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Pool oscillations in tungsten inert gas welding pools have been used in a closed-loop control system for orbital welding of ultra high purity tubing, determining a target level of penetration by altering the welding current in real-time. The technique is ideally suited to this application since it is does not contravene the cleanliness requirements for the inner bore and can be implemented outside the small orbital heads that are commonly used. The results presented in this thesis show how clear pool oscillation signals in extremely small molten pools can be monitored by optimising the welding conditions and signal processing of the arc voltage signal. As an indicator of the likely variation in cast behaviour present particularly in austenitic stainless steels, a 'time-to-penetrate' characterisation was made of the materials, using the time of the transition from the Mode 1 to the Mode 3 oscillation behaviour as the measured variable. By applying the test across a range of welding currents, significant insight was obtained into the cast and associated penetration behaviour. Late transitions indicated casts that exhibited significantly different responses to the more usually applied welding procedures, especially at the lower levels of welding current (highlighting their potentially more problematic penetration behaviour). It was shown that the established theoretical models were difficult to apply with certainty to moving weld pools, and consequently a fuzzy logic model was used in the control strategy. The closed-loop system comprised a user-interface PC, a control rack and commercial welding power source - control signals were applied every 2 to 3 Hz. Mode 3 pool oscillations were found to offer a more than satisfactory sensitivity to the inner bead width created for the various casts of 1.65 mm wall thickness materials studied.

Wear resistant surfaces with high toughness and impact resistant properties are to be created to improve the life cycle cost of brake discs for trains. A potential solution to this industrial problem is to use an arc cladding process. This work describes the application of gas tungsten arc welding (GTAW) for a structural ceramic Metal Matrix Composite (MMC) on steel. The structure of the two ceramics examined indicates the possibility of development of a wear resistant surface, which would extend the life of the brake disc. Silicon Carbide (SiC) and Tungsten Carbide (WC) ceramics were studied to embed them in a steel matrix by an advanced GTAW method. WC particles penetrated the liquid weld pool and also partially dissolved in the steel matrix, whereas, SiC because of the physical properties never penetrated deeper into the weld pool but segregated on the surface. Successful embedding and bonding of WC led to the decision to exercise an in-depth analysis of the bonding between the WC particles and the matrix. Chemical analysis of the matrix revealed more WC dissolution as compared to particle form within the clad. It was observed that WC reinforcement particles built a strong chemical bond with the steel matrix. This was shown by electron backscatter diffraction (EBSD) analysis. The hard clad layer composed of WC reinforced steel matrix gave an matching friction coefficient to high-strength steel in cold wear conditions through Pin-on-Disc wear and friction testing. A prototype railway brake disc was created with the established GTAW parameters to find out the difficulties of producing industrial scale components.

