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Shahryari, Arash. "Enhancement of biocompatibility of 316LVM stainless steel by electrochemical cyclic potentiodynamic passivation." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=107543.
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Note:<br>as hip and knee prosthesis, orthopaedic fixations and coronary stents. The definition of a material's biocompatibility necessitates meeting a number of criteria, including high corrosion resistance and desirable interactions of the material's surface with biological species, such as cells, platelets, and serum proteins. SSs offer acceptable resistance to uniform (general) corrosion when used as materials of construction in sorne industrial applications, which is due to the formation of a thin passive oxide film on their surface. [...]<br>Les aciers inoxydables (AI) 316-L sont fréquemment utilisés dans le domaine biomédical. Par exemple, nous les retrouvons dans les prothèses de hanche et de genou, dans les fixatures orthopédiques et dans les prothèse vasculaires. Pour qu'un matériel soit biocompatible, il doit avoir une résistence élevée à la corrosion. De plus, la surface du matériel doit avoir des intéractions favorables avec les différentes espèces biologiques c'est-à-dire les cellules.[...]
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Lavvafi, Hossein. "EFFECTS OF LASER MACHINING ON STRUCTURE AND FATIGUE OF 316LVM BIOMEDICAL WIRES." Case Western Reserve University School of Graduate Studies / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=case1352743353.
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Desroches, Marie-Josée. "Electrochemical and PM-IRRAS studies of the interaction of plasma protein fibrinogen with a biomedical-grade 316LVM stainless steel surface." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99757.
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It is widely accepted that the initial event that significantly influences biocompatibility is the nearly instantaneous adsorption of proteins from biological fluids onto the biomaterial surface. For blood-contacting devices, the complex layer of adsorbed plasma proteins is generally unfavourable and leads to major complications, including thrombus formation, inflammatory tissue responses, and microbial infections. Furthermore, protein interaction with passive films on metallic biomaterial surfaces may contribute to enhanced in vivo corrosion. To gain a better understanding of this phenomenon, the present thesis investigated the fundamental aspects of the interaction of the serum protein fibrinogen with a medical-grade stainless steel 316LVM surface using electrochemical and IR spectroscopy techniques. Aspects of this interaction included the thermodynamics and kinetics of fibrinogen adsorption, the effect of fibrinogen adsorption on the corrosion behavior of 316LVM stainless steel, and the conformational changes of fibrinogen upon its adsorption onto the stainless steel surface.<br>It was shown that fibrinogen readily adsorbs onto the 316LVM stainless steel surface. Increases in the bulk protein concentration resulted in a corresponding increase of the surface coverage, a dependence that was described by the Langmuir isotherm. Large, negative values of the calculated Gibbs energy of adsorption indicated a highly spontaneous and strong adsorption of fibrinogen onto the 316LVM stainless steel at all investigated temperatures. Although the adsorption process was shown to be endothermic under the applied experimental conditions, the primary driving force for the adsorption process was found to be the positive entropy gain that arises from structural loss and/or rearrangement of the protein upon adsorption, as well as dehydration of the protein and stainless steel surface during the adsorption process. Kinetic measurements indicated that fibrinogen adsorption occurs rapidly.<br>It was determined that for short contact times (1 hour), the addition of fibrinogen to the electrolyte enhanced the corrosion rate of the 316LVM stainless steel at the open circuit potential. For longer contact times (24 hours), an increase in the polarization resistance values was obtained, indicating an enhanced corrosion resistance of the material. It was postulated that the protein was not capable of complexing the well-stabilized passive film, and instead remained adsorbed to form a protective barrier to diffusion of oxygen-containing species from the electrolyte to the stainless steel surface.<br>The secondary structure of the surface-adsorbed fibrinogen molecules was investigated by modeling the experimental PM-IRRAS spectra. It was shown that the protein lost a certain extent of its secondary structure upon adsorption to the steel surface. Fibrinogen molecules adsorbed from more dilute solutions were also shown to possess a lower alpha-helical content than those adsorbed from more concentrated solutions, suggesting they laid on the stainless steel surface in a more linear configuration.
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Mottu, Nathalie. "Etude d'aciers austénitiques 316LVM traités par implantation ionique de molybdène en surface : corrélation entre réactivité et propriétés physico-chimiques et structurales." Orléans, 2001. http://www.theses.fr/2001ORLE2082.
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L'implantation ionique de molybdène à une énergie de 49 keV dans l'acier inoxydable austénitique 316LVM induit des modifications physico-chimiques et structurales sur 30 nm. L'objectif de cette étude est de corréler le comportement électrochimique avec la composition et la structure en surface des échantillons traités pour des doses variant de 1 à 35 1015 ions/cmø (dose de sursaturation). L'analyse par Diffraction des Rayons X en Incidence Rasante (GIXD) a permis de visualiser les structures présentes dans le matériau sur différentes profondeurs, des analyses par spectroscopie de photoélectrons X (XPS) couplée au bombardement ionique, par spectroscopie de rétrodiffusion de Rutherford (RBS) et par simulation numérique (SRIM 2000) ont déterminé la composition chimique de la couche implantée et de la couche d'oxydation. Des études électrochimiques en milieu NaCl 0. 9% ont permis la caractérisation de la résistance à la corrosion des échantillons implantés.
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Ahmed, Khawtar. "A PM-IRRAS study of the influence of surface potential on the kinetics and thermodynamics of bovine serum albumin (BSA) adsorption on a 316LVM stainless steel surface." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40824.
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ABSTRACT This thesis discusses the influence of surface charge (i.e. surface potential) on the kinetics and thermodynamics of bovine serum albumin (BSA) adsorption on a biomedical-grade 316LVM stainless steel surface. A technique of polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) was efficiently employed for this purpose. The kinetics of BSA adsorption on the 316LVM surface was found to greatly depend on the surface potential. With an increase in surface potential towards more negative values, both the BSA initial adsorption rate and the saturated surface concentration of BSA also increase. Both effects were explained predominantly on the basis of replacement of well-ordered water molecules at the 316LVM/solution interface. Equilibrium experiments showed that the adsorption of BSA on the 316LVM surface is a highly spontaneous process, characterized by a highly negative apparent Gibbs energy of adsorption. The process was described using the Langmuir isotherm. With an increase in surface potential towards negative values, the apparent Gibbs energy of BSA adsorption also increases, as well as the saturated surface (monolayer) concentration. This effect was also explained on the basis of replacement of well-ordered water molecules at the 316LVM/solution interface. It was demonstrated that the adsorption of BSA on the 316LVM surface is a reversible process. The adsorbed BSA monolayer can be spontaneously desorbed at open circuit potential, but the kinetics of this process is slow. However, by cathodically polarizing the surface in the potential region of hydrogen evolution, the rate of the BSA desorption process can be significantly increased.<br>Résumé Ce Mémoire discute de l‟influence de la charge de surface (i.e. potentiel de la surface) sur la cinétique et la thermodynamique de l‟adsorption du sérum de l‟albumine bovin (BSA) sur la surface d‟acier inoxydable de calibre biomédical. La technique de la spectroscopie de modulation de polarisation en réflexion infrarouge (PM-IRRAS) fut efficacement utilisée pour cet objectif. Il fut observé que la cinétique d‟adsorption du BSA sur une surface de 316LVM est fortement dépendante sur le potentiel de surface. Lorsque le potentiel de surface augmente, les valeurs de plus en plus négatives, le taux d‟adsorption initiale de BSA ainsique sa concentration de surface saturée croissent également. Les deux effets sont expliqués par le remplacement des molécules d‟eau bien ordonnées à l‟interface de la solution/316L VM. Les expériences d‟équilibre ont montré que l‟adsorption du BSA sur la surface 316L VM est un processus très spontané ; caractérisé par une forte apparente énergie d‟adsorption négative de Gibbs. Le processus fut décrit par l‟isotherme de Langmuir. Avec une augmentation du potentiel de surface vers des valeurs négatives, l‟énergie Gibbs apparente de l‟adsorption de BSA augmente également, ainsi que la concentration de la surface saturée (monocouche). Cet effet est aussi expliqué par le remplacement des molécules d‟eau bien ordonnées à l‟interface de la solution/316 L VM. Il fut démontré que l‟adsorption du BSA sur la surface 316L VM est un processus réversible. La monocouche adsorbée du BSA peut être spontanément désorbé (enlevé) avec le potentiel de circuit ouvert. Par contre, la cinétique de ce circuit est lente. Cependant, avec une polarisation cathodique de surface dans la région potentielle de l‟évolution d‟hydrogène, le taux du processus de désorption de BSA peut augmenter significativement.
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Cunto, Gabriel Giannini de. "Aplicação do conceito \"vazamento antes da falha\" (LEAK BEFORE BREAK) em tubulações de aço 316LN soldado com metal de adição 316L." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-10042017-151324/.
