled Restraint Weldability (CRW) test) a été proposé dans cette étude afin d'analyser la susceptibilité à la fissuration de solidification du matériau 316L(N) et d’un métal d'apport de nuance Thermanit 19-15H. L'objectif de ce test est, en fonction de l'intensité du chargement extérieur, d'amorcer une fissure dans un régime thermique établi, puis d’arrêter la propagation de cette fissure si les conditions thermomécaniques locales sont remplies. Le modèle de comportement du matériau choisi est une loi élasto-visco-plastique à écrouissage mixte. Des essais thermomécaniques sur un simulateur Gleeble ont été réalisés à haute température afin d'identifier et d’améliorer la loi de comportement du matériau 316L(N). Le grossissement des grains dans la zone affectée thermiquement a été modélisé et intégré dans ce modèle. Les intervalles de fusion et de solidification du matériau 316L(N) ont été déterminés par des essais ATD (Analyse Thermique Différentielle). Des analyses des microstructures de solidification ont été également menées afin de mieux comprendre le phénomène de fissuration à chaud. Certains essais CRW ont ensuite été modélisés et simulés par éléments finis en utilisant les logiciels Cast3M et Abaqus afin valider le critère de fissuration à chaud et de déterminer un seuil critique de fissuration pour l'acier 316L(N)The austenitic stainless steel AISI 316L(N) (X2CrNiMo17-12-2) with controlled nitrogen content is widely used for manufacture of vessel and primary circuit structures of the 4th Generation sodium- cooled fast reactors. Multi-pass welds with an appropriate filler metal is used to assemble thick components. Solidification cracks may occur in the mushy zone near the melting weld poor during solidification when a liquid film is distributed along grains boundaries and interdendritic regions and the shrinkage strains across the boundaries cannot be accommodated. It is therefore necessary to prevent this defect using a hot cracking criterion. The approach used in this study is to initiate experimentally a hot crack by a weldability test, and then to simulate these tests to identify a critical strain using a hot crack criterion for the prediction of solidification cracking. Therefore, a hot cracking test (Controlled Restraint Weldability (CRW) test) is proposed in the present study to analyze the susceptibility to hot cracking for base metal 316L(N) and its filler metal 19-15H Thermanit grade. This test is designed to initiate a hot crack in thermal steady state, and then to stop the crack once the local thermomechanical conditions are met. The initiation and stop of the crack depend on external mechanical preload. The material constitutive equations chosen for the material is a visco-plastic model with isotropic and kinematic hardening. The Gleeble thermomechanical tests have been performed at high temperature in order to identify material parameters. The increase of the grain size in the thermally affected zone was modeled and integrated into constitutive equations. The temperature range of melting and solidification of 316L(N) were determine by using the Differential Thermal Analysis (DTA). The analysis of the solidification microstructures were also carried out in order to better understand the phenomenon of hot cracking. Some CRW tests were then simulated by finite element method using the Cast3M and Abaqus software in order to valid the hot cracking criterion and to determine a thermomechanical criterion of hot cracking for 316L(N)
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Craig, C. H. "Enhanced radiopacity austenitic stainless steel foil." Thesis, Cranfield University, 2007. http://hdl.handle.net/1826/2059.
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Austenitic stainless steel designed for implant applications is used to fabricate balloon expandable coronary stents. The alloy was not designed for this purpose but has been found to work well except for relatively low radiopacity in the energy range used for stent deployment, typically 80kV to 100kV. Stents made of more dense elements such as tantalum exhibit high radiopacity in this energy range. Low radiopacity is due to a combination of tubular stents having a thin wall (strut) thickness (less than 0.13mm) and the alloy being comprised of low-density elements, approximately 2/3 iron and 1/3 chromium and nickel. To retain the desired thickness and increase radiopacity, alloy density may be increased by partial substitution with dense element(s). The new alloy must maintain the biocompatibility, corrosion resistance, non-ferromagnetic structure, strength, ductility, and fatigue- and fracture-resistant characteristics that made the original alloy attractive to stent designers. Coronary stents are subject to intensive review by regulatory authorities prior to being approved for human use, thus stent designers are hesitant to depart from accepted standards in selecting new alloys. Revising an existing alloy is the preferred approach to achieve subtle feature changes. A set of criteria was set that maintained chromium, nickel, and molybdenum within prescribed compositional ranges and diminished iron to its minimum level, allowing platinum to be substituted for approximately 1/3 the total elemental weight (wt%). Above 20wt% platinum, undesirable precipitates were found. An alloy containing 20wt% platinum, in the form of foil and at a thickness of 0.127mm, was found to be free of precipitates not found in the base or original alloy and to provide approximately 20% radiopacity increase at 80kV and 15% radiopacity increase at 100kV, exceeding minimum programme goals at 80kV and equaling those at 100kV.Boston Scientific Corporation/SCIMED (Sponsor) has granted Cranfield University permission to publish this Thesis.
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Buckley, J. R. "Hydrogen embrittlement of austenitic stainless steel." Thesis, University of Newcastle Upon Tyne, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315550.
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Butler, J. J. F. "Hydrogen embrittlement of austenitic stainless steel." Thesis, University of Newcastle Upon Tyne, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374127.
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Craig, Charles Horace. "Enhanced radiopacity austenitic stainless steel foil." Thesis, Cranfield University, 2007. http://dspace.lib.cranfield.ac.uk/handle/1826/2059.
Full textAbstract:
Austenitic stainless steel designed for implant applications is used to fabricate balloon expandable coronary stents. The alloy was not designed for this purpose but has been found to work well except for relatively low radiopacity in the energy range used for stent deployment, typically 80kV to 100kV. Stents made of more dense elements such as tantalum exhibit high radiopacity in this energy range. Low radiopacity is due to a combination of tubular stents having a thin wall (strut) thickness (less than 0.13mm) and the alloy being comprised of low-density elements, approximately 2/3 iron and 1/3 chromium and nickel. To retain the desired thickness and increase radiopacity, alloy density may be increased by partial substitution with dense element(s). The new alloy must maintain the biocompatibility, corrosion resistance, non-ferromagnetic structure, strength, ductility, and fatigue- and fracture-resistant characteristics that made the original alloy attractive to stent designers. Coronary stents are subject to intensive review by regulatory authorities prior to being approved for human use, thus stent designers are hesitant to depart from accepted standards in selecting new alloys. Revising an existing alloy is the preferred approach to achieve subtle feature changes. A set of criteria was set that maintained chromium, nickel, and molybdenum within prescribed compositional ranges and diminished iron to its minimum level, allowing platinum to be substituted for approximately 1/3 the total elemental weight (wt%). Above 20wt% platinum, undesirable precipitates were found. An alloy containing 20wt% platinum, in the form of foil and at a thickness of 0.127mm, was found to be free of precipitates not found in the base or original alloy and to provide approximately 20% radiopacity increase at 80kV and 15% radiopacity increase at 100kV, exceeding minimum programme goals at 80kV and equaling those at 100kV.
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Perdahcioglu, Emin Semih. "Constitutive modeling of metastable austenitic stainless steel." Enschede : University of Twente [Host], 2008. http://doc.utwente.nl/60279.
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Mörtberg, Johanna. "Mixed Acid Pickling of Austenitic Stainless Steel - High acid concentration in standard stainless steel processing : Effect of temperature on pickling efficiency of austenitic stainless steel." Thesis, Luleå tekniska universitet, Industriell miljö- och processteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-70050.
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Kornegay, Cynthia E. "Impact fracture of austenitic stainless steels." Thesis, Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/50038.
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Industry is constantly searching for improved
materials for use in highly demanding applications. The
materials chosen must withstand a wide range of
temperatures and extended exposure in aggressive
environments, including hydrogen gas. Because of the
risk of catostrophe if brittle failure occurs, careful
material selection is imperative. Austenitic stainless
steels may be a likely choice for hydrogen service
because their behavior in high pressure hydrogen ranges
from no apparent damage to relevent, but generally small
ductility loss (13). Because of this Variation in
behavior, a single category cannot be established to
encompass all austenitic steels and studies must be
performed on each type of steel to determine its behavior
under specific circumstances. Two steels being currently
under consideration for use in hydrogen are Armco 21-6-9
and Tenelon, both are fully austenitic stainless steels
which may be used over a wide range of temperatures,
including service at liquid nitrogen temperature.Master of Science
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Mai, Le Phuong Tam. "Attachment of Listeria monocytogenes to austenitic stainless steel." Auburn, Ala., 2006. http://repo.lib.auburn.edu/2006%20Summer/Dissertations/MAI_TAM_29.pdf.
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Bass, Matthew Ian. "Steam oxidation of shot peened austenitic stainless steel." Thesis, University of Birmingham, 2018. http://etheses.bham.ac.uk//id/eprint/8046/.
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Shot peened steel tubing made from 304HCu-grade austenitic stainless steel was exposed to temperatures of 600-750°C in three atmospheres: vacuum, deoxygenated atmospheric pressure steam and deoxygenated 70bar steam. The microstructural changes and oxide morphologies of the shot peened material were observed with SEM, TEM, microhardness testing and TKD mapping. An estimate of the lifetime of the shot peened microstructure in service conditions was made based on service temperature. MnCr2O4 spinel was observed on oxidized samples and the consequences of this are discussed.
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Naraghi, Reza. "Martensitic Transformation in Austenitic Stainless Steels." Thesis, KTH, Metallografi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-37214.
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Martensitic transformation is very important in austenitic stainless steels where the transformation induced plasticity phenomenon provides a combination of good mechanical properties, such as formability and strength. However, the difficulty of predicting the material behaviour is one of the major drawbacks of these steels. In order to model this behaviour it is of great importance to be able to characterize the morphology, crystallography and the amount of different types of martensite. The morphology and crystallography of thermal and deformation induced lath martensite in stainless steels were re-examined by means of optical microscopy and electron backscatter diffraction (EBSD) technique. The experiments were performed on AISI301, 304 and 204Cu austenitic stainless steels. Plastic deformation was carried out by means of uniaxial tensile tests at the strain rate of to produce strain induced α’-martensite at a temperature ranging from 0 to 60ºC. An in-situ measurement of the martensite content was performed during the tensile testing using a Ferritescope to provide the necessary experimental values for modelling. Optical microscopy revealed the morphology of the strain induced α’-martensite as sets of thin parallel needles that go through the parent austenite grain and stop at the grain or annealing twin boundaries. Large amount of α’-martensite could be seen at the intersection of shear bands. However, considerable amount of α’-martensite was also observed when only one set of bands is activated. EBSD was successfully used to analyze the morphology and crystallography of martensite. The α’-martensite maintained the Kurdjumov-Sachs (K-S) orientation relationship with the austenite phase. Although all six possible variants did not appear within a single packet, one or two variants were often favoured out of six related to the specific {111} plane. The misorientations between the neighbouring variants were mainly <111> 60º or <110> 49.5º.
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Hussain, Patthi Bin. "Diffusion bonding of sialon and stainless steel." Thesis, University of Strathclyde, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249842.
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Parascandola, S. "Nitrogen transport during ion nitriding of austenitic stainless steel." Forschungszentrum Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-29591.
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Chaudhary, Zia-Ul-Hasan. "Pitting corrosion of austenitic stainless steel in slag cement." Thesis, University of Oxford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.291082.
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Laiarinandrasana, Lucien. "High temperature crack initiation in an austenitic stainless steel /." Gif-sur-Yvette : Direction de l'information scientifique et technique, CEA Saclay, 1996. http://catalogue.bnf.fr/ark:/12148/cb35851322v.
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Parascandola, S. "Nitrogen transport during ion nitriding of austenitic stainless steel." Forschungszentrum Rossendorf, 2001. https://hzdr.qucosa.de/id/qucosa%3A21786.
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Reiter, Matt J. "Partial Penetration Fiber Laser Welding on Austenitic Stainless Steel." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1243339754.
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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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Carvalho, M. "Precipitation in an austenitic steel containing niobium and nitrogen." Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355004.
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