A vida da moça, que ainda criança começara a ouvir vozes lhe revelando a missão de libertar a França dos invasores ingleses, que liderou um exército, coroou o seu rei e teve um destino trágico, sendo queimada viva como herege, parece saída de uma obra literária, mas como bem lembra Colette Beaune Joana dArc é provavelmente, a figura de mulher mais documentada de toda a História. Atualmente contam-se 20.000 estátuas públicas, centenas de biografias e peças de teatro, dezenas de filmes, óperas e músicas. Seria possível desvendar as razões para tamanho sucesso? Essa popularidade foi alcançada ao longo de um processo contínuo e homogêneo, ou houve rupturas, sobressaltos e novas atribuições à heroína que possam ser verificados ao longo do tempo? Essa tese discute a importância da primeira metade do século XIX para esse fenômeno. Nesse período a historiografia francesa se esforçou para enquadrar Joana dArc, heroína há muito honrada pelo reino da França, nos padrões da sociedade pósrevolucionária. Longe de desqualificá-la como figura incompatível com a modernidade pretendida por aquele país, tal como proposto no contexto revolucionário, Joana foi alçada ao panteão dos heróis nacionais tendo sua imagem amalgamada aos ideais de 1789. Buscamos desvendar o processo que tornou possível a popularização de uma nova Joana dArc naquele período, processo intimamente ligado aos valores burgueses então difundidos: a nação, o povo, a pátria, o indivíduo. As novas características atribuídas à Joana correspondiam às expectativas burguesas a partir de um discurso ligado a uma nova visão da História que passou a ser considerada como potencial produtora de verdades e justificativas que embasassem a configuração social que se anunciava. / The life of the young lady whose childhood was haunted by the hearing of voices which revealed to her a mission to free France from English invaders, who led an army, crowned her king had a tragic fate and was burned at the stake as a heretic seems to be taken from a literature work. But as Colette Beaune has rightly pointed out Joan of Arc is probably the most documented woman figure in all World History. It can be numbered about 20,000 public statues, hundreds of biographies and plays, dozens of films, operas and other pieces of music. Would it be possible to unfold the reasons for such an interest in her? The question lies, however, in how quite high popularity was gained. Was it the result of a continuous and homogeneous process or were there interruptions, surprises and new attributions assigned to the heroine that can be verified over time? This thesis discusses the importance of the former half of the nineteenth century to this phenomenon. Throughout this period French historiography struggled to fit Joan of Arc, the heroine overly honored by the kingdom of France, in the patterns of a post-revolutionary society. Far from discrediting her reputation as a figure incompatible with modernity desired by that country, as proposed in the revolutionary context, Joan was elevated to the national pantheon of heroes and had her image amalgamated to the ideals of 1789. Its sought to disclose the process that led to a substantial popularization of a new Joan of Arc at that time, and is intimately connected to bourgeois values disseminated then: nation, people, homeland and individual. New features attributed to Joan met the bourgeoisie expectations through a discourse on a new way of looking at History that turned out to be regarded as a potential producer of truths and justifications to support the social setting that was being announced.