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Este trabalho apresenta um estudo prático da aplicação do conceito Leak Before Break (LBB), usualmente aplicado em usinas nucleares, em uma tubulação fabricada a partir de aço AISI 316LN soldada com a utilização de eletrodo revestido AISI 316L. O LBB é um critério fundamentado em análises de mecânica da fratura, que considera que um vazamento proveniente de uma trinca, presente em uma tubulação, possa ser detectado por sistemas de detecção de vazamento, antes que esta trinca alcance um tamanho crítico que implique na falha da tubulação. Na tubulação estudada, foram realizados ensaios mecânicos de tração e análises de Ramberg-Osgood, bem como ensaios de tenacidade à fratura para a obtenção da curva de resistência J-R do material. Os ensaios foram realizados considerando o metal base, a solda e a zona termicamente afetada (ZTA), nas temperaturas de operação de uma planta nuclear. Para as propriedades mecânicas encontradas nos ensaios foram realizadas análises de carga limite para se determinar o tamanho da trinca que cause um vazamento detectável e, também, o seu tamanho crítico que cause a falha por colapso plástico. Para o tamanho crítico de trinca encontrado na solda, região que apresentou a menor tenacidade, foram realizadas análises de Integral J e de módulo de rasgamento T, considerando falha por rasgamento dúctil. Os resultados demonstram um comportamento bem definido entre o metal base, a ZTA e a solda, onde o metal base apresenta um comportamento altamente tenaz, a solda um comportamento pouco tenaz e a ZTA apresentou propriedades mecânicas intermediárias entre o metal base e a solda. Utilizando o software PICEP, foram determinadas as curvas de taxa de vazamento versus tamanho de trinca e também o tamanho crítico da trinca, considerando análise por carga limite. Observou-se que, após certo tamanho de trinca, a taxa de vazamento do metal base é muito maior do que para a ZTA e solda, para um mesmo comprimento de trinca. Isso ocorre porque é esperado que a trinca cresça de forma mais arredondada no metal base, devido à sua maior tenacidade. O menor tamanho crítico de trinca foi encontrado para o metal base para trincas circunferenciais. Para as análises de Integral J realizadas na solda, foi demonstrado que a falha por rasgamento dúctil não ocorrerá nas condições consideradas e essa hipótese foi sedimentada pela análise de mecânica da fratura elasto-plástica (MFEL) com o uso do diagrama J/T. Dessa forma, pode-se concluir que a tubulação estudada estaria apta a ser empregada em um circuito primário de um reator que utilizasse o critério de LBB, nas condições de carregamento e geometria consideradas. Adicionalmente, concluiu-se que nessas condições apenas o modo de falha por colapso plástico é esperado.<br>This work presents a study of application of the Leak Before Break (LBB) concept, usually applied in nuclear power plants, in a pipe made from steel AISI type 316LN welded a coated electrode AISI type 316L. LBB concept is a criterion based on fracture mechanics analysis to show that a crack leak, present in a pipe, can be detected by leak detection systems, before this crack reaches a critical size that results in pipe fail. In the studied pipe, tensile tests and Ramberg-Osgood analyses were performed, as well as fracture toughness tests for obtaining the material resistance curve J-R. The tests were performed considering the base metal, weld and heat affected zone (HAZ), at the same operating temperatures of a nuclear power plant. For the mechanical properties found in these tests, load limit analyses were performed in order to determine the size of a crack which could cause a detectable leakage and the critical crack size, considering failure by plastic collapse. For the critical crack size found in the weld, which is the region that presented the lowest toughness, Integral J and tearing modulus T analyses were performed, considering failure by tearing instability. Results show a well-defined behavior between the base metal, HAZ and weld zones, where the base metal has a high toughness behavior, the weld has a low toughness behavior and the HAZ showed intermediate mechanical properties between the base metal and the weld. Using the PICEP software, the leak rate curves versus crack size and also the critical crack size were determined by considering load limit analysis. It was observed that after a certain crack size, the leak rate in base metal is much higher than for the HAZ and the weld, considering the same crack length. This occurs because in the base metal crack, it is expected that the crack grows in a more rounded form due to its higher toughness. The lowest critical crack size was found for the base metal presenting circumferential cracks. For the Integral J analyses performed in the weld, it was demonstrated that the failure by tearing instability will not occur under the considered conditions and this hypothesis was confirmed by elastic-plastic fracture mechanic (EPFM) analysis using the J/T diagram. Thereby, it can be concluded that it would be possible to apply the investigated pipe in a primary circuit of a reactor that utilizes the criterion LBB under the considered geometry and load conditions. Additionally, it was found that under these conditions, only the failure mode by plastic collapse is expected.
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Dudognon, Julien. "Etude des modifications structurales induites par implantation ionique dans les aciers austénitiques." Phd thesis, Université d'Orléans, 2006. http://tel.archives-ouvertes.fr/tel-00136939.
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L'implantation ionique dans les aciers, bien que largement utilisée pour l'amélioration des propriétés d'usage, entraîne des modifications structurales des couches superficielles, qui restent sujettes à controverse. Dans ce cadre, différents éléments (N, Ar, Cr, Mo, Ag, Xe et Pb) ont été implantés (à des énergies allant de 28 à 280 keV) dans un acier 316LVM austénitique dans une couche d'épaisseur limitée à 80 nm avec une concentration maximale en élément implanté n'excédant pas 10 %.at. L'analyse de la couche implantée par diffraction des rayons X en incidence rasante permet de mettre en évidence des déformations des raies de l'austénite, l'apparition de ferrite et l'amorphisation de la couche.<br />La phase ferritique apparaît aux joints de grains, quelle que soit la nature de l'élément implanté, à partir d'une quantité « seuil » d'énergie totale envoyée (produit de la dose par l'énergie d'un ion). La formation de ferrite ainsi que l'amorphisation de la couche implantée ne dépendent que de la quantité totale d'énergie envoyée.<br />Afin de comprendre les déformations des raies de diffraction de l'austénite, un modèle de simulation de ces raies a été élaboré. Le modèle écrit correctement les déformations (élargissement, décalage, dédoublement) observées à partir de l'hypothèse que l'expansion de la maille austénitique est due à la présence de l'élément implanté et est proportionnelle à la concentration de l'élément au travers d'un coefficient k'. Ce coefficient ne dépend que de l'élément et varie linéairement avec son rayon.
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CUNTO, GABRIEL G. de. "Aplicação do conceito "vazamento antes da falha" (LEAK BEFORE BREAK) em tubulações de aço 316LN soldado com metal de adição 316L." reponame:Repositório Institucional do IPEN, 2017. http://repositorio.ipen.br:8080/xmlui/handle/123456789/27963.
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Submitted by Marco Antonio Oliveira da Silva (maosilva@ipen.br) on 2017-11-01T17:02:12Z
No. of bitstreams: 0<br>Made available in DSpace on 2017-11-01T17:02:12Z (GMT). No. of bitstreams: 0<br>Este trabalho apresenta um estudo prático da aplicação do conceito Leak Before Break (LBB), usualmente aplicado em usinas nucleares, em uma tubulação fabricada a partir de aço AISI 316LN soldada com a utilização de eletrodo revestido AISI 316L. O LBB é um critério fundamentado em análises de mecânica da fratura, que considera que um vazamento proveniente de uma trinca, presente em uma tubulação, possa ser detectado por sistemas de detecção de vazamento, antes que esta trinca alcance um tamanho crítico que implique na falha da tubulação. Na tubulação estudada, foram realizados ensaios mecânicos de tração e análises de Ramberg-Osgood, bem como ensaios de tenacidade à fratura para a obtenção da curva de resistência J-R do material. Os ensaios foram realizados considerando o metal base, a solda e a zona termicamente afetada (ZTA), nas temperaturas de operação de uma planta nuclear. Para as propriedades mecânicas encontradas nos ensaios foram realizadas análises de carga limite para se determinar o tamanho da trinca que cause um vazamento detectável e, também, o seu tamanho crítico que cause a falha por colapso plástico. Para o tamanho crítico de trinca encontrado na solda, região que apresentou a menor tenacidade, foram realizadas análises de Integral J e de módulo de rasgamento T, considerando falha por rasgamento dúctil. Os resultados demonstram um comportamento bem definido entre o metal base, a ZTA e a solda, onde o metal base apresenta um comportamento altamente tenaz, a solda um comportamento pouco tenaz e a ZTA apresentou propriedades mecânicas intermediárias entre o metal base e a solda. Utilizando o software PICEP, foram determinadas as curvas de taxa de vazamento versus tamanho de trinca e também o tamanho crítico da trinca, considerando análise por carga limite. Observou-se que, após certo tamanho de trinca, a taxa de vazamento do metal base é muito maior do que para a ZTA e solda, para um mesmo comprimento de trinca. Isso ocorre porque é esperado que a trinca cresça de forma mais arredondada no metal base, devido à sua maior tenacidade. O menor tamanho crítico de trinca foi encontrado para o metal base para trincas circunferenciais. Para as análises de Integral J realizadas na solda, foi demonstrado que a falha por rasgamento dúctil não ocorrerá nas condições consideradas e essa hipótese foi sedimentada pela análise de mecânica da fratura elasto-plástica (MFEL) com o uso do diagrama J/T. Dessa forma, pode-se concluir que a tubulação estudada estaria apta a ser empregada em um circuito primário de um reator que utilizasse o critério de LBB, nas condições de carregamento e geometria consideradas. Adicionalmente, concluiu-se que nessas condições apenas o modo de falha por colapso plástico é esperado.<br>Dissertação (Mestrado em Tecnologia Nuclear)<br>IPEN/D<br>Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
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Degallaix, Suzanne. "Rôle de l'azote interstitiel et combiné sur le comportement en plasticité cyclique et monotone d'aciers inoxydables austénitiques Z2 CND 17-12 (AISI 316L - 316LN)." Lille 1, 1986. http://www.theses.fr/1986LIL10016.
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En traction monotone, on note un fort durcissement de solution solide, tandis qu'en déformation cyclique, des interactions complexes interstitiels-dislocations provoquent une phase d'accommodation caractérisée par un durcissement suivi d'un fort adoucissement. Amélioration de la résistance en fatigue oligocyclique. L'azote précipitée sous forme de carbonitrures provoque un durcissement de type oravan qui modifie très peu les modes de déformation observes en fatigue plastique
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Pavlik, Anastasiia. "Étude de l'influence d'un traitement DUPLEX sur les propriétés tribologiques d'un acier AISI 316LM." Electronic Thesis or Diss., Université de Lorraine, 2020. http://www.theses.fr/2020LORR0111.
