Submitted by Juliano Torteli De Godoi Zucato (jtgzucato@gmail.com) on 2018-08-15T17:17:02Z No. of bitstreams: 1 Dissertação Juliano Zucato.pdf: 6062254 bytes, checksum: c2ecd162aff92215ef89a486bafa836f (MD5) / Approved for entry into archive by Cristina Alexandra de Godoy null (cristina@adm.feis.unesp.br) on 2018-08-15T20:07:28Z (GMT) No. of bitstreams: 1 zucato_jtg_me_ilha.pdf: 6062254 bytes, checksum: c2ecd162aff92215ef89a486bafa836f (MD5) / Made available in DSpace on 2018-08-15T20:07:28Z (GMT). No. of bitstreams: 1 zucato_jtg_me_ilha.pdf: 6062254 bytes, checksum: c2ecd162aff92215ef89a486bafa836f (MD5) Previous issue date: 2018-07-03 / O trabalho consiste em um estudo da soldagem sobre uma placa da liga de titânio ASTM (Ti-6Al-4V) de espessura 1,44 mm, utilizando o processo de soldagem à laser Nd:YAG na condição autógena, realizando alterações de parâmetros no processo de soldagem afim de alterar o aporte térmico, encontrando propriedades características como a dureza, tensão de escoamento e microestrutura do material. Os ensaios realizados para a pesquisa foram: análise macrográfica, ensaio de tração, ensaio de microdureza e caracterização microestrutural. Para revelação dos detalhes no metal de solda, foi utilizado um ataque químico com o reagente Kroll. As medidas de geometria (largura e profundidade de penetração) dos cordões de solda, assim como a presença de descontinuidades, foram realizadas através de imagens obtidas pelo microscópio estéreo Zeiss Discovery.V8. O processamento e medição das imagens foi realizado através do software "AxioVision", um software associado ao microscópio utilizado. A análise da microestrutura foi realizada através do Microscópio Óptico Neophot 21, já o ensaio de tração foi realizado através de uma Máquina Universal de Ensaios, além do ensaio de microdureza, que foi realizado na escala Vickers. As análises das propriedades mecânicas foram confrontadas com a microestrutura obtida de acordo com a variação do aporte térmico. Como resultados, foram encontradas várias características essenciais para uma boa soldagem da liga, pois a cada incremento de aporte térmico, o cordão de solda aumenta em largura, profundidade e dureza, porém isto tem vantagem até determinado valor, pois conforme há o aumento do aporte térmico, a soldagem se fragiliza, pelo fato de existir vaporização do material e inclusão de poros na zona fundida. / The work consists of a study of the welding on a plate of titanium alloy ASTM (Ti-6Al-4V) of thickness 1.44 mm, using the welding process Nd: YAG in the autogenous condition, making changes of parameters in the process of welding in order to change the thermal input, finding characteristic properties such as hardness, yield stress and microstructure of the material. The tests carried out for the research were: macrographic analysis, tensile test, microhardness test and microstructural characterization. To reveal the details in the weld metal, a chemical attack was used with the Kroll reagent. The measurements of the geometry (width and depth of penetration) of the weld beads, as well as the presence of discontinuities, were made through images obtained by the stereo microscope Zeiss Discovery.V8. The images were processed and measured using the "AxioVision" software, a software associated with the microscope used. The analysis of the microstructure was performed through the Optical Microscope Neophot 21, and the tensile test was performed through a Universal Testing Machine, in addition to the microhardness test, which was performed on the Vickers scale. The analysis of the mechanical properties were compared with the microstructure obtained according to the variation of the thermal input. As a result, several essential characteristics have been found for a good welding of the alloy, because with each increment of thermal input, the weld bead increases in width, depth and hardness, however this has advantage until a certain value, since as there is increase of the contribution thermal, welding becomes fragile, due to the fact that there is vaporization of the material and inclusion of pores in the molten zone.