Estudos anteriores mostraram que a soldagem de aço USI-SAC-50 com adição de pó metálico pode promover o aparecimento de microfases que interferem nas propriedades mecânicas. Este trabalho, teve o objetivo de estudar os efeitos de variações nos consumíveis, aporte de calor e do tratamento térmico pós-soldagem na diminuição ou eliminação das microfases. Chapas de aço USI-SAC-50 foram soldadas por arco submerso com adição de pó metálico utilizando-se fluxos de soldagem BX-200 e OK-1071,arames de soldagem EM-12K e EB-2 e aportes de calor de 4,8 kJ/mm e 3,6 kJ/mm. Tensão e corrente foram mantidas em 34 V e 600 A, respectivamente. Após a soldagem, metade das chapas foi submetida a um tratamento térmico de alívio de tensões a 580ºC por 1 h. Foram realizados ensaios mecânicos de dureza, tração a -10ºC e CTOD a -10ºC, assim como foram realizadas metalografias preto e branco e coloridas para identificação e quantificação de fases. As composições químicas obtidas nos cordões de solda foram adequadas para que a quantidade de ferrita acicular presente assegurasse as boas propriedades mecânicas. As mudanças na composição química, em relação à trabalhos anteriores, ocasionadas pela variação dos fluxo e as variações nos aportes de calor promoveram uma sensível diminuição na quantidade de microfase para faixa de 2,5 a 10%. Entre os cordões ensaiados para avaliação de CTOD aquele com maior teor de austenita retida apresentou um CTOD menor, mostrando a influência dessa fase sobre a tenacidade. Também o tratamento térmico de alívio de tensões contribuiu para a diminuição da quantidade de microfase para a faixa de 0 a 1,5%, sendo que a microfase restante apresentou uma forma esferoidal. / Previous studies showed that the welding of steel USI-SAC-50 with addition of metal powder can promote the appearing of one phase that interfere in the mechanical properties. This work had the objective of studying the effects of variations in the consumable ones, contribution of heat input and of the thermal treatment in the decrease or elimination of this phase. Plates of steel USI-SAC-50 were welded by submerged are weld with addition of metal powder being used welding fluxes BX-200 and OK-1071, welding wires EM-12K and EB-2 and heat inputs of 4,8 kJ/mm and 3,6 kJ/mm. Tension and current were maintained in 34 V and 600 A, respectively. After the welding, half of the plates was submitted to a thermal treatment of relief of tensions to 580ºC for 1 h. Mechanical tests of hardness, traction to -10ºC and CTOD to -10ºC were carried out, as well as black and white and colored metalographies were carried out for identification and quantification of phases. The chemical compositions obtained in the weld beads they were appropriate so that the amount of acicular ferrite present assured the good mechanical properties. The changes in the chemical composition, in relation to previous works, caused by the variation of the fluxes and the variations in the heat inputs they promoted a sensitive decrease in the amount of microphase for strip from 2,5 to 10%. The thermal treatment of relief of tensions also contributed to the decrease of the amount of microphase for the strip from 0 to 1,5%, and the remaining microphase presented a spherical shape.

Il existe aujourd'hui de nombreux procédés de soudage répondant à la très grande variété d'assemblage à réaliser et aux caractéristiques des métaux utilisés. Le premier chapitre décrit les différentes sources d'énergie utilisées en soudage. Suite à cela, une explication plus détaillée du soudage à l'arc électrique est donnée. Enfin nous présentons la conception d'une plateforme d'essai de soudage. Il est possible, bien sûr, d'utiliser une approche empirique pour optimiser un procédé. Néanmoins il y a des avantages à choisir une approche analytique puisqu'on peut en attendre des avancées significatives dans la compréhension des interactions dynamiques présentes dans l'arc. C'est pourquoi nous présentons dans le chapitre 2 les connaissances théoriques de la physique quant au comportement du métal liquide transféré en soudage MIG/MAG. Ce travail comporte donc également un aspect expérimental nécessaire à l'élaboration des bases de données utilisées pour la construction des modèles. Les différents enregistrements ont été effectués au CTAS sur une plate forme équipée d'un système d'acquisition de données pour les mesures de tension, courant, vitesse fil et d'un système de vidéo rapide. Le chapitre 3 présente notre recherche d'une méthode de segmentation permettant d'obtenir le suivi de variables pertinentes. Nous y proposons un capteur logiciel basé sur la théorie des contours actifs et montrons de bons résultats obtenus sur des vidéos expérimentales. Une étape d'ajustement de certains paramètres est indispensable. Elle est donnée dans le chapitre 4. Le simulateur créé permet d’interpréter certains phénomènes importants en soudage, de réaliser une étude de sensibilité « sans risque » et de donner les signatures théoriques de défauts. / Nowadays there is a lot of welding processes giving an answer to the great diversity of joints to realize and to the characteristics of the metals employed. The first chapter describes the different power sources used in welding. After that, a more detailed explanation of arc welding is given. Finally we present the design of a welding test bed. One can, of course, use an empirical approach to optimize a process. Nevertheless there are advantages in choosing an analytical approach since we can expect significant progress in the understanding of the dynamical interactions in the arc. That’s why we present in the second chapter the theoretical knowledge concerning the behaviour of the molten metal transferred during Gas Metal Arc Welding. This work involves as well an experimental aspect required for the elaboration of the databases used to build the model. The recordings were made at CTAS on a test bed equipped with an acquisition system for measuring voltage, current, wire feed speed and high speed videos. The third chapter presents our research of a segmentation method to measure some relevant quantities. We propose a software sensor based on the active contour theory and we show good results on experimental movies. An adjustment step of the model is needed and described in the fourth chapter. The created simulator allows us to interpret some important phenomena in welding, to make a sensitive study “without risk” and to give theoretical defects signatures.

