Stainless steel has garnered attention as an alternative structural material to conventional carbon steel due to its corrosion resistance properties and aesthetic appearance. Of interest are single angles, which are frequently used in trusses, transmission towers, and as bracing diaphragms. When subjected to compression, knowledge concerning the behavior, analysis, and design of stainless steel single angles is very limited. This thesis addresses the behavior of duplex stainless steel single equal-leg angles subject to concentric compressive loading. Two complementary approaches are used in this study, the first of which was experimental and consisted of conducting 33 full-scale buckling tests on S32003 duplex stainless steel single equal-leg angle components. Angles specimens had slenderness ratios ranging from 35 to 350 and leg width-to-thickness ratios of 7.5 to 12.3. In the second approach, computational models that accounted for material nonlinearity, material anisotropy, and geometric out-of-straightness were developed and validated using the experimentally obtained test results. These models were subsequently used to perform numerical buckling experiments to shed light on the behavior of axially loaded compression duplex stainless steel single angles for a wide range of practical leg width-to-thickness ratios. Results from the full-scale tests and from the numerical models are shown to correlate well with the classical mechanics-based formulae, which considers nonlinear stress-strain relationships, for predicting flexural and flexural-torsional buckling strengths of singly symmetric stainless steel members. Finally, design criteria in the form of load and resistance factor design (LRFD) with a reliability index of 3 for buckling limit states are proposed for possible adoption in future US national standards.

The objective of this study is to characterize the long-term behavior of an austenitic-ferritic stainless steel-based pretensioned system for strengthening reinforced concrete bridge pier caps in shear. Stress relaxation experiments were conducted on UNS S32101 stainless steel bars subjected to various initial stresses and temperatures within the low homologous temperature (LHT) regime. Data from these experiments were used to develop a viscoplastic constitutive model to describe the long-term time- and temperature-dependent behavior of the stainless steel bars. This mechanics-based approach is integrated with an analytical method based on strut-and-tie analysis to compute the shear strength of reinforced concrete pier caps strengthened with this external pretensioned system.

Note: / 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. [...] / 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.[...]

Thesis (M.Sc. in Applied Science(Metallurgical Engineering))--University of Pretoria, 2008. / Abstract in English. Includes bibliographical references (leaves 67-69).

Orientador: Amauri Hassui / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-26T12:29:08Z (GMT). No. of bitstreams: 1 Pereira_LuisAntonio_M.pdf: 7325377 bytes, checksum: 3508593610f7af7aa2e9b0fb82eac784 (MD5) Previous issue date: 2014 / Resumo: O fresamento consiste em um processo de usinagem no qual a peça a ser usinada é efetua os movimentos de avanço contra uma ferramenta cilíndrica rotativa com várias arestas de corte. No processo de fresamento o corte é considerado crítico, pois neste momento as variações de temperatura e força resultam em danos nas superfícies das peças, podendo comprometer o seu desempenho. Com isso, vários estudos buscam alternativas que visam explicar as ocorrências desses defeitos. Esse campo é conhecido também como Integridade Superficial. Este trabalho tem por objetivo avaliar as influências das condições de usinagem na integridade de superficial do aço inoxidável 15-5PH. Para isso foram feitos ensaios de fresamento utilizando fresa de facear com pastilhas redondas, geometria neutra e positiva, novas e em fim de vida. O fresamento foi discordante, com dois níveis de avanço por dente (fz = 0,15 e 0,25 mm/dente) e dois de velocidade de corte (vc = 170 e 195 m/min). Posteriormente foi avaliada a rugosidade 3D, dureza e feita a microscopia eletrônica da superfície e subsuperfície da peça usinada. Os resultados obtidos demonstram que utilizando uma ferramenta da classe (M40), com a geometria M-MM (positiva) com cobertura de MTCVD, obteve-se uma rugosidade melhor que a (M25). Foi possível também evidenciar os defeitos gerados na superfície usinada com a utilização do (MEV), microcavidades, sulcos gerados por microcavacos, repasse da ferramenta e resto de material / Abstract: Milling is a machining process in which the workpiece makes feed movements against a rotating cylindrical tool with multiple cutting edges. In the milling process the cut is considered critical because at this time the temperature and force variations result in damage to the surfaces of the workpiece, which can compromise their performance. Consequently, several studies aim to explain the occurrences of failures. This field is also known as Surface Integrity. This work aims to evaluate the influence of machining conditions on the surface integrity of stainless steel 15-5PH. In order to do so, milling tests were carried on using face mills with round inserts, neutral and positive geometry (new and in the end of tool life). Up milling condition along with two levels of feed per tooth (fz = 0.15 and 0.25 mm/tooth) and two cutting speeds (vc = 170 and 195 m/min). Later, the 3D roughness and hardness were evaluated and scanning electron microscopy (SEM) was carried on the workpiece¿s surface and subsurface. The results obtained show that using (M40) class tool, and M-MM geometry (positive) with MTCVD coating provided a better surface finish than the (M25) class tool. Using the (SEM), it was also possible to highlight the defects generated in the machined surface such as microcavities, grooves generated by microchips, tool backcutting and the remaining material / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica

Abstract: Oil pollution and spills cause serious damage to marine ecosystems and coastal environments. Currently, oily waters recuperated form a spill must be shipped onshore for treatment. This limits the volume of water that can be treated during a spill. There is a need to develop technologies to treat oily waters below 15 ppm (parts per million) at the site of the spill. Synthetic membrane technologies are widely used in water treatment and purification. They can offer an on-site solution to contaminated oily water treatment in oil production and spills. The suitability of a membrane for use in this application is determined by the type of material used in its fabrication. Compared to polymeric membranes, inorganic membranes are inert to microbiological degradation, offer high chemical and thermal resistance, and can easily be backflushed and cleaned once fouled. However, inorganic membranes consisting of metal oxides are heavier and more expensive than polymeric membranes, due to their bulky and brittle ceramic support layers. This limits their application when the overall weight of a process unit is of concern. A newly developed 2D/3D material, named twinned alumina nanosheets (TAN), has recently been used to make dynamic membranes. The nanoplatelets forming TAN have a length of 4 µm, a width of 1 µm, and a thickness of 100 nm. They have a very high permeability, a 0.2 µm-pore size and a porosity up to 88% due to their low nanosheet volume. These unique characteristics make TAN a very promising material to form membrane selective layers. However, they must be supported on a very open layer in order to take advantage of their high porosity. In this work, a composite membrane was produced with a selective layer of 2D/3D alumina nanoplatelets deposited onto stainless steel meshes and ceramic supports. The structure of the TAN in the selective layer was reinforced with binders. The main objective of this work was to verify the adhesion of the TANs onto the support. The crystallization of TAN was optimized to obtain an open 2D/3D structure. This structure was then deposited on a stainless-steel mesh. The mesh was pretreated by electrochemical etching to achieve a re-entrant surface. The mesh was immersed in an etching solution and placed parallel to a conductive graphite plate under a constant electric potential of 5V for 4 min. Aqueous solutions of silica sol and colloidal silver were tested as binding agents. They were deposited on the mesh with TAN and sintered for 4 hrs. Experiments were performed on testing stainless steel meshes with different opening sizes and comparing different calcination temperatures. The best sintering temperature was 800°C for a mesh with an opening size of 35µm. The synthesized membrane was challenged with a suspension of 10 ppm bentonite clay at a constant pressure of 100 mbar. The integral structure of a TAN membrane produced with a 2.5wt% silica binder was maintained after backflushing. The 2.5wt% silica membrane had a high flux and the particle filtration process for this membrane was modelled as pore constriction and intermediate blocking, indicating that backflushing provided the deep cleaning of pores. According to the SEM images, the 2.5wt% silica membrane preserved the integral structure of the TAN, while the pores tended to fill with silica at higher silica concentrations. The effective pore size of the 2.5wt% silica membrane was estimated to be the smallest, which is approximately 0.53 μm. The 7.5wt% silica membrane had half the permeate flux of the other membranes, because of the high concentration of binder filling the pores of the TAN selective layer. The SiO 2 binder had a positive effect in reinforcing the TAN particles. The flux of the membrane did not increase after backflushing indicating that the selective layer of the membrane was securely bound to the stainless steel mesh. The membrane exhibited flux decline between backflushings indicating that particles were retained on its surface. SEM images taken after the filtration showed that this membrane completely released bentonite particles form its pores. Tests were also performed with a membrane having two TAN coatings on the wire mesh. This reduced the flux but did not improve the retention of fine particles. Colloidal silver was found to be a poor binding agent as particles were released particles from its selective layer. Silica was a highly successful binding agent while colloidal silver was not. TAN was also successfully deposited onto ceramic supports. It was also retained on top of the membrane after backflushing. The results of this work demonstrate that TANs reinforced and bound with silica are a promising type of material to form membrane selective layers. These layers have an open pore structure with a three-dimensional channel connectivity on both stainless steel and ceramic supports. The selective layer was successfully bound to the stainless steel supports. If the pore size of this membrane were to be reduced, it would meet the requirements for use at the site of an oil spill to treat contaminated waters as it does not need the heavier supports found in traditional ceramic membranes. Résumé: La pollution et