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Pilkvist, Andreas. "Analys och modellering av ljusbåglängdsregleringen i pulsad MIG/MAG-svetsning." Thesis, Linköping University, Department of Electrical Engineering, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-2370.
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This master thesis deals with problems in the arc length control in Pulsed MIG/MAG Welding. The main problem is that it is not possible to measure the arc length. In the present solution the voltage over both the electrode and the arc represents the arc length.
To improve the arc length control a model of the electrode melting has been built. One output from the model is the voltage over the electrode and with this voltage together with the measured voltage it is possible to calculate the voltage over just the arc. Then, having the arc voltage as a value of arc length the arc length control can be improved, which is showed in the end by simulations. Simulations with the present control system are compared with the new one, when the controller is able to control the arc voltage instead of the sum of both the electrode voltage and the arc voltage.
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Liu, WenDi. "Optimization of Molybdenum Electrodes for Glass Melting." Digital WPI, 2015. https://digitalcommons.wpi.edu/etd-dissertations/208.
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The U.S. glass industry is a $28 billion enterprise and millions of tons of glasses are melted each day by different heating techniques, such as conventional oil fired furnaces or via electrical heating. The share of electrical heating is bound to rise steadily because it is cleaner and more energy efficient. Due to this situation molybdenum will play a significant role in electrical glass melting, since it is the most frequently used electrode material to deliver the electricity into the glass melts. Although it has a high melting point, high electrical and thermal conductivity and a low coefficient of expansion, molybdenum electrodes fail because of lack of sustainability during the glass melting process. Melt reaction with electrodes is the fundamental barrier to higher melting temperatures. Glass manufacturers have suggested that the need for better performance of molybdenum electrodes will see a rapid advancement in the use of electric heating system in the U.S. This work first focused on post-mortem analysis on used molybdenum electrodes with and without the current load in order to establish failure mechanisms for molybdenum during glass melting. It was determined that service life of molybdenum electrodes are limited by poor oxidation and corrosion resistance of molybdenum with redox reactions. Various studies have shown that the failure mode for molybdenum electrodes is a complex phenomenon. It depends on chemical composition of the electrode, current density and frequency, and chemical composition of the glass melt, specifically polyvalent ions that may be present in the melt. In this work, the MoSiB coating was validated as a promising protection for molybdenum from oxidation attack. Several molybdenum and molybdenum based-alloy electrodes were tested in different molten glasses in the remelter furnace to optimize the structural characteristics that are needed in Mo electrodes. Moreover, the quantitative data and fundamental knowledge gained in this work is being applied for molybdenum electrode production to extend its service life and also improve its quality.
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Ellis, Jonathan Dudley. "Quality assurance by electron beam button melting." Thesis, Imperial College London, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286213.
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Powell, Adam Clayton IV. "Transport phenomena in electron beam melting and evaporation." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/39623.
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Klingvall, Ek Rebecca. "SURFACE PROPERTIES OF IMPLANTS MANUFACTURED USING ELECTRON BEAM MELTING." Licentiate thesis, Mittuniversitetet, Avdelningen för kvalitetsteknik, maskinteknik och matematik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-27125.
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This thesis summarizes the results concerning the manufacture of medical implants for bone replacement using electron beam melting (EBM) which is an additive manufacturing (AM) technology, and aims to satisfy the engineering needs for the medical functionality of manufacturing technology. This thesis has focused on some microscopic properties for surfaces and bone integration. The process parameters of EBM manufacturing were studied to ascertain whether they have impacts on surface appearance, as surface properties have impacts on bone integration and implant performance. EBM manufacturing uses an electron beam to melt metal powder onto each layer in a manner akin to welding. The electron beam is controlled by process parameters that may be altered to a certain extent by the operator. There are individual process parameters for every material, and new parameters are set when developing new materials. In this thesis, process parameters in default settings were altered to ascertain whether it was possible to specify process parameters for implant manufacturing. The blood chamber model was used for thromboinflammation validation, using human whole blood. The model is used to identify early reactions of coagulation and immunoreactions. The material used in this study was Ti6Al4V-ELI, which is corrosion resistant and has the same surface oxide layers as titanium, and CoCr-F75, which has high stiffness, is wear-resistant and is commonly used in articulating joints. The study shows that among the process parameters researched, a combination of speed and current have the most impact on surface roughness and an interaction of parameters were found using design of experiment (DOE). As-built EBM surfaces show thrombogenicity, which in previous studies has been associated with bone ingrowth. Surface structure of as-build EBM manufactured surfaces are similar to implants surfaces described by Pilliar (2005), but with superior material properties than those of implants with sintered metals beads. By altering the process parameters controlling the electron beam, surface roughness of as-build parts may be affected, and the rougher EBM manufactured surfaces tend to be more thrombogen than the finer EBM manufactured surfaces. As-build EBM manufactured surfaces in general show more thrombogenicity than conventional machined implants surfaces.Denna avhandling behandlar tillverkning av medicinska implantat för integration i ben. I fokus är den additiva tillverkningstekniken ”elektronstrålesmältning” ( Electron Beam Melting –EBM), en av flera tekniker som populärt beskrivs med termen 3D-skrivare. Avhandlingen fokuserar på mikroskopiska ytegenskaper och dess inverkan på benintegration. Processparametrarna för EBM-tillverkning studerades för att fastställa hur de påverkar ytans utseende, efter som ytegenskaper har effekt på implantatens funktion. EBM-tillverkning använder en elektronstråle som likt svetsning smälter ihop metallpulver. Elektronstrålen styrs av processparametrar som till viss mån kan justeras av maskinoperatören. Det finns individuella processparametrar för varje material och nya parametrar utvecklas till varje ny legering. I denna avhandling har ”grundinställningarnas processparametrar” studerats för att ta reda på om det är möjligt att ställa in specifika parametrar till implantattillverkning. Med hjälp av blodkammarmetoden, som använder humant blod, har thromboinflammatoriska egenskaper undersökts. Metoden identifierar tidiga koagulations- och immunologiska reaktioner. Legeringarna som undersökts i denna studie var Ti6Al4V-ELI, som är korrosionsbeständigt med samma uppsättning oxider på ytan som titan har, och CoCr-F75, en legering som har hög styvhet, är slitstarkt och är vanligt förekommande i implantat för leder. Bland de undersökta processparametrarna visar en kombination av hastighet och ström ha mest inverkan på ytjämnhet och en interaktion mellan parametrar identifierades med hjälp av försöksplanering. EBM-tillverkade ytor visade på thrombogena egenskaper som i tidigare studier kan relateras till god integration i benvävnad. Ytstrukturen hos EBM-tillverkade ytor liknar de implantatytor som Pilliar (2005) beskriver, men materialegenskaperna är bättre än de materialegenskaper som implantat, med sintrad yta, har. Genom att ändra processparametrarna som styr elektronstrålen kan ytstrukturen påverkas. Grövre EBM-tillverkade ytor tenderar att vara mer thrombogena än de finare EBM-tillverkade ytorna är. Obehandlade EBM-tillverkade ytor i allmänhet är mer thrombogena än vad konventionellt framställda implantatytor är.
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Conti, Alfredo. "Tecniche della manifattura additiva - applicazioni in ambito aeronautico e aerospaziale." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/13306/.
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Il potenziale delle nuove tecnologie digitali applicate al settore industriale ha consentito di ridurre enormemente la durata dei cicli produttivi grazie alla rapida gestione di quantità di dati sempre più considerevoli attraverso l’introduzione delle Macchine a Controllo Numerico (Computer Numerical Control – CNC).
Nel corso delle ultime tre decadi, l’industria manifatturiera ha subito notevoli e sostanziali cambiamenti grazie ad una sempre più forte connessione con il mondo dell’informatica.
La più grande rivoluzione in tale ambito è stata segnata dall’avvento della Manifattura Additiva (Additive Manufacturing - AM), conosciuta sotto diversi nomi, tra i quali Prototipazione Rapida (Rapid Prototyping), Manifattura Rapida (Rapid Manufacturing) o Libera Fabbricazione di Forme (Free Form Fabrication).
Materia di ricerca e sviluppo sin dalla fine degli anni ’80, la Manifattura Additiva consente la creazione di elementi fisici tridimensionali partendo da modelli CAD attraverso la sovrapposizione successiva di materiale strato per strato (layer by layer), offrendo i benefici di una elevata flessibilità geometrica degli elaborati, altrimenti irraggiungibile attraverso le tradizionali tecniche di Manifattura Sottrattiva operanti per asportazione di materiale. In seguito ad intensive ricerche, progressi significativi sono stati fatti nello sviluppo e nella commercializzazione di nuovi ed innovativi processi AM.
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Timans, P. J. "Time resolved reflectivity studies of electron beam processing of semiconductors." Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234108.
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This work describes methods for making dynamic observations of the effects of electron beam heating, in a range of applications to semiconductors. The studies were based on the use of the time resolved reflectivity (TRR) method, in which the reflectivity of the specimens surface is measured during the heating cycle. The best experimental conditions for this technique have been identified and several applications are described in detail. Studies were made of epitaxial regrowth of amorphous layers created by ion implantation into silicon. The TRR method was applied using red and infra-red wavelengths, to characterize the regrowth kinetics, paying special attention to the influence of electrically active dopants. The results demonstrate that doping has a large effect on the regrowth process, for reasons which are related to both electrical and structural factors. The use of isothermal electron beam heating for annealing silicon-on-sapphire (SOS) specimens was investigated. In these studies, the TRR technique was applied to measurement of the temperature of the specimens and to observation of epitaxial recrystallization of amorphous layers created by self-implantation. In SOS films the amorphous layers could be at the surface or buried beneath a thin single crystal layer, and these cases resulted in different regrowth behaviour. TRR methods using green and red probe wavelengths proved to be sensitive to the type of crystallization, as well as the rate at which it occurs. They should also help to identify the best conditions for improvement of the crystal quality of SOS films. TRR was also used to examine heating of silicon-on-insulator materials by swept line electron beams. Temperature distributions were evaluated by measuring the reflectivity of a small area as the electron beam passed through it and the effects of various changes in the heating conditions were explored. Studies were made of zone melting recrystallization by observing the abrupt reflectivity changes which occur when silicon melts or freezes. In future work, TRR techniques could be developed to allow detailed investigation of the recrystallization process in structures intended for seeded recrystallization.
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Goel, Sneha. "Post-treatment of Alloy 718 produced by electron beam melting." Licentiate thesis, Högskolan Väst, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-13547.
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Electron beam melting (EBM), a metal additive manufacturing (AM) process, has received considerable industrial attention for near net shape manufacture of complex geometries with traditionally difficult-to-machine materials. This has fuelled considerable academic interest in investigating EBM of Alloy 718, a nickel ironbased superalloy possessing an exciting combination of good mechanical behaviour and cost effectiveness. EBM production of Alloy 718 is particularly promising for aerospace and other sectors which value rapid production of components with large scope for design flexibility. The EBM builds are characterized by presence of inevitable defects and, anisotropy within a build is also a concern. Consequently, as-built Alloy 718 has to be subjected to post-build thermal-treatments (post-treatments) to ensure that the parts eventually meet the critical service requirements. Not withstanding the above, limited knowledge is available about optimal post-treatments for EBM-built Alloy 718. Therefore, the main focus of the work presented in this thesis was to systematically investigate the response of EBM-built material to post-treatments, which include hotisostatic pressing (HIPing), solution treatment (ST), and aging. HIPing of EBM-built Alloy 718 led to more than an order of magnitude reduction in defect content, which was reduced from as high as 17% to < 0.2% in samples built with intentionally introduced porosity to investigate limits of defect closure achievable through HIPing. In addition, HIPing also caused complete dissolution of δ and γ" phases present in the as-built condition, with the latter causing dropin hardness of the material. HIPing had no effect on the carbides and inclusions such as TiN, Al2O3 present in the built material. The evolution of microstructure during ST and aging was systematically investigated. Growth of potentially beneficial grain boundary δ phase precipitates was found to cease after a certain duration of ST, with samples subjected to prior-HIPing exhibiting lesser precipitation of the δ phase during ST. While the specimen hardness increased onaging, it was observed to plateau after a duration significantly shorted than the specified ASTM 'standard' aging cycle. Therefore, prima facie there are promising prospects for shortening the overall heat treatment duration. A combination of HIPing, ST, and aging treatments in a single uninterrupted cycle was also explored. Future work involving incorporation of a shortened heat treatment schedule in a combined cycle can have significant industrial implications.Articles submitted to journals and unpublished manuscripts are not included in this registration
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Roos, Stefan. "Process Development for Electron Beam Melting of 316LN Stainless Steel." Licentiate thesis, Mittuniversitetet, Institutionen för kvalitets- och maskinteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-37840.
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Additive manufacturing (AM) is a technology that inverts the procedure of traditional machining. Instead of starting with a billet of material and removing unwanted parts, the AM manufacturing process starts with an empty workspace and proceeds to fill this workspace with material where it is desired, often in a layer-by-layer fashion. Materials available for AM processing include polymers, concrete, metals, ceramics, paper, photopolymers, and resins. This thesis is concerned with electron beam melting (EBM), which is a powder bed fusion technology that uses an electron beam to selectively melt a feedstock of fine powder to form geometries based on a computer-aided design file input. There are significant differences between EBM and conventional machining. Apart from the process differences, the ability to manufacture extremely complex parts almost as easily as a square block of material gives engineers the freedom to disregard complexity as a cost-driving factor. The engineering benefits of AM also include manufacturing geometries which were previously almost impossible, such as curved internal channels and complex lattice structures. Lattices are lightweight structures comprising a network of thin beams built up by multiplication of a three-dimensional template cell, or unit cell. By altering the dimensions and type of the unit cell, one can tailor the properties of the lattice to give it the desired behavior. Lattices can be made stiff or elastic, brittle or ductile, and even anisotropic, with different properties in different directions. This thesis focuses on alleviating one of the problems with EBM and AM, namely the relatively few materials available for processing. The method is to take a closer look at the widely used stainless steel 316LN, and investigate the possibility of processing 316LN powder via the EBM process into both lattices and solid material. The results show that 316LN is suitable for EBM processing, and a processing window is presented. The results also show that some additional work is needed to optimize the process parameters for increased tensile strength if the EBM-processed material is to match the yield strength of additively laser-processed 316L material.Vid tidpunkten för framläggningen av avhandlingen var följande delarbete opublicerat: delarbete 3 (inskickat).
At the time of the defence the following paper was unpublished: paper 3 (submitted).
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Ou, Jun. "Melting of solids in liquid titanium during electron beam processing." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/55908.
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Both experiments and numerical modeling work have been carried out to understand the phenomena contributing to the melting of solid condensate in liquid titanium alloys during Electron Beam Cold Hearth Re-melting (EBCHR). To begin, ice/water and ethanol/water analogue physical models were adopted to study the melting of a low melting point solid introduced into liquid and to provide data suitable for developing a comprehensive numerical-based modeling framework. The results revealed that thermal and compositional driven buoyancy and surface tension (Marangoni) flows, when present, can have a significant impact on solid melting in a system where forced convection is not significant.
In work that followed, the melting behavior of Commercial Purity Titanium (CP-Ti) rods in liquid CP-Ti was investigated with the aid of an Electron Beam Button Furnace (EBBF) to examine the melting kinetics in the titanium system in the absence of compositional effects. The results showed that the liquid titanium initially froze onto the cold rod when it was immersed, resulting in the formation of a solid/solid interface that acted to retard melting when present. Data collected from the experiments included the evolution in the solid profile of the rod with time and the evolution in temperature obtained from a thermocouple embedded in the rod. The numerical modeling framework developed for the ethanol/water system was modified and applied to support analysis of the experimental results including the determination of an effective interfacial heat transfer coefficient (EIHTC). A similarity solution was also developed to assess the numerical model derived EIHTC.
In the final phase of the study, work was conducted on Ti-Al solid rods partially immersed in liquid CP-Ti and liquid Ti-6wt%Al-4wt%V (Ti64) as a means of approximating the behavior of condensate in industry. The melting behavior of Ti-Al was observed to differ significantly from that of CP-Ti rods. Despite having a lower melting point, the Ti-Al rod was found to heat up and melt at a much slower rate. Metallographic examination of partially melted rods and a sensitivity analysis conducted with the numerical model has been able to partially, but not fully explain this difference.Applied Science, Faculty of
Materials Engineering, Department of
Graduate
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Suard, Mathieu. "Characterization and optimization of lattice structures made by Electron Beam Melting." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAI055/document.
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Le récent développement de la Fabrication Additive de pièces métalliques permet d'élaborer directement des structures à partir de modèles 3D. En particulier, la technologie "Electron Beam Melting" (EBM) permet la fusion sélective, couche par couche, de poudres métalliques. Elle autorise la réalisation de géométries très complexes mais apporte de nouvelles contraintes de fabrication.Ce travail se concentre sur la caractérisation géométrique et mécanique de structures treillis produites par cette méthode. Les pièces fabriquées sont comparées au design initial à travers des caractérisations par tomographie aux rayons X. Les propriétés mécaniques sont testées en compression uni-axiale. Pour les poutres de faibles épaisseur, la différence entre la structure numérique et celle fabriquée devient significative. Les écarts au design initial se traduisent pour chaque poutre par un concept de matière mécaniquement efficace. D'un point de vue modélisation, ce concept est pris en compte en remplaçant la poutre fabriquée par un cylindre avec un diamètre mécaniquement équivalent. Ce diamètre équivalent est utilisé dans des simulations et optimisations "réalistes" intégrant ainsi les contraintes de fabrication de la technologie EBM.Différentes stratégies sont aussi proposées pour réduire la proportion de volume "inefficace" et améliorer le contrôle de la taille des poutres, soit en jouant sur les paramètres procédé et les stratégies de fusion, soit en effectuant des post-traitementsThe recent development of Additive Manufacturing for the fabrication of metallic parts allows structures to be directly manufactured from 3D models. In particular, the "Electron Beam Melting" (EBM) technology is a suitable process which selectively melts a powder bed layer by layer. It can build very complex geometries but brings new limitations that have to be quantified.This work focuses on the structural and mechanical characterization of lattice structures produced by such technology. The structural characterization mainly rely on X-ray tomography whereas mechanical properties are assessed by uni-axial compression. The geometry and related properties of the fabricated structures are compared with the designed ones. For small strut size, the difference between the designed structure and the produced one is large enough to impact the desired mechanical properties. The concept of mechanical efficient volume is introduced. For the purpose of simulation, this concept is taken into account by replacing the struts by a cylinder with a textit{mechanical equivalent diameter}. After validation, it has been used into "realistic" simulation and optimization procedures, thus taking into account the process constraints.Post-treatments (Chemical Etching and Electro-Chemical Polishing) were applied on lattice structures to get rid of the inefficient matter by decreasing the surface roughness. The control of the size of the fabricated struts was improved by tuning the process strategies and parameters
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Chauvet, Edouard. "Mise en œuvre de superalliages base Nickel par Electron Beam Melting." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREA1084.
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Aujourd’hui, la fabrication additive de pièces métalliques par le procédé EBM (fusion sélective par faisceau d’électrons) concerne essentiellement les alliages de titane et les alliages cobalt-chrome. Une forte demande du secteur aéronautique pousse à étudier la possibilité d'étendre les champs d’application de ce nouveau procédé d'élaboration à d'autres matériaux à haute valeur ajoutée, notamment les superalliages base Nickel.Après la caractérisation des poudres et la description des particularités du procédé EBM (mise en œuvre, paramètres, thermique…), ce travail s'est attaché à développer une méthodologie permettant de structurer l’utilisation d’un nouveau matériau par EBM. Cette méthodologie a dans un premier temps été validée sur un superalliage base Nickel soudable: l'inconel 625.La mise en œuvre d’un superalliage non-soudable a révélé une problématique de fissuration à chaud. Une partie du travail de thèse a été consacrée à la compréhension de l'origine de la fissuration à partir de caractérisations microstructurales multi-échelles. L'étude de la genèse des microstructures et des défauts hérités de la fabrication a permis de proposer des règles de fabrication afin de limiter, et même d'éviter complètement la fissuration. Une adaptation des paramètres opératoires et des stratégies de fusion lors du procédé EBM est utilisée pour générer des microstructures présentant des structures de grains différentes allant de structures équiaxes jusqu'à la fabrication de monocristaux en passant par des structures colonnaires de différentes tailles.Le couplage entre un modèle de solidification prédisant la transition colonnaire-équiaxe et des simulations éléments finis permettant de quantifier les gradients thermiques et les vitesses de solidification a permis d’établir des liens entre les paramètres procédé et les microstructures résultantesOver the last decade, new processing routes based on additive manufacturing (AM) have emerged. Among the AM processes, Electron Beam Melting (EBM) was mainly dedicated to the fabrication of components made of titanium or chromium-cobalt alloys. Aeronautic industry has been a driving force to investigate the possibility to extend the EBM process to other materials and in particular to Ni-based superalloys.The first objective of this work was to develop a methodology to rationalize the use of a new material in the EBM machine. This can be achieved by studying the main characteristics of the EBM process: powder requirements, melting parameters and strategies, thermal aspects.... The methodology was first validated on a weldable Ni-based superalloy: the Inconel 625 grade.The methodology was then extended to the fabrication of a non-weldable Ni-based superalloy, i.e. a grade containing a large fraction of the γ' strengthening phase. Processing such non-weldable superalloys by EBM usually induced cracks in the fabricated components. The microstructures were characterized in order to identify the mechanism at the origin of the cracks. Understanding the mechanism responsible for the development of cracks has allowed to propose new melting strategies limiting or completely avoiding the formation of cracks.Adjusting melting parameters and strategies turns out to be an efficient way for tailoring the grain structure. Equiaxed grains, columnar grains with different sizes as well as single crystals can thus be generated with suitable process parameters.Finally, coupling a solidification model predicting the equiaxed/columnar transition and finite element calculations quantifying the magnitude of the thermal gradient and solidification velocity allowed to establish some links between microstructures and EBM melting parameters
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Cortelli, Giorgio. "Ultrafast electron diffraction on materials exposed to intense free electron laser pulses." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/19305/.
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The advent of Free Electron Lasers (FELs) has opened unprecedented opportunities for the study of transient states of matter. The use of the seeding technique, developed at the FERMI FEL in Trieste (Italy), pushed further the frontier allowing to perform pump-probe experiments with femtosecond time resolution. FELs permit shedding light onto unexplored non-equilibrium dynamics and processes in matter. In this thesis, a pioneering setup for monitoring sub-picosecond atomic structure changes in materials is described. The FEL is used as an isochoric pump while a 100 keV compressed electron bunch is used as a structural probe thus obtaining an ultrafast electron diffraction (UED) facility. Results of a pilot UED experiment on selected samples (gold and diamond) are presented and analysed.
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Milton, Samuel. "Study on the machinability and surface integrity of Ti6Al4V produced by Selective Laser Melting (SLM) and Electron Beam Melting (EBM) processes." Thesis, Tours, 2018. http://www.theses.fr/2018TOUR4011/document.
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Les technologies de fabrication additive(FA) basées sur la technique de fusion laser sur lit de poudres, telles que les procédés de fusion sélective laser (Selective Laser Melting ‘SLM’) et de fusion par faisceau d'électrons (Electron Beam Melting ‘EBM’), ne cessent de se développer afin de produire des pièces fonctionnelles principalement dans les domaines aérospatial et médical. Le procédé de fabrication additive offre de nombreux avantages, tels que la liberté de conception, la réduction des étapes de fabrication, la réduction de la matière utilisée, et la réduction de l'empreinte carbone lors de la fabrication d'un composant. Néanmoins, les pièces obtenues nécessitent une opération d’usinage de finition afin de satisfaire les tolérances dimensionnelles et l’état de surfaceAdditive Manufacturing (AM) techniques based on powder bed fusion like Selective Laser Melting(SLM) and Electron Beam Melting processes(EBM) are being developed to make fully functional parts mainly in aerospace and medical sectors. There are several advantages of using AM processes like design freedom, reduced process steps, minimal material usage and reduced carbon footprint while producing a component. Nevertheless, the parts are built with near net shape and then finish machined to meet the demands of surface quality and dimensional tolerance
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Mahale, Tushar Ramkrishna. "Electron Beam Melting of Advanced Materials and Structures, mass customization, mass personalization." NCSU, 2009. http://www.lib.ncsu.edu/theses/available/etd-11052009-143257/unrestricted/etd.pdf.
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Kourtis, Lampros. "Electron beam melting of titanium aluminides : process development and material properties optimisation." Thesis, University of Sheffield, 2017. http://etheses.whiterose.ac.uk/18002/.
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Additive Manufacturing (AM) process development was conducted to the production of high- Niobium Titanium Aluminide components with properties suitable for structural aerospace applications. Computational analysis of experimental data from statistically designed experiments and numerical heat source modelling revealed the effect of key Electron Beam Melting (EBM) process parameters on the melting response of ?- Titanium Aluminides. Dimensionless terms for melt pool depth and operational parameters for various literature data and experimental data from this study show a very good fitting; which proves that predictive models and process windows could be generated and used to rapidly and efficiently develop process themes for a given material and required melting response. Heating, preheating and melting EBM process themes were developed for fabricating simple geometries. Using a Design of Experiments (DOE) approach melting (hatching) process themes were optimised for surface finish, maximum component density without process defects and minimum Aluminium evaporation loss. Post-processing for eliminating defects and porosity from the bulk and surface was performed by machining and hot isostatic pressing (HIP). Optimum HIP treatment conditions were identified. Microstructural analysis and mechanical properties were investigated for the as-built and HIPed specimens at room and elevated temperatures. Excess Aluminium evaporation loss was identified as the main issue during the process development of this study. Evaporation per surface area, during EBM processing, from a metallic substrate mainly depends on surface temperature, heating time and chamber pressure and is a function of material properties and operational parameters. The main parameters affecting evaporation were investigated by numerical modelling using a modified Rosenthal equation. Impeding pressure for suppressing Aluminium evaporation versus surface temperature was also investigated.
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Persenot, Théo. "Fatigue of Ti-6Al-4V thin parts made by electron beam melting." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEI117/document.
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De nos jours, il est crucial pour les industries de réduire leur consommation énergétique. Pour les industries du transport, cela peut se faire par le biais de l’allègement des pièces de structure. Dans ce contexte, les structures cellulaires représentent une des solutions les plus prometteuses. Grâce au développement de la fabrication additive, l’élaboration de telles géométries complexes n’est plus un frein à leur utilisation. Néanmoins, cette dernière restera limitée tant que les propriétés mécaniques – et plus particulièrement la résistance en fatigue pour les pièces aéronautiques – ne seront pas maîtrisées. Ce travail de thèse a pour objectif de déterminer les mécanismes qui gouvernent le comportement en fatigue de ces structures cellulaires. Pour cela, le travail s’est focalisé sur l’élement unitaire les constituant : la poutre. Des éprouvettes minces représentatives de la poutre ont été élaborées par Electron Beam Melting puis caractérisées à l’état brut de fabrication à l’aide de différentes techniques (tomographie aux rayons X, microscopie optique et électronique, …). Leurs propriétés statique et cyclique en traction ont ensuite été évaluées. L’état de surface et en particulier les défauts d’entaille ont été identifiés comme responsable de la perte de résistance. L’impact de ces défauts sur la résistance en fatigue a été prédit avec succès par le biais de diagrammes de Kitagawa. L’impact de l’orientation de fabrication a également été observé et prédit. Différents post-traitements ont ensuite été utilisés afin d’améliorer ces propriétés. Le polissage chimique et le grenaillage ultrasonique ont réduit de manière significative la criticité des défauts de surface ce qui a grandement amélioré les propriétés mécaniques des éprouvettes, jusqu’à se rapprocher de celles obtenues après usinage. Par ailleurs, la compression isostatique à chaud a provoqué la fermeture de l’entièreté des défauts internes ainsi qu’un grossissement de la microstructure. Ce dernier point permet une amélioration supplémentaire de la performance en fatigue une fois combiné avec un traitement de surface. Enfin, une méthode permettant de détecter automatiquement tous les défauts d’entailles et de déterminer leur criticité et leur influence sur la résistance en fatigue a été proposée et discutée. Elle a ensuite été appliquée avec succès aux échantillons attaqués chimiquement mais des modifications demeurent nécessaire pour l’appliquer à d’autres états de surfaceNowadays, reducing the energy consumption is crucial for most of the industries. For transportation industries, it can be achieved through weight reduction. In this context, cellular structures turn out to be one of the most efficient solution. Thanks to the development of additive manufacturing, producing such complex geometries is no longer an issue. However, their use will remain limited as long as their fatigue performances are not known. This PhD work aimed at understanding the mechanisms that govern the fatigue behaviour of such cellular structures. It was first decided to focus on their unitary element, i.e. a single strut. Single struts samples were manufactured by Electron Beam Melting and then characterized in as-built conditions using different experimental techniques (X-ray tomography, optical and electron microscopy, etc.). Their static and cyclic tensile properties were then evaluated. The rough surface and in particular notch-like defects were found to be responsible for the knockdown of the mechanical properties. Regarding the fatigue resistance, their detrimental impact was predicted using Kitagawa diagrams. It also enabled to explain the impact of the build orientation. Different post-treatments were used in order to improve these mechanical properties. Chemical etching and ultrasonic shot peening (USP) significantly reduced the severity of surface defects of as-built thin struts and thus increased their mechanical properties. After USP, the fatigue properties of machined samples were almost matched. Hot Isostatic Pressing lead to the closure of all internal defects and to the coarsening of the microstructure. When combined with one of the surface treatments, the fatigue properties were further improved. Finally, a method enabling to systematically and automatically extract from the surface the most critical defects and quantitatively analyze their influence on fatigue life was proposed and discussed. It was successfully applied to chemical etched samples but improvements are mandatory for other surface conditions
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Carroll, Lisa M. "Rapid steady state solidification of Al alloys." Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298796.
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Karimi, Neghlani Paria. "Electron beam melting of Alloy 718 : Influence of process parameters on the microstructure." Licentiate thesis, Högskolan Väst, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-13140.
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Additive manufacturing (AM) is the name given to the technology of building 3D parts by adding layer-by-layer of materials, including metals, plastics, concrete, etc. Of the different types of AM techniques, electron beam melting (EBM), as a powder bed fusion technology, has been used in this study. EBM is used to build parts by melting metallic powders by using a highly intense electron beam as the energy source. Compared to a conventional process, EBM offers enhanced efficiency for the production of customized and specific parts in aerospace, space, and medical fields. In addition, the EBM process is used to produce complex parts for which other technologies would be either expensive or difficult to apply. This thesis has been divided into three sections, starting from a wider window and proceeding to a smaller one. The first section reveals how the position-related parameters (distance between samples, height from build plate, and sample location on build plate) can affect the microstructural characteristics. It has been found that the gap between the samples and the height from the build plate can have significant effects on the defect content and niobium-rich phase fraction. In the second section, through a deeper investigation, the behavior of Alloy 718 during the EBM process as a function of different geometry-related parameters is examined by building single tracks adjacent to each other (track-by-track) andsingle-wall samples (single tracks on top of each other). In this section, the main focus is to understand the effect of successive thermal cycling on microstructural evolution. In the final section, the correlations between the main machine-related parameters (scanning speed, beam current, and focus offset) and the geometrical (melt pool width, track height, re-melted depth, and contact angle) and microstructural (grain structure, niobium-rich phase fraction, and primary dendrite arm spacing) characteristics of a single track of Alloy 718 have been investigated. It has been found that the most influential machine-related parameters are scanning speed and beam current, which have significant effects on the geometry and the microstructure of the single-melted tracks.
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Shuster, Riley Evan. "Modeling of aluminum evaporation during electron beam cold hearth melting of titanium alloy ingots." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/44553.
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Electron beam cold heart melting (EBCHM) is a consolidation and refining process capable of consolidating titanium scrap and sponge material into high quality titanium alloy ingots. Unlike other consolidation processes for titanium, EBCHM is efficient in removing both high and low density inclusions. During the final stage of casting in EBCHM, operators must balance the potential to form large shrinkage voids, caused by turning off the electron beam heating, against the tendency to evaporate alloying additions, which occurs if the top surface remains molten. To this end, a comprehensive understanding of the evaporation and fluid flow conditions occurring during the final stage of EBCHM is required in order to optimize ingot production. This research focused on developing a coupled thermal, fluid flow and composition model, capable of predicting the temperature, fluid flow and composition fields within an EBCHM cast, Ti-6Al-4V ingot. The physical phenomena of thermal and compositional buoyancy, mushy zone flow attenuation and aluminum evaporation were incorporated in the model formulation. Industrial scale experiments were carried out at the production facilities of a leading industrial producer of titanium to provide data and measurements used for model verification. The model has been used to study the effects of variation of electron beam power input and hot top time duration on the evaporative losses and position of solidification voids. Model predictions for liquid pool profile, last liquid to solidify and composition fields are in good agreement with the industrially measured results. Sensitivity analysis was performed by varying electron beam power and hot top duration independently and observing the effect on the composition fields and last liquid to solidify. For the cases examined, there was a strong correlation between electron beam power and alloying element losses, while hot top duration variation results indicated a stronger dependence on last liquid to solidify than on alloying element losses. Therefore a classic optimization problem arises between balancing hot top duration with alloying element losses.
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Karlsson, Joakim. "Optimization of Electron Beam Melting for Production of Small Components in Biocompatible Titanium Grades." Doctoral thesis, Uppsala universitet, Tillämpad materialvetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-236709.
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Additive manufacturing (AM), also called 3D-printing, are technologies where parts are formed from the bottom up by adding material layer-by-layer on top of each other. Electron Beam Melting (EBM) is an AM technique capable of manufacturing fully solid metallic parts, using a high-intensity electron beam to melt powder particles in layers to form finished components. Compared to conventional machining, EBM offers enhanced efficiency for production of customized and patient specific parts such as e.g. dental prosthetics. However, dental prosthetics are challenging to produce by EBM, as their small sizes mean that mechanical and surface properties may be altered as part sizes decreases. The aim of this thesis is to gain new insights that could lead to optimization for production of small sized components in the EBM. The work is focused to understand the process-property relationships for small size components production. To improve the surface resolution and part detailing, a smaller sized powder was used for production and compared to parts made with standard sized powder. The surface-, chemical and mechanical properties were evaluated for parts produced with both types of powders. The results indicate that the surface roughness may be influenced by powder and build layer thickness size, whereas the mechanical properties showed no influence of the layer-wise production. However, the mechanical properties are dependent on part size. The outermost surface of the parts consists of a surface oxide dominated by TiO2, formed as a result of reaction between the surface and residual gases in the EBM build chamber. The surface oxide thickness is comparable to that of a conventionally machined surface, but is dependent on build height. This work concludes that the surface resolution and component detailing can be improved by various measures. Provided that proper process themes are used, the EBM manufactured material is homogenous with properties comparable to conventional produced titanium. It has also been shown that the material properties will be altered for small components. The results point towards different ways of optimizing manufacturing of dental prosthetics by EBM, which will make dental prosthetics available for an increased number of patients.
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Günther, Johannes [Verfasser]. "Electron beam melting of metastable austenitic stainless steel : processing – microstructure – mechanical properties / Johannes Günther." Kassel : kassel university press c/o Universität Kassel - Universitätsbibliothek, 2020. http://d-nb.info/1228485488/34.
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Shrestha, Sanjay. "Wear behavior of Ti-6Al-4V for Joint Implants manufactured by Electron Beam Melting." Youngstown State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1495471138802038.
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Nilsson, Erik, and Daniel Johansson. "Testing and evaluation of component made using electron beam melting and Alloy 718 powder." Thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-35566.
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The aerospace industry is constantly striving to becoming more economical and environmentally friendly. One of many efforts to achieve this is the Lightcam project which in this case is evaluating the use of additive manufacturing in the form of electron beam melting in conjunction with the nickel-based superalloy, Alloy 718. This combination is not fully explored and examined. For this purpose, a demonstrator vane was produced and it was subsequently evaluated in this thesis. The evaluation was performed in as-built condition and was divided in non-destructive testing, evaluation of these methods and metallographic review to confirm the results, and potentially revealing more properties. The non-destructive testing was performed using conventional radiography and computed tomography. Both methods struggled to deliver complete and reliable results, for varying reasons. Radiography could deliver results of the whole vane, but these were impossible to evaluate due to the rough surface created by the electron beam melting process. The computed tomography on the other hand was not affected by the rough surface and produced usable, though not complete, results of the vane. The reason for the computed tomography’s inability to deliver complete results was the material, varying thickness and complex geometry of the vane. As a complement and to verify the results from the non-destructive testing, a metallographic examination was conducted. These tests were conducted with the aim of answering the following three questions: What non-destructive testing methods are suitable to evaluate Alloy 718 components manufactured with electron beam melting? - Neither radiography nor computed tomography are suitable as a sole evaluation method, for various reasons. All surface dependent methods were deemed unsuitable without testing due to the rough surface. What types of defects and in what quantity can they be found in the produced vane? - Defects found are: Porosity and lack of fusion, both found as internal and partially external and in varying sizes. Where are the defects located? - Pores are mainly found in the center of sections modeled to a 3mm thickness. Lack of fusion was found between build layers in all thicknesses. Apart from these results, hardness was found to vary depending on build height, increasing from the bottom towards the top. Microstructure was also found to vary with the build height, but always consisting of either equiaxed or columnar grains.Lightcam
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Doutre, Pierre-Thomas. "Comment intégrer et faire émerger des structures architecturées dans l'optimisation de pièces pour la fabrication additive par faisceaux d’électrons." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAI039.
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Grâce à la fabrication additive, il est aujourd'hui possible de fabriquer de nouvelles géométries. Les perspectives offertes par les moyens de fabrications conventionnelles et additives sont très différentes. Des propositions de design très contraintes peuvent devenir beaucoup plus libres avec la fabrication additive. Cette liberté qu'elle offre fait émerger une multitude de possibilités. Dans ce manuscrit, nous nous sommes focalisés sur un type particulier de structures (les octetruss) ainsi que sur les moyens de fabrication EBM (Electron Beam Melting) de la société ARCAM. Les travaux présentés dans cette thèse ont été réalisés au sein des laboratoires G-SCOP et SIMAP ainsi qu'en partenariat avec l'entreprise POLY-SHAPE. Ce manuscrit est articulé autour de trois principaux points.Il s'agit tout d'abord de faire émerger des structures treillis lors du processus de conception. Pour cela, deux approches existantes sont détaillées. La première met en œuvre l'optimisation topologique et la seconde s'appuie sur le concept de matériau équivalent. Ensuite deux méthodologies permettent de faire émerger des zones dans lesquelles l'intégration de structures treillis est adaptée. La première consiste à réaliser les différentes zones en s'appuyant sur un champ de contraintes issu d'un calcul Eléments Finis, la seconde se base sur un résultat d'optimisation topologique pour établir les différentes zones. Cette seconde méthodologie est appliquée à un cas d'étude industriel.Ensuite nous étudions comment remplir les différentes zones avec des structures treillis adaptées en nous focalisant tout d'abord sur leur génération. Un accent particulier est porté sur l'intersection des différents barreaux par la mise en place de sphères. Une méthodologie permettant de générer des arrondis est également proposée. Une étude est menée sur l'ensemble des paramètres et informations à considérer pour intégrer une structure treillis à une zone donnée. Cette étude conduit à une proposition de méthodologie qui est appliquée à un cas d'étude industriel.Enfin, les aspects liés à la fabrication sont pris en compte. Pour cela, nous considérons différentes limites du moyen de fabrication EBM pour des structures treillis comme les dimensions maximales réalisables ou les problématiques thermiques. Une étude consistant à prédire la dépoudrabilité des pièces est réalisée. Enfin, des essais mécaniques sont effectués. Nos résultats sont comparés à ceux obtenus dans d'autres travaux. L'impact des arrondis sur le comportement mécanique d'une pièce est discutéThanks to additive manufacturing, it is now possible to manufacture new geometric shapes. The prospects offered by the methods of conventional and additive manufacturing are very different. Highly constrained design proposals can become much freer with additive manufacturing. The freedom it offers brings forward a multitude of possibilities. In this manuscript, we focused on a particular type of structures (the octetruss) as well as the use of EBM (Electron Beam Melting) of ARCAM as a means of manufacturing. The work presented in this thesis was carried out in the laboratories G-SCOP and SIMAP as well as in partnership with the company POLY-SHAPE. This manuscript focuses on three main points.The first of which is the action of emergence of lattice structures during the design process. For this, two existing approaches are detailed. The first uses topological optimization and the second is based on the concept of equivalent material. Following these, there are two methodologies used to identify areas in which the integration of lattice structures is possible and appropriate. The first consists of creating the different zones by relying on a stress field resulting from a finite element calculation, the second establishes the different zones using a topological optimization result. This second methodology is applied to an industrial case study.Secondly, we study how to fill the different areas with appropriate lattice structures by focusing first on their generation. Particular emphasis is placed on the intersection of the various bars by the establishment of spheres. A methodology for generating rounded-shape is also proposed. A study is carried out on all the parameters and information in order to integrate a lattice structure to a given area. This study leads to a proposed methodology that is applied to an industrial case study.Finally, aspects related to manufacturing are taken into account. For this, we consider different limits of the EBM manufacturing and what they mean for lattice structures; such as maximum achievable dimensions or thermal problems. A study to predict powder removal in order to extract the fabricated structure is performed. Mechanical tests are carried out. Our results are compared to those obtained in other works. The impact of curve on the mechanical behavior of a product is discussed
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Piaget, Alexandre. "Maîtrise de la qualité en fabrication additive." Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAI004/document.
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En utilisant des solutions de production issues des technologies de Fabrication Additive (FA), l’industrie s’ouvre de nouvelles possibilités pour la fabrication de pièces à haute valeur ajoutée. Dans le but d’être pleinement exploitables, ces procédés de fabrication doivent permettre la réalisation de pièces dont la qualité est adaptée aux besoins de l’industrie. Ces travaux se concentrent sur deux points ciblés de la maîtrise de la qualité en FA appliquée à la technologie Electron Beam Melting (EBM).Le premier point abordé s’intéresse à l’impact de la position d’une pièce dans l’espace de fabrication d’une machine sur la qualité géométrique de cette pièce. Pour caractériser l’espace de fabrication de la machine Arcam A1, plusieurs séries de pièces sont fabriquées à différentes localisation de l’espace, puis comparées à leur design initial. Les écarts mesurés entre les pièces et leur géométrie souhaitée montrent que la périphérie de l’espace de fabrication est une zone sujette à d’importants défauts géométriques. Ces défauts sont caractérisés et des solutions sont proposées pour en limiter l’impact sur la qualité géométrie des pièces.Le second point traite de la porosité des pièces fabriquées. Lorsque l’apport énergétique du faisceau d’électron n’est pas adéquat pour fondre correctement la poudre, des pores peuvent se former dans le matériau des pièces fabriquées. La géométrie et le matériau des pièces rendent difficiles la détection de ses pores. Une méthode de détection est proposée pour détecter la présence de pores dans une pièce via un contrôle standardisé sur un élément qui copie les conditions de fusion de la pièce. Cette méthode propose deux alternatives de contrôle : un contrôle optique (rapide, abordable mais peu précis) et un contrôle tomographique (plus précis que le précédent mais moins rapide et abordable). Un algorithme de traitement d’image innovant a été développé dans le cadre de cette étude afin de rendre les tomographies du témoin plus fiablesBy using production solutions from Additive Manufacturing (AM) technologies, the industry is opening up new possibilities for manufacturing high added value parts. In order to be fully exploitable, these manufacturing processes must allow the production of parts whose quality is adapted to the needs of the industry. This work focuses on two aiming points of quality control in AM applied to Electron Beam Melting (EBM) technology.The first point deals with the impact of a part position in the manufacturing space of a machine on the geometric quality of this part. To characterize the manufacturing space of the Arcam A1 machine, several series of parts are manufactured at different locations of the space, then compared to their initial design. The differences measured between the parts and their desired geometry show that the periphery of the manufacturing space is a zone subject to important geometrical defects. These defects are characterized and solutions are proposed to limit the impact on the geometrical quality of parts.The second point deals with the porosity of manufactured parts. When the energy supply of the electron beam is not adequate to melt the powder properly, pores can form in the material of the manufactured parts. The geometry and material of the parts make it difficult to detect its pores. A detection method is provided to detect the presence of pores in parts via a standardized control on an item that copies the parts merging conditions. This method offers two control alternatives: an optical control (fast, affordable but not very accurate) and a tomographic control (more accurate than the previous one but slower and costlier). An innovative image processing algorithm is developed as part of this study to make the item tomography scans more reliable
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Blomström, Tommy, and Victor Lindberg. "Strategier för att minimera porositet vid tillverkning med Electron Beam Melting : Hur smältstrategier och geometrisk utformning påverkar porositet och porfördelning i komponenter tillverkade med EBM." Thesis, Mittuniversitetet, Avdelningen för kvalitets- och maskinteknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-39682.
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Additiv tillverkning (AM) är en tillverkningsmetod som skapar komponenter genom att addera material där det tidigare inte fanns, detta möjliggör tillverkning av geometrier som annars hade varit omöjliga eller mycket tidskrävande. Electron Beam Melting är en pulverbaserad AM metod där ett metallpulver smälts samman av en elektronstråle. De två största nackdelarna med pulverbaserad AM är en ojämn yta och inre porositet i tillverkade komponenter. Den grova ytan avhjälps i de fall det behövs genom att efterbehandla komponenter genom skärande bearbetning och porositeten åtgärdas idag med HIP, Hot Isostatic Pressing. Arbetet i denna rapport har som syfte att minimera porositeten in situ för att öka tillförlitligheten och repeterbarhet hos materialegenskaperna i EBM-tillverkade komponenter genom optimerandet av smältstrategin. Detta har skett genom ett experiment där fem smältstrategier har använts vid tillverkning av fyra olika utformade provstavar varvid porositeten har granskats i avseendena porandel av ytarea och porfördelning. De fem strategierna var S0, Standard; S1, Enkelriktad ifyllnad före kontur; S2.0, Endast kontur utifrån och in; S2.1, Endast kontur inifrån och ut; S2.2, Som S2.1 utan MultiBeam, och de fyra provstavsutformningarna var ett rätblock, en cylinder, ett rör med 3 mm tjocka väggar och ett timglas. Lägst porositet gavs av S2.1 med en genomsnittlig densitet på 99,993 % och högst gavs av S2.0 med en denistet på 98,63 % där S0 resulterade i en genomsnittlig densitet på 99,94%.Additive manufacturing (AM) is a manufacturing method that creates components by adding material where there previously was none, this enables fabrication of geometries which otherwise had been impossible or very time consuming. Electron Beam Melting is a powder based AM-method where a metallic powder is melted by an electron beam. The two largest issues with powder based AM is its high surface roughness and internal porosity of manufactured components. The uneven surface is remedied where necessary by making the part larger than its final dimensions and machining it to size while the porosity today is rectified with HIP, Hot Isostatic Pressing. This works aims to minimize the porosity in situ in order to improve the reliability and repeatability of the material properties of EBM-manufactured parts through the optimization of the melting strategy. This has been done through an experiment in which five melting strategies have been applied to four different test rods after which the porosity was examined in terms of porosity and pore distribution. The five strategies were S0, Standard; S1, One-way hatch before contour; S2.0, Only contour outside and in; S2.1, Only contour inside and out; S2.2, Like S2.1 without MultiBeam, and the four test bar designs were a cuboid, a cylinder, a tube with 3 mm thick walls and an hourglass. The lowest porosity was given by S2.1 with a mean average density of 99 993% and highest was S2.0 with 98.63% density whereas S0 resulted in a mean average density of 99.94%.
Betyg 2020-08-02
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Ervin, Jennifer Kelly. "Post Heat Treatment Effects of Ti-6Al-4V Produced via Solid Freeform Electron Beam Melting." NCSU, 2008. http://www.lib.ncsu.edu/theses/available/etd-05012008-105845/.
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Traditionally, Ti-6Al-4V components are fabricated by forging or casting. However, these methods of production require expensive dies or molds. The cost per part is very high for those parts produced in low quantities. The solid freeform electron beam melting process aims to produce high dimensional tolerance parts with similar mechanical properties at a lower cost by melting Ti-6Al-4V powder in a layer by layer fashion using high energy electrons. Due to the directional solidification effects, the microstructure seen in this process consists of a columnar grain structure along the growth direction and an equiaxed structure at the cross-sectional growth plane. This type of structure is thought to contribute to the anisotropy of tensile properties discovered in previous research. Although, preferred orientation of the α laths may play a role as well. Heat treatments above the β transus are performed in order to improve the tensile properties, specifically ductility, with intensions to remove preferred orientation and to disunite the columnar grain structure. Tensile testing, fractography, optical microscopy, and x-ray diffraction are used to characterize and compare the as-processed and β heat treated electron beam melted specimens. It is found for all β treated conditions, the ductility increases compared to the as-processed specimens, although the strength decreases. The mode of fracture changes from ductile dimple rupture in the asprocessed condition to transgranular cleavage with ductile dimple rupture for the heat treated specimens. The macrostructure and microstructure in the as-processed and heat treated specimens contrasted greatly. The macrostructure changes from a fully columnar structure to a mixture of columnar and equiaxed grains. A fine acicular microstructure is observed in the as-processed samples, whereas a broad lamellar colony microstructure is formed during heat treatment. The presence of a colony microstructure is a possible reason for the improvement in ductility. From the x-ray data obtained, the preferred orientation is not reduced but instead increases after heat treating in the β region which likely is a result of the favorable rearrangement of slip systems due to the change in α lath orientation.
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Jenkins, Sarah Nield Morrish. "Mechanical properties and structural evaluation of diamond structure Ti6Al4V lattices made by Electron Beam Melting." Thesis, University of Sheffield, 2017. http://etheses.whiterose.ac.uk/20954/.
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Sabri, Hanna Etwal. "Electron Beam Melting : En State of the Art Rapport och komparativ studie av additiva tillverkningsmetoder." Thesis, KTH, Hållbar produktionsutveckling (ML), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-293351.
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Additive tillverkning (AM) är en tillverkningsteknik som har använts i stor utsträckning i industrier de senaste åren. Electron beam melting (EBM) är en innovativ teknik för tillverkning inom ortopediska implantat- och flygindustrin för att EBM erbjuder hög produktivitet och lägre kostnad per del. Jämfört med traditionella tillverkningsmetoder kan EBM tillverka delar med betydande mekaniska egenskaper, men det finns några vanliga brister som hindrar EBMs förmåga att bli en vanligare bearbetningsmetod vid tillverkning. I detta arbete, som tar an formen av en State of the Art Rapport, introduceras EBM-metoden på teknisk nivå och jämförs med andra AM-metoder och konventionella tillverkningsmetoder.Additive manufacturing (AM) is a manufacturing technology that has been widely used in industries in recent years. Electron beam melting (EBM) is an innovative technology for manufacturing of the orthopedic implant and aerospace industry because EBM offers high productivity and lower cost per part. Compared to traditional manufacturing methods, EBM can produce parts with significant mechanical properties, but there is some common shortcoming that prevent EBM's ability to become a more common processing method in manufacturing. This work, which takes the form of a State of the Art Report, introduces the EBM method at the technical level and compares with other AM methods and conventional manufacturing methods.
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Meng, Tao. "Factors influencing the fluid flow and heat transfer in electron beam melting of Ti-6Al-4V." Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/15531.
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Electron Beam Cold Hearth Remelting (EBCHR) and its associated casting process is an important consolidation technique for the treatment of virgin titanium sponge and scrap. The development of robust models to describe the casting process hinge on accurately capturing heat transfer phenomena within the ingot and fluid flow phenomena within the liquid pool. The flow field that develops within the liquid pool is influenced by several factors including buoyancy driven flow due to thermal gradients within the pool, surface tension, or Marangoni, driven flow due to the large thermal gradients induced on the surface by the Electron Beam and the ability of the mushy, or semi-solid, zone to attenuate the flow.
A mathematical model describing fluid flow and heat transfer in a Ti6Al4V button sample during electron beam melting has been developed to examine the relative contribution of the three factors cited above on the pool profile and flow field within the pool. The model has also been used to compare the steady state solution for a time averaged circular beam pattern with a transient solution obtained for the case where the beam pattern is comprised of a series of discrete points scribing the same circle. The latter, in which the beam spot is periodically stationary for small but finite periods, is intended to more closely mimic the industrial process.
The model is also used to examine the sensitivity of the predictions to changes in numerical and process parameters. The results indicate that the electron beam power and heat transfer coefficient have the largest influence on the liquid pool profile while the surface tension coefficient has little effect (i.e. 25% change in electron beam power results in ~25% liquid pool profile while 100% change in time step results in less than 1% in prediction).
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Zhang, Zhongkui. "Modeling of Al evaporation and Marangoni flow in Electron Beam Button Melting of Ti-6Al-4V." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/43996.
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The Electron Beam Cold Hearth Remelting (EBCHR) process has emerged as a key process in producing high quality Ti-6Al-4V ingot and electrode as it is able to effectively consolidate both sponge and scrap material while removing undesired impurities and inclusions, such as Low Density Inclusions (LDIs) and High Density Inclusions (HDIs). However, the challenge of composition control arises in processing alloys such as Ti-6Al-4V where evaporative loss of elements with higher vapor pressure (Al in this case) cannot be ignored. Therefore, in order to cast a product of specified composition, a thorough understanding of the evaporation mechanism and melt flow conditions becomes crucial in process control and optimization. This research presents a comprehensive model of the melt pool produced during Electron Beam Button Melting (EBBM) which has been developed to serve as an intermediate step in the development of a comprehensive tool for analysis and optimization of the industrial EBCHR process. With proper geometry and boundary conditions, the EBBM model can be readily applied to an industrial EBCHR furnace to minimize costly experiments in optimizing process parameters. A thermal-fluid-compositional model has been developed that includes Al evaporation, thermal and compositional buoyancy, thermal and compositional Marangoni flow and flow attenuation in the mushy regime. Experiments on Ti-6Al-4V and CP titanium with a circular electron beam pattern were conducted in a laboratory scale EBBM furnace in order to study the evaporation process and fluid flow in the liquid pool. The data obtained from the experimental work was used to tune the thermal boundary conditions and validate the model predictions. The temperature, surface velocity, pool profile and concentration profile have been experimentally quantified and used for validation of the mathematical model.
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Vaidyalingam, Arumugam Karthik. "Effect of Process Parameters on Contour Properties in Inconel 718 Structures Fabricated by Electron Beam Melting." Thesis, Linköpings universitet, Konstruktionsmaterial, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-163314.
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Additive Manufacturing (AM), commonly known as 3D printing is a production method that utilises repeated addition of layers in order to produce a final shape. AM utilises less raw material and does not have drawbacks such as tool wear and material wastage as seen in conventional machining. However, they do have drawbacks such as poor surface and internal defects. A common practice in AM is the fabrication of contour and bulk region using separate parameters. The aim of this project was to study the effects of various process parameters on the contour properties. The process parameters considered were scanning speed, beam current and focus offset. The Nickel alloy Inconel 718 was utilised in Electron Beam Melting (EBM) to fabricate the test specimen. The samples used in this project were in an as-built condition which was priorly subjected to tensile testing for a different project. The tests performed in this project are hardness testing and microstructural investigation about grains, precipitates and the various defects. The test results helped to understand the effect of various process parameters on the hardness and microstructure of the samples. The samples with lower scanning speed had higher hardness and lesser lack of fusion than samples with higher speed. In the case of varying beam current, the samples with higher beam current had higher hardness values and fewer lack of fusions. Similarly, the effects of varying two or more process parameters were also studied and their findings recorded. The microstructure consisted of a large number of shrinkage porosities in the bulk and contour regions. The presence of Niobium rich precipitates at grain boundaries and the grain structure for various process parameters were identified and recorded.
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Charles, Amal Prashanth, and Taylor Claudio Alexander Gonzalez. "Development of a Method to Repair Gas Turbine Blades using Electron Beam Melting Additive Manufacturing Technology." Thesis, KTH, Industriell produktion, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-202367.
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This study focuses in using the electron beam melting additive manufacturing process to develop a framework to repair high performance gas turbine blades. These are currently fabricated using highly engineered super alloys, more specifically Inconel 738LC. The thesis focusses on the research on the current production methods of gas turbine blades, the operating environment inside the gas turbine, the most common failure modes as well as current methods of blade repair. This investigation includes studying the methods of production of metallic powders and the alloying effects of different elements in our required powder. A brief analysis was made to determine the economic viability for the usage of AM technology for mass production, and a proposition has been developed for the repair of turbine blades using additive manufacturing.
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Nakamura, Hideo. "The effect of beam oscillation rate on Al evaporation behavior in the electron beam melting process." Thesis, University of British Columbia, 1989. http://hdl.handle.net/2429/27944.
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Electron beam hearth melting process is widely used in producing superalloys, Ti and its alloys because of its excellent metallurgical characteristics. However, one of the disadvantages of the process is that alloying elements with high vapor pressure evaporate under the highly reduced operating pressure. This makes it very difficult to carry out an accurate chemical composition control. In order to prevent the excess evaporative loss by reducing the superheating of the molten pool, the beam scanning technique is employed in normal operation. Although the effect of this technique is well known empirically, few fundamental studies' have been made to date. The purpose of this study is, therefore, to clarify the quantitative effect of the beam oscillation rate on the evaporation behavior.
Small amounts of Ti-6Al-4V alloy were melted in an EB melting furnace. The temperature on the melt surface was measured in situ by an optical pyrometer during the melting period. The evaporation loss of both Ti and Al was also investigated.
On the basis of the experimental results, a two dimensional unsteady heat and mass transfer model was developed. (A one dimensional model was developed in the case of a stationary beam.) The model was used to investigate the effect of the beam oscillation rate on the evaporation behavior and also to discuss the optimum beam scanning rate. It was clearly shown that the evaporative loss of both Ti and Al could be suppressed by the increase of the beam oscillation rate. With the beam oscillation rate at more than 1.0 Hz, however, this effect could not be observed clearly anymore. It was also found that the beam scanning technique is useful not only in controlling Al concentration, wt%Al, but also in suppressing the total evaporative loss of both Ti and Al.Applied Science, Faculty of
Materials Engineering, Department of
Graduate
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MUCSI, CRISTIANO S. "Proposição de um processo alternativo à fusão via forno VAR para a consolidação de cavacos prensados de zircaloy e estudo do sistema dinâmico do arco elétrico." reponame:Repositório Institucional do IPEN, 2005. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11400.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Skoglund, Per. "Prosthetic socket in Titanium : An outer shell prosthetic socket for a lower-leg amputee manufactured in Ti6Al4V by Electron Beam Melting." Thesis, Mittuniversitetet, Avdelningen för kvalitetsteknik, maskinteknik och matematik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-26993.
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The common manufacturing process of prosthetic sockets is usually a time- and labor consuming activity. This project’s purpose was to look for alternative manufacturing methods that could speed up the process and enhance the experience for the patient for example make some personal design or make the socket lighter. The main goal was to investigate which properties could be achieved by applying Electron Beam Melting as an alternative manufacturing process for prosthetic sockets by applying an earlier developed methodology. An investigation of earlier scientific works with the keywords (additive manufacturing, free form fabrication, orthopedic, prosthetic sockets and rapid manufacturing) was done as well as gathering knowledge how to operate and handle the machines necessary to carry out the project. An updated version of the methodology was developed where the design was verified using finite element analysis. With the updated version the methodology contained nine steps, which in short was as follows. First apprehend an inner socket from an orthopedic clinic with a pattern drawn up on it, the pattern is then transferred to a computer environment and manipulated to the desired shape and thickness. A compressive strength test, both virtual and experimental, was designed by a modified version of the ISO-10328 standard and the virtual design was verified before the socket was manufactured in the Electron Beam Melting machine. The manufactured socket was tested in the experimental set-up to verify the virtual one. The result was a personal designed socket of Ti6Al4V including the male pyramid for connection and a suspension system, which consisted of an inner socket and a one-way valve. It was concluded that Electron Beam Melting could be used as an alternative manufacturing process of prosthetic sockets.
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Lambert, Océane. "Solutions architecturées par fabrication additive pour refroidissement de parois de chambres de combustion." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAI048/document.
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En vue de leur refroidissement, les parois de chambres de combustion aéronautiques sont perforées de trous à travers lesquels de l’air plus froid est injecté. La paroi est ainsi refroidie par convection et un film isolant est créé en surface chaude (film cooling). Cette thèse a pour objectif d’utiliser les possibilités de la fabrication additive pour proposer de nouvelles solutions architecturées qui permettraient d’augmenter les échanges de chaleur internes et d’obtenir ainsi de meilleures efficacités de refroidissement.La première approche consiste à élaborer de nouveaux designs de plaques multiperforées par Electron Beam Melting (EBM) et Selective Laser Melting (SLM) aux limites de résolution des procédés. Les architectures sont caractérisées en microscopie, en tomographie X et en perméabilité. Des simulations aérothermiques permettent de mettre en évidence l’effet de ces nouveaux designs sur l’écoulement et les échanges de chaleur, et de proposer des voies d’amélioration de la géométrie.La deuxième approche consiste à élaborer de façon simultanée une pièce architecturée par EBM, avec des zones denses et poreuses. A partir d’analyse d’images associée à une cartographie EBSD grand champ, il est possible de remonter aux mécanismes de formation du matériau poreux et de relier la perméabilité et la porosité aux paramètres procédé. Afin de favoriser le film cooling, il pourrait être avantageux que les zones microporeuses soient orientées dans le sens de l’écoulement. Pour ce faire, un nouveau procédé dénommé Magnetic Freezing, où des poudres métalliques forment une structure orientée par un champ magnétique, est mis au point.Les diverses solutions développées durant cette thèse sont testées sur un banc aérothermique. Les essais montrent qu’elles offrent un refroidissement plus efficace et plus homogène que la référence industrielle. Enfin, de premiers tests en combustion sur l’une des structures retenues, plus légère et plus perméable que la référence, montrent qu’il s’agit d’une solution aussi efficace à un débit traversant donné, et donc a priori plus efficace à une surpression donnéeCombustion chamber walls are perforated with holes so that a cooling air flow can be injected through them. The wall is cooled by convection and an insulating film is created on the hot surface (film cooling). This PhD thesis aims to use the possibilities of additive manufacturing to provide new architectured solutions that could enhance the internal heat exchanges, and lead to a higher cooling effectiveness.The first approach is to develop new designs of multiperforated walls by Electron Beam Melting (EBM) and Selective Laser Melting (SLM) used at the resolution limits of the processes. They are characterized by microscopy, X-ray tomography and permeability tests. Some aerothermal simulations help understanding the effects of these new designs on the flow and on heat exchanges. These results lead to a geometry adaptation.The second approach is to simultaneously manufacture an architectured part with dense and porous zones by EBM. Thanks to image analysis combined with large field EBSD, it is possible to investigate the mechanisms leading to the porous zones and to link them to permeability and porosity. The film cooling effect could be favoured by the orientation of pores towards the cooling flow. Therefore, a new powder-based manufacturing process named Magnetic Freezing, where metallic powders organize into an oriented structure thanks to a magnetic field, is developed.The various solutions studied during this thesis are tested on an aerothermal bench. They all show a more efficient and homogeneous cooling than the industrial reference. Some first tests on one of the selected solutions are performed on a combustion bench. This lighter and more permeable structure proves to be a solution as efficient as the industrial reference at a given flow rate. It should therefore be a more efficient solution for a given overpressure
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Al-Bermani, Sinan Saadi. "An investigation into microstructure and microstructural control of additive layer manufactured Ti-6Al-4V by electron beam melting." Thesis, University of Sheffield, 2011. http://etheses.whiterose.ac.uk/14694/.
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An additive layer manufacturing (ALM) technique, electron beam melting, has been used for the production of simple geometries, from pre-alloyed Ti-6Al-4V powder. Microstructure, texture and mechanical properties achieved under standard conditions have been investigated, alongside numerical modelling of the electron beam and attempts to modify solidification through the addition of boron. Experimentation reveals an asymmetric electron beam which can be manipulated to produce different material responses. The electron beam has been used in this work, at its least powerful, as a means of preheating powder particles and, at its most powerful; to produce what is effectively a macro-scale electron beam weld. Numerical modelling and extraction of solidification parameters reveal that solidification occurs in the columnar region - columnar grains are observed experimentally and are a feature of the process. I Observed microstructures indicate a complicated thermal history that is capable of producing diffusion-less and diffusional transformation products. Electron backscatter diffraction (EBSD) and prior ~ grain reconstruction reveal a strong texture perpendicular to the build axis. Mechanical properties, tested over a range of build temperatures, are sensitive to temperature over the tested range of 625 - 700 °e. Attempts to disrupt columnar solidification via the addition of boron to Ti-6Al-4V, before subsequent EBM processing, were unsuccessful. Solidification remained in the columnar regime with no refinement in grain morphology observed.
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Hernández-Nava, Everth. "A study on the mechanical properties of micro-truss Ti-6Al-4V materials fabricated by electron beam melting." Thesis, University of Sheffield, 2015. http://etheses.whiterose.ac.uk/15488/.
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Electron beam melting (EBM) has been used to manufacture Ti-6Al-4V micro-truss materials for light weight mechanical applications. Several structures were examined, including a cubic lattice, a diamond structure and randomly-structured foams. The “As-built" material, after the selection of processing parameters and fabrication, has been characterised at a micro and macro level through optical microscopy (OM) and x-ray tomography (XCT) respectively. In order to assess the beam penetration and dimensions of the material after the deposition, a numerical method was employed to study the heat source interaction with the metal to be melted. Fabricated structures were evaluated after compression testing, identifying the collapse behaviour. The influence of the microstructure was investigated in the “As-built" condition and after post-builds heat treatments at lower and higher temperatures than the beta-transus. From this study, is it suggested that the incidence of volumetric defects from the additive manufacturing (AM) process influences the mechanical resistance and performance more dramatically than the bulk material properties. Additionally, due to the nature of the alloy system with work hardening and low heat conductivity, the observed failure mode was related to the development of adiabatic shear bands. This type of failure was characterised by deformation at high strain rates through Hopkinson bar tests.
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Feldt, Daniel, Petra Hedberg, Asker Jarlöv, Elsa Persson, Mikael Svensson, Filippa Vennberg, and Therese You. "Independent Project in Chemical Engineering and Materials Engineering : A literature study of powder-based additive manufacturing." Thesis, Uppsala universitet, Institutionen för teknikvetenskaper, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-354425.
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The focus of this literary study was additive manufacturing (AM) and the purpose was to find general trends for selected materials that have been additively manufactured and compare them to results from other reviews. The raw materials studied were stainless steels 316L, 17-4 PH, 15-5 PH and 420, as well as tool steel H13 and nickel alloys 625, 718 and Hastelloy X.The AM techniques studied were selective laser melting (SLM), electron beam melting (EBM) and binder jetting (BJG). A total of 69 articles have been studied to fulfill the purpose above. The articles were used to write a summary of the techniques, compare them to each other and to conventional methods. They were also used to create a database to compile information on mechanical properties, microstructure and process parameters. Based on the database mechanical properties for SLM tend to be higher compared to EBM. This however varied somewhat depending on the processed material. Furthermore the yield and tensile strength obtained from the database for SLM seemed to be higher compared to the values in review articles for almost all materials. Unfortunately not enough values were found for BJG to compare it to SLM and EBM.AM seems to produce weaker, equal and superior products compared to conventional methods. However due to the limited nature of the project and the research found no conclusions can be drawn about any trends, how to achieve the different results or how parameters affect the finished product. To be able to say anything with more certainty more research has to be done. Not only in general concerning the AM techniques, but more studying of existing articles is needed. Finally a standardization on how to reference properties and process parameters is necessary. Currently it is very difficult to compare results or draw conclusions due to different designations, units and a lot of missing essential information.
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Hiricoiu, Alexandre. "Contribution à l'analyse expérimentale et numérique pour l'élaboration d'absorbeurs d'énergie obtenus par procédés de fabrication additive." Thesis, Valenciennes, 2018. http://www.theses.fr/2018VALE0011.
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La rentabilité des hélicoptères de transport civil est un paramètre clé qui oblige les avionneurs à toujours repousser les limites en termes d’optimisation des structures. Les nouvelles générations d’appareils devront parcourir des distances plus longues et avoir des capacités de transport plus grandes. Le gain en masse sur les équipements à bord des appareils est donc un facteur déterminant pour atteindre les objectifs de performances accrues pour le futur. Les travaux de recherche menés durant la thèse sont à l’initiative de l’équipementier aéronautique Zodiac Seats France, leader français sur le marché des sièges techniques pour hélicoptères civils. L’objectif souhaité de l’entreprise est le développement à moyen terme d’un siège passager ayant un gain de masse ciblé à 50% des équipements actuels. Cette amélioration n’est aujourd’hui envisageable qu’à travers une rupture technologique avec les solutions déjà existantes. Les nouveaux procédés notamment en matière de fabrication additive permettent à ce jour d’envisager des réalisations de structures innovantes à forme complexe. Le choix de la technologie de fabrication additive EBM « Electron Beam Melting » est fixé.La Recherche menée ici, vise à assurer la sécurité des futurs sièges en cas de crash, grâce à l’étude de nouvelles solutions techniques pour permettre une absorption optimale d’énergie lors de l’impact. Les travaux présentés s’organisent en trois volets. Le premier concerne la caractérisation en traction statique et dynamique ainsi que la modélisation numérique du titane Ti–6Al–4V obtenu par fabrication additive EBM. Pour cela un protocole expérimental ainsi qu’un plan d’expérience ont été définis. Le second volet vise à valider les propriétés matériau établies par le biais d’essais et de simulations à l’échelle de structures complexes dans un objectif de fournir au concepteur un outil de modélisation numérique permettant un dimensionnement efficace. Enfin, le troisième volet présente la stratégie développée au cours de la thèse pour permettre à l’aide d’un outil d’optimisation la définition numérique de futures formes de structures capables d’absorber un maximum d’énergie dans un espace géométrique disponibleThe profitability of civil transport helicopters is a key parameter that forces aircraft manufacturers to always push forward innovation and design optimization. Next generation of aircraft must be able to fly longer and have increased transport capacities. Weight reduction on in-flight equipment is a critical factor to achieve better performances in the future. The research work carried out during the PhD thesis was initiated by the aeronautical equipment manufacturer Zodiac Seats France, the French leader in the market of technical seats for civil helicopters. The desired objective of the company is the mid-term development of a passenger seat with a targeted mass reduction of 50% to current equipments. This improvement is only possible today with technological breakthrough. New processes, particularly in the field of additive manufacturing, allow nowadays the production of innovative structures with complex shapes. The choice of additive manufacturing technology EBM "Electron Beam Melting" is fixed. The research conducted here aims to ensure the safety of future seats in the event of a crash, thanks to the study of new technical solutions to allow optimal absorption of energy at impact. The works presented are organized in three parts. The first concerns the static and dynamic tensile characterization as well as the numerical modeling of titanium Ti-6Al-4V obtained by additive manufacturing EBM. For this purpose, an experimental protocol and an experimental plan have been defined. The second part aims to validate the material properties established by means of tests and simulations at the scale of complex structures in order to provide the designer with a numerical modeling tool allowing efficient dimensioning. Finally, the third part presents the strategy developed during the thesis to help in optimizing, through the numerical simulation, the future structures capable of absorbing a maximum of energy for a given geometrical space
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Gustavsson, Bengt. "Effect of Beam Scan Length on Microstructure Characteristics of EBM Manufactured Alloy 718." Thesis, KTH, Materialvetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-225416.
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Additive Manufacturing (AM) as a method is on the rise and allow for a high freedom to create unique shapes without being limited by conventional machining methods. The Electron Beam Melting method, developed by Arcam AB in Mölndal, Sweden, use Powder Bed Fusion together with an electron beam and at an elevated temperature (+1000ºC) to lower stress due to thermal gradients. The purpose of this paper is to study the influence of Scan Length during Electron Beam Melting of Alloy 718 in regards to the appearance of shrinkage, porosity, primary carbide precipitation (mainly NbC), primary dendrite width and hardness. Samples built had the dimensions of 10x15xVar mm3 (Height x Depth x Width) with widths ranging from 10 mm in steps of 5 mm up to a maximum of 90 mm. The parameters were set as a single entry within the build project and as such each layer was melted as a single unit. A Light-Optical Microscope (LOM) and a Scanning Electron Microscope (SEM) was used to obtain images for manual counting to calculate the fraction of porosity and NbC-precipitates as well as the columnar grain width. The space between lines of interdendritical precipitation of NbC was used to determine the dendrite arm widths and a series of Hardness Vickers (500g for 15s) indents was performed. An Energy-Dispersive X-Ray Spectroscope (EDS) was used to help identify precipitates and phases. Columnar grain width and the spacing between vertical bands of interdendritical NbC was measured according to ASTM112-13 while porosity and hardness was measured according to ASTM562-11. Both of these only looked at the XZ-plane instead of all three planes. The columnar grain width was measured in the 10 mm, 40 mm and 90 mm samples at a distance of 4 mm from the top and with a slight spread over the sample width according to ASTM112-13 but using only one plane for counting. No significant change to columnar width was found. Primary dendrite arm width was measured on the 10 mm, 40 mm and 90 mm samples at about 5 mm from the top. An average for all samples was found to be 7.82 μm ± 2.89. No significant trend could be found with increased sample width. A total average porosity of 0.33% ± 0.16 was found. Variations between samples were less than the standard deviation. Even though the variations were not high enough to be significant, no obvious trend could be seen in regards to sample width, position on the base plate or heat transfer through the build. The presence of NbC was investigated in all samples with a total average of 0.36% ± 0.23 with variations between sample lengths being within the standard deviation. An insignificant trend could be seen between the smaller samples together with the wider samples having a higher degree of NbC compared to the middle samples. No significant trend could be seen in NbC based on row. Across all samples, the mean hardness was found to be 406.75 HV0.5 ± 16.53. No significant trend could be seen with increased sample width. Based on sample rows no significant trend could be seen.
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Klassen, Alexander [Verfasser], Carolin [Akademischer Betreuer] Körner, Carolin [Gutachter] Körner, and Andreas [Gutachter] Otto. "Simulation of Evaporation Phenomena in Selective Electron Beam Melting / Alexander Klassen ; Gutachter: Carolin Körner, Andreas Otto ; Betreuer: Carolin Körner." Erlangen : FAU University Press, 2018. http://d-nb.info/1160444307/34.
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Gaytan, Guillen Sara Marisela. "Additive layer manufacturing of TI-6AL-4V by electron beam melting from powder particles solid, mesh and foam components study /." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2009. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
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Tepe, Julius. "Development of a Data Transformation Method for a Customized Stent usingAdditive Manufacturing." Thesis, KTH, Industriell produktion, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-226523.
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Conventionally manufactured stents are available in uniform sizes and straight forms. These standard products are not suitable for all patients and research indicates that this is the reason for migration of stents in the vessel, and tubular structure in general, after deployment. The occurrence of migration makes readmission into hospital and the removal of the deployed stent necessary. This thesis develops a method which results in patient-customized stents which can be manufactured through additive manufacturing. These individualized stents intent to offer the same advantages of conventional stents while mitigating the disadvantages. The work’s core part is thedesign of a stent based on the geometric information through a medical scan. It converts the relevant areas from the medical scan data which is in the DICOM format to the STL file format. After cleaning and further processing, the shape will be the base for the design process of a stent using CAD software. Additionally, it also gives insight into the subjacent technologies such as medical scanning, additive manufacturing, choice of material and necessary further processing steps. A process chain from scanning, data transformation, 3D printing and post processing is described.The developed method delivers a reliable model and results in a fully individualized stent. In the current stage, it involves manual work since the representation of data in the steps is different. Further suggestions for steps to automate the process and an estimation of economic efficiency is given.Det finns konventionellt tillverkade stenter i likformiga storlekar och raka former. Dem här standardprodukter är inte lämpliga för alla patienter och forskning tyder på att detta är orsaken till migrationen av stenter i blodkärl efter placering. Förekomsten av migration skapa återtagande på sjukhus och avlägsnande av den placerade stenten är nödvändig. Den här avhandlingen utvecklar en metod som resulterar i patient anpassade stenter som kan varatillverkad genom additiv tillverkning. Dessa individualiserade stenter avser att erbjuda samma fördelar som konventionella stenter och mildra nackdelarna. Arbetets kärna är designen av en stent baserad på den geometriska informationen baserande på en medicinsk bildteknik. Det omvandlar relevanta kroppsdelar från det medicinska bildteknik som finns i DICOM-formatet till STLfilformatet. Efter rengöring och vidare bearbetning kommer formen att vara basen för stentens designprocess med CAD-mjukvara. Dessutom ger den också inblick i de underliggande teknikerna som medicinsk bildteknik, tillsatsframställning, materialval och nödvändig vidarebehandling steg. En processkedja från skanning, datatransformation, 3D-utskrift och efterbehandling är beskrivits.Den utvecklade metoden ger en tillförlitlig modell och resulterar i en helt individualiserad stent. I det aktuellt stadium, innebär det manuellt arbete eftersom representationen av data i stegen är annorlunda. Ytterligare förslag till åtgärder för att automatisera processen och en uppskattning av ekonomisk effektivitet är given.
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Chougrani, Laurent. "Modélisation avancée de formes complexes de pièces mécaniques pour lesprocédés de fabrication additive." Thesis, Paris, ENSAM, 2017. http://www.theses.fr/2017ENAM0054.
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Les procédés de fabrication additive ont connus un fort essor dans les dernières décennies et entament aujourd'hui leur phase d'industrialisation pérenne. L'industrie, dans un souci d'améliorer sans cesse le ratio masse/rigidité des systèmes qu'elle produit (notamment l'industrie aéronautique), a pris conscience du potentiel de ces technologies à produire des structures plus complexes que les procédés classiques. Elle cherche aujourd'hui à tirer profit de ce potentiel pour alléger encore plus les pièces produites en utilisant notamment des géométries de type réseaux ou alvéolaires (Lattice en anglais). Les travaux présentés dans ce manuscrit ont pour but de proposer une méthodologie, des modèles et des outils permettant la conception, le dimensionnement et l'optimisation de telles structures en vue de leur fabrication par procédés additifs. Le framework proposé peut être résumé par les huit étapes ci-dessous:- Importation de l'espace de conception, comprenant également les cas de chargement.- Optimisation topologique sur l'espace de conception.- Reconstruction de la géométrie, appelée primitive, qui servira de support à l'insertion du réseau.- Calcul par éléments finis qui peut être réalisé pour s'assurer de la bonne tenue mécanique.- Définition de la topologie du réseau, par l'intermédiaire d'un graphe 3D.- Déformation du réseau et optimisation mécanique du réseau.- Reconstruction des volumes.- Préparation des fichiers de données et impression 3DAdditive manufacturing processes have been quickly growing those past decades and are now getting to their sustainable industrial. Industry has been caring about the mass to rigidity ratio of the structures it produces (especially in aeronautics), and is now acknowledging the potential of additive processes to produce more complex shapes than classical processes. Industry is now trying to take advantage of this potential by designing highly complex structures like lattices or metal foams. The work that is presented in this document propose a methodology, models and numerical tools allowing the conception, dimensioning and optimization of such structures through additive manufacturing. The proposed framework can be describe through the height following steps:- Importing the design space and the technical requirement (load cases).- Topology optimization of the design space- Geometry reconstruction to create a primitive which will be the lattice insertion area.- Finite elements computation to ensure that the structure meets the requirements.- Lattice topology definition using 3D graphs.- Lattice deformation and optimization.- Creation of the volumes around the lattice.- Printing file creation and 3D printing
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Piazza, Gianluigi. "Studio microstrutturale e tribologico di leghe leggere prodotte mediante additive manufacturing." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/22593/.
Full textAbstract:
In questo lavoro è stato valutato il comportamento tribologico di leghe prodotte mediante i più diffusi processi di Powder Bed Fusion: SLM (Selective Laser Melting) ed EBM (Electron Beam Melting). Nella prima parte è stata studiata l’influenza di processi di anodizzazione innovativi come PEO (Plasma Electrolytic Oxidation) ed ECO (ElectroChemical Oxidation) sulla lega di alluminio A357 prodotta mediante SLM con due diverse combinazioni di parametri di processo volte ad ottimizzare rispettivamente, la microstruttura (M) e la produttività (P). Nella seconda parte è stato studiato il comportamento tribologico della lega Ti6Al4V prodotta per EBM, in relazione al processo produttivo, alla finitura superficiale e all’orientazione derivante dal processo EBM.
Lo studio tribologico è stato effettuato con prove di strisciamento non lubrificato (geometria pattino-su-cilindro contro acciaio EN 100Cr6), con carichi applicati nell’intervallo 20-60 N, nel caso della lega A357 SLM anodizzata, e di 10 N per la lega Ti6Al4V EBM, in entrambi i casi con velocità di strisciamento di 0,3 m/s.
Nel primo caso i risultati ottenuti hanno dimostrato come entrambi i processi di anodizzazione abbiano migliorato la resistenza ad usura della lega SLM A357 as-built rispetto al substrato non rivestito. Il rivestimento ECO ha dato luogo ad una maggiore resistenza ad usura rispetto al PEO, grazie alle migliori proprietà di coesione ed adesione.
Nel secondo caso i risultati ottenuti hanno evidenziato come il processo EBM sulla lega di Ti6Al4V abbia prodotto resistenza ad usura maggiori rispetto a quella convenzionale, grazie alla maggiore finezza microstrutturale. Nei casi studiati, un aumento di rugosità superficiale ha condotto sempre ad un incremento del tasso d’usura. Al contrario, la sezione di crescita, con orientazione dei grani perpendicolare alla direzione di strisciamento, ha portato ad un’usura minore, rispetto alla sezione a grani equiassici perpendicolare alla direzione di crescita.
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Hällgren, Sebastian. "Some aspects on designing for metal Powder Bed Fusion." Licentiate thesis, Örebro universitet, Institutionen för naturvetenskap och teknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-62947.
Full textAbstract:
Additive Manufacturing (AM) using the Powder Bed Fusion (PBF) is a relatively new manufacturing method that is capable of creating shapes that was previously practically impossible to manufacture. Many think it will revolutionize how manufacturing will be done in the future. This thesis is about some aspects of when and how to Design for Additive Manufacturing (DfAM) when using the PBF method in metal materials. Designing complex shapes is neither easy nor always needed, so when to design for AM is a question with different answers depending on industry or product. The cost versus performance is an important metric in making that selection. How to design for AM can be divided into how to improve performance and how to improve additive manufacturability where how to improve performance once depends on product, company and customer needs. Using advanced part shaping techniques like using Lattices or Topology Optimization (TO) to lower part mass may increase customer value in addition to lowering part cost due to faster part builds and less powder and energy use. Improving PBF manufacturability is then warranted for parts that reach series production, where determining an optimal build direction is key as it affects many properties of PBF parts. Complex shapes which are designed for optimal performance are usually more sensitive to defects which might reduce the expected performance of the part. Non Destructive Evaluation (NDE) might be needed to certify a part for dimensional accuracy and internal defects prior use. The licentiate thesis covers some aspects of both when to DfAM and how to DfAM of products destined for series production. It uses design by Lattices and Topology Optimization to reduce mass and looks at the effect on part cost and mass. It also shows effects on geometry translation accuracies from design to AM caused by differences in geometric definitions. Finally it shows the effect on how different NDE methods are capable of detecting defects in additively manufactured parts.
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Brochs, Christoffer. "Defektidentifieringvid EBM-tillverkning." Thesis, Mittuniversitetet, Avdelningen för kvalitets- och maskinteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-34780.
Full textAbstract:
Tillverkning av slutprodukter med additiv tillverkning blir allt vanligare. Slutprodukter har högre krav på detaljens mekaniska egenskaper än prototyper gör. Forskning har visat att porositeten är av stor betydelse för en detaljs hållfasthet. Med additiv tillverkning finns goda möjligheter för direkt processövervakning och kontrollsystem. Inom electron beam melting finns sådana system men de saknas en validering av resultatet från dom systemen. I de här arbetet har prover med designade defekter tillverkats. LayerQam bilder från tillverkningen har analyserats med Defect Detector. Data från analysen har visualiserats. Resultatet har studerats samt att det har tagits fram en Defect Detector-analys med högre precision. Utvalda prover har undersökts i ett tvärsnitt med optisk mikroskopi samt i 3D med mikrotomografi. Undersökningarna har jämförts med varandra, de tyder på att Defect Detector har brister i sin bedömning av densiteten. De designade defekterna har en överskattad storlek samt brister i kompensation av förvrängningen i synfältet i bilderna.Betyg: 180827