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Dans le cadre de l'amélioration des propriétés de glissement à sec des aciers, des traitements de structuration de surface et de nitruration ont été effectués sur de deux échantillons AISI 316LM Afin de créer des motifs géométriques maitrisés (plots rectangulaires). Ces motifs ont été obtenus par gravure ionique à travers des masques dans un réacteur à plasma MDECR. Le même dispositif a été utilisé pour le traitement de nitruration à basse température (400 C), en formant les couches d'austénite expansées. Des tests tribologiques ont été effectués par des essais de glissement alternatif à sec (avec une bille d'alumine, sous une charge de 5 N). On a observé tout d’abord que la durabilité des échantillons AISI 316 LM structurés mais non nitrurés avérée très faible. Le motif est complètement détruit après quelques centaines de cycles. Par contre, nous avons constaté une forte réduction de l'usure pour tous les échantillons structurés et nitrurés avec une répartition différente des débris d'usure le long des pistes pour les deux configurations de motifs. Ces débris d'usure se trouvent dans les vallées de la configuration W100-D100 (espacement entre aspérités le plus faible), alors que des quantités négligeables de débris sont observées dans les vallées de la configuration W100-D300. En outre, des accumulations de débris se produisent aux extrémités des pistes d'usure et apparaissent bien plus importante pour la configuration W100-D300. Après nitruration, on constate que le coefficient de frottement (COF) moyen dépend de la configuration des modèles. Le traitement Duplex augmente le COF moyen pour les échantillons W100-D300 et le réduit pour les échantillons W100-D100. Ces résultats sont liés aux mécanismes d'usure qui semblent être différents pour les deux configurations de motifs : avec un mode abrasif pour le W100-D100et une combinaison de modes abrasif, adhésif, de fatigue et d’oxydation pour le W100-D300. Les pressions de contact hertziennes apparaissent très élevées pour les deux configurations de motifs (de 2,1 à 2,2 GPa pour la configuration W100-D300,). En outre, un modèle analytique énergétique montre également que l'énergie mécanique produite lors de l'interaction de la bille contre les bords d'aspérité est plus élevée sur le W100-D300 que sur la configuration W100-D100. Cette étude démontre que la durabilité des surfaces à motifs peut être largement améliorée par un traitement de nitruration. Nos résultats ouvrent également de nouvelles perspectives quant à l’adaptation des propriétés de frottement par une géométrie de motifs appropriée<br>Within the frame of improving the dry sliding properties of steels, nitriding treatments were conducted on linear strip-like patterns etched in AISI 316LM samples in two configurations: W100-D100 and W100- D300, W being the width of asperity and D the distance between them, in micrometers. Such patterns were obtained by ion etching in a MDECR plasma reactor through masks. The same device was used for the low-temperature nitriding treatment (400 C), which results in expanded austenite layers. Tribological tests were performed by ball-on plane dry reciprocal sliding tests carried out with an alumina ball under a load of 5 N. First of all, the durability of non-nitrided AISI 316 LM patterned samples is shown to be very low. The texture is completely destroyed after a few hundred cycles. We found a strong reduction of wear for all the nitrided textured samples. A different repartition of the wear debris along the tracks between both patterned configurations was revealed. Wear debris are found within the valleys of W100-D100 configuration, whereas negligible quantities of debris are observed in the valleys of W100-D300 configuration. In addition, debris accumulations occur at the tips of the wear tracks. Such accumulation is higher for the W100-D300 configuration. After nitriding, the average µ is found to be dependent on the configurations of the patterns. A duplex treatment increases the average µ for the W100D300 samples and reduces it for the W100-D100 ones. These observations are linked to the wear mechanisms appearing to be different for the two patterns configurations: abrasive mode for the W100-D100, combination of abrasive, adhesive, fatigue and oxidation modes for the W100-D300. Hertz pressure based model demonstrates high contact pressures for both patterned configurations (for the W100-D300 configuration to be from 21 to 2.2 GPa). Furthermore, energetic model shows that the mechanical energy produced during the interaction of the ball against the asperity edges is higher on W100-D300 than for W100-D100 configuration. Finally, this study demonstrates that the durability of patterned surfaces can be widely improved by a nitriding treatment. Our results also open new perspectives to tailor friction properties by an appropriate patterns geometry
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Galloway, Alexander M. "The weldability of nitrogen enriched austenitic stainless steels (316LN)." Thesis, University of Strathclyde, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.423871.
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Roos, Stefan. "Process Development for Electron Beam Melting of 316LN Stainless Steel." Licentiate thesis, Mittuniversitetet, Institutionen för kvalitets- och maskinteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-37840.
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Additive manufacturing (AM) is a technology that inverts the procedure of traditional machining. Instead of starting with a billet of material and removing unwanted parts, the AM manufacturing process starts with an empty workspace and proceeds to fill this workspace with material where it is desired, often in a layer-by-layer fashion. Materials available for AM processing include polymers, concrete, metals, ceramics, paper, photopolymers, and resins. This thesis is concerned with electron beam melting (EBM), which is a powder bed fusion technology that uses an electron beam to selectively melt a feedstock of fine powder to form geometries based on a computer-aided design file input. There are significant differences between EBM and conventional machining. Apart from the process differences, the ability to manufacture extremely complex parts almost as easily as a square block of material gives engineers the freedom to disregard complexity as a cost-driving factor. The engineering benefits of AM also include manufacturing geometries which were previously almost impossible, such as curved internal channels and complex lattice structures. Lattices are lightweight structures comprising a network of thin beams built up by multiplication of a three-dimensional template cell, or unit cell. By altering the dimensions and type of the unit cell, one can tailor the properties of the lattice to give it the desired behavior. Lattices can be made stiff or elastic, brittle or ductile, and even anisotropic, with different properties in different directions. This thesis focuses on alleviating one of the problems with EBM and AM, namely the relatively few materials available for processing. The method is to take a closer look at the widely used stainless steel 316LN, and investigate the possibility of processing 316LN powder via the EBM process into both lattices and solid material. The results show that 316LN is suitable for EBM processing, and a processing window is presented. The results also show that some additional work is needed to optimize the process parameters for increased tensile strength if the EBM-processed material is to match the yield strength of additively laser-processed 316L material.<br><p>Vid tidpunkten för framläggningen av avhandlingen var följande delarbete opublicerat: delarbete 3 (inskickat).</p><p>At the time of the defence the following paper was unpublished: paper 3 (submitted).</p>
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Imgrund, Philipp. "Sinterverhalten und Grenzflächeneigenschaften von Werkstoffverbunden aus 316L-17-4PH- und 316L-Eisen, hergestellt durch Mikro-Metallpulverspritzgiessen." Aachen Shaker, 2007. http://d-nb.info/987695924/04.
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Imgrund, Philipp [Verfasser]. "Sinterverhalten und Grenzflächeneigenschaften von Werkstoffverbunden aus 316L/ 17-4PH und 316L/ Eisen, hergestellt durch Mikro-Metallpulverspritzgießen / Philipp Imgrund." Aachen : Shaker, 2008. http://d-nb.info/1164342789/34.
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Soulas, Romain. "Effet de la cristallographie sur les premiers stades de l'oxydation des aciers austénitiques 316 L." Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00875564.
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Les conduites primaires des centrales nucléaires REP (304L et 316L) sont protégées contre la corrosion par une couche d'oxyde. Ces conduites, qui forment une barrière entre le milieu primaire et l'extérieur, subissent des phénomènes liés à la corrosion sous contrainte (assisté ou non par irradiation) pouvant entrainer des dommages. L'objectif de cette étude est de comprendre les phénomènes régissant les stades initiaux de formation des couches d'oxydes sur ces alliages en tenant compte de l'orientation cristallographique des grains sous-jacents. En utilisant des techniques de caractérisation avancées comme GIXRD, spectroscopie Raman, XPS, MEB et MET (BF, HRTEM, Astar, EELS et HREELS), sur les toutes premières étapes de l'oxydation, une séquence d'oxydation a été proposée pour l'alliage 316L.
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Alali, M. "Through-thickness microstructure and mechanical properties of electron beam similar welded AISI 316L stainless steel and dissimilar welded AISI 316L/Ti6Al4V." Thesis, University of Sheffield, 2017. http://etheses.whiterose.ac.uk/18019/.
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Through thickness microstructure and mechanical properties of defect-free electron beam welded 20 mm thick AISI 316L austenitic stainless steel has been investigated as a function of beam power. The weld microstructure is characterised by a columnar and equiaxed dendritic ferrite in an austenite matrix. The dendritic structure was finer at the bottom of the weld zone. A microstructural boundary called “Parting” was seen along the weld centreline. Tensile tests, using a digital image correlation technique, demonstrated that the highest strain was concentrated in the fusion zone. The bottom section of the weld metal exhibited a yield strength of about 14 – 52 MPa higher than the top section. The ultimate tensile strength in the bottom of the weld was also about 4% higher than the top. The final fracture was detected in the parting region. It was observed from the EBSD scan that the grains in the weld zone contained a weak orientation and showed a high Schmid factor intensity with interception between some strong grains and soft grains at the weld centreline boundary. This explains the high weld ductility and the failure to happen in the parting region. Dissimilar welding of 20 mm thick AISI 316L stainless steel to TiAl6V4 using electron beam welding process was carried out. A successful joint was possible through using of copper sheet with 1.5 mm thick as a transition layer between the two metals. Preheating the weld samples was performed to lower the heat input and reduce the residual stresses. A double pass welding technique was applied to achieve full weld penetration. The weld microstructure was studied by SEM, EDS and XRD. The sensitivity of the microstructure to cracking was evaluated by a microhardness test of the weld cross-section. The weld region near the stainless steel contained Fe and Cu in solid solution. While the weld area near the titanium alloy characterised by the copper solid solution with Cu-Ti and Cu-Fe- Ti intermetallic phases. Ti-Fe intermetallic compounds was suppressed and replaced by relatively soft Cu-Ti intermetallics, which significantly improved the joint toughness. However, the formation of Ti-Cu at the Ti/Cu interface makes this region still susceptible to cracking.
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Zhong, Yuan. "Sub-grain structure in additive manufactured stainless steel 316L." Doctoral thesis, Stockholms universitet, Institutionen för material- och miljökemi (MMK), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-144519.