Wire and Arc Additive Manufacturing is a novel Additive Manufacturing technology. As a result, the process for progressing from a solid model to manufacturing code, i.e. the Part Programming process, is undeveloped. In this report the Part Programming process, unique for Wire and Arc Additive Manufacturing, has been investigated to answer three questions; What is the Part Programming process for Wire and Arc Additive Manufacturing? What are the requirements on the Part Programming process? What software can be used for the Part Programming process? With a systematic review of publications on Wire and Arc Additive Manufacturing and related subjects, the steps of the Part Programming process and its requirements have been clarified. The Part Programming process has been used for evaluation of software solutions, resulting in multiple recommendations for implemented usage. Verification of assumptions, made by the systematic review, has been done by physical experiments to give further credibility to the results.

<p>Steel heating and melting processes consume the majority of the energy used in advanced short-process steelmaking practices. Economic and environmental pressures from energy consumption drive the research to improve the furnace operation efficiency and energy efficiency. The goal of this research is to utilize computational fluid dynamics (CFD) modeling to provide useful tools and recommendations on the steel heating and melting practices in the steelmaking process. The steel slab reheating process, the steel scrap preheating process and the steel scrap melting process are studied.</p> <p> </p> <p>A transient three-dimensional (3-D) CFD model was developed to simulate the flow characteristics, combustion process and multi-scale, multi-mode heat transfer inside the reheating furnace. The actual geometry of an operating industrial furnace was used and typical operating conditions were simulated. Specific walking speeds of slabs in production were modeled using a dynamic mesh model which is controlled by a user-defined function (UDF) solved using ANSYS Fluent. Fuel variations at different zones with respect to time were also considered. The model was validated with instrumented slab trials conducted at the SSAB Mobile (Alabama) mill. The temperature field in the furnace and the temperature evolution of a slab predicted by the CFD model are in good agreement with those obtained from the instrumented slab trials. Based on the simulation results, the slab reheating process and the temperature uniformity of a slab at discharge were able to be properly evaluated. In addition, a comprehensive two-dimensional (2-D) numerical heat transfer model for slab reheating in a walking beam furnace was developed using the finite difference method. An in-house code was developed. The model is capable of predicting slab temperature evolution during a reheating process based on real time furnace conditions and steel physical properties. The model was validated by using mill instrumented slab trials and production data. The results show that the temperature evolution predicted by the model is in good agreement with that measured by the thermocouples embedded in the instrumented slab. Compared with 3-D CFD simulation of a reheating process, this 2-D heat transfer model used for predicting slab temperature evolution requires less computing power and can provide results in a few seconds. A graphical user interface was also developed to facilitate the input and output process. This is a very convenient and user-friendly tool which can be used easily by mill metallurgists in troubleshooting and process optimization.</p> <p> </p> <p>CFD models for steel scrap preheating and melting processes by the combined effects of the heat source from both oxy-fuel combustion and electric arc were also developed. The oxy-fuel burners firing natural gas (NG) are widely used in EAF operation during the scrap preheating and melting stages. In order to understand the role of oxy-fuel combustion and potentially increase the energy input from NG while decreasing the electricity consumption, numerical simulation of scrap preheating by oxy-fuel combustion in an EAF was firstly conducted. A 3-D CFD model was developed with detailed consideration of gas flow, oxy-fuel combustion, heat transfer between gas and solid scrap and scrap oxidation. The model was validated by a small-scale experimental study and applied onto a real-scale EAF.