Thesis, (Ph. D.)--Oregon Graduate Institute of Science and Technology, 1996.

Thesis (M.S.)--University of Michigan, 1973.

Thesis (M.S.)--University of Michigan, 1973.

Made available in DSpace on 2014-06-11T19:27:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-08-02Bitstream added on 2014-06-13T20:16:09Z : No. of bitstreams: 1 hashimoto_mmb_me_guara.pdf: 4222707 bytes, checksum: 27f8c8d0ab8e7954c8e4ec0d9dcc1c48 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A ferrita acicular é um desenvolvimento recente do conceito dos aços HSLA e envolve nucleação da ferrita a partir de partículas não metálicas, de forma intragranular e heterogênea. O mecanismo de transformação da ferrita acicular é semelhante à formação da bainita, diferenciando-se basicamente no local onde cada constituinte se nucleia e a aparência da microestrutura. A presença de carbonitretos precipitados e a microestrutura acicular desorganizada tende a desviar a propagação de trincas e aumentar tenacidade do material. Desta forma, os aços com microestrutura de ferrita acicular têm sido apontados como ótimos candidatos para aplicações em tubulações de óleo e gás em condições ambientais e operacionais severas. Este trabalho investiga os constituintes de um aço baixo carbono e baixos teores de elementos de ligas com contendo microestrutura de ferrita acicular, obtida através de tratamento de crescimento de grãos e, posteriormente, submetido a diversas rotas de tratamento isotérmico. A caracterização microestrutural foi obtida através de microscopia óptica e processamento metalográfico com o reagente Nital. Avaliou-se, também, o comportamento da resistência à tração do material antes e após os ciclos de tratamento térmico. Os resultados obtidos revelam a possibilidade de se obter estruturas multifásicas contendo grandes frações de ferrita acicular, promovendo excelente combinação das propriedades mecânicas de resistência e ductilidade / The acicular ferrite is a recent development of HSLA steels and involves a ferrite nucleation from non-metallic particles, as intragranular and heterogeneous mode. The acicular ferrite transformation mechanism is similar to bainite, differing primarily in where each constituent initiates nucleates and appearance of the microstructure. The presence of carbonitriding precipitated and disorganized acicular microstructure tends to deflect the crack propagation and increase toughness of the material. Thus, steels with acicular ferrite microstructure have been considered good candidates for applications in oil pipes and gas in several environmental and operational conditions. This work investigates the constituents of a low carbon steel and low concentration of alloys with microstructures containing acicular ferrite, obtained by grain growth treatment and, subsequently, subject to various route of isothermal treatments. The microstructural characterization was obtained by optical microscopy and metallographic processing with Nital reagent. We evaluated also the behavior of the tensile strength of the material before and after the heat treatment cycles. The results show the possibility of obtaining multiphase structures containing large fractions of acicular ferrite, promoting excellent combination of mechanical properties of strength and ductility

Orientador: Elidiane Cipriano Rangel / Banca: Idalina Vieira Aoki / Banca: Clodomiro Alves Junior / Resumo: Devido às suas propriedades mecânicas, soldabilidade e baixo custo, o aço carbono é um material amplamente utilizado nos mais diversos setores. Entretanto, o aço carbono é facilmente oxidado quando exposto ao ambiente. Para evitar esse problema, alguns trabalhos sugerem o desenvolvimento de revestimentos protetivos utilizando técnicas de deposição a plasma baseadas no composto hexametildisiloxano, HMDSO. A partir deste composto podese obter desde estruturas organosilicones até as inorgânicas pela alteração dos parâmetros de deposição. Revestimentos tipo óxido de silício são mais resistentes à corrosão que os organosilicones, porém sua estabilidade física é menor. Com o objetivo de associar as propriedades favoráveis de ambos os tipos de revestimentos, investigou-se, no presente trabalho, a possibilidade de revestir o aço carbono com sistemas bicamadas SiOx/SiOxCyHz através da combinação de metodologia de deposição e oxidação em plasmas de baixa pressão. Para tanto, filmes do tipo SiOxCyHz foram depositados a plasma de mistura de HMDSO (70%), O2 (20%) e Ar (10%) excitado por radiofrequência (150 W). A pressão total da atmosfera de deposição foi de 20 Pa. Os filmes foram depositados por 30 min e, posteriormente, expostos a plasmas de O2 (3,3 Pa, 10-300 W, 60 min) com o objetivo de criar uma camada superficial inorgânica. Foram investigados os efeitos da potência de excitação do plasma de O2 na espessura de camada, estrutura química e composição elementar das amostras. Avaliou-s... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Due to its mechanical properties, welding and low cost, carbon steel is a material widely used in several sectors. However, carbon steel is easily oxidized when exposed to the environment. To avoid this problem, some work suggests the development of protective coating using plasma deposition techniques based on the compound hexamethyldisiloxane, HMDSO. From this compound it is possible to obtain from organosilicones structures to inorganic by changing the parameters of deposition. Silicon oxide type coatings are more resistant to corrosion than organosilicones, but their physical stability is lower. With the objective of associating the favorable properties of both types of coatings, the present work investigated the possibility of coating the carbon steel with SiOx/SiOxCyHz bilayer systems through the combination of deposition and oxidation methodology in low pressure plasmas. For that, SiOxCyHz films were deposited in a mixture plasma of HMDSO (70%), O2 (20%) and Ar (10%) excited by radiofrequency (150 W). The total pressure of the atmosphere of deposition was 20 Pa. The films were deposited for 30 min and subsequently exposed to O2 plasmas (3.3 Pa, 10-300 W, 60 min) to create an inorganic surface layer. The effects of the excitation power of the O2 plasma on the layer thickness, chemical structure and elemental composition of the samples were investigated. The effect of the oxidation plasma power was also evaluated in the barrier properties of the coating deposited on carb... (Complete abstract click electronic access below) / Mestre