Orientadora: Profa. Dra. Patrícia Aparecida da Ana / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Biotecnociência, 2014.

Submitted by OTACILIO DONISETE FRANZINI null (otaciliodf@hotmail.com) on 2016-12-21T11:37:28Z No. of bitstreams: 1 APLICAÇÃO DE LASER PULSADO Nd YAG NA SOLDAGEM DO AÇO SUPER DUPLEX UNS S32750.pdf: 3133785 bytes, checksum: 7f73ce4a1615cca31edb63d392f368f2 (MD5) / Approved for entry into archive by Felipe Augusto Arakaki (arakaki@reitoria.unesp.br) on 2016-12-22T12:59:13Z (GMT) No. of bitstreams: 1 franzini_od_me_ilha.pdf: 3133785 bytes, checksum: 7f73ce4a1615cca31edb63d392f368f2 (MD5) / Made available in DSpace on 2016-12-22T12:59:13Z (GMT). No. of bitstreams: 1 franzini_od_me_ilha.pdf: 3133785 bytes, checksum: 7f73ce4a1615cca31edb63d392f368f2 (MD5) Previous issue date: 2016-12-13 / Os aços inoxidáveis Duplex e Super Duplex, 50% austenita e 50% ferrita, combinam as características mais desejáveis dos aços ferríticos e austeníticos, possuem excelente resistência mecânica e à corrosão para uma ampla variedade de meios, com expressiva resistência à corrosão em água do mar e outros ambientes contendo cloreto, devido a seu elevado nível de cromo, molibdênio, e nitrogênio. Quando soldado a região do metal de solda desses aços perdem suas características de resistência mecânica e à corrosão devido ao desbalanceamento das fases ferrita e austenita. No presente trabalho foi analisado a influência do processo de soldagem autógena a laser Pulsado Nd:YAG nas características mecânicas e microestruturais da junta soldada, variando a taxa de sobreposição dos pulsos de 40 a 90% em chapas de aço inoxidável Super Duplex UNS S32750 com 1,5 mm de espessura. Utilizou-se uma fonte laser pulsada Nd.YAG, United Winner 150A, com potência máxima de 150 W. A energia do pulso de soldagem foi fixada em 10J, potência de pico de 2 kW, largura temporal de 5 ms e frequência variando entre 1,5 e 9,0 Hz. Como gás de proteção utilizou-se argônio puro com vazão de 10 l/min. A caracterização microestrutural foi realizada através de microscopia ótica e microscopia eletrônica de varredura. Os resultados mostraram que o aumento da taxa de sobreposição da junta de 40% até 90% aumenta a resistência mecânica e a dureza do metal de solda. Em relação à microestrutura do metal de solda observou-se uma ferritização da mesma com pequena fração volumétrica de austenita nas regiões de contorno de grão. Não foi observada a presença de fases frágeis no metal de solda. / Duplex Stainless steels and Super Duplex 50% austenite and 50% ferrite, combine the most desirable traits of ferritic and austenitic steels possess excellent mechanical strength and corrosion resistance to a wide variety of ways, with substantial corrosion resistance in seawater and other environments containing chloride, due to its high level of chromium, molybdenum, and nitrogen. When welded to the weld metal region of these steels lose their mechanical strength features and corrosion due to the imbalance of the ferrite and austenite phases. In this paper we analyzed the influence of the welding process autogenous laser Pulsed Nd: YAG laser on the mechanical and microstructural features of the welded joint, by varying the overlap rate of pulses from 40 to 90% in stainless steel plates Super Duplex UNS S32750 with 1.5 mm thick. We used a pulsed laser source Nd.YAG, United Winner 150A, with maximum power of 150 W. The power of the welding pulse was set at 10 J, peak power of 2 kW, temporal width of 5 ms and frequency ranging from 1.5 and 9.0 Hz. As shielding gas used is pure argon with a flow rate of 10 l / min. Microstructural characterization was performed by optical microscopy and scanning electron microscopy. The results showed that increasing the overlap rate of 40% to 90% joint strength increases and the hardness of the weld metal. Regarding the welding ferritização observed a metal microstructure thereof with small volume fraction of the austenite grain boundary regions. It was observed the presence of brittle phases in the weld metal.

