This diploma thesis deals with design of welding power supply for MIG / MAG and MMA technique with continuous output current 120 A. The first, theoretical part is devoted to welding process technology, physical characteristics of electric arc and description of individual welding methods. The thesis also deals with the concept of power converter. The design of the switched-mode power supply is based on a full bridge topology. In order to implement advanced controls of welding power supply, the ARM Cortex M4 microprocessor was selected. Due to the large power consumption of the stepper motor for drive the welding wire, an auxiliary switched-mode power supply was also implemented. The documentation describing the realization of the welding power supply and the results of the measurements are in the last part of the thesis. The welding power supply was successfully revived and reached nominal parameters. Inert gas welding has not been tested yet, due to lack of time caused by extensive work in order to complete mechanical realization.

The project aimed at the selection of the optimal welding method for a „fuel cell“ component in terms of the VN-Ú Ltd engineering company. The goal is to compare the methods available in VN-Ú, that is: TIG, MIG/MAG and CMT. It is necessary to analyze the specifics of each of the technologies and the operation conditions which the component will be exposed to. For the comparison of the methods, non-destructive testing of the components, as well as destructive tests of the produced samples have been used. The economic evaluation has been used to compare the costs of different welding methods of the components and to assess the potential investments in CMT device that has only been leased by VN-U so far.

Undersökningen syftar till att utreda huruvida historiemedvetandet hos elever med ett dubbelt kulturarv från Sverige och ett arabisktalande land kan inkluderas i historiegymnasiekursen 1a1. Med hjälp av relevant litteratur och utifrån problemformuleringen: ”Hur kan pedagogen lära känna elevens historiemedvetande?” har jag utarbetat intervjufrågor som avser till ett ta fram exempel på dessa elevers historiemedvetande. Undersökningens urval var sex elever som gått på yrkesförberedande gymnasium och har läst eller läser historiekursen 1a1. Intervjuerna är utarbetade med hjälp av litteratur kring historiemedvetandet främst utifrån perspektiven kultur, identitet och intresse. Resultatet av intervjuerna visar på att det för pedagogen går att få kunskap om delar av elevens historiemedvetande. Min andra frågeställning i undersökningen lyder: ”Hur kan dessa elevers historiemedvetande rymmas inom läroplanen för historiekursen 1a1? Här har jag kommit fram till att det är möjligt att inkludera elever med arabisktalande dubbla kulturarv i undervisningen i historiekursen 1a1. Genom den pedagogiska uppgiften ”boken om mig” fick de intervjuade eleverna berätta om sig själva och vilka historiska perspektiv de var intresserade av. Intervjusvaren skiljde sig mycket åt men individuella svar gav uppslag att undersöka om dessa rymdes inom historiekursen 1a1. Vilket de gjorde. Alla intervjupersonerna ville veta mer om Islams påverkan på historien vilket det också finns utrymme för i läroplanen. Studien visar vidare att genom Ross Dunns historieperspektiv Patterns of Change Model som fokuserar på kulturmöten istället för exempelvis nationalstaters konflikter och sammarbeten kunde dessa elevers historiemedvetande inkluderas.

This research is aimed at understanding the effect of thermal cycles on the metallurgical and microstructural characteristics of the heat affected zone of a multi-pass pipeline weld. Continuous Cooling Transformation (CCT) diagrams of the pipeline steel grades studied (X65, X70 and X100) were generated using a thermo mechanical simulator (Gleeble 3500) and 10 mm diameter by 100 mm length samples. The volume change during phase transformation was studied by a dilatometer, this is to understand the thermodynamics and kinetics of phase formation when subjected to such varying cooling rates. Samples were heated rapidly at a rate of 400°C/s and the cooling rates were varied between t8/5 of 5.34°C/s to 1000°C/s. The transformation lines were identified using the dilatometric data, metallographic analysis and the micro hardness of the heat treated samples. Two welding processes, submerged arc welding (SAW) and tandem Metal Inert Gas (MIG) Welding, with vastly different heat inputs were studied. An API-5L grades X65, X70 and X100 pipeline steels with a narrow groove bevel were experimented with both welding processes. The welding thermal cycles during multi-pass welding were recorded using thermocouples. The microstructural characteristics and metallurgical phase formation was studied and correlated with the fracture toughness behaviour as determined through the Crack Tip Opening Displacement (CTOD) tests on the welded specimens. It was observed that SAW process is more susceptible to generate undesirable martensite-austenite (M-A) phase which induce formation of localised brittle zones (LBZ) which can adversely affect the CTOD performance. Superimposition of the multiple thermal cycles, measured in-situ from the different welding processes on the derived CCTs, helped in understanding the mechanism of formation of localised brittle zones. Charpy impact samples were machined from the two X65 and X70 grades, for use in thermal simulation experiments using thermo mechanical simulator (Gleeble). The real thermal cycles recorded from the HAZ of the SAW were used for the thermal simulations, in terms of heating and cooling rates. This is to reproduce the microstructures of the welds HAZ in bulk on a charpy impact sample which was used for impact toughness testing, hardness and metallurgical characterisation. The three materials used were showing different response in terms of the applied thermal cycles and the corresponding toughness behaviours. The X65 (a) i.e. the seamless pipe was showing a complete loss of toughness when subjected to the single, double and triple thermal cycles, while the X65 (b), which is a TMCP material was showing excellent toughness in most cases when subjected to the same thermal cycles at different test temperatures. The X70 TMCP as well was showing a loss of toughness as compared to the X65 (b). From the continuous cooling transformation diagrams and the thermally simulated samples results it could be established that different materials subjected to similar thermal cycle can produce different metallurgical phases depending on the composition, processing route and the starting microstructure.

In this thesis, new methods for shear strength are proposed and backed up through extensive experimentation, ABAQUS models and data analysis of Titanium welds of three different alloys. The results are compared with those obtained by using the procedure outlined by AWS B4 for calculating Shear Strength in the transverse and longitudinal directions; this equation is widely used by the American Welding Society (AWS) and all those in search of more efficient designs involving welding. It is a well-documented issue that the equation provided by AWS yields a large discrepancy between the values for shear strength of longitudinal and transverse welds.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / O uso de componentes revestidos por ligas de nÃquel do sistema Ni-Cr-Mo em equipamentos da indÃstria do petrÃleo pode vir a ser mais freqÃente, pois os aumentos no Ãndice de acidez naftÃnica e no peso molecular do petrÃleo nacional requerem materiais mais resistentes à corrosÃo, temperatura e pressÃo. Desta forma, como parte de um estudo sistemÃtico, este trabalho pretende definir faixas operacionais para revestir de forma adequada aÃo estrutural com o eletrodo ERNiCrMo-3, atravÃs da soldagem MIG/MAG, e avaliar caracterÃsticas microestruturais e propriedades mecÃnicas de revestimentos na condiÃÃo como soldados e envelhecidos. Para atingir o objetivo, foram realizadas soldagens automÃticas com utilizaÃÃo de robà industrial, fonte eletrÃnica e argÃnio puro como gÃs de proteÃÃo. Para definiÃÃo das faixas operacionais, as soldagens foram em simples deposiÃÃo, com avaliaÃÃo de aspecto superficial, geometria e diluiÃÃo da solda. Nesta etapa, foi constatado que a solda apresenta alta convexidade em corrente eficaz abaixo de 200 A e a variaÃÃo da corrente, para o cÃlculo da energia, influencia de forma mais significativa na convexidade e na diluiÃÃo da solda, em comparaÃÃo com a variaÃÃo da velocidade de soldagem, para o cÃlculo das mesmas energias. AtravÃs dos testes preliminares, foi selecionada a corrente de 290 A em duas energias de soldagem (10 e 14 kJ/cm). O revestimento foi em Ãnica camada aplicada em aÃo ASTM A516 g60 de 12,7 mm de espessura, com sobreposiÃÃo acima de 40 % e temperatura de interpasse abaixo de 100 oC. A diluiÃÃo em ambas as energias ficou em torno de 15 %. O envelhecimento foi na temperatura de 600 oC por tempos de 100 e 300 horas. Para caracterizaÃÃo metalÃrgica foram utilizados: perfis de microdureza, microscopia Ãtica (MO) e eletrÃnica de varredura (MEV), energia dispersiva de raio X (EDX), difraÃÃo de raio X, energia de elÃtrons retro-espalhados (EBSD) e ensaio de arrancamento, segundo norma ASTM A 265-03. Os perfis de microdureza e estruturas observadas foram semelhantes para ambas as energias de soldagem utilizadas. ApÃs envelhecimento foi observado uma descarbonetaÃÃo da ZAC-GG onde as ferritas passaram a nÃo possuir segundas fases (carbonetos). A estrutura dendrÃtica do revestimento apresentou microfases do tipo MC e Laves na condiÃÃo como soldada. ApÃs o envelhecimento, houve formaÃÃo de carbonetos secundÃrios, dissoluÃÃo de carbonetos primÃrios e formaÃÃo de fase gamaââ. Os perfis de dureza indicaram que na condiÃÃo como soldada a dureza do revestimento foi de 240 HV e da ZAC-GG de 190 HV, com o envelhecimento a dureza na ZAC-GG caiu para 120 HV, e a do revestimento cresceu para 290 HV em 100 h