</p> <p> </p> <p>Scrap melting in bath is comprehensively studied with a CFD model developed to simulate the melting in bath process under given operating conditions. Two sub-models were developed for model integration: steel melting model and coherent jet model. The multiphase volume of fluid (VOF) model and the enthalpy-porosity technique are applied to describe the steel melting process. The coherent jet model calculates the gas jet momentum and is integrated into the flow model to calculate its effect on the fluid flow in the bath. The electric arc was treated as a heat flux to represent the heat transfer from the electric arc during the melting process. Model validations were conducted for each sub-model to ensure their accuracy. Parametric studies were also carried out to obtain useful information for real practice. </p><p>Overall, the CFD models developed in this research work have demonstrated value in improving energy efficiency in the energy-intensive steelmaking processes. The developed CFD models also provide insights for better understanding of the multi-physics processes.<br></p> <p> </p>

Este trabalho apresenta uma análise das condições de soldagem sobre o desgaste abrasivo de um revestimento duro. O revestimento foi feito pela deposição metálica por arco submerso variando os parâmetros de soldagem e utilizando fluxos comerciais. Foram utilizados dois conjuntos de parâmetros de soldagem (conjunto 01 com velocidade de soldagem de 55 cm/min, extensão do eletrodo de 35,0 mm, tensão de 30V, corrente de 450A e o conjunto 02 com velocidade de soldagem de 50 cm/min, extensão do eletrodo de 25,5 mm, tensão do arco de 26V e corrente de 440A) e quatro fluxos comerciais (identificados como E, M, L e R) formando assim oito condições de soldagem. Foram feitas duas camadas com três cordões de solda cada sobre uma chapa base de aço SAE 1020. Corrente contínua com polaridade direta (CC-) foi utilizada em ambas condições. A resistência ao desgaste abrasivo a baixa-tensão foi avaliada pelo ensaio de desgaste do tipo Roda de borracha/areia seca conforme a norma ASTM G65-94. A análise microestrutural foi feita por microscopia óptica e a análise da região desgastada por microscopia eletrônica de varredura. A resistência ao desgaste abrasivo dos revestimentos do conjunto 01 foi superior em comparação com os revestimentos do conjunto 02, para todos os fluxos utilizados. Os fluxos E e R proporcionaram os melhores desempenho e a martensita de agulhas foi a microestrutura com a qual foram obtidos os melhores resultados de desgaste abrasivo a baixa-tensão neste estudo realizado. / This work presents an analysis of the welding conditions and its effects in the abrasive wear of hardfacings. The hardfacings were obtained by submerged arc surfacing. The welding variables were changed and the commercials fluxes were used. Two groups of welding variables were used (group 01: a traveI speed of 55 cm/min, an electrode extension of 35,0 mm, a voltage of 30V and an amperage of 450A; group 02: a traveI speed of 50 cm/min, an electrode extension of 25,0 mm, a voltage of 26V and an amperage of 440A) and four commercials fluxes (E, M, L e R designated) establishing eight welding conditions. Double-Iayered ot three beads were deposited (applied) on a SAE 1020 base metal plate. Direct current electrode negative polarity (CC-) were used in both groups of welding. The low stress abrasion resistance evaluation was carried out by dry sand/rubber wheel apparatus according to the ASTM G65-94. The microstructural analysis were done by optical microscopy and the worn surface analysis were done by scanning electronic microscopy. The abrasion resistance of the group 01 was superior as compared to the group 02, independent of the fluxe was used. The fluxes E and R presented the best results and the befter abrasion resistant microstructure was lath martensite.