Die additiven Fertigungstechnologien erleben seit einigen Jahren einen enormen Zuspruch bei der Herstellung von Einzelteilserien mit komplexen, endkonturnahen Geometrien und der Verarbeitung von Sonder- oder hybriden Werkstoffen. Prinzipiell lassen sich die Verfahren gemäß VDI- Richtlinie 3404 in drahtbasierte und pulverbasierte unterteilen. Eine weitere Unterteilung erfolgt hinsichtlich der Ausschmelztechnologie. Allen Verfahren ist gleich, dass schichtweise der Grundwerkstoff an den Stellen aufgetragen wird, wo er gemäß Endkontur benötigt wird. Damit ist ein immer wiederkehrender Wärmeeintrag verbunden, der somit Einfluss auf die Mikrostruktur der Bauteile und gleichzeitig auch auf die mechanischen Endeigenschaften ausübt. Die so erzeugten Komponenten sollten wenig Verzug oder Eigenspannungen als auch keine Porosität aufweisen, um die Gebrauchseigenschaften nicht negativ zu beeinflussen. Das Ziel ist es mittlerweile, diese verschiedenen Technologien numerisch abzubilden, um die Bauteileigenschaften vorherzusagen und ggf. Optimierungspotenziale zu eruieren. Der untersuchte Prozess ist das drahtbasierte Mehrlagenschweißen mittels des Metallschutzgasschweißens, bei dem neben der Simulation auch die Validierung im Fokus hinsichtlich Geometrie und Gefügeausbildung in den Schweißlagen stand. Diesbezüglich wurden im vorliegenden Fall zum einen alle, für die numerische Simulation notwendigen Materialparameter (mechanische und thermophysikalische Kenngrößen) des Schweißzusatzwerkstoffes G4Si1 bestimmt und in ein kommerzielles FEM-Programm (MSC Marc Mentat) implementiert. Zum anderen erfolgt zukünftig die wissenschaftliche Analyse der Verbesserung der Bauteileigenschaft, in dem die Schweißnaht unter Ausnutzung der Schweißhitze warmumgeformt wird. Erste Ergebnisse numerischer Simulationsergebnisse zeigen positive Effekte. Diese zeigen mikrostrukturelle Veränderungen (Kornfeinung durch Rekristallisation) und führten letztendlich zur Steigerung der mechanischen Eigenschaften. Der Vorteil dieser Verfahrenskombination ist außerdem die Kompensation des Verzuges durch die gezielte Umformung und einem gleichzeitigen „Richten“.

This diploma thesis deals with the development of multifunction welding machine for manual metal arc welding MMA and metal inert/active gas welding MIG/MAG. The goal of this work was to design compactly shaped welding inverter considering ergonomics and technological aspects. The thesis is divided into two parts. First part contains historical progress of arc welding, basic principles of chosen methods and view on contemporary market with welding machines. The second part deals with the development of the design, analysis and options of the final proposal.

O objetivo deste trabalho foi avaliar o efeito da soldagem TIG (\"tungsten inert gas\") e compará-la com soldagem a laser, em hastes cilíndricas e supra-estruturas implantosuportadas, confeccionadas em titânio comercialmente puro (Ti cp) por meio dos ensaios de resistência mecânica (tração e flexão) e desajuste marginal, respectivamente. Foram confeccionados noventa corpos-de-prova em titânio cp, sendo sessenta, na forma de hastes cilíndricas, obtidas por fundição de hastes de latão, e trinta na forma de supra-estruturas implanto-suportadas, obtidas por modelo de gesso com quatro análogos de implantes Microunit (Conexão), com dez repetições para cada grupo (controle, solda TIG, solda a Laser). Para a obtenção dos corpos-de-prova, foi realizada inclusão em revestimento Rematitan Plus, de acordo com as instruções fabricante. Os anéis foram submetidos aos ciclos térmicos e posicionados na máquina de fundição (Rematitan), sob arco voltaico, vácuo e atmosfera de argônio, com injeção de titânio sob vácuo-pressão. Após resfriamento, as fundições foram desincluídas e jateadas com óxido de alumínio. Os corpos-de-prova obtidos em forma de hastes cilíndricas foram distribuídos aleatoriamente, em três grupos, para ambos os ensaios, resistência à tração e flexão: grupo controle (sem solda), solda TIG e solda a Laser. As trinta supra-estruturas foram divididas aleatoriamente em três grupos: I- controle - monobloco; II-B- pós-soldagem TIG e III-B- pós-soldagem a Laser; os grupos II-A e III-A, foram constituídos dos espécimes antes do processo de soldagem: II-A- pré-soldagem TIG e III-A- pré-soldagem a Laser. Os dados obtidos para o Ensaio de Tração (MPa) foram analisados estatisticamente pelos testes ANOVA e Tukey (&alpha;= 0,05). O teste complementar de Tukey (p = 0,05) evidenciou que houve diferença entre o grupo controle (605,84 ± 19,83) e os métodos de soldagem TIG (514,90 ± 37,76) e Laser (515,85 ± 62,07). Para o Ensaio de Flexão (MPa), o teste não-paramétrico de Kruskal-Wallis mostrou que não houve