e 310 HV em 300 h. Na interface foram observadas, somente apÃs o envelhecimento, regiÃes duras da ordem de 800 HV, devido a grande concentraÃÃo de carbonetos e envelhecimento da zona parcialmente diluÃda, com teor elevado de ferro, que atua na formaÃÃo de gamaââ. Apesar das elevadas diferenÃas de dureza entre o revestimento, metal base e interface nÃo foram identificadas trincas nas anÃlises metalogrÃficas. A carga mÃxima no ensaio de arrancamento foi superior a da norma (140 MPa) nas condiÃÃes analisadas. O perfil de penetraÃÃo dos cordÃes (tipo taÃa) favoreceu esse resultado, e o envelhecimento provocou um aumento gradativo de resistÃncia ao cisalhamento. / The use of nickel alloy cladding components could be more frequently in petroleum industry. The crescent naphthenic corrosion and high molecular weight of national petroleum contribute for needs of materials with more resistance to corrosion, to temperature and to pressure. At this way, how part of systematic study, this work pretends to define operational range for adequate ERNiCrMo-3 weld overlay in structural steel with application of GMAW process, and to evaluate microstructural characteristics and mechanical properties in as welded and aging conditions. To realize the objective, were used an industrial robot, an electronic power source and an argon shielding gas for automated welding. To define the operational range, simple deposit welds and evaluation of superficial aspect, geometry and dilution were conducted. This step indicated that the welds in efficient current below 200 A showed high convexity and the variation of current for the calc of heat input is more significant for convexity and dilution of the weld than the variation of welding speed for the calc of same heat input. It was selected 290 A as welding current in two heat inputs (10 and 14 kJ/cm). The overlay at ASTM A 516 g60 steel was in simple layer, had overlap up to 40 pct between passes and had about 15 pct of dilution at the two heat inputs. The aging temperature employed was 600 oC for times of 100 and 300 hours. To metallurgical characterization was used: microhardness measures, optical microscope, scanning electron microscope, composition variations (EDAX), x-ray diffraction, electron backscatter diffraction and shear tests according ASTM A 265-03 standard specification. The microhardness and structures observed were, approximately, the same for the two heat inputs. Post aging HAZ showed absence of carbides. The dendritic structure had MC and Laves micro-phases in as welded condition and the aging provoked formation of secondary carbides, dissolution of primary carbides and formation of gamaââ. As welded overlay microhardness was 240 HV and as welded HAZ was 190 HV. Aging HAZ was 120 HV and aging overlay was 290 HV for 100 h and 310 HV for 300 h. Only for aging conditions, were observed hard zones (800 HV) in interface of overlay, due to carbide concentration and aging of partially dilution zone, where the Fe favored the formation of gamaââ. Despite the hardness differences of overlay, base metal and interface, were identified no cracks in metallographic analyses. The maximum shear strength was above of the specification requirement (140 MPa) in all conditions employed, the penetration shape (like finger) favored this result, and the aging provoked a gradual grow up in shear resistance.