A new testing facility for fully reversed tension-torsion high cycle fatigue testing has been designed. The specimens used for the test programme were solid and made from a medium carbon steel. The test programme involved a tension-torsion multiaxial non-proportional loading sequence i.e. fully reversed torsion followed by a push-pull load interruption and then the continuation of the same torsion loading to failure. The push-pull load interruption represented a significantly low damage i.e. 4% damage according to Miner's linear damage theory, and was applied after different prior torsion cycle ratios. The tests were conducted with various interruption stress amplitudes all of which had fatigue lifetimes in the high cycle fatigue region. The torsion fatigue life was found to change significantly due to the application of push-pull load interruption which was considered to cause only a minor damage due to Miner's rule. Miner's linear damage theory cannot account for the predicted cumulative fatigue damage (Sigman/N[f]) for the push-pull interrupted torsion fatigue loading sequences used in the current test programme. The fatigue life was markedly enhanced when the interruption was applied at an early stage of torsion loading whilst the effect was less prominent when the interruption was applied at a later stage of torsion loading. At higher interruption stress amplitudes the torsion fatigue lifetime was reduced considerably and the damage summation was well below the unity predicted by the Miner's rule. The inability to predict damage accumulation by Miner's rule can be attributed to the complexity in the crack growth associated with the application of push-pull interruption. Crack growth equations to represent microstructural short crack (MSC) and the physically small crack (PSC) growth were determined for the material of the form;MSC - da/dN = C[m](d[i] - a)...(1) and PSC - da/dN = C[p]a-D ...(2). Material parameters for the models were derived using torsion and uniaxial constant amplitude fatigue S-N data, no crack coalescence, branching or re-initiation was considered. The crack growth model was able to predict the fatigue life in loading cases which were dominated by an uninterrupted crack growth. However, such a model was shown to significantly underestimate the torsion fatigue life in situations where the fatigue life was affected by secondary crack initiation due to the push-pull load interruption.

The objective of this work, achieved in the framework of the BIOCOR European Network, has been to provide the operators of Sea-Water Injection System (SWIS) with improved decision support. The implication of biological component on carbon steel corrosion was explored as well as the possible synergy with other elements (mechanical stress, material properties…). This work showed that biogenic sulphide production, a corrosion threat for steel, can have different origins in seawater. The production rate can determine kinetics and morphology of corrosion attack, which might be governed by the type of microorganisms present. The key parameters are the availability of electron acceptors and the surrounding environment temperature. Sulfate-Reducing Bacteria (SRB) exhibit more vigorous attack compared to sulfidogenic bacteria or genera Clostridium, both found in the studied SWIS. Microbial activity also affects the mineralization process naturally occurring on carbon steel surface leading to architectures composed of mixed iron (II) and (III) minerals such as iron sulfides, magnetite, iron oxyhydroxides, chukanovite and green rust (sulfated or carbonated) as well as calcareous deposits. Inner layers of these structures could possibly provide an anaerobic habitat for SRBs, where they can flourish by using sulfate from GR(SO42-) as a terminal electron acceptor for their dissimilatory respiration. This enables continuous degradation of steel. Finally, significance of material microstructure and impact of mechanical stress on corrosion processes was also recognized. Grain boundaries and inclusions are playing a role during the initial stage of corrosion attack. This impact can diminish during the immersion time. An elevated bacterial activity coupled with mechanical stress leads to an increase of material deterioration. However, the mechanisms are not different from those usually observed for unstressed steel. Moreover, sulfidogenic microbial activity does not seem to lead to a failure mechanism related to Stress Corrosion Cracking (SCC). In conclusion, the outcomes indicate the possible situations, which may (or may not) lead to breach the safe operating window for a given SWIS.