diferença estatisticamente significante entre os processos de soldagem TIG (1559,66) e Laser (1621,64), contudo a diferença foi significante entre estes grupos e o controle (1908,75). Para análise dos resultados do desajuste marginal (&mu;m) das supra-estruturas implanto-suportadas, o teste nãoparamétrico de Kruskal-Wallis revelou que não houve diferença estatisticamente significante entre os grupos pós-soldagem TIG (250) e pós-soldagem Laser (241), entretanto, o grupo controle (770) apresentou o maior desajuste. Pelos resultados obtidos e dentro das limitações deste estudo, pode-se afirmar que a soldagem a TIG propicia a obtenção de resultados similares à soldagem a Laser. / The aim of this study was to evaluate the effect of TIG welding (tungsten inert gas) and compare it with Laser welding, of the cylindrical rods and implant-supported frameworks, obtained by in commercially pure titanium (cp) through the mechanical resistance (tensile and flexural strength) and misfit marginal, respectively. Ninety specimens have been fabricated titanium cp, and sixty, cylindrical rods, obtained by casting of the brass rods, and thirty implant-supported frameworks, obtained by plaster die with four similar - Microunit implants (Connection), with ten repetitions for each group (control, TIG welding, laser welding). The specimens were invested in Rematitan Plus, according to the manufacturer instructions. The rings were subjected to thermal cycling and positioned in the machine of casting (Rematitan) under voltaic arc, vacuum and atmosphere of argon, with injection of titanium vacuumpressure. After cooling, were manually and airbone-particle abraded with aluminum oxide. The specimes cylindrical rods were randomly distributed in three groups, for tests, tensile and flexural strength: the control group (without welding), TIG welding and soldering laser. The above thirty-structures were randomly divided into three groups: I- one-piece-cast (control)-, II-B-after-TIG welding and III-B-after-Laser welding, the Group II-A, III-A, consisted of specimens before the process of welding: II-A-before-TIG welding and III-A before-Laser welding. The results for the test Traction were submitted to variance analysis ANOVA (p < 0.05) being observed difference between groups. The supplementary Tukey test (p = 0.05) showed that there was a difference between the control group (605.84 ± 19.83) and the methods of welding TIG (514.90 ± 37.76) and laser (515.85 ± 62.07). To test the Flexion nonparametric test Kruskal-Wallis showed that there was no statistically significant difference between the processes of TIG welding (1559.66) and Laser (1621.64), but the difference was significant between these groups and control (1908.75). For analysis of the results of marginal misfit implant-supported frameworks, the non-parametric Kruskal-Wallis test revealed that there was no statistically significant difference between groups after-TIG welding (250) and after- Laser welding (241), however, the control group (770) showed the largest misfit. With these and the limitations of this study TIG welding in may be to Laser welding.

O objetivo deste trabalho foi avaliar o efeito da soldagem TIG (\"tungsten inert gas\") e compará-la com soldagem a laser, em hastes cilíndricas e supra-estruturas implantosuportadas, confeccionadas em titânio comercialmente puro (Ti cp) por meio dos ensaios de resistência mecânica (tração e flexão) e desajuste marginal, respectivamente. Foram confeccionados noventa corpos-de-prova em titânio cp, sendo sessenta, na forma de hastes cilíndricas, obtidas por fundição de hastes de latão, e trinta na forma de supra-estruturas implanto-suportadas, obtidas por modelo de gesso com quatro análogos de implantes Microunit (Conexão), com dez repetições para cada grupo (controle, solda TIG, solda a Laser). Para a obtenção dos corpos-de-prova, foi realizada inclusão em revestimento Rematitan Plus, de acordo com as instruções fabricante. Os anéis foram submetidos aos ciclos térmicos e posicionados na máquina de fundição (Rematitan), sob arco voltaico, vácuo e atmosfera de argônio, com injeção de titânio sob