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The thesis focuses on exploring the sub-grain structure in stainless steel 316L prepared by additive manufacturing (AM). Two powder-bed based AM methods are involved: selective laser melting (SLM) and electron beam melting (EBM). It is already known that AM 316L has heterogeneous property and hierarchy structure: micro-sized melt pools, micro-sized grains, nano-sized sub-grain structure and nano-sized inclusions. Yet, the relation among these structures and their influence on mechanical properties have not been clearly revealed so far. Melt pool boundaries having lower amount of sub-grain segregated network structures (Cellular structure) are weaker compared to the base material. Compared with cell boundaries, grain boundaries have less influence on strength but are still important for ductility. Cell boundaries strengthen the material without losing ductility as revealed by mechanical tests. Cellular structure can be continuous across the melt pool boundaries, low angle sub-grain boundaries, but not grain boundaries. Based on the above understanding, AM process parameters were adjusted to achieve customized mechanical properties. Comprehensive characterization were carried out to investigate the density, composition, microstructure, phase, magnetic permeability, tensile property, Charpy impact property, and fatigue property of both SLM and EBM SS316L at room temperature and at elevated temperatures (250°C and 400°C). In general, SLM SS316L has better strength while EBM SS316L has better ductility due to the different process conditions. Improved cell connection between melt pools were achieved by rotating 45° scanning direction between each layer compared to rotating 90°. Superior mechanical properties (yield strength 552 MPa and elongation 83%) were achieved in SLM SS316L fabricated with 20 µm layer thickness and tested in the building direction. Y2O3 added oxide dispersed strengthening steel (ODSS) were also prepared by SLM to further improve its performance at elevated temperatures. Slightly improved strength and ductility (yield strength 574 MPa and elongation 90%) were obtained on 0.3%Y2O3-ODSS with evenly dispersed nanoparticles (20 nm). The strength drops slightly but ductility drops dramatically at elevated temperatures. Fractographic analysis results revealed that the coalescence of nano-voids is hindered at room temperature but not at elevated temperatures. The achieved promising properties in large AM specimens assure its potential application in nuclear fusion. For the first time, ITER first wall panel parts with complex inner pipe structure were successfully fabricated by both SLM and EBM which gives great confidence to application of AM in nuclear industry.<br><p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Manuscript. Paper 5: Manuscript.</p>
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Antunes, Renato Altobelli. ""Caracterização do comportamento frente à corrosão de um aço inoxidável austenítico para aplicações biomédicas com revestimentos PVD de TiN, TiCN e DLC"." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-30052007-161859/.
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Biomateriais metálicos devem apresentar uma combinação de propriedades como resistência à corrosão, biocompatibilidade e resistência mecânica. Os aços inoxidáveis austeníticos, especialmente do tipo AISI 316L, aliam estas propriedades com a possibilidade de fabricação a um baixo custo. No entanto, são susceptíveis à corrosão nos fluidos fisiológicos e seus produtos de corrosão podem causar reações alérgicas ou infecciosas nos tecidos vizinhos ao implante. No presente trabalho, a aplicação de revestimentos obtidos por processos de deposição física de vapor (PVD) sobre um aço inoxidável austenítico do tipo AISI 316L foi realizada a fim de aumentar sua resistência à corrosão e biocompatibilidade. Os filmes depositados foram de nitreto de titânio (TiN), carbonitreto de titânio (TiCN) e de carbono tipo diamante (DLC). Estes materiais têm alta dureza e resistência ao desgaste, além de biocompatibilidade intrínseca, características altamente desejáveis para aplicações biomédicas. A caracterização do comportamento eletroquímico do aço com os três tipos de revestimentos mostrou que a presença de defeitos na superfície das camadas depositadas exerce uma influência negativa sobre a resistência à corrosão do substrato. A presença dos defeitos foi evidenciada por microscopia eletrônica de varredura. Foi proposto um mecanismo, com base nos dados obtidos por espectroscopia de impedância eletroquímica, para explicar a evolução do comportamento eletroquímico do aço com os diferentes revestimentos ao longo do tempo de imersão. Foram também empregados dois tratamentos de passivação da superfície do aço em soluções de ácido sulfúrico e ácido nítrico, a fim de aumentar a resistência à corrosão do substrato. Os resultados indicaram que os tratamentos utilizados não foram eficientes para melhorar esta característica, mas podem ser modificados visando um desempenho superior. As propriedades eletrônicas dos filmes passivos formados, tanto sobre o aço sem tratamento de passivação como sobre o aço passivado, foram estudadas utilizando a abordagem de Mott-Schottky. Os filmes apresentaram um caráter duplex, mostrando comportamento de um semicondutor altamente dopado acima e abaixo do potencial de banda plana. A concentração de dopantes no filme passivo foi associada à resistência à corrosão do material. Os três revestimentos PVD investigados apresentaram comportamento não citotóxico. Considerando a diminuição do coeficiente de atrito do aço 316L, os revestimentos de TiCN e o DLC foram os mais eficientes. Estas características, aliadas ao fator custo, sugerem que a aplicação comercial destes materiais sobre implantes ortopédicos pode ser viável. No entanto, a resistência à corrosão, conforme a avaliação realizada no presente estudo, não foi adequada quando comparada ao desempenho do aço sem nenhum tipo de revestimento. Ao final do texto, são apresentadas algumas sugestões a fim de conseguir um desempenho superior para a capacidade protetora dos revestimentos PVD.<br>Metallic biomaterials must present a combination of properties such as corrosion resistance, biocompatibility and mechanical resistance. Austenitic stainless steels, especially AISI 316L combine these properties with the easy of fabrication at low cost. However, they are prone to corrosion in physiological solutions. Furthermore, their corrosion products may lead to infectious ou allergenic reactions in the tissues around the implant device. In the present work, coatings produced by physical vapour deposition (PVD) methods have been applied on the surface of a 316L stainless steel to increase its corrosion resistance and biocompatibility. Three thin films were tested: titanium nitride (TiN), titanium carbonitride (TiCN) and diamond-like carbon (DLC). These materials present high hardness, wear resistance and intrinsic biocompatibility that are key features when considering biomedical applications. The characterization of the electrochemical behavior of the stainless steel coated with the three different films showed that the presence of surface defects are deleterious to the corrosion resistance of the substrate. These defects were observed using scanning electron microscopy. The evolution of the electrochemical behavior of the coated steel was explained through a mechanism based on the experimental results obtained using electrochemical impedance spectroscopy. Two different passivation treatments were carried out on the stainless steel surface, either in sulfuric or nitric acid solutions, to increase its corrosion resistance. The results suggested que these treatments were not efficient, but may be modified to improve its performance. The electronic properties of the passive films of the non-passivated and passivated stainless steel were studied using the Mott-Schottky approach. The films presented a duplex character. Below the flatband potential the behavior is typical of a highly doped type-p semiconductor. Above the flatband potential is typical of a highly doped type-n semiconductor. The doping concentration in the passive film was determined and associated with the corrosion resistance of the substrate. All PVD coatings investigated showed non-cytotoxic behavior. DLC and TiCN coatings decreased the friction coefficient of the stainless steel substrate. These properties allied with the stainless steel low cost recommend their commercial use for implants materials purposes. Nevertheless the corrosion resistance presented by the coated-steel was inferior to that of the bare steel and should be improved. At the end of the present text, some suggestions are proposed in order to improve the corrosion protection performance of the PVD coatings.
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O'Donnell, Lucas John. "TRIBOLOGY OF 316L AUSTENITIC STAINLESS STEEL CARBURIZED AT LOW TEMPERATURE." Case Western Reserve University School of Graduate Studies / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=case1251912164.
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Nekouie, Esfahani Mohammadreza. "Laser welding of dissimilar carbon steel to stainless steel 316L." Thesis, Loughborough University, 2015. https://dspace.lboro.ac.uk/2134/19760.
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Laser welding of metals and alloys is extensively used in industry due to its advantages of controlled heating, narrow weld bead, low heat affected zone (HAZ) and its ability to weld a wide range of metals and dissimilar metals. Laser welding of dissimilar metals such as carbon steels and stainless steel is still a challenging task, particularly due to the formation of brittle phases in the weld, martensitic formation in the HAZ and solidification cracking in the fusion zone. These issues can significantly deteriorate the strength of the welded joint. The aim of this work is to investigate the fundamental phenomena that occur inside the dissimilar weld zone and their effect on weld quality. In order to establish the key process variables, an initial study concentrated on the effect of different laser process parameters on dissimilar weld quality. In the second part of the work, a comprehensive study was performed to understand and subsequently control the alloying composition in laser dissimilar welding of austenitic stainless steel and low carbon steel. A dissimilar weld that is predominantly austenitic and homogeneous was obtained by controlling the melt pool dynamics through specific point energy and beam alignment. The significance of dilution and alloying elements on joint strength was established. A coupled CFD and FEM numerical model was developed to assist in understanding the melt pool dynamics and transportation processes of alloying elements. The model has been validated by a series of laser welding experiments using various levels of specific point energy. The laser welding characteristics in terms of geometric dimensions, surface morphology, alloying concentration, and dilution, were compared, and it is concluded that the specific point energy and laser beam position are the key parameters that can be controlled to obtain a weld bead with characteristics most suitable for industrial applications. In the third part of the work, a comparative study was performed to understand the significance of cooling rate, and alloying composition on the microstructure and phase structure of the dissimilar weld zone. Results show that the HAZ within the high carbon steel has significantly higher hardness than the weld area, which severely undermines the weld quality. A new heat treatment strategy was proposed based on the results of the numerical simulation, and it is shown to control the brittle phase formation in HAZ of high carbon steel. A series of experiments was performed to verify the developed thermo-metallurgical FEA model and a good qualitative agreement of the predicted martensitic phase distribution is shown to exist. Although this work is presented in the context of dissimilar laser welding of mild steel to stainless steel, the concept is applicable to any dissimilar fusion welding process.
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Wolfart, Junior Mario. "Nitretação a plasma do aço ABNT 316L em baixas temperaturas." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2002. http://hdl.handle.net/10183/2775.