Na manutenção de tubulações e dutos de aços de alta resistência baixa liga (ARBL), os reparos são executados com eletrodo revestido e com o equipamento operação, com o intuito de reduzir custos com paradas. Nesta aplicação, os gradientes de temperatura são mais elevados quando comparados com sondagens realizadas ao ar, o que pode levar à redução das propriedades mecânicas nessas juntas soldadas e causar maiores impactos financeiros ou mesmo ambientais. No metal depositado resultante do eletrodo revestido AWS E7018-1, usualmente utilizado no reparo de dutos de aços ARBL, as propriedades mecânicas têm forte relação com a ferrita acicular, microestrutura que ocorre intergranularmente, nucleando preferencialmente em inclusões do metal depositado. O objetivo desse trabalho é analisar a influência de diferentes condições de soldagem e de resfriamento sobre o teor de oxigênio e sobre a microdureza do metal depositado resultante do uso de eletrodos revestidos AWS E7018-1, usando técnicas de planejamento experimental como as metodologias Taguchi e experimentos fatoriais. Usando o método Taguchi foi possível observar que os três fatores (fabricante do eletrodo, corrente de soldagem e condição de resfriamento) influenciam no teor de oxigênio e que o fornecedor do eletrodo é o fator com maior efeito sobre a resposta, seguido pela corrente de sondagem. Com relação à etapa de experimentos fatoriais mapas operacionais para o teor de oxigênio e microdureza dos cordões de solda foram construídos. Foi possível observar que a corrente de soldagem tem efeito mais impactante que a taxa de resfriamento sobre o teor de oxigênio e a microdureza. / Covered electrodes had been developed at the beginning of the 20th Century and, despite the evolution of several welding processes, the shielded metal arc welding (SMAW) still find widespread application, even within the oil and gás industry, e.g. repairing of high strength low (HSLA) steel pipes. The pipe repairing is carried out during its operation (in order to reduce costs) and, therefore, the temperature gradients in the base metal are higher compared to removing the pipe system from service. This could lead to reducing mechanical properties in these welded joints that could cause higher financial or even environmental impacts. In the low carbon weld metal (e.g. AWS E7018-1 electrode is usually employed in HSLA pipe repair). The mechanical properties have a strong relationship with the acicular ferrite fraction, which occurs intergranularly and nucleating preferentially in inclusions within weld metal. The objective of this work is to analyze the influence of different welding and cooling conditions on the oxygen content ando n the mechanical properties of the weld metal from the AWS E7018-1 covered electrodes, using design of experiments techniques as Taguchi\'s method and response surface methodology (RSM). Using the Taguchi\'s method, it was possible to observe that three factors (namely electrode supplier, welding current and cooling condition) have influence on the oxygen content and the electrode supplier is the factor with the greatest effect on the response, followed by the welding current. Regarding to the factorial experiment, operational maps for the oxygen content and microhardness of the weld beads were constructed. It was possible to observe that the welding current hás a more impactful effect than the cooling rate on the oxygen content and microhardness.

Este trabalho tem por objetivo estudar o aproveitamento do pó de aciaria elétrica (PAE) na sinterização de minério de ferro visando a eliminação de zinco. Primeiramente, foi feita uma caracterização física e química do resíduo através de análises químicas, granulométricas, morfológicas e de difração de raios-X. O minério de ferro, principal componente do processo de sinterização, foi caracterizado através de análise química, granulométrica e de umidade. Em seguida, foram fabricadas micropelotas de 3,0 a 5,0mm de diâmetro compostas por 70% de PAE e 30% de moinha de coque, que foram classificadas por peneiramento e secas em esfufa. Depois de aglomerado, o resíduo foi incorporado na sinterização de minério de ferro em diferentes proporções, condições de processo e formas de adição (micropelotas, undersize da micropelotização com granulometria entre 1,0 e 2,0mm, ou mistura de PAE e coque em pó). A cada processo de sinterização foram retiradas amostras de sínter, os materiais foram analisados através de Microscópio Eletrônico de Varredura (MEV), macroscopia e análises químicas por espectrofotometria de absorção atômica para verificar o teor de zinco. Amostras de misturas não sinterizadas também foram submetidas a análises químicas para determinar a quantidade inicial de zinco, ou seja, verificar a quantidade de zinco contido na mistura antes do processo de sinterização. Mediante a comparação do teor de zinco das amostras não sinterizadas com os sínteres, foi possível determinar a eliminação de zinco nos ensaios realizados. Aproximadamente 92% de zinco foi eliminado (junto com os gases de saída) com a incorporação de 10% de micropelotas na mistura a sinterizar. Os resultados mostraram que a eliminação do metal no processo é proporcional à relação redutor/resíduo. / The aim of this work was to study the use of electric arc furnace dust (EAFD) in iron ore sintering process aiming zinc elimination. Firstly, physical and chemical characterizations of the waste were made using X-ray diffraction, microscopy, chemical and size analyses. Iron ore is the main component of the sintering process, this material was characterized by chemical, size and humidity analyses. After, micropellets composed of EAFD 70% and coke breeze 30% with diameters of 3.0-5.0 mm were produced, then they were dried in kiln and classified by sieving. The pellets were incorporated into the iron ore sintering charge using differents proportions, process conditions and addition forms (micropellets, undersize with diameters of 1.0-2.0 mm, or a mixture of EAFD and coke breeze). Sintered samples were collected in each sintering process. These materials were analyzed by scanning electron microscopy (SEM), macroscopy and chemical analysis using atomic absorption spectrophotometry in order to determine the zinc content. Samples of not sintered mixtures were also characterized by chemical analysis aiming the determination the initial amounts of zinc, i.e. in order to check the zinc amounts present in the mixture before the sintering process. The comparation between the zinc contents of sintered samples and not sintered allowed to determine the elimination of zinc during the experiments. About 92% of zinc was eliminated (along with the output gas) with the incorporation of 10% of micropellet in the sintering mixture. Results showed that the zinc elimination in the process is proportional to the ratio reducer/waste.