Na Ficha Catalogr?fica consta o t?tulo: "Monitoramento qu?mico da composi??o e da a??o do biodiesel do ?leo de am?ndoa da maca?ba no contato direto com a?o carbono e a?o carbono galvanizado". / Submitted by Jos? Henrique Henrique (jose.neves@ufvjm.edu.br) on 2018-11-01T18:00:34Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) claudia_eliane_dias_batista.pdf: 1707707 bytes, checksum: f480bf5d3fe108357404021690844f2f (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2018-11-10T11:52:57Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) claudia_eliane_dias_batista.pdf: 1707707 bytes, checksum: f480bf5d3fe108357404021690844f2f (MD5) / Made available in DSpace on 2018-11-10T11:52:57Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) claudia_eliane_dias_batista.pdf: 1707707 bytes, checksum: f480bf5d3fe108357404021690844f2f (MD5) Previous issue date: 2018 / O biodiesel ? uma importante fonte alternativa de energia, pois ? derivado da biomassa fotossint?tica de plantas oleaginosas. ?leos de muitas esp?cies de plantas t?m sido investigados por serem material precursor para a produ??o de biodiesel. Maca?ba (Acrocomia aculeata) ? uma palmeira nativa do Brasil, cuja fruta tem uma propor??o significativa de ?leo, com potencial real para a produ??o industrial de biodiesel. Existe uma ampla gama de quest?es ainda a serem sistematicamente exploradas, a fim de se obter uma vis?o adequada do manejo racional da cultura da palma, extra??o e processamento do ?leo para a produ??o e armazenamento comercial do biodiesel. O comportamento qu?mico dos ?steres met?licos de ?cidos graxos do ?leo da am?ndoa de maca?ba e a lixivia??o de elementos met?licos por contato dos a?os carbono usados na constru??o de tanques e dutos s?o o foco principal deste trabalho experimental. A composi??o em ?steres met?licos do biodiesel obtido da rea??o de transesterifica??o de triacilglicer?is do ?leo de am?ndoa da maca?ba com metanol, em contato direto com os a?os carbono ASTM A283 grau C e API X65 galvanizados e n?o galvanizados foi monitorada. A lixivia??o de elementos qu?micos da estrutura dos a?os carbono foi tamb?m investigada. Os resultados obtidos por espectroscopia M?ssbauer neste trabalho tamb?m mostraram que o contato com o biodiesel de maca?ba confere prote??o aos a?os n?o galvanizados contra a corros?o oxidativa no contato direto com o ar. Al?m disso, observou-se ainda a forma??o de esp?cies qu?micas contendo ferro, nomeadamente magnetita (Fe3O4) e w?stita (Fe1-xO), na superf?cie das barras de a?o n?o galvanizado quando em contato direto com o ar, mas sem contato com o biodiesel; nenhum ?xido de ferro foi detectado nas barras de a?o usadas no biodiesel, monitoradas at? 105 dias de armazenamento. As taxas de corros?o s?o baixas, de acordo com a norma NACE-RP0775, Standard Recommended Practice: Preparation, Installation, Analysis, and Interpretation of Corrosion Coupons in Oilfield Operations. O biodiesel do ?leo da am?ndoa da maca?ba tem 63,44 massa% de ?steres de ?cidos graxos saturados. Uma condi??o que assegura relativamente alta estabilidade oxidativa do combust?vel, mesmo em contato (na presente experi?ncia, por imers?o) com o a?o carbono API ou ASTM, galvanizado ou n?o. / Disserta??o (Mestrado) ? Programa de P?s-gradua??o em Biocombust?veis, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2018. / Biodiesel is an important alternative source of energy, as it is derived from the photosynthetic biomass of oleaginous plants. Oils of many plant species have been investigated for being precursor material for the production of biodiesel. Maca?ba (Acrocomia aculeata) is a native palm in Brazil, whose fruit has a significant proportion of oil, with real potential for the industrial production of biodiesel. There is a wide range of issues still to be systematically explored, in order to achieve an adequate view of the rational crop management of the palm, extraction and processing of the oil for the production and the commercial storage of biodiesel. The chemical behavior of the fatty acid methyl esters from the maca?ba oil and the leaching of metal elements put directly in contact with carbon steels used in the construction of tanks and pipelines are the main focus of the present experimental work. The composition in methyl esters of the biodiesel obtained from the transesterification reaction of triacylglycerols of the maca?ba fruit kernel oil with methanol, in direct contact with the galvanized and non-galvanized carbon steels ASTM A283 grade C and API X65. The M?ssbauer spectroscopy results obtained in this work also showed that the contact with the maca?ba biodiesel gives protection to the non - galvanized steels against the oxidative corrosion in direct contact with air. Also the formation of iron-bearing chemical species, namely magnetite (Fe3O4) and w?stite (Fe1-xO), on the surface of the non-galvanized bar steels when in direct contact with air; no such iron oxide was detected on the steel bars used in the biodiesel, by monitoring up to 105 days of storage. But the corrosion rates are low, according to the NACE-RP0775, Standard Recommended Practice: Preparation, Installation, Analysis, and Interpretation of Corrosion Coupons in Oilfield Operations. These results allow better evaluate and more adequately specify conditions of storage and transportation of biodiesel obtained from the maca?ba oil. The biodiesel of the maca?ba almond oil has 63.44 mass% of esters of saturated fatty acids. A condition that ensures relatively high oxidative stability of the fuel, even in contact (in the present experiment, by immersion) with API or ASTM carbon steel, galvanized or not.