vácuo-pressão. Após resfriamento, as fundições foram desincluídas e jateadas com óxido de alumínio. Os corpos-de-prova obtidos em forma de hastes cilíndricas foram distribuídos aleatoriamente, em três grupos, para ambos os ensaios, resistência à tração e flexão: grupo controle (sem solda), solda TIG e solda a Laser. As trinta supra-estruturas foram divididas aleatoriamente em três grupos: I- controle - monobloco; II-B- pós-soldagem TIG e III-B- pós-soldagem a Laser; os grupos II-A e III-A, foram constituídos dos espécimes antes do processo de soldagem: II-A- pré-soldagem TIG e III-A- pré-soldagem a Laser. Os dados obtidos para o Ensaio de Tração (MPa) foram analisados estatisticamente pelos testes ANOVA e Tukey (&alpha;= 0,05). O teste complementar de Tukey (p = 0,05) evidenciou que houve diferença entre o grupo controle (605,84 ± 19,83) e os métodos de soldagem TIG (514,90 ± 37,76) e Laser (515,85 ± 62,07). Para o Ensaio de Flexão (MPa), o teste não-paramétrico de Kruskal-Wallis mostrou que não houve diferença estatisticamente significante entre os processos de soldagem TIG (1559,66) e Laser (1621,64), contudo a diferença foi significante entre estes grupos e o controle (1908,75). Para análise dos resultados do desajuste marginal (&mu;m) das supra-estruturas implanto-suportadas, o teste nãoparamétrico de Kruskal-Wallis revelou que não houve diferença estatisticamente significante entre os grupos pós-soldagem TIG (250) e pós-soldagem Laser (241), entretanto, o grupo controle (770) apresentou o maior desajuste. Pelos resultados obtidos e dentro das limitações deste estudo, pode-se afirmar que a soldagem a TIG propicia a obtenção de resultados similares à soldagem a Laser. / The aim of this study was to evaluate the effect of TIG welding (tungsten inert gas) and compare it with Laser welding, of the cylindrical rods and implant-supported frameworks, obtained by in commercially pure titanium (cp) through the mechanical resistance (tensile and flexural strength) and misfit marginal, respectively. Ninety specimens have been fabricated titanium cp, and sixty, cylindrical rods, obtained by casting of the brass rods, and thirty implant-supported frameworks, obtained by plaster die with four similar - Microunit implants (Connection), with ten repetitions for each group (control, TIG welding, laser welding). The specimens were invested in Rematitan Plus, according to the manufacturer instructions. The rings were subjected to thermal cycling and positioned in the machine of casting (Rematitan) under voltaic arc, vacuum and atmosphere of argon, with injection of titanium vacuumpressure. After cooling, were manually and airbone-particle abraded with aluminum oxide. The specimes cylindrical rods were randomly distributed in three groups, for tests, tensile and flexural strength: the control group (without welding), TIG welding and soldering laser. The above thirty-structures were randomly divided into three groups: I- one-piece-cast (control)-, II-B-after-TIG welding and III-B-after-Laser welding, the Group II-A, III-A, consisted of specimens before the process of welding: II-A-before-TIG welding and III-A before-Laser welding. The results for the test Traction were submitted to variance analysis ANOVA (p < 0.05) being observed difference between groups. The supplementary Tukey test (p = 0.05) showed that there was a difference between the control group (605.84 ± 19.83) and the methods of welding TIG (514.90 ± 37.76) and laser (515.85 ± 62.07). To test the Flexion nonparametric test Kruskal-Wallis showed that there was no statistically significant difference between the processes of TIG welding (1559.66) and Laser (1621.64), but the difference was significant between these groups and control (1908.75). For analysis of the results of marginal misfit implant-supported frameworks, the non-parametric Kruskal-Wallis test revealed that there was no statistically significant difference between groups after-TIG welding (250) and after- Laser welding (241), however, the control group (770) showed the largest misfit. With these and the limitations of this study TIG welding in may be to Laser welding.