Orientador: Vicente Afonso Ventrella / Resumo: Os aços inoxidáveis Duplex e Super Duplex, 50% austenita e 50% ferrita, combinam as características mais desejáveis dos aços ferríticos e austeníticos, possuem excelente resistência mecânica e à corrosão para uma ampla variedade de meios, com expressiva resistência à corrosão em água do mar e outros ambientes contendo cloreto, devido a seu elevado nível de cromo, molibdênio, e nitrogênio. Quando soldado a região do metal de solda desses aços perdem suas características de resistência mecânica e à corrosão devido ao desbalanceamento das fases ferrita e austenita. No presente trabalho foi analisado a influência do processo de soldagem autógena a laser Pulsado Nd:YAG nas características mecânicas e microestruturais da junta soldada, variando a taxa de sobreposição dos pulsos de 40 a 90% em chapas de aço inoxidável Super Duplex UNS S32750 com 1,5 mm de espessura. Utilizou-se uma fonte laser pulsada Nd.YAG, United Winner 150A, com potência máxima de 150 W. A energia do pulso de soldagem foi fixada em 10J, potência de pico de 2 kW, largura temporal de 5 ms e frequência variando entre 1,5 e 9,0 Hz. Como gás de proteção utilizou-se argônio puro com vazão de 10 l/min. A caracterização microestrutural foi realizada através de microscopia ótica e microscopia eletrônica de varredura. Os resultados mostraram que o aumento da taxa de sobreposição da junta de 40% até 90% aumenta a resistência mecânica e a dureza do metal de solda. Em relação à microestrutura do metal de solda observou-se u... (Resumo completo, clicar acesso eletrônico abaixo) / Mestre

Die vorliegende Arbeit zielte auf die Erarbeitung der verfahrens- und legierungstechnischen Grundlagen zur Randschichtbehandlung von TiAl6V4 durch Dispergieren/Legieren mit Diboriden ab. Für die Untersuchungen zum Dispergieren/Legieren wurden sowohl unterschiedliche Lasersysteme (CO2, CO2-Slab, diodengepumpter Nd:YAG, Diodenlaser) als auch der Elektronenstrahl gewählt. Das Konzept für die Vorbehandlung und die Prozessgestaltung wurde entwickelt und erfolgreich getestet. Anhand von Untersuchungen zum Dispergieren/Legieren wurde das Prozessparameterfeld erarbeitet, wobei sich die nachfolgend aufgeführten Einflussgrößen als wesentlich erwiesen: • Pulverkorngröße (Kornfraktion 5 - 125 µm), • Pulvereintragsmenge (Förderparameter, Förderrate, Pulvervor-/-nachlauf, Pastenschichtdicke), • Prozessparameter (Strahlleistung, Defokussierung, Streckenenergie, Ablenkfigur). Zusammenfassend wurde die gute Eignung des Dispergierens/Legierens mittels Hochleistungsstrahlquellen für die Erzeugung boridverstärkter Randschichten an Bauteilen aus TiAl6V4 nachgewiesen.

Master's thesis deals with consideration possibility of conventional and unconvetional welding methods of wrought magnesium alloys. Methods of Friction Stir Welding, Pulsed Nd:YAG laser and Continuous Fiber laser was used to join magnesium alloy sheets AZ31, AZ61, ZE10 and ZE41. For studying influence of processing parameters on microstructure and mechanical properties were used methods of light microscopy, scanning electron microscopy, tensile tests and microhardness measurements. The results of tensile tests show that from the point of view of keeping ultimate tensile strength is the best methods for welding magnesium alloys Friction Stir Welding. Compared with Nd:YAG laser, fiber laser give better properties of welds. From comparing microstructure and mechanical properties . It wasn't found publications about Friction Stir Welding of magnesium ZE alloys or about FSW sheets with thickness only 0,8 mm and 1,6 mm.