les déversements d'hydrocarbures causent de graves dommages aux écosystèmes marins et aux environnements côtiers. À l'heure actuelle, les eaux huileuses récupérées d'un déversement doivent être expédiées à terre pour leur décontamination. Ceci limite le volume d’eau contaminé qui peut être traité. Il est nécessaire de développer des technologies permettant de traiter les eaux huileuses en dessous de 15 ppm (parties par million) sur le site du déversement. Les technologies membranaires sont largement utilisées dans le traitement et la purification de l'eau. La possibilité de se servir d’une membrane dans cette application est déterminée par les matériaux utilisés dans sa fabrication. Comparées aux membranes polymères, les membranes inorganiques sont inertes vis-à-vis de la dégradation microbiologique, offrent une résistance chimique et thermique élevée et peuvent facilement être rincées et nettoyées une fois encrassées. Cependant, les membranes inorganiques constituées d'oxydes métalliques sont plus lourdes et plus coûteuses que les membranes polymères, en raison de leurs couches de support en céramique volumineuses et cassantes. Cela limite leur application lorsque le poids total d'une unité de traitement est préoccupant. Un matériau 2D/3D récemment développé, appelé TAN (Twinned Alumina Nanosheets), a récemment été utilisé dans la formation de membranes dynamiques. Les nano-plaquettes formant les TAN ont une longueur de 4 µm, une largeur de 1 µm et une épaisseur de 100 nm. Ils ont une très haute perméabilité, une taille de pores de 0,2 µm et une porosité allant jusqu'à 88% en raison du faible volume des nanofeuilles. Ces caractéristiques uniques font du TAN un matériau très prometteur pour la formation de couches sélectives de membranes. Cependant, ils doivent être déposes sur une couche très ouverte afin de tirer parti de leur grande porosité. Au cours de ce travail, une membrane composite a été réalisée avec une couche sélective de nanoplaques d’alumine 2D / 3D (TAN) déposées sur deux types de supports; des mailles en acier inoxydable et des supports en céramique. La structure du TAN dans la couche sélective a été renforcée avec des liants. L'objectif principal de ce travail était de vérifier l'adhérence des TAN sur le support. La cristallisation des TAN a été optimisée pour obtenir une structure 2D/3D ouverte. Cette structure a ensuite été déposée sur un treillis en acier inoxydable. Les mailles ont été prétraitées pour obtenir une surface réentrante. Le maillage a été immergé dans une solution de gravure et placé parallèlement à une plaque de graphite conductrice sous un potentiel électrique constant de 5 V pendant 4 min. Des solutions aqueuses de sol de silice et d’argent colloïdal ont été testées en tant que liants. Ils ont été déposés sur la maille et frittés pendant 4 heures. Des expériences ont été effectuées sur des mailles en acier inoxydable avec différentes tailles d’ouverture et températures de calcination. La meilleure température de frittage était de 800 ° C pour un treillis ayant une taille d'ouverture de 35 µm. La membrane synthétisée a été mise à l’essai avec une suspension de 10 ppm d'argile bentonite à une pression constante de 100 mbar. La structure intégrale de la membrane couche de TAN produite avec un liant à 2,5wt% de silice a été maintenue après les tests de perméabilité. La structure 3D poreuse a tendance à se remplir de silice à des concentrations de silice supérieures à 2,5wt%. La taille effective des pores de la membrane produite avec 2,5wt% de liant de silice a été estimée à 0,53 µm. Le flux de la membrane n'a pas augmenté après le rinçage, indiquant que la couche sélective de la membrane était liée de manière sûre au maillage en acier inoxydable. La membrane présentait un déclin de flux entre les rinçages indiquant que des particules étaient retenues à sa surface. Les images au microscope à balayage prises après la filtration ont montré que cette membrane libère complètement les particules de bentonite de ses pores. Des essais ont également été réalisés avec une membrane comportant deux revêtements TAN sur le treillis métallique. Cela réduit le flux mais n'améliore pas la rétention des particules fines. L'argent colloïdal s'est avéré être un agent de liaison médiocre car des particules sont libérées de sa couche sélective. La silice était un liant très efficace, contrairement à l'argent colloïdal. Le TAN a également été déposé avec succès sur des supports en céramique. Il est également resté sur la membrane après le rinçage à contre-courant. Les résultats de ce travail démontrent que les TAN renforcés avec un liant de silice sont un type de matériau prometteur pour former des couches sélectives, avec des structures à pores ouverts possédant une connectivité de canal tridimensionnelle, sur des supports en acier inoxydable et en céramique. La couche sélective a été liée avec succès au support en acier inoxydable. Si la taille des pores de cette membrane devait être réduite, elle pourrait être utilisée sur le site d'un déversement d'hydrocarbures pour traiter les eaux contaminées car elle ne nécessite pas les supports plus lourds que l'on trouve dans les membranes de céramique traditionnelles.