Allergic asthma is an immunological disease, mediated by CD4+ Th2 cells, and its prevalence has increased over recent decades. Features of allergic asthma include airway hyperresponsiveness (AHR), airway eosinophilia, excessive airway mucus production, and increased IgE and Th2 cytokine levels. Airway remodeling with pulmonary fibrosis is noted in the progress of asthma. In this thesis, a murine model of allergic asthma was used to investigate the effect of cyclophosphamide (CY) on asthma and the involvement of regulatory T cells (Treg), and the role of Granulocyte-macrophage colony stimulating-factor (GM-CSF) in allergic asthma by using GM-CSF knockout mice. CY is a cytotoxic agent, which paradoxically augments several immune responses. The first part of this thesis was aimed to study the effects of CY in a murine model of allergic airway inflammation. BALB/c mice were immunized with ovalbumin (OVA) on days 0 and 14, and challenged with aerosolized OVA from days 21 to 27. Some mice additionally received CY on days -2 and 12. In the CY-treated animals, pronounced worsening of inflammatory features was noted, including increases in eosinophil infiltration, epithelial thickness, mucus occlusion and eosinophil numbers in bronchoalveolar lavage fluid (BALF). Increased total and OVA-specific serum IgE were also noted in the CY-treated animals. In cell cultures from peritracheal lymph nodes, the Th2 cytokines IL-4 and IL-5 were elevated in animals treated with CY. It was hypothesized that the effects of CY could be caused by reduced immunosuppression mediated by Treg. mRNA expression of the immunosuppressive cytokines IL-10 and TGF-beta was reduced in the lungs of CY-treated mice. The expression of FoxP3, a marker of naturally occurring Treg, was significantly reduced in spleens, thymuses and peritracheal lymph nodes after the second injection of CY, and in the lung tissue after allergen challenge in CY-treated mice. Furthermore, lung IL-10-producing CD4+ T cells and CTLA-4+-bearing CD4+ T cells were reduced after allergen aerosol challenge in CY-treated mice. Thus CY worsened the features of allergic pulmonary inflammation in this model, in association with increased production of IgE and Th2 cytokines. The reduction in expression of FoxP3 and immunosuppressive cytokines by CY suggests that toxicity to Treg may contribute to the increased inflammation. GM-CSF plays a role in the growth, development, and maturation of bone marrow hemopoietic cells into mature blood cells, and has been proposed to be involved in potentiating the function of inflammatory cells in allergic inflammation. In the second part of this thesis, GM-CSF knockout (KO) mice were used to investigate the role of GM-CSF. In allergic KO mice, airway eosinophils were only shown in the perivascular, but not peribronchial areas in the lung, compared to the allergic wild-type (WT) mice in which eosinophil infiltration appeared in both areas. Eosinophil numbers were drastically reduced in the bronchoalveolar lavage fluid (BALF) of KO mice. IL-5 production in the lung tissue and BALF in allergic KO mice was reduced; similar results were also found in peritracheal draining lymph nodes after in vitro stimulation assays. However, IL-4 and IL-13 production, airway hyperresponsiveness (AHR), and serum IgE production were not affected in allergic KO mice. Surprisingly, lung IFN-gamma mRNA and BALF levels were increased in allergic KO mice. Lung mRNA levels of CCR3, a key chemokine receptor on eosinophils, were significantly reduced in allergic KO mice, whereas expression of the chemokines eotaxin and RANTES were at similar levels in allergic KO and WT mice. Lung mRNA levels of the IFN-gamma-inducible chemokines Mig (CXCL9) and IP-10 (CXCL10), which are antagonists of CCR3, and their receptor CXCR3 were increased in allergic KO mice, compared with allergic WT mice. Data obtained from flow cytometry showed more eosinophils survived in the lung of WT mice than KO mice. Another allergy model, a peritoneal allergy model was performed to investigate inflammation in a different model. Leukocyte subpopulations such as neutrophils, eosinophils, macrophages, and lymphocytes were reduced in the peritoneal lavage fluid of allergic KO mice. The findings revealed that GM-CSF is essential for IL-5 production, pulmonary airway eosinophilia and eosinophil survival. In the absence of GM-CSF, over-production of IFN-???? may induce chemokines, including Mig and IP-10, which are antagonists for CCR3 and may reduce airway eosinophil infiltration. In this thesis, a murine model of allergic asthma has been used to obtain novel findings on the regulation of allergic inflammation. The results with CY are relevant to the treatment of asthma patients with CY and other cytotoxic agents. The findings in the GM-CSF KO mice suggest that GM-CSF is a potential therapeutic target in asthma, and that in assessment of new therapeutic agents for asthma, effects on GM-CSF should be considered.

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.<br />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.<br />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.<br />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.

Allergic asthma is an immunological disease, mediated by CD4+ Th2 cells, and its prevalence has increased over recent decades. Features of allergic asthma include airway hyperresponsiveness (AHR), airway eosinophilia, excessive airway mucus production, and increased IgE and Th2 cytokine levels. Airway remodeling with pulmonary fibrosis is noted in the progress of asthma. In this thesis, a murine model of allergic asthma was used to investigate the effect of cyclophosphamide (CY) on asthma and the involvement of regulatory T cells (Treg), and the role of Granulocyte-macrophage colony stimulating-factor (GM-CSF) in allergic asthma by using GM-CSF knockout mice. CY is a cytotoxic agent, which paradoxically augments several immune responses. The first part of this thesis was aimed to study the effects of CY in a murine model of allergic airway inflammation. BALB/c mice were immunized with ovalbumin (OVA) on days 0 and 14, and challenged with aerosolized OVA from days 21 to 27. Some mice additionally received CY on days -2 and 12. In the CY-treated animals, pronounced worsening of inflammatory features was noted, including increases in eosinophil infiltration, epithelial thickness, mucus occlusion and eosinophil numbers in bronchoalveolar lavage fluid (BALF). Increased total and OVA-specific serum IgE were also noted in the CY-treated animals. In cell cultures from peritracheal lymph nodes, the Th2 cytokines IL-4 and IL-5 were elevated in animals treated with CY. It was hypothesized that the effects of CY could be caused by reduced immunosuppression mediated by Treg. mRNA expression of the immunosuppressive cytokines IL-10 and TGF-beta was reduced in the lungs of CY-treated mice. The expression of FoxP3, a marker of naturally occurring Treg, was significantly reduced in spleens, thymuses and peritracheal lymph nodes after the second injection of CY, and in the lung tissue after allergen challenge in CY-treated mice. Furthermore, lung IL-10-producing CD4+ T cells and CTLA-4+-bearing CD4+ T cells were reduced after allergen aerosol challenge in CY-treated mice. Thus CY worsened the features of allergic pulmonary inflammation in this model, in association with increased production of IgE and Th2 cytokines. The reduction in expression of FoxP3 and immunosuppressive cytokines by CY suggests that toxicity to Treg may contribute to the increased inflammation. GM-CSF plays a role in the growth, development, and maturation of bone marrow hemopoietic cells into mature blood cells, and has been proposed to be involved in potentiating the function of inflammatory cells in allergic inflammation. In the second part of this thesis, GM-CSF knockout (KO) mice were used to investigate the role of GM-CSF. In allergic KO mice, airway eosinophils were only shown in the perivascular, but not peribronchial areas in the lung, compared to the allergic wild-type (WT) mice in which eosinophil infiltration appeared in both areas. Eosinophil numbers were drastically reduced in the bronchoalveolar lavage fluid (BALF) of KO mice. IL-5 production in the lung tissue and BALF in allergic KO mice was reduced; similar results were also found in peritracheal draining lymph nodes after in vitro stimulation assays. However, IL-4 and IL-13 production, airway hyperresponsiveness (AHR), and serum IgE production were not affected in allergic KO mice. Surprisingly, lung IFN-gamma mRNA and BALF levels were increased in allergic KO mice. Lung mRNA levels of CCR3, a key chemokine receptor on eosinophils, were significantly reduced in allergic KO mice, whereas expression of the chemokines eotaxin and RANTES were at similar levels in allergic KO and WT mice. Lung mRNA levels of the IFN-gamma-inducible chemokines Mig (CXCL9) and IP-10 (CXCL10), which are antagonists of CCR3, and their receptor CXCR3 were increased in allergic KO mice, compared with allergic WT mice. Data obtained from flow cytometry showed more eosinophils survived in the lung of WT mice than KO mice. Another allergy model, a peritoneal allergy model was performed to investigate inflammation in a different model. Leukocyte subpopulations such as neutrophils, eosinophils, macrophages, and lymphocytes were reduced in the peritoneal lavage fluid of allergic KO mice. The findings revealed that GM-CSF is essential for IL-5 production, pulmonary airway eosinophilia and eosinophil survival. In the absence of GM-CSF, over-production of IFN-???? may induce chemokines, including Mig and IP-10, which are antagonists for CCR3 and may reduce airway eosinophil infiltration. In this thesis, a murine model of allergic asthma has been used to obtain novel findings on the regulation of allergic inflammation. The results with CY are relevant to the treatment of asthma patients with CY and other cytotoxic agents. The findings in the GM-CSF KO mice suggest that GM-CSF is a potential therapeutic target in asthma, and that in assessment of new therapeutic agents for asthma, effects on GM-CSF should be considered.