Les études sur les procédés de soudage et sur la fiabilité des structures assemblées apparaissent actuellement comme un domaine de recherche actif, ouvert et complexe, car elles nécessitent de combiner de nombreuses connaissances dans différents domaines de la physique, de la mécanique et des procédés. La distribution des contraintes résiduelles joue un rôle important dans la vie des structures en favorisant la rupture par fatigue ou par fissuration. Ainsi, une meilleure compréhension des contraintes résiduelles évite l'utilisation de facteurs de sécurité plus élevés et, par conséquent permet de mieux optimiser le cycle de vie des structures soudées. A travers ce travail de thèse, nous nous sommes intéressés au soudage par laser d’un acier dual phase DP600, soudé en configuration par recouvrement, dont l’application est l’utilisation dans le domaine automobile. Cette thèse présente deux volets : un volet expérimental et un volet numérique.L’étude expérimentale nous a permis d’une part d’appréhender les conséquences métallurgiques et mécaniques du procédé laser sur l’acier DP600 et d’autre part d’utiliser et de valider les résultats numériques des modèles développés. L’étude numérique a eu pour objectif de prédire l’histoire thermique, métallurgique et l’évolution des caractéristiques mécaniques des tôles soudées par faisceau laser. Nous avons développé, sur un code de calcul par élémentsfinis Abaqus, trois modèles numériques. Le modèle thermomécanique, nous a permis de simuler la distribution spatio-temporelle de la température. Dans ce cas, le chargement appliqué est dépendant des paramètres du procédé etdes caractéristiques du faisceau laser et est associé à des conditions aux limites. Pour le modèle mécanique, nous avonsconsidéré un comportement élasto-plastique avec un chargement thermique transitoire, résultat du modèle thermique.Le deuxième modèle thermo-métallurgique nous a permis de simuler les phénomènes d’austénisation pendant la phase de chauffage (modèle de Waeckel) et de prendre en compte les fractions volumiques des phases martensitiques générées par les transformations de phases austénite–martensite lors du refroidissement (modèle de Koistinen-Marburger). Enfin, dans la dernière partie de simulation, nous avons réalisé le couplage thermo-metallo-mécanique. Les résultats obtenus dans la partie précédente, ont été implémentés dans deux modèles mécaniques : le modèle mécanique classique et le modèle mécanique avec prise en compte de la déformation liée aux effets de dilatation métallurgique. Cet effet a été intégré à travers le coefficient de dilatation thermique des phases ferritiques et martensitiques et des fractions volumiques obtenues à partir du modèle thermo-métallurgique. Les résultats ont montré que la répartition des contraintes résiduelles dans la zone de fusion et dans la zone affectée thermiquement sous l’effet de la déformation thermo-métallurgique donne des valeurs supérieures à celles estimées par le modèle élasto-plastique classique. / Studies on welding processes and the reliability of assembled structures currently appear as an area of active research, open and complex as they need to combine knowledge in many different fields of physics, mechanics and processes. The distribution of residual stress plays an important role in the life of welded structures by promoting fatigue failure or cracking. Thus, a better understanding of residual stress avoids the use of higher safety factors and therefore helps to optimize the life cycle of welded structures. Through this work, we are interested in laser welding of steel DP600 dual phase welded overlap configuration, the application is the use in the automotive field. This thesis has two components: an experimental and a numerical part. The experimental study allowed us, firstly to understand the metallurgical and mechanical effects of laser welding on steel DP600 and secondly to use and validate the numerical results of the developed models. The numerical study aimed to predict the thermal history, and metallurgical changes in mechanical properties of laser beam welded sheets. We have developed three numerical models by using a finite element code inside Abaqus. The thermomechanical model allowed us to simulate the temporal and spatial distribution of temperature. In this case, the applied load is dependent on the processing parameters and characteristics of the laser beam and is associated with boundary conditions. For the mechanical model, we considered an elastoplastic behavior with a transient thermal loading result of the thermal model. The second thermo-metallurgical m odel allowed us to simulate the phenomena austenitizing during the heating phase (Waeckel model) and take into account the volume fraction of martensitic phase transformations generated by the austenite-martensite transformation during cooling (Koistinen-Marburger model). Finally, in the last part of simulation, we have achieved the metallothermo- mechanical coupling. The results obtained in the previous section have been implemented in two mechanical models: the classical mechanics model and the mechanical model taking intoaccount the deformation due to the effects of metallurgical expansion. This effect has been built through the coefficient ofthermal expansion of ferritic and martensitic phases and volume fractions obtained from the thermo-metallurgical model. The results showed that the distribution of residual stresses in the fusion zone and the heat affected as a result of the eformation thermometallurgical field gives values higher than those estimated by the classical elastic-plastic model.

Due to their inherent BW capacity, optical interconnect (OI) offers a means of replacement to BW limited copper as bottlenecks begin to appear within the various interconnect levels of electronics systems. Low-cost optically enabled printed circuit boards are a key milestone on many electronics roadmaps, e.g. iNEMI. Current OI solutions found in industry are based upon optical fibres and are capable of providing a suitable platform for inter-board applications especially on the backplane. However, to allow component assembly onto high BW interconnects, an integral requirement for intra-board applications, optically enabled printed circuit boards containing waveguides are essential. Major barriers to the deployment of optical printed circuit boards include the compatibility of the technique, the cost of acquiring OI and the optical power budget. The purpose of this PhD research programme is to explore suitable techniques to address these barriers, primarily by means of laser material processing using UV and IR source lasers namely 248 nm KrF Excimer, 355 nm UV Nd:YAG and 10.6 μm IR CO2. The use of these three main lasers, the trio of which dominates most PCB production assembly, provides underpinning drive for the deployment of this technology into the industry at a very low cost without the need for any additional system or system modification. It further provides trade-offs among the suitable candidates in terms of processing speed, cost and quality of waveguides that could be achieved. This thesis presents the context of the research and the underlying governing science, i.e. theoretical analysis, involving laser-matter interactions. Experimental investigation of thermal (or pyrolitic) and bond-breaking (or photolytic) nature of laser ablation was studied in relation to each of the chosen lasers with regression analysis used to explain the experimental results. Optimal parameters necessary for achieving minimum Heat Affected Zone (HAZ) and surface/wall roughness were explored, both of which are key to achieving low loss waveguides. While photochemical dominance - a function of wavelength and pulse duration - is desired in laser ablation of photopolymers, the author has been able to find out that photothermallyprocessed materials, for example at 10.6 μm, can also provide desirable waveguides. Although there are literature information detailing the effect of certain parameters such as fluence, pulse repetition rate, pulse duration and wavelength among others, in relation to the etch rate of different materials, the machining of new materials requires new data to be obtained. In fact various models are available to try to explain the laser-matter interaction in a mathematical way, but these cannot be taken universally as they are deficient to general applications. For this reason, experimental optimisation appears to be the logical way forward at this stage of the research and thus requiring material-system characterisation to be conducted for each case thereby forming an integral achievement of this research. In this work, laser ablation of a single-layer optical polymer (Truemode™) multimode waveguides were successfully demonstrated using the aforementioned chosen lasers, thus providing opportunities for rapid deployment of OI to the PCB manufacturing industry. Truemode™ was chosen as it provides a very low absorption loss value < 0.04 dB/cm at 850 nm datacom wavelength used for VSR interconnections - a key to optical power budget - and its compatibility with current PCB fabrication processes. A wet-Truemode™ formulation was used which required that optical polymer layer on an FR4 substrate be formed using spin coating and then UV-cured in a nitrogen oxygen-free chamber. Layer thickness, chiefly influenced by spinning speed and duration, was studied in order to meet the optical layer thickness requirement for multimode (typically > 9 μm) waveguides. Two alternative polymers, namely polysiloxane-based photopolymer (OE4140 and OE 4141) from Dow Corning and PMMA, were sparingly utilized at some point in the research, mainly during laser machining using UV Nd:YAG and CO2 lasers. While Excimer laser was widely considered for polymer waveguide due to its high quality potential, the successful fabrication at 10.6 μm IR and 355 nm UV wavelengths and at relatively low propagation loss at datacom wavelength of 850 nm (estimated to be < 1.5 dB/cm) were unprecedented. The author considered further reduction in the optical loss by looking at the effect of fluence, power, pulse repetition rate, speed and optical density on the achievable propagation but found no direct relationship between these parameters; it is therefore concluded that process optimisation is the best practice. In addition, a novel in-plane 45-degree coupling mirror fabrication using Excimer laser ablation was demonstrated for the first time, which was considered to be vital for communication between chips (or other suitable components) at board-level.