Orientador: Marcelo dos Santos Pereira / Banca: Antonio Jorge Abdalla / Banca: Cristina de Carvalho Ares Elisei / Resumo: A ferrita acicular é um desenvolvimento recente do conceito dos aços HSLA e envolve nucleação da ferrita a partir de partículas não metálicas, de forma intragranular e heterogênea. O mecanismo de transformação da ferrita acicular é semelhante à formação da bainita, diferenciando-se basicamente no local onde cada constituinte se nucleia e a aparência da microestrutura. A presença de carbonitretos precipitados e a microestrutura acicular desorganizada tende a desviar a propagação de trincas e aumentar tenacidade do material. Desta forma, os aços com microestrutura de ferrita acicular têm sido apontados como ótimos candidatos para aplicações em tubulações de óleo e gás em condições ambientais e operacionais severas. Este trabalho investiga os constituintes de um aço baixo carbono e baixos teores de elementos de ligas com contendo microestrutura de ferrita acicular, obtida através de tratamento de crescimento de grãos e, posteriormente, submetido a diversas rotas de tratamento isotérmico. A caracterização microestrutural foi obtida através de microscopia óptica e processamento metalográfico com o reagente Nital. Avaliou-se, também, o comportamento da resistência à tração do material antes e após os ciclos de tratamento térmico. Os resultados obtidos revelam a possibilidade de se obter estruturas multifásicas contendo grandes frações de ferrita acicular, promovendo excelente combinação das propriedades mecânicas de resistência e ductilidade / Abstract: The acicular ferrite is a recent development of HSLA steels and involves a ferrite nucleation from non-metallic particles, as intragranular and heterogeneous mode. The acicular ferrite transformation mechanism is similar to bainite, differing primarily in where each constituent initiates nucleates and appearance of the microstructure. The presence of carbonitriding precipitated and disorganized acicular microstructure tends to deflect the crack propagation and increase toughness of the material. Thus, steels with acicular ferrite microstructure have been considered good candidates for applications in oil pipes and gas in several environmental and operational conditions. This work investigates the constituents of a low carbon steel and low concentration of alloys with microstructures containing acicular ferrite, obtained by grain growth treatment and, subsequently, subject to various route of isothermal treatments. The microstructural characterization was obtained by optical microscopy and metallographic processing with Nital reagent. We evaluated also the behavior of the tensile strength of the material before and after the heat treatment cycles. The results show the possibility of obtaining multiphase structures containing large fractions of acicular ferrite, promoting excellent combination of mechanical properties of strength and ductility / Mestre