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No description available.

Fatigue-crack propagation and residual static-strength data on PH15-7Mo (TH 1050) stainless steel are presented in this thesis. In addition, the capability of McEvily and Illg's crack-growth analysis and Kuhn and Figge's residual strength analysis to correlate the test data has been investigated. Axial-load fatigue-crack propagation (at R = 0 and -1) and residual static-strength tests were conducted, on 2-inch-wide sheet specimens made of PH15-7Mo (TH 1050) stainless steel. Analysis of the data showed that as individual analysis methods both analyses satisfactorily correlated the majority of the test data. However, the material constants derived in the two analyses differed significantly. This difference was attributed to the different amounts of work-hardening which occurs in the material prior to failure in the two cases. The effects of the different stress ratios on fatigue-crack growth were studied. In addition, the capability of the residual-strength analysis to predict the effects of changing buckling restraint in the vicinity of the crack.and of changing specimen width were investigated. / Master of Science

Relaxation spectra were determined for a high chromium-high nickel vacuum cast stainless steel. The specimens were tested in the following three conditions: (1) as-received and solution heat treated, (2) nitrided 20 hours and solution heat treated, and (3) nitrided 40 hours and solution heat treated. No internal friction peaks were found in any of the experimental runs. There was no precipitation of nitrides during testing in the torsional pendulum. This was verified by an electron microscopic examination of the specimens after testing. Since there were no nitrides precipitated, no internal friction relaxation peaks were evident. / M.S.