A redução no volume de resíduos produzidos, industriais e agrícolas, vem se tornando uma exigência constante em todos os processos de produção. A falta de espaço físico para a disposição destes resíduos, a contaminação ambiental causada por eles, além da necessidade de preservação dos recursos naturais não-renováveis e da diminuição do consumo de energia e emissão de poluentes, tornam a reciclagem e a reutilização dos resíduos uma alternativa bastante atraente. A construção civil apresenta-se como um setor bastante apto à utilização de técnicas de reaproveitamento de resíduos, provenientes das mais diversas indústrias. Além de todos os benefícios ambientais, este reaproveitamento, pela construção civil, pode gerar recursos financeiros, bem como, possibilita a melhora das características de alguns materiais de construção, e pode diminuir o custo de construção, fator importante, quando se avalia o déficit de habitacional existente no Brasil. Neste trabalho, desenvolveu-se um estudo baseado no aproveitamento de escória de aciaria elétrica, resíduo gerado a partir da reciclagem do aço, empregada como agregado para concreto de cimento Portland, em substituição total ou parcial dos materiais convencionais. Os resultados obtidos apontaram para a viabilidade de utilização deste resíduo como agregado. / The reduction on the volume of produced wastes, from industries or agriculture, is becoming a current demand in all production processes. The lack of space to dispose these wastes, the environment contamination caused by them, besides the necessity to preserve the non-renewable natural resources, to reduce energy consumption and greenhouse gas emission , are making wastes recycling and reutilization an interesting alternative. The civil construction presents itself as a field quite able to utilize techniques to reuse wastes from different industries. Besides all the environmental benefits, this reuse by the civil construction can create new profits, as well as, the improvement of the characteristics of some construction materials and it can also decrease the costs of the construction, which is a major factor, considering the Brazilian habitation deficit. In the present work a study was developed based on the reutilization of the electric arc furnace slag, a metallurgic waste from the steel recycling process, employed as an aggregate to the concrete of Portland cement, totally or partially replacing the conventional materials. The obtained results indicate this waste reutilization viability.

Nodal semimetals host either degenerate points (Dirac/Weyl points) or lines whose band topology in Brillouin zone can be classified either as trivial (normal nodal semimetals) or non trivial (topological nodal semimetals). This thesis investigates the electronic structure of two different categories of topological nodal semimetals probed by angleresolved photoemission spectroscopy (ARPES): The first material is Indium Bismuth (InBi). InBi is a semimetal with simple tetragonal structure with P4/nmm space group. This space group is predicted to host protected nodal lines along the perpendicular momentum direction at the high symmetry lines of the Brillouin zone boundary even under strong spin-orbit coupling (SOC) situation. As a semimetal with two heavy elements, InBi is a suitable candidate to test the prediction. The investigation by ARPES demonstrates not only that InBi hosts the nodal line in the presence of strong SOC, it also shows the signature of type-II Dirac crossing along the perpendicular momentum direction from the center of Brillouin zone. However, as the nodal line observed is trivial in nature, there is no exotic drumhead surface states observed in this material. This finding demonstrates that Dirac crossings can be protected in a non-symmorphic space group. The second material is NbIrTe₄ which is a semimetal that breaks inversion symmetry predicted to host only four Weyl points. This simplest configuration is confirmed by the measurement from the top and bottom surface of NbIrTe₄ showing only a pair of Fermi arcs each. Furthermore, it is found that the Fermi arc connectivity on the bottom surface experiences re-wiring as it evolves from Weyl points energy to the ARPES Fermi energy level. This change is attributed to the hybridisation between the surface and the bulk states as their projection lie within the vicinity of each other. The finding in this work demonstrates that although Fermi arcs are guaranteed in Weyl semimetals, their shape and connectivity are not protected and may be altered accordingly.