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-04-01T12:36:05Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) MINHA DISSERTAÇÃO TODA CORRIGIDA PARA ENTREGAR FINALMENTE.pdf: 4033631 bytes, checksum: 08588f757c83774b5bae906b82926ffe (MD5) / Made available in DSpace on 2016-04-01T12:36:05Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) MINHA DISSERTAÇÃO TODA CORRIGIDA PARA ENTREGAR FINALMENTE.pdf: 4033631 bytes, checksum: 08588f757c83774b5bae906b82926ffe (MD5) Previous issue date: 2015-08-18 / CAPEs / O aço é um dos materiais mais comuns utilizados na construção de sistemas de armazenamento e de distribuição de derivados de petróleo. O contato direto entre a superfície metálica e um combustível contaminado com água pode proporcionar condições necessárias para o desenvolvimento de micro-organismos, os quais podem alterar a interface metal/meio, ou reagir diretamente com a superfície do metal, colaborando para sua deterioração química. O uso do óleo Diesel S10 foi estabelecido no mercado em 2013, com o objetivo de disponibilizar combustíveis alternativos que contribuíssem para a redução da emissão de poluentes dos veículos automotores, por possuir baixo teor de enxofre (10ppm). Sendo assim, tem-se a necessidade de desenvolver estudos sobre a contaminação microbiana nestes combustíveis para obter informações quanto à corrosão nos sistemas de armazenamento da indústria do petróleo. O presente trabalho teve como objetivo avaliar o processo de corrosão e biocorrosão do aço carbono ASTM A283, quando exposto ao sistema bifásico óleo Diesel S10/água doce, em condições estáticas, nas proporções de 1:1. Na água doce foram avaliados os parâmetros relacionados ao processo de corrosão e, analisou-se o efeito da biodegradação em diesel, devido ao sinergismo microbiano. Foram realizadas as caracterizações físico-químicas do diesel e da água, além da quantificação dos micro-organismos sésseis e planctônicos nos fluidos estudados, no biofilme e no resíduo depositado no fundo do reator, nos tempos de 0, 30, 60 e 90 dias. A avaliação do processo de corrosão foi realizada por ensaios de perda de massa e por análise da superfície através de Microscopia Ótica (MO), Microscopia Eletrônica de Varredura (MEV) e Espectroscopia de Energia Dispersiva (EDS), análises de Topografia e Rugosidade e Difração de Raio-X (DRX). Os resultados obtidos indicaram que houve corrosão alveolar em algumas regiões dos cupons. A corrosão bacteriana se concentrou principalmente nas superfícies que se encontravam imediatamente abaixo da interface diesel/água, onde houve a formação de produtos de corrosão e a aderência de biofilme. A corrosão localizada foi observada nas áreas imersas em óleo Diesel S10. Através da perda de massa, obteve-se a taxa de corrosão, classificada moderada para os cupons submetidos ao sistema bifásico, e classificada baixa para os cupons imersos em óleo diesel puro. As caracterizações da água mostraram que a composição original do meio foi alterada, devido ao comportamento do processo de corrosão. Não foi detectada atividade microbiana no diesel, que se manteve dentro das especificações ao longo de 90 dias. / The steel is one of the most common materials used in the construction of storage systems and distribution of petroleum products. The direct contact between the metal surface and a fuel contaminated with water can provide necessary conditions for the development of microorganisms, which can change the metal interface/middle, or react directly with the metal surface, contributing to their deterioration. The use of Diesel fuel S10 was established in the market in 2013, with the objective of providing alternative fuels that contribute to the reduction of the emission of pollutants from motor vehicles, it has low sulphur content (10ppm). Therefore, there is a need to develop studies on microbial contamination in these fuels for to get information about storage systems corrosion of oil industry. The present work had as objective to evaluate the corrosion process and biocorrosion of carbon steel ASTM A283, when exposed to the two-phase system Diesel S10/fresh water, under static conditions, in the proportions of 1:1. In fresh water were evaluated the parameters related to the corrosion process and examined the effect of biodegradation on diesel, due to microbial synergism. The physical and chemical characterization of diesel and water, in addition to the quantification of sessile and planktonic microorganisms in fluids studied, in the biofilm and in the residue deposited at the bottom of the reactor, in the time of 0, 30, 60 and 90 days were performed. The evaluation of the corrosion process was conducted out by mass loss and tests for surface analysis by optical microscopy, scanning electron microscopy (SEM) and Energy Dispersive spectroscopy (EDS), Topography and Roughness analyses and x-ray Diffraction (DRX). The results indicated that there was alveolate corrosion in some regions of the coupons. Bacterial corrosion focused mainly on the surfaces that were immediately below the diesel/water interface, where the formation of products of corrosion and biofilm adhesion. Localized corrosion was observed in the areas immersed in Diesel S10. Through the loss of mass, the corrosion rate was classified moderate for the coupons submitted to the two-phase system, and classified low to the coupons immersed in pure diesel oil. The characterizations of the water showed that the original composition of the medium has changed, due to the behavior of corrosion process. Microbial activity was not detected in the diesel, which is maintained within specifications throughout 90 days.