This diploma thesis deals with the technology of noncontact hot plate welding and hot gas welding and with the optimizing of welding parameters of the chosen thermoplastics, especially of POM and PPA. The individual chapters in the theoretical part focus on following topics: technology of noncontact hot plate welding, technology of noncontact hot gas welding, description of the test welding machines and tools, main process parameters and evaluation of the advantages and disadvantages of each technology. In the practical part the welding parameters are optimized by the Design of Experiment systematic, the short-term capability machine and the microtome analysis are evaluated. In the end there are the results of the welding parameters optimization and comparison of noncontact welding technologies.

Orientadores: Antonio J. Ramirez, Maria Clara F. Ierardi / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-09T21:56:05Z (GMT). No. of bitstreams: 1 Seraphim_RafaelMolena_M.pdf: 6485115 bytes, checksum: 380cfffee5fa982ec74a9cdc78c88e3a (MD5) Previous issue date: 2007 / Resumo: O avanço cientifico no estudo de átomos, moléculas e proteínas tem recebido uma contribuição significativa dos aceleradores de partículas, que em sua grande maioria são utilizados para a geração de radiação síncrotron. Por isso, o aprimoramento destas máquinas mostra-se de extrema importância para manter a ciência em seu contínuo avanço. O sistema de vácuo destas máquinas apresenta-se como um importante parâmetro para o seu bom funcionamento e melhorias neste promovem diretamente melhorias na qualidade da radiação síncrotron gerada. Logo, o desenvolvimento deste trabalho teve como principal objetivo o estudo das juntas soldadas das câmaras de vácuo que compõem o acelerador do Laboratório Nacional de Luz Síncrotron (LNLS). As juntas foram preparadas com o processo de soldagem GTAW (Gás Tungsten Arc Welding) mediante a utilização de diferentes gases de proteção, como Argônio, Hélio e Nitrogênio, e misturas entre estes. Os estudos concentraram-se na análise da influência dos gases de proteção na dessorção de gases das juntas soldadas. Para a caracterização destas utilizaram-se as técnicas de análise de superfícies Dessorção Estimulada por Elétrons (DEE) e Dessorção Estimulada por Fótons (DEF). Adicionalmente, realizou-se um estudo comparativo entre as duas técnicas buscando-se estabelecer relações entre os resultados fornecidos pelas mesmas. Os resultados mostraram que a dessorção de gases independe do gás de proteção de soldagem, mas depende sim do nível de oxidação das juntas soldadas, as quais podem apresentar altas taxas de dessorção caso estejam muito oxidadas e os óxidos não sejam camadas contínuas. Em conclusão pode-se dizer que as juntas soldadas para câmaras de vácuo de aceleradores de partículas devem apresentar baixos níveis de oxidação, e apesar das semelhanças encontradas entre a DEE e a DEF é aconselhável utilizar a DEF para a caracterização de superfícies para trabalharem com radiação síncrotron / Abstract: The scientific advance of atoms, molecules and proteins studies has received an important contribution from particle accelerators, which are mainly used to generate synchrotron radiation. Hence, the improvement of these machines is necessary to maintain the continuous advance of science. One of the key components for the adequate operation of these accelerators is the vacuum system. Thus, its improvement directly impacts on the quality of the generated synchrotron radiation. Therefore, the principal purpose of this work is to study the gas desorption from the welding joints on the particle accelerators vacuum chambers. The welds were prepared using the GTAW (Gas Tungsten Arc Welding) process with different shielding gases, as argon, helium and nitrogen, and some mixtures of them. The study concentrated on the analysis of the shielding gas influence on the gas desorption from the welded joints. The gas desorption of the joints was evaluated using Electron Stimulated Desorption (ESD) and Photon Stimulated Desorption (PSD). In addition, it was carried out a comparative study between both desorption techniques to establish relationships between the results provided by them. The results showed that the gas desorption from the welding joints does not depend on the welding shielding gas, but on the oxidation level of the joint, which can present high desorption yield if it is highly oxidized and these oxides are not a continuous film. Therefore, it is advisable to minimize the oxidation during welding of vacuum chambers for particle accelerators. Regarding the comparison between ESD and PSD they were found some similarities. However, PSD will have better performance characterizing surfaces that will be exposed to synchrotron radiation / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica