Made available in DSpace on 2014-06-11T19:27:12Z (GMT). No. of bitstreams: 0 Previous issue date: 2011Bitstream added on 2014-06-13T19:35:03Z : No. of bitstreams: 1 munekata_rm_me_ilha.pdf: 4705141 bytes, checksum: 56254cadfa4c90cb796f3b90671140ee (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O presente trabalho estudou a influência da energia do pulso de soldagem, no caso processo laser de Nd:YAG operando no modo pulsado, na soldagem de duas lâminas finas com 100 μm de Hastelloy C-276, utilizado no revestimento de sensores que trabalham em ambiente corrosivo da indústria sucroalcooleira, química petroquímica e alimentícia. Utilizou-se energia de pulso de 1,0 Joule a 2,25 Joules, com incremento de 0,25 Joules com a velocidade de soldagem de (ν) taxa de repetição (Rr) fixas de 525mm/min e 39Hz respectivamente e largura temporal de 4 ms. As soldas foram realizadas com proteção gasosa de argônio. Foram realizadas análises macrográficas e micrográficas das juntas soldadas, através de secções transversais das mesmas e ensaios de microdureza Vickers e ensaio de tração. Os resultados obtidos mostraram que o controle da energia do pulso, em processo de soldagem por laser de lâminas finas é de fundamental importância para a geração de juntas soldadas livres de descontinuidades. Os parâmetros geométricos da junta soldada, tais como largura do cordão, largura de união e profundidade do cordão, aumentaram em função do aumento da energia do pulso. O processo mostrou-se muito sensível à formação de porosidade e à presença de gap entre as lâminas / This work measured experimental investigations were carried out using a pulsed neodymium: yttrium aluminum garnet laser welding to examine the influence of the pulse energy in two thin foil welding with 100 μm thickness, employed to cover sensors that work in corrosive environment of the sugar and alcohol industry,chemical petrochemistry and nourishing. The pulse energy was varied from 1,0 to 2,25 J at an increment of 0.25 J and an increment of 0.25 Joules with a welding speed and(ν) repetition rate (Rr) fixed 525mm/min and 39Hz respectively and 4 ms pulse duration. The specimens were laser-welded in an argon atmosphere. The welds were analyzed by macroscopic and microscopic observations using optical microscopy and micro hardness and tensile test. The results indicated that pulse energy control, in laser welding of thin foils, is of considerable importance for weld quality since it can generate discontinuities free weld joints. The geometric parameters of the welded joints like bead width, connection width and bead depth increased with the pulse energy increasing. The process showed very sensitive to porosity formation and gap between couple

Orientador: Vicente Afonso Ventrella / Resumo: O presente trabalho consistiu em uma análise da influência da adição de elementos gamagênicos, estabilizadores da austenita, no processo de união autógena do aço superduplex UNS S32750, soldados com Laser Pulsado Nd:YAG. Os corpos de prova foram soldados utilizando duas técnicas: introdução de nitrogênio gasoso na atmosfera protetora, e adição de uma liga de níquel (Inconel 625 e Hastelloy C-276) na junta a ser soldada, tendo-se como objetivo a avaliação das propriedades mecânicas e microestruturais da junta soldada, como microdureza e tração. Todos os dados foram obtidos nos laboratórios da área de Materiais e Processos de Fabricação e no Laboratório de Soldagem da UNESP – Universidade Estadual Paulista Júlio de Mesquita Filho, Campus de Ilha Solteira, SP. O processo de soldagem foi realizado com a máquina de solda a laser UW 150A. Para a revelação dos detalhes dos cordões de solda foi utilizado o reagente Behara modificado. As medidas geométricas dos cordões de solda, como largura e profundidade, foram realizadas no microscópio Estéreo Zeiss Discovery V8. O MEV (Microscópio Eletrônico de Varredura) foi utilizado para a obtenção dos detalhes microscópicos dos cordões de solda. Os ensaios de tração foram realizados na Máquina Universal de Ensaios, e os valores de microdureza Vickers foram obtidos com o apoio do ultramicrodurômetro digital Shimadzu, modelo DUH 211S. Os resultados da microdureza Vickers, e dos ensaios de tração, nos corpos de prova obtidos com o uso dos gases d... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The present work consisted in an analysis of the influence of the addition of gamma - genic elements, stabilizers of austenite, in the process of autogenous union of the superduplex steel UNS S32750, welded with Nd: YAG Pulsed Laser. The specimens were welded using two techniques: introduction of gaseous nitrogen into the protective atmosphere and addition of a nickel alloy (Inconel 625 and Hastelloy C-276) in the joint to be welded, with the objective of evaluating the mechanical properties and microstructural weld joints, such as microhardness and tensile strength. All data were obtained from laboratories in the area of Materials and Processes of Manufacture and at the Welding Laboratory of UNESP - Paulista State University Júlio de Mesquita Filho, Campus de Ilha Solteira, SP. The welding process was performed with the UW 150A laser welding machine. For the development of details of the weld beads, the modified Behara reagent was used. The geometric measurements of the weld beads, such as width and depth, were performed on the Zeiss Discovery V8 Stereo Microscope. SEM (Scanning Electron Microscope) was used to obtain the microscopic details of the weld beads. The tensile tests were performed in the Universal Testing Machine, and the Vickers microhardness values were obtained with the support of the Shimadzu digital ultramicrodurometer, model DUH 211S. The results of the Vickers microhardness and the tensile tests on the specimens obtained with the protection gases Argon and... (Complete abstract click electronic access below) / Mestre

Resumo: O presente trabalho estudou a influência da energia do pulso de soldagem, no caso processo laser de Nd:YAG operando no modo pulsado, na soldagem de duas lâminas finas com 100 μm de Hastelloy C-276, utilizado no revestimento de sensores que trabalham em ambiente corrosivo da indústria sucroalcooleira, química petroquímica e alimentícia. Utilizou-se energia de pulso de 1,0 Joule a 2,25 Joules, com incremento de 0,25 Joules com a velocidade de soldagem de (ν) taxa de repetição (Rr) fixas de 525mm/min e 39Hz respectivamente e largura temporal de 4 ms. As soldas foram realizadas com proteção gasosa de argônio. Foram realizadas análises macrográficas e micrográficas das juntas soldadas, através de secções transversais das mesmas e ensaios de microdureza Vickers e ensaio de tração. Os resultados obtidos mostraram que o controle da energia do pulso, em processo de soldagem por laser de lâminas finas é de fundamental importância para a geração de juntas soldadas livres de descontinuidades. Os parâmetros geométricos da junta soldada, tais como largura do cordão, largura de união e profundidade do cordão, aumentaram em função do aumento da energia do pulso. O processo mostrou-se muito sensível à formação de porosidade e à presença de gap entre as lâminas / Abstract: This work measured experimental investigations were carried out using a pulsed neodymium: yttrium aluminum garnet laser welding to examine the influence of the pulse energy in two thin foil welding with 100 μm thickness, employed to cover sensors that work in corrosive environment of the sugar and alcohol industry,chemical petrochemistry and nourishing. The pulse energy was varied from 1,0 to 2,25 J at an increment of 0.25 J and an increment of 0.25 Joules with a welding speed and(ν) repetition rate (Rr) fixed 525mm/min and 39Hz respectively and 4 ms pulse duration. The specimens were laser-welded in an argon atmosphere. The welds were analyzed by macroscopic and microscopic observations using optical microscopy and micro hardness and tensile test. The results indicated that pulse energy control, in laser welding of thin foils, is of considerable importance for weld quality since it can generate discontinuities free weld joints. The geometric parameters of the welded joints like bead width, connection width and bead depth increased with the pulse energy increasing. The process showed very sensitive to porosity formation and gap between couple / Orientador: Ruis Camargo Tokimatsu / Coorientador: Vicente Afonso Ventrella / Banca: Alessandro Roger Rodrigues / Banca: Ricardo Cury Ibrahim / Mestre

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Microstructure and micro-mechanical characterization of as-built and heat-treated samples of Hastelloy X produced by laser powder bed fusion (LPBF) process has been carried out in this study. As-built LPBF blocks were solution heat-treated at 1177°C and 1220°C followed by fast cooling. The microstructure of as-built and heat-treated samples were studied by light optical microscopy, scanning electron microscopy, and electron backscatter diffraction. Instrumented indentation micro Vickers testing was performed to obtain microhardness and elastic modulus of asbuilt and heat-treated samples. Microtensile samples from as-built and heat-treated blocks were prepared and polished for mechanical characterization. Microtensile testing inside the scanning electron microscope was performed to evaluate the mechanical properties and to get information about the microstructural changes during plastic deformation. Microstructure characterization revealed disrupted epitaxial grain growth for the as-built samples whereas the two heated-treated Hastelloy X samples exhibited equiaxed grains with varying twin fractions. As-built Hastelloy X samples exhibited higher mean hardness than heat-treated samples. The yield strength of as-built samples reveals higher values as compared to conventional wrought Hastelloy X samples, whereas lower yield strength and higher elongation were observed for heat-treated samples as compared to as-built samples. Higher elongation and lower yield strength values were observed for the samples solution heat-treated at 1220°C compared to the solution heat-treated at 1177°C. Microstructural evaluation at different plastic strains during in-situ microtensile testing reveals a clear difference in dislocation density for as-built and heat-treated samples.