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Journal ArticleDOI

Additive manufacturing of 316L stainless steel by electron beam melting for nuclear fusion applications

TL;DR: A feasibility study was performed to fabricate ITER In-Vessel components by one of the metal additive manufacturing methods, Electron Beam Melting® (EBM®). Solid specimens of SS316L with 99.8% rela...
About: This article is published in Journal of Nuclear Materials.The article was published on 2017-04-01. It has received 206 citations till now.
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TL;DR: In this article, the authors evaluated the effect of the arc mode on the manufacturing process stability, structural integrity, component morphology, microstructure, and mechanical properties of the SpeedPulse and SpeedArc additive manufacturing processes.
Abstract: Wire arc additive manufacturing (WAAM) features advantages such as low cost and high disposition rate, and thus WAAM is a feasible additive manufacturing process. Although some characteristics of WAAM have been documented in the literature, the process stability, structural integrity, component morphology, microstructure, and mechanical properties during WAAM under different arc modes are not comprehