Advancements in the area of additive manufacturing have led to the development of new methods with the purpose of optimizing component properties and expanding operating environments. In a comparative study, the influence of process parameters including beam and laser current, translation speed, and wire feed and deposition rate on 316L stainless steel deposits produced by both Laser Engineered Net Shaping (LENS®) and Electron Beam Freeform Fabrication (EBF3) processes are investigated. Tensile tests are used to obtain information on the mechanical properties of the specimens. A metallographic analysis is performed using optical microscopy and SEM to characterize solidification grain structure, porosity, secondary dendrite arm spacing, and possible modes of failure. This study highlights the distinct characteristics of both additive methods and how they lead to different microstructure and mechanical properties. Also included in this study is the upgrade and repair of the LENS machine at CAVS.

Electron beam freeform fabrication (EBF3) is a rapid metal deposition process that works efficiently with the wieldable alloy Inconel 718 (IN 718). EBF3 is a developing additive manufacturing (AM) process that can manufacture IN 718 parts directly from computer aided design (CAD) data. EBF3 can produce parts significantly faster and more energy efficient than competing IN 718 AM technologies. The EBF3 process utilizes metal wire feedstock which is induced into a molten pool using a focused electron beam in a vacuum environment. This allows parts to be built layer by layer, creating intricate shapes that can be produced cheaper and faster than traditionally manufactured IN 718 parts. Furthermore, it allows traditionally manufactured parts to be modified as additional form is added to them using EBF3. Multiple industries rely on IN 718 parts and can utilize this technology including aerospace engineering, oil refinery, nuclear power generation, and food processing.A main drawback of EBF3 is the lack of knowledge of the effect different EBF3 build techniques will have on the properties of the deposited materials. Most of the reliable data on the mechanical properties relate to a linear build-up strategy and focus on the mechanical properties in the deposition direction (DD). There is no data related to other build-up techniques such as rotation build-up or transitional builds from forged material to EBF3 material. Reliable data on the behavior and microstructure of EBF3 material in a direction other than the DD is also difficult to find. Previous studies showed build-up height influenced mechanical properties but its role is not fully understood yet. This paper presents the mechanical properties and microstructure of an IN 718 plate built using a EBF3 rotational build-up strategy through utilizing a forged plug in the center. The tensile properties of samples at the transition from forged to EBF3 material showed higher ductility and reduced strength than pure EBF3 material. This is likely due the influence of the forge material in one half of the specimen. Samples taken at approximately 15 degree increments from 0 to 90 degrees rotation to the DD in the additive portion of the plate were subjected to tensile testing. Along the build height, or the transverse direction (TD), the lowest strength was demonstrated and the TD aligned strongly to a <001> texture. Samples 45 degrees to the DD showed the greatest strength due to their preference for aligning to a <111> texture. Samples low on the build height demonstrated a higher strength than those on the top and displayed grain structures along the TD which were long, linear, and narrow across multiple deposition layers.

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京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第21335号 / 医博第4393号 / 新制||医||1031(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 髙折 晃史, 教授 濵﨑 洋子, 教授 江藤 浩之 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

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