Ces travaux ont porté dans un premier temps sur la mise en forme et l’étude de la densification de céramiques transparentes de YAG:Nd de grandes dimensions. Le choix des paramètres de coulage sous pression et de compaction isostatique à froid ont permis de contrôler les dimensions et la microstructure des pièces crues élaborées. Le frittage sous vide de ces céramiques a cependant conduit à une hétérogénéité microstructurale entre le coeur et le bord des échantillons. Plus particulièrement, des pores résiduels ont été détectés au coeur des céramiques, altérant les propriétés optiques. Des post-traitements HIP (Hot Isostatic Pressing) ont alors été mis en oeuvre pour mieux contrôler la microstructure des céramiques. Cette voie a démontré son efficacité pour réduire en nombre et en taille les pores résiduels, avec cependant certaines limites concernant notamment la réoxydation des céramiques de grandes dimensions. Finalement, les céramiques élaborées ont montré des performances laser proches de celles des monocristaux de même composition.Dans un second temps, un procédé de coulage en bande pour l’élaboration de céramiques transparentes de YAG multicouches a été développé. Plus particulièrement, un travail original a été mené sur l’étude de l’influence de la formulation des suspensions sur les propriétés mécaniques des bandes céramiques crues. Cette étude a ainsi permis d’élaborer des bandes pouvant être ultérieurement manipulées et transformées. Une céramique multicouche avec une bande centrale dopée en ion Nd3+ d’épaisseur contrôlée a alors pu être mise en forme par thermocompression de bandes de différentes compositions (YAG et YAG:Nd). Après déliantage et frittage, une céramique transparente de type « guide d’onde planaire » a finalement été obtenue. / The first step of this work was focused on the shaping and sintering of large sized Nd:YAG transparent ceramics. The choice of the pressure casting and cold isostatic pressing parameters allowed to control the thickness and the microstructure of the green bodies. However, vacuum sintering of these parts led to a microstructural heterogeneity between the core and the edge of the samples. More particularly, residual pores have been detected in the core of the ceramics, decreasing the optical properties. Then, HIP (Hot Isostatic Pressing) post-treatments were implemented to control the ceramics microstructure. This route helped to reduce the number and size of residual pores. But limitations appeared, especially concerning the large ceramics. Finally, the obtained ceramics showed laser performances close to those of the single crystals of same composition.The second part was devoted to the development of a tape casting process for the elaboration of YAG multilayered transparent ceramics. More particularly, the influence of the slurry formulation on the mechanical properties of the green tapes was studied. This original work allowed the shaping of green tapes with good mechanical properties and a controlled organic content. Then, a multilayered ceramic with a central Nd-doped layer could be elaborated by thermolamination of layers with different compositions (YAG and YAG: Nd). After debinding and sintering, a transparent ceramic planar waveguide was finally obtained.

No description available.