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A nitretação dos aços inoxidáveis austeníticos apresenta grande interesse tecnológico, pois tanto em processos convencionais tais como as nitretações a gás e em banho de sais como em processos a plasma, obtêm-se um aumento significativo de sua dureza superficial e resistência ao desgaste. No entanto, devido as altas temperaturas utilizadas nos processos convencionais, observa-se uma extensa formação de precipitados de nitretos de cromo, com consequente redução de resistência à corrosão do material. A proposta deste trabalho é utilizar a tecnologia de plasma para nitretar um aço inoxidável austenítico neste caso o ABNT 316 L a temperaturas relativamente baixas a fim de evitar precipitação de nitretos). As temperaturas utilizadas foram de 350, 375 e 400 0C, variandose o tempo de nitretação de 3 ,4 e 5 horas com duas misturas gasosas (76%N2 e 24%H2 e 5%H2 e 95%N2). As amostras foram analisadas através da microdureza superficial (método convencional e nanodureza), caracterização microestrutural por microscopia ótica, eletrônica de varredura e de transmissão, medida da profundidade de camadas formadas (MEV), rugosidade, determinação das fases presentes (Raios - X), nanodureza , perfil da composição química (GDOS) e resistência à corrosão (névoa salina e curvas de polarização) As amostras nitretadas nestas temperaturas e tempos produziram camadas de 1,9 a 5,5 µm medidas via GDOS e durezas que vão de 330HK a 987HK não observando-se a precipitação de nitretos de cromo, mas sim a formação de uma estrutura supersaturada de nitrogênio intersticial, chamada de “fase S” identificada por difração de Raios - X. As camadas nitretadas apresentaram um gradiente de nitrogênio que diminui, indicando um gradiente junto as características microestruturais, níveis de tensões residuais favoráveis para uma boa adesão, com a formação de uma camada com menor fragilidade. Esta fase “S”, além de produzir altas durezas superficiais, aumentou a resistência à corrosão do aço. Testes em campo com navalhas de corte e facas móveis tiveram um aumento de vida útil de 100% e 217%.
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Martinez, Michae̋l. "Jonction 16mnd5-Inconel 690-316ln par soudage-diffusion : élaboration et calcul des contraintes résiduelles de procédé." ENSMP, 1999. http://www.theses.fr/1999ENMP0923.
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Le soudage-diffusion est un procédé de soudage à l’état solide, la liaison se faisant par diffusion sous pression et température élevées. Il est ici appliqué à une soudure courante en milieu nucléaire, mais de réalisation délicate : celle de l'acier de cuve 16mnd5 sur l'acier inoxydable 316ln. L'objectif de l’étude est d'une part d’élaborer et de caractériser de telles jonctions et d'autre part de développer un outil de simulation permettant de prévoir les microstructures après soudage ainsi que les contraintes résiduelles de procédé. L'étude a montré la nécessité d'utiliser un matériau d'insert, le choix s'est porte sur l'inconel 690, pour éviter la carburation du 316ln, et de procéder à un traitement de trempe et de revenu sur les jonctions après soudage, afin de restaurer la structure du 16mnd5. Les liaisons 16mnd5-inconel 690-316ln ont été caractérisées métallurgiquement et mécaniquement. Afin de simuler les évolutions métallurgiques de nouveaux modules ont été développés dans castem 2000, le code aux éléments finis du cea, concernant la diffusion du carbone sur l'interface 16mnd5-inconel 690, la croissance de grain austénitique et les transformations de phases dans le 16mnd5. Ces dernières sont calculées selon une version modifiée du modèle de Waeckel, tenant notamment compte des effets taille de grain et concentration en carbone. L'effet de transformations sur le calcul mécanique est traduit par l'introduction d'un terme de plasticité de transformation et de dilatation métallurgique. Le comportement des matériaux est choisi viscoplastique et a été identifié sur les trois matériaux entre 20 et 900\c. Il est tenu compte, quand il y a lieu, de la concentration en carbone et, pour le 16mnd5, de la composition en phases. Le résultat du calcul montre l'importance de premier ordre de la plasticité de transformation.
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POLA, ENRIQUE J. G. "Desenvolvimento e caracterizacao de filtros porosos de aco inoxidavel AISI 316L." reponame:Repositório Institucional do IPEN, 1994. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9261.
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Bromley, Darren Michael. "Hydrogen embrittlement testing of austenitic stainless steels SUS 316 and 316L." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/925.
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The imminent emergence of the hydrogen fuel industry has resulted in an urgent mandate for very specific material testing. Although storage of pressurized hydrogen gas is both practical and attainable, demands for increasing storage pressures (currently around 70 MPa) continue to present unexpected material compatibility issues. It is imperative that materials commonly used in gaseous hydrogen service are properly tested for hydrogen embrittlement resistance. To assess material behavior in a pressurized hydrogen environment, procedures were designed to test materials for susceptibility to hydrogen embrittlement.
Of particular interest to the field of high-pressure hydrogen in the automotive industry, austenitic stainless steels SUS 316 and 316L were used to validate the test programs. Tests were first performed in 25 MPa helium and hydrogen at room temperature and at -40°C. Tests in a 25 MPa hydrogen atmosphere caused embrittlement in SUS 316, but not in 316L. This indicated that alloys with higher stacking fault energies (316L) are more resistant to hydrogen embrittlement. Decreasing the test temperature caused slight embrittlement in 316L and significantly enhanced it in 316. Alternatively, a second set of specimens was immersed in 70 MPa hydrogen at 100°C until reaching a uniform concentration of absorbed hydrogen. Specimens were then loaded in tension to failure to determine if a bulk saturation of hydrogen provided a similar embrittling effect. Neither material succumbed to the effects of gaseous pre-charging, indicating that the embrittling mechanism requires a constant supply of hydrogen at the material surface rather than having bulk concentration of dissolved hydrogen. Permeation tests were also performed to ensure that hydrogen penetrated the samples and to develop material specific permeation constants.
To pave the way for future work, prototype equipment was constructed allowing tensile or fatigue tests to be performed at much higher hydrogen pressures. To determine the effect of pressure on hydrogen embrittlement, additional tests can be performed in hydrogen pressures up to 85 MPa hydrogen. The equipment will also allow for cyclic loading of notched tensile or compact tension specimens for fatigue studies.
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Jeon, Kyeong-Lak. "Rupture en mode mixte I+II de l'acier inoxydable austénitique 316L /." Gif-sur-Yvette : Commissariat à l'énergie atomique, 1993. http://catalogue.bnf.fr/ark:/12148/cb35626900f.
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Ayers, Lauren Juliet. "The hardening of Type 316L stainless steel welds with thermal aging." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/76926.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2012.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (p. 34-35).<br>Welded stainless steel piping is a component of boiling water reactors (BWRs). Reirculation and other large diameter piping are fabricated from Type 304 or 316 stainless steels. Delta ferrite is present in welds, because of its ability to reduce hot cracking; however, its presence can make the microstructure unstable. Delta ferrite is susceptible to spinodal decomposition, a process during which the given material separates into two phases with different compositions and properties, which can lead to brittleness and weakness in the steel. The H.H. Uhlig Corrosion Laboratory is investigating the effect of thermal aging on the physical properties of stainless steel piping. Stainless steel piping, of the same standards of that used in boiling water reactors, was welded and aged at temperatures of 300-400*C for 1,000 - 40,000 hours. The properties of the material were examined using several techniques, including Vickers hardness testing, to evaluate the evolution of hardness of the material, Charpy V-notch testing, to measure the evolution of toughness, and tensile testing. This thesis will focus on the variations in hardness with respect to aging time and location within the weld. Both a low ferrite series (FN=10) and a high ferrite series (FN=13) of Type 316L stainless steel welds were examined for the purposes of this paper. For each series, three materials were tested: an as welded material, a material that was aged at 400°C for 1000 hours, and a material that was aged at 400*C for 5000 hours. A two-dimensional Vickers hardness map was taken of each sample so that how hardness varies within the weld and heat affected zone can be understood. Nanoindentation was also done over small regions of each weld sample, to analyze whether the hardness changes over the dendrite boundaries. The overall hardness of the welds is found to increase to 1000 h and subsequently decrease slightly to 5000 h. The hardness map for each sample was found to be roughly symmetric across the weld centerline, but the hardness values were not found to be consistent along the weld centerline. In general the weld is harder when narrower, and softens as the weld widens. This trend was observed regardless of aging time or ferrite number.<br>by Lauren Juliet Ayers.<br>S.B.
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Jeon, Kyeonglak. "Rupture en mode mixte I+II de l'acier inoxydable austénitique 316L." Châtenay-Malabry, Ecole centrale de Paris, 1993. http://www.theses.fr/1993ECAP0278.
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La stabilité de défauts en mode mixte I+II a été étudiée a l'aide de barreaux de flexion a quatre points d'appuis en acier inoxydable austénitique type 316L vieilli. Les expressions du moment de flexion et de l'effort tranchant, du rapport de mixité, de la charge limite et de la force d'extension de fissure J sont établies et comparées avec les résultats de calculs élastoplastiques par éléments finis. À partir de résultats d'essais et de calculs, l'application et la validation de la règle r6 et de certains critères locaux (modèles de Beremin, de McClintock, de Guennouni-François et de Lemaitre) sont réalisées. Pour la règle r6, on constate que la courbe de non-rupture dépend peu du mode de chargement et de la géométrie de l'éprouvette. L’option 1 est conservative pour tous les essais effectues, mais l'option 3 apparait généralement non conservative surtout pour les cas proches du mode i. Il faut noter que ce non-conservatisme apparent est probablement du à la définition différente de l'amorçage des éprouvettes ctj25 et des barreaux de flexion. D'après les critères locaux utilisés, on constate que les paramètres d'endommagement correspondant à la charge à l'amorçage sont assez stables, particulièrement dans les modèles de Beremin et de Guennouni-François sauf pour les barreaux de flexion dans les cas les plus proches du mode I. Il est important de souligner que l'utilisation de ces critères locaux est douteuse dans le cas des éprouvettes ae à cause de l'influence probable de la rupture des bandes de ferrite transformée. Des examens fractographiques sont également discutes pour différents modes de rupture
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Moneghan, Matthew John. "Microstructural Deformation Mechanisms and Optimization of Selectively Laser Melted 316L Steel." Thesis, Virginia Tech, 2020. http://hdl.handle.net/10919/104170.
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In this paper, a novel approach is utilized to investigate the deformation mechanisms at the microstructural level in 3D printed alloys. The complex in-situ heat treatments during 3D printing leaves a unique and complicated microstructure in the as-built 3D printed metals, particularly alloys. The microstructure is made of a hierarchical stacking of some interconnected geometrical shapes, namely meltpools, grains, and cells. These are connected to each other by boundaries that might have different element compositions, and consequently, material properties, compared to the interior region of each geometrical unit. Deformation mechanisms in this microstructure are still highly unexplored, mainly because of the challenges on the way of performing experiments at the micrometer length scale. In this work, we establish an image processing framework that directly converts the SEM images taken from the microstructure of 3D printed 316L stainless steel alloys into CAD models. The model of the complicated microstructure is then scaled up, and the scaled model is 3D printed using polymeric materials. For 3D printing these samples, two polymers with contrasting mechanical properties are used. Distribution of these two polymers mimics the arrangement of soft and stiff regions in the microstructure of 3D printed alloys. These representative samples are subjected to mechanical loads and digital image correlation is utilized to investigate the deformation mechanisms, particularly the delocalization of stress concentration and also the crack propagation, at the microstructural level of 3D printed metals. Besides experiments, computational modeling using finite element method is also performed to study the same deformation mechanisms at the microstructure of 3D printed 316L stainless steel. Our results show that the hierarchical arrangement of stiff and soft phases in 3D printed alloys delocalizes the stress concentration and has the potential to make microstructures with significantly improved damage tolerance capabilities.<br>Master of Science<br>Many researchers have studied the impacts of laser parameters on the bulk material properties of SLM printed parts; few if any have studied how these parts break at a microstructural level. In this work we show how SLM printed parts with complex microstructures including grains, meltpools, and cells, deform and break. The cellular network that occurs in some SLM printed parts leads to a multi-material hierarchical structure, with a stiff network of thin boundaries, and a bulk "matrix" of soft cell material. This leads to similar properties as some composites, whereby the stiff network of cell boundaries leads to increased damage tolerance. We show both computationally through finite element analysis, and experimentally through multi-material 3D fabrication, that the microstructure leads to increased crack length in failure, as well as lower toughness loss and strength loss in the event of a crack. Essentially, the complex nature of the formation of these parts (high heating and cooling rates from laser melting) leads to a beneficial microstructure for damage tolerance that has not been studied from this perspective before.
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Fong, Clinton. "High frequency near-threshhold corrosion fatigue of AISI 316L stainless steel." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/25092.
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High frequency corrosion fatigue crack propagation behavior of AISI 316L stainless steel was studied in 1M NaCl and 1M NaCl + 0.01M Na₂S₂O₃, under various anodically and cathodically polarized potentials, and dessicated air at 22°C and 1 atmosphere pressure. Constant load amplitude fracture mechanics techniques employing single edge notch specimens were used to assess the fatigue crack growth rate in the various environments. Unique specimen preparation procedures were developed which allowed near-threshold behaviors to be studied under gradually rising crack tip stress intensity conditions.
Polarization studies showed that the presence of thiosulphate catalyzed the dissolution of stainless steel in low pH solutions(pH~1), due to reduction of thiosulphate species to H₂S, but had no effect in the near neutral solutions. Fatigue
tests conducted in the neutral NaCl + Na₂S₂O₃ solution at cathodic potentials showed that the presence of thiosulphate had an insignificant effect. This indicated that high frequency fatigue produces efficient exchange of bulk solution with the crack tip environment, which prevented the lowering of pH in the crack by hydrolysis effects and prevented reduction of thiosulphate to H₂S.
Fatigue crack retardation phenomena were very pronounced in the near-threshold regions in most of the fatigue tests. The cause of this retardation was attributed mainly to the surface-roughness- induced crack closure effect, which reduced the effective crack tip cyclic stress intensity ΔKth to a lower
level. This closure effect only predominated in the near-threshold region where significant Mode II loading was present.
The influence of various imposed anodic and cathodic potentials was found to be consistent with the surface-roughness-induced crack closure effects. The observed crack growth accelerating effect of high anodic potentials was attributed to the corresponding high removal rate of surface roughness in the wake of the crack, which kept the effective cyclic stress intensity level near the applied values.
Crack fractography was studied by scanning electron microscopy. It showed that the fractography generally consisted of three regions; a crystallographic cleavage-like near-threshold region, a feathery and fibrous transition region, and a striated region.
Using an etch pitting technique, it was determined that the crack plane and crack propagation directions in the near-threshold region were mainly those of {111} <110>, {110} <112>, {110} <001>, and other higher indexed planes. These crack orientations were effected by the activation of a single slip system or the alternate activation of two intersecting slip systems.<br>Applied Science, Faculty of<br>Mechanical Engineering, Department of<br>Graduate
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Pommier, Harry. "Fissuration en relaxation des aciers inoxydables austénitiques de type AISI 316L." Thesis, Paris, ENMP, 2015. http://www.theses.fr/2015ENMP0073/document.
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La fissuration en relaxation (FER) peut apparaître dans les zones affectées par la chaleur de larges pièces soudées pendant leur utilisation entre 500 et 700°C. Il est admis que ce phénomène est induit par la relaxation à haute température de champs de contraintes résiduelles initialement introduits lors du soudage. L'objectif de ce travail est d'identifier, dans les aciers de type AISI 316L, les caractéristiques de ce type de matériaux, ainsi que les forces motrices, responsables du développement de la fissuration en relaxation.La méthodologie proposée consiste à reproduire les conditions de la FER dans cinq aciers de type AISI 316L de compositions chimiques différentes en utilisant des éprouvettes de type « Compact Tension » (CT) pré-comprimées. L'étude des éprouvettes à l'aide du MEB, de l'EBSD, du MET et de la tomographie X a révélé que de l'endommagement intergranulaire s'était développé dans quelques une d'entre elles. Le niveau d'endommagement mesuré dans chaque éprouvette dépend de la nuance de l'acier, de la température et de la durée d'exposition thermique, et du rayon d'entaille.Ce travail implique également la prédiction numérique des champs de déformations et de contraintes résiduelles dans les éprouvettes à l'aide d'une nouvelle loi de comportement viscoplastique à variables internes. La comparaison entre les champs de contraintes résiduelles prédits dans les éprouvettes de type CT et les distributions d'endommagement mesuré par tomographie a permis de déduire le niveau de contrainte résiduelle critique nécessaire pour l'initiation de la FER. Finalement, les distributions d'endommagement mesurées expérimentalement ont pu être correctement prédites numériquement avec une loi phénoménologique d'endommagement scalaire alimentée par les prédictions du modèle de comportement viscoplastique<br>Stress relaxation cracking can potentially be found in the heat affected zone of large welded parts after service in the 500-700°C temperature range. This phenomenon, known as reheat cracking (RC), is driven by the high temperature relaxation of residual stress fields initially introduced during welding. The main objective of this doctoral thesis is to identify the material and microstructural characteristics as well as the driving forces responsible for RC damage development in AISI 316L-type austenitic stainless steels.The proposed methodology relies on the reproduction of RC conditions in five chemically different AISI 316L-type steels using pre-compressed CT-like specimens. Subsequent investigation using SEM, EBSD, TEM and X-ray tomography revealed that intergranular damage had developed in some of the specimens. The extent of damage was found to depend on the steel grade, the temperature and duration of the thermal exposure, and the notch radius.The numerical investigation of the local residual stress and strain fields in the specimens was carried out using a novel internal state variable-based viscoplastic constitutive model. A comparison between the predicted residual stress fields in the CT-like specimens and the intergranular damage distributions measured by X-ray tomography enabled the threshold level of local residual stresses associated with the initiation of stress relaxation microcracks to be inferred. Finally, the distribution of the measured local RC damage was modelled numerically by explicitly linking a suitable phenomenological scalar damage law with the above constitutive model. The corresponding results were found to be consistent with the observed damage distributions
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Barros, Isabel Ferreira de. "Dissimilar welding of ferritic stainless steel AISI 444 and AISI 316L austenitic stainless steel through the autogenous TIG process using pulsed current." Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=14072.
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FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico<br>The use of stainless steels has intensified with the industrial demand growing, which extends its application for various sectors such as the oil and gas, desalination equipment in industry, sugar industry, among others. In that context, the use of ferritic stainless steels has grown in recent years on account of its excellent relationship between corrosion resistance and cost, and a great option in substitution of austenitic stainless steels. Intending to study the connection of dissimilar stainless steels by means of a welding process, this paper will lay the submit the ferritic stainless steel AISI 444 and AISI 316L austenitic stainless steel with TIG welding autogenous (without filler metal) with pulsed current. That union seeks to get a fused zone with better mechanical properties together with the correction of possible related to welding those steels problems, such as grain growth in ferritic steels, to which its refinement is possible through the use of pulsed current during the procedure. The choice of these two materials was based on the characteristics of each one separately for they possess closest properties, despite having different classifications, allowing the combined use of both, and thus ferritic act in order to partially replace the austenitic stainless steel in situations where the combination of high corrosion resistance and mechanical strength are not relevant. That action combined, and does not affect the characteristics of the set of negative way is to use lower cost benefit, because the presence of nickel austenitic stainless steels by more expensive finishes them. Thus, it is expected to provide, through this work, further deepening the respect of dissimilar welding between stainless steel AISI 444 ferritic and austenitic stainless steel AISI 316L, evaluating operational parameters such as the pulse of current and heat input on obtained microstructure and mechanical properties.<br>A utilizaÃÃo dos aÃos inoxidÃveis tem se intensificado juntamente com a crescente demanda industrial, em que sua aplicaÃÃo se estende pelos mais variados setores, como por exemplo, na indÃstria de petrÃleo e gÃs, em equipamentos de dessalinizaÃÃo, na indÃstria sucroalcooleira, entre outros. Neste contexto, o uso de aÃos inoxidÃveis ferrÃticos tem crescido nos Ãltimos anos devido a sua excelente relaÃÃo entre resistÃncia à corrosÃo e custo, sendo uma Ãtima opÃÃo em substituiÃÃo aos aÃos inoxidÃveis austenÃticos. Objetivando estudar a uniÃo de aÃos inoxidÃveis dissimilares por meio de um processo de soldagem, o presente trabalho submeterà o aÃo inoxidÃvel ferrÃtico AISI 444 e o aÃo inoxidÃvel austenÃtico AISI 316L à soldagem TIG autÃgeno (sem metal de adiÃÃo) com corrente pulsada. Essa uniÃo visa obter uma zona fundida com melhores propriedades mecÃnicas juntamente com a correÃÃo dos possÃveis problemas relacionado à soldagem desses aÃos, como por exemplo, o crescimento de grÃo nos aÃos inoxidÃveis ferrÃticos, em que seu refinamento se torna possÃvel atravÃs da utilizaÃÃo de corrente pulsada durante o procedimento. A escolha desses dois materiais baseou-se nas caracterÃsticas inerentes a cada um separadamente e tambÃm por possuÃrem propriedades muito prÃximas, apesar de possuÃrem classificaÃÃes diferentes, permitindo a utilizaÃÃo combinada de ambos e dessa forma o aÃo inoxidÃvel ferrÃtico atuarà de forma a substituir parcialmente o aÃo inoxidÃvel austenÃtico nas situaÃÃes em que a combinaÃÃo de elevada resistÃncia à corrosÃo e resistÃncia mecÃnica nÃo sÃo tÃo relevantes. Essa utilizaÃÃo combinada, alÃm de nÃo afetar as caracterÃsticas do conjunto de maneira negativa tem como benefÃcio reduzir custos, visto que a presenÃa de nÃquel nos aÃos inoxidÃveis austenÃticos acaba por encarecÃ-los. Dessa forma, espera-se fornecer atravÃs deste trabalho um maior aprofundamento a respeito da soldagem dissimilar entre o aÃo inoxidÃvel ferrÃtico AISI 444 e o aÃo inoxidÃvel austenÃtico AISI 316L, avaliando os parÃmetros operacionais, como a pulsaÃÃo da corrente e a energia de soldagem sobre a microestrutura obtida, bem como as propriedades mecÃnicas.
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Bhamji, Imran Mahmed. "Development of the linear friction welding process." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/development-of-the-linear-friction-welding-process(21c73f31-88a9-45a9-ab04-3ffdb412cb57).html.
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The linear friction welding process is currently commercially used solely to produce titanium alloy aeroengine bladed disks (blisks). The process can, however, be potentially used to produce welds in non-aeroengine materials for non-aeroengine applications. The aim of this thesis was therefore to demonstrate the capabilities of the process to join materials not commonly used in the aeroengine industry and to develop understanding of the process. The focus of this thesis has been on the linear friction welding of 316L stainless steel and the linear friction welding of dissimilar materials: aluminium to copper, aluminium to magnesium and aluminium to steel. For all of these studies it was seen that weld line and near weld line microstructure could be altered by the use of different welding parameters. This property of linear friction welding was used to advantage to optimise microstructures in dissimilar welds. Intermetallic formation is usually a major challenge to the achievement of welds with good mechanical properties, and for work in this thesis welding parameters were optimised to allow welds with limited intermetallic formation. The welding of 316L and the dissimilar welding of aluminium to copper proved viable. For the welding of 316L and aluminium to copper, fracture during tensile testing occurred in the parent material (aluminium parent material for aluminium to copper). The welding of aluminium to magnesium and aluminium to steel showed promising results, with weld strength comparable to the aluminium parent material for aluminium to steel and comparable to the parent materials in O temper for aluminium to magnesium. However, repeatability of mechanical properties was poor for these dissimilar welds, which would be a significant barrier to commercial exploitation. Further work needs to be conducted to improve repeatability. Weld microstructures were characterised using optical and scanning electron microscopy as well as electron backscatter diffraction and X-ray diffraction techniques.
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Ajdini, Alen. "Studio del processo produttivo mediante metallurgia delle polveri dell'acciaio inossidabile austenitico 316L." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
Find full textAbstract:
L'elaborato tratta lo studio di un processo produttivo di componenti in acciaio inossidabile austenitico 316L mediante metallurgia delle polveri.
L'attività è stata svolta in collaborazione con l'azienda Sinteris S.P.A.(esperta di produzione di componenti sinterizzati).
In particolare viene studiato l'effetto della de-lubrificazione dei componenti sia in aria che in azoto e la successiva sinterizzazione eseguita sottovuoto ad una temperatura di circa 1240°C.
I componenti ottenuti sono poi stati testati dal punto di vista del loro comportamento a corrosione mediante prova in nebbia salina della durata di circa 300 ore.
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Leclerc, Rémi. "Paramètres influençant la résistance à la corrosion de l'acier inoxydable 316L fritté." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0020/MQ53964.pdf.
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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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Eriksson, Philip. "Evaluation of mechanical and microstructural properties for laser powder-bed fusion 316L." Thesis, Uppsala universitet, Tillämpad materialvetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-355882.
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This thesis work was done to get a fundamental knowledge of the mechanical and microstructural properties of 316L stainless steel fabricated with the additive manufacturing technique, laser powder-bed fusion (L-PBF). The aims of the thesis were to study the mechanical and microstructural properties in two different building orientations for samples built in two different machines, and to summarize mechanical data from previous research on additive manufactured 316L. Additive manufacturing (AM) or 3D-printing, is a manufacturing technique that in recent years has been adopted by the industry due to the complexity of parts that can be built and the wide range of materials that can be used. This have made it important to understand the behaviour and properties of the material, since the material differs from conventionally produced material. This also adds to 316L, which is an austenitic stainless steel used in corrosive environments. To study the effect of the building orientation, samples of 316L were built in different orientations on the build plate. The density and amount of pores were also measured. Tensile testing and Charpy-V testing were made at room temperature. Vickers hardness was also measured. Microstructure and fracture surfaces were examined using light optical microscope (LOM) and scanning electron microscope (SEM). The microstructure of the 316L made with L-PBF was found to have meltpools with coarser grains inside them, sometime spanning over several meltpools. Inside these coarser grains was a finer cellular/columnar sub-grain structure. The tensile properties were found to be anisotropic with higher strength values in the orientation perpendicular to the building direction. Also high dense samples had higher tensile properties than low dense samples. The impact toughness was found to be influenced negatively by high porosity. Hardness was similar in different orientations, but lower for less dense samples. Defects due to lack of fusing of particles were found on both the microstructure sample surfaces and fracture surfaces. The values from this study compare well with previous reported research findings.
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Gaudin, Christophe. "Etude des mécanismes associés au rochet cyclique d'un acier austénitique AISI 316L." Compiègne, 2002. http://www.theses.fr/2002COMP1399.
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Avec le vieillissement du parc nucléaire français, l’accumulation de déformation plastique sous chargement cyclique (effet de rochet) peut s’avérer dangeruse pour une structure donnée. Une large base expérimentale a été réalisée sur un acier austénitique AISI 316L afin d’apporter une interprétation physique au phénomène de rochet. La démarche suivie sur des analyses qualitatives et quantitatives des modes de déformations en microscopie électronique en transmission) corrélées aux états de contrainte interne à longue et à courte distance. Dans un premier temps, une interprétation des modes de déformation issus de la déformation de rochet à température ambiante est donnée pour de multiples conditions de chargement uniaxiaux. Le comportement en traction est abordé pour caractériser la nature de l’écrouissage associée à la pré-déformation lors du premier quart de cycle. La stabilité ses diverses structures de dislocations ainsi développées est ensuite étudiée pour divers chargement cyclique. Dans un deuxième temps, l’influence d’une sollicitation biaxiale (traction-torsion) à température ambiante est analysée. Les effets du chargement primaire en traction ainsi que plusieurs trajets de chargement non proportionnels sont étudiés et comparés aux résultats du rochet 1D. Dans un troisième temps, les effets de la température sur le rochet uniaxial sont discutés. L’écrouissage et les modes de déformations issus de la traction sont caractérisés. Puis l’influence de la température sur la vitesse de rochet est interprétée en terme d’activation de processus de vieillessement dynamique dans une certaine gamme de contrainte et de température. Enfin, une simulation du rochet 1D à température ambiante est proposée dans le cadre d’un modèle polycristallin. L’originalité du modèle réside dans la différenciation de la déformation plastique dans les zones dures et molles ainsi que sur la nature polarisée et dipolaire des dislocations à l’échelle du grain.
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Vernault, Cyril. "Interaction couches d'oxyde et résistance à la fatigue de l'acier inoxydable 316L." Poitiers, 1998. http://www.theses.fr/1998POIT2324.
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Une des causes de rupture de pieces en service provient de leur sollicitation par fatigue. L'endommagement qui en resulte est accru et parfois modifie par la presence d'un environnement oxydant. Dans ce contexte, nous avons etudie l'influence des couches d'oxyde sur les mecanismes de fissuration par fatigue d'un acier inoxydable type 316l. Ceci a necessite la caracterisation des processus et des produits d'oxydation a 300c et 600c sur un materiau non pre-deforme ainsi que pre-deforme par fatigue. Nous avons alors, etabli l'effet intrinseque de ces couches sur l'endommagement en fatigue plastique du 316l, par la comparaison d'eprouvettes pre-oxydees ou non pre-oxydees sollicitees sous vide. Ceci a permis de demontrer l'existence d'interactions entre la plasticite et les joints de grains oxydes. Celles-ci conduisent a une augmentation des fissures intergranulaires. Des lors, les conditions de sollicitation ou la tenue en fatigue est controlee par le stade d'amorcage (fatigue endurance) sont optimales pour observer un effet significatif des oxydes sur la duree de vie.
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Hahne, William. "Optimization of laser powder bed fusion process parameters for 316L stainless steel." Thesis, Uppsala universitet, Oorganisk kemi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-448263.
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The interest for additive manufacturing techniques have in recent years increased considerably because of their association to good printing resolution, unique design possibilities and microstructure. In this master project, 316L stainless steel was printed using metal laser powder bed fusion in an attempt to find process parameters which yield good productivity while maintaining as good material properties as possible. Laser powder bed fusion works by melting a powder bed locally with a laser. When one slice of the material is done, the powder bed is lowered, new powder is added on top, and the process is repeated, building the components layer by layer. In this thesis, samples produced with a powder layer thickness of 80 μm and 100 μm has been investigated. Process parameters like laser power, scanning speed and hatch spacing were investigated in order to establish clear processing windows where the highest productivity and lowest porosity are obtained. The most common defects in all sample batches were lack of fusion, gas pores, and spatter related pores. The best samples with regard to both porosity and build rate were obtained at normalized build rates between 1,3-1,6 and porosity-values in the 0,01-0,1 % range.
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Lohser, Julian R. "Evaluation of Electrochemical and Laser Polishing of Selectively LaserMelted 316L Stainless Steel." DigitalCommons@CalPoly, 2018. https://digitalcommons.calpoly.edu/theses/1920.
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Selective laser melting has shown incredible growth as a metallic additive manufacturing process in recent years. While it does provide many solutions and new ways to approach challenges, it does not come without issues of its own, namely, surface roughness. In the as-printed state, the surface roughness of selectively laser melted parts is unacceptable for use in engineering applications. Additionally, selective laser melting is used to produce complex geometries with hard to reach features, preventing conventional mechanical polishing from being successful. Therefore, it is necessary to evaluate non-mechanical polishing processes as treatments for surface roughness. In this study, electrochemical and laser polishing were investigated as potential start-to-finish treatments for the surface roughness of selectively laser melted parts. Following this preliminary study, a follow-up study investigating the effect on the mechanical strength of a lattice design that electropolishing would have. Electropolishing was found to significantly reduce the surface roughness of the as-printed part, but not to a usable value. Additionally, electropolishing was found to be unacceptable for use on lattice parts. Laser polishing was found to significantly reduce the surface roughness of the part but had feature size issues preventing a perfectly smooth surface.
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Yamanaka, Hajime. "The Effects of Weld Thermal Cycles on Additively Manufactured 316L Stainless Steel." DigitalCommons@CalPoly, 2019. https://digitalcommons.calpoly.edu/theses/2029.
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To address the size limitation of the powder bed fusion system in additive manufacturing, the welding properties of 316L stainless steel manufactured by SLM 125HL are investigated by conducting hot ductility test and nil strength temperature (NST) test with a physical thermal mechanical simulator, Gleeble. In this study, the print orientations (Zdirection and XY-direction) and the laser patterns (stripe and checker board) are studied. In NST test, the orientation showed a statistical significance in NST: Z-direction was 1384°C and XY-direction was 1400°C. In hot ductility test, all of ductility curves show similar behaviors: hardening region, recrystallization region, and liquation region. The additively manufactured 316L shows poor ductility compared to wrought 316L stainless steel. Also, there is a noticeable difference in ductility between laser pattern. Finally, ductility after the thermal cycle shows higher than that before the thermal cycle. For the future recommendation, investigation on the interelayer temperatures and sigma phase determination should be conducted to confirm the hypotheses to explain the phenomena observed in this study.
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Goss, Cullen. "SLM 125 Single Track and Density Cube Characterization for 316L Stainless Steel." DigitalCommons@CalPoly, 2019. https://digitalcommons.calpoly.edu/theses/2050.
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Selective Laser Melting is a rapidly developing additive manufacturing technique that can be used to create unique metal parts with tailormade properties not possible using traditional manufacturing. To understand the process from a most basic level, this study investigates system capabilities when melting single tracks of material. Individual tracks allow for a wide range of scan speeds and laser powers to be utilized and the melt pools analyzed. I discuss how existing studies and simulations can be used to narrow down the selection of potentially successful parameter combinations as well as the limitations of interpretation for single track information. Once we attain a solid understanding of what parameters perform well at a bead level, we can move onto looking at complete 3D parts. A challenge we have faced is creating near fully dense parts and determining a reliable density measurement technique that is accessible for operators at our university. Our results show that the previously determined optimized scan speed and laser power can consistently create parts with >99.5% density over a range of sizes using an analysis method utilizing readily available equipment and software.
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Ge, Yindong. "Low-Temperature Acetylene-Based Carburization and Nitrocarburization of 316L Austenitic Stainless Steel." Case Western Reserve University School of Graduate Studies / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=case1373032714.
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Wu, Dandan. "Low-Temperature Gas-Phase Nitriding and Nitrocarburizing of 316L Austenitic Stainless Steel." Case Western Reserve University School of Graduate Studies / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=case1346900583.
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Miller, Jacob T. "Sulfuric Acid Corrosion to Simulate Microbial Influenced Corrosion on Stainless Steel 316L." Youngstown State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ysu151621775594905.
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Matthews, Ryan Paul. "Oxidation kinetics of 316l stainless steel in the pressurised water reactor environment." Doctoral thesis, Faculty of Engineering and the Built Environment, 2019. http://hdl.handle.net/11427/30416.
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With a view to improving the prediction of primary water stress corrosion cracking in austenitic stainless steels, this investigation measured the oxide growth kinetics of 316L stainless steel when exposed to a simulated primary water environment of a pressurised water reactor (PWR). It is generally accepted that intergranular oxidation at the surface of a metal forms a preferential site for stress corrosion crack (SCC) initiation; therefore the kinetics of both surface and intergranular oxidation were measured. The influence of temperature, within the range of PWR primary water (290°C, 320°C and 360°C), as well as the influence of starting condition (annealed, 20% elongated, 30% elongated and 20% cold rolled) was investigated. Samples were prepared with the various starting conditions and exposed to simulated primary water, at the specified temperatures, for various durations from 1 hour through to several thousand hours to plot the oxide growth on a log scale time axis. Subsequent to the exposure tests, the Cr rich inner oxide depth was measured locally at selected locations. The surface and intergranular oxide depth was directly measured from cross-sections either with a transmission electron microscope for short duration exposures or, for longer exposures with deeper oxides, within a scanning electron microscope. No significant difference was noted on the oxide kinetics between the various starting conditions evaluated. Temperature, however, had a significant influence with oxide growth kinetics decreasing, rather counter-intuitively, as temperature increased through the measured range. In addition a strong dependency on grain orientation was observed. A modification to the Point Defect Model was proposed to arrive at a quantitative expression to describe surface and intergranular inner oxide growth as a function of temperature in 316L stainless steel, which accommodated the deviation from Arrhenius behaviour through the measured temperature range. Functions for both the rate constant, ��3 0 , and the transfer coefficient, α3, associated with the metal/oxide interface reactions were developed. The resultant model was able to predict, with reasonable accuracy, the growth of the Cr-rich inner oxide over time. The most consistent explanation for the deviation from Arrhenius behaviour was that the coherency across the metal/oxide interface degraded as the temperature increased through the tested temperature range. This would reduce the potential for ionic transfer across the interface necessary for the interface to migrate and increase the oxide depth. Since a similar temperature dependence on the growth of intergranular stress corrosion cracking (IGSCC) in the primary water environment has been observed within the same temperature range, it is proposed that the above explanation, observed in the absence of applied stress, extends to explain the behaviour of IGSCC kinetics in austenitic stainless steel.
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Schwartz, Julien. "Approche non locale en plasticité cristalline : application à l'étude du comportement mécanique de l'acier AISI 316LN en fatigue oligocyclique." Phd thesis, Ecole Centrale Paris, 2011. http://tel.archives-ouvertes.fr/tel-00628907.
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Si l'amorçage des fissures de fatigue est aujourd'hui bien compris dans le cas de monocristaux de métaux purs, ce phénomène s'avère plus complexe à cerner et à prédire dans le cas d'alliages métalliques polycristallins tels que l'acier AISI 316LN.D'un point de vue expérimental, notre étude s'est concentrée sur la caractérisation du comportement mécanique et l'étude, à différentes échelles, des phénomènes liés à l'amorçage des fissures de fatigue oligocyclique dans l'acier 316LN. Pour des niveaux de déformation appliquée de Δε/2 = 0,3 et 0,5%, l'adoucissement cyclique observé au cours des essais coïncide avec l'organisation des dislocations sous forme de bandes. Ces bandes sont liées à l'activation des systèmes de plus haut facteur de Schmid. Elles portent la majeure partie de la déformation et provoquent en surface des intrusions et extrusions favorisant l'apparition et la coalescence de fissures.D'un point de vue modélisation, nous avons proposé un nouveau modèle de plasticité cristalline intégrant des dislocations géométriquement nécessaires (GND) directement calculées à partir du second gradient de la rotation élastique. Implémenté dans les codes d'éléments finis AbaqusTM et Cast3mTM, ce modèle s'inspire des travaux sur le monocristal en transformations finies de Peirce et al. (1983) et de Teodosiu et al. (1993). Adapté au cas des polycristaux par Hoc (1999) et Erieau (2003), il a été enrichi par l'introduction GND selon la théorie proposée par Acharya et Bassani (2000). Les simulations réalisées sur des différents types d'agrégats (2D extrudé et 3D) montrent que la prise en compte de GND permet :- de reproduire les effets de taille de grains au niveau macroscopique et local,- de décrire plus finement les champs de contraintes calculés.Ces simulations ont permis de mettre en évidence l'influence des matrices d'élasticité et d'écrouissage sur les valeurs et l'évolution des contraintes macroscopique effective et cinématique moyenne et le rôle important des conditions aux limites lors des calculs d'agrégats.
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Talamantes-Silva, Jose. "Liquid phase sintering of austenitic stainless steel 316L powder using tin and nickel." Thesis, University of Nottingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287168.
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Wignall, Colin Michael. "Torsional fatigue of three 316L stainless steels in air and artificial sea water." Thesis, University of Sheffield, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286379.
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Depradeux, Lionel Jullien Jean-François. "Simulation numérique du soudage - Acier 316L validation sur cas tests de complexité croissante /." Villeurbanne : Doc'INSA, 2005. http://docinsa.insa-lyon.fr/these/pont.php?id=depradeux.
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