The MIG/MAG process is nowadays the most important welding process. This is due to its high production capacity, characteristic searched by industries to improve their manufacturing processes. Thus, due to this process relevance, development of tools that helps to understanding how it works comes out as necessary, especially in relation to proper welding setting up. One tool for this task is the transfer mode map, which predicts the type of metal transfer according to the welding setting up. However, these maps, normally, are more scientific oriented rather that for practical purposes. In this context, the objective of this work was to map the transfer modes in such a way that welders, supervisors and engineers could be helped in the choice of the best setting up needed. For this purpose, a methodology was developed to provide more information than transfer modes according to the parameter setting up. The proposed mapping had the intention of obtaining transfer regions with proper operating characteristics (stable transfer resulting of appropriate welding conditions) and also information about weld bead conditions, production, thermal cycle and arc radiation. For each transfer mode looked for working at typical welding conditions, which mean that the contact tip-to-work distance was different for the two main transfer modes (short-circuit and spray). A large number of experiments was performed to map the transfers, with the objective to determine a stable operating regions of short-circuit and spray transfer mode using the ER70S-6 welding wire with three different shielding gases. After mapping, single-welded butt joint were carried-out using specific points of the maps instead of bead-on-plate. The proposed methodology was efficient in exterminating regions of operational stability, according to the experiments. It was also possible to have better welding geometries, in general, for setting ups within the map region of operational stability, but the results also depend on the shielding gas and the transfer mode. For setting ups outside the map region of operational stability the bead finish gets worse, except for spray transfer mode when working below the region of operational stability. The deposition efficiency is lower for setting ups outside the region and with gases containing higher levels of CO2, except for short-circuit transfer. The arc radiation intensity is lower in regions below the operational stability and higher above this position, but it is highly dependent of the arc length. Changes in the contact tip-to-work distance and/or in the power source inductance have no influence on the region of operational stability, except for short-circuit transfer, in which the contact tip-to-work distance is able to reduce the set voltage for this region. / O processo de soldagem MIG/MAG é dos mais importantes processos de união de metais na atualidade. Isto se deve à sua alta capacidade de produção, característica constantemente cobiçada pelas indústrias em seus processos de fabricação. Assim, devido à relevância desse processo, torna-se necessária a construção de ferramentas que auxiliem no entendimento do funcionamento do mesmo, principalmente no que se refere à correta regulagem dos parâmetros de soldagem. Uma ferramenta utilizada para isto são os mapas de transferência metálica, que a partir dos parâmetros de regulagem, prevêem como resposta o tipo de transferência metálica. Porém, estes mapas, da forma que são normalmente confeccionados, são de caráter mais científico do que prático. Neste contexto, o objetivo deste trabalho foi a confecção de mapas de transferência práticos que venham auxiliar os usuários de soldagem (soldadores, supervisores e engenheiros) na escolha da melhor regulagem em função de suas necessidades. Para isto, foi desenvolvida uma metodologia que proporcionasse mais do que a informação sobre o tipo de transferência a partir da regulagem dos parâmetros. Nestes mapas propostos, objetivou-se obter uma região de transferência com característica operacional (transferência estável com condições de soldagem apropriadas) e também informações sobre o acabamento e perfil do cordão, rendimento de deposição, ciclo térmico e radiação emitida pelo arco. E para cada modo de transferência se procurou trabalhar apenas em condições típicas, o que fez com que a DBCP fosse diferenciada para dois modos principais de transferência (curto-circuito e goticular). Uma grande quantidade de experimentos foi realizada para mapear as transferências, com objetivo de delimitar uma região de estabilidade operacional de transferências por curto-circuito e outra goticular, utilizando o arame ER70S-6 e três gases de proteção para cada tipo de transferência. Após o levantamento, foram realizadas soldagens em pontos específicos dos mapas utilizando juntas ao invés de soldagem de cordão sobre chapa. Os resultados obtidos mostram que a metodologia proposta foi eficiente na determinação das regiões de estabilidade operacional. Mostraram também que o acabamento e a geometria do cordão, em geral, ficam melhores para regulagens dentro da região de estabilidade operacional, mas com resultados também dependentes do gás de proteção e tipo de transferência utilizada. Para regulagens fora da região de estabilidade operacional o acabamento piora, exceto para transferência goticular em regulagens abaixo da região. O rendimento de deposição é menor fora da região e com gases de proteção com maior teor de CO2, exceto para transferência por curto-circuito, onde, regulagens acima desta região não causam prejuízo. A intensidade de radiação emitida pelo arco é menor abaixo da região e maior acima desta, sendo dependente principalmente do comprimento de arco. A mudança da DBCP e da indutância da fonte não mostraram influência sobre a região de estabilidade operacional, exceto para transferência por curto-circuito, onde a DBCP promove a diminuição da regulagem das tensões desta região. / Mestre em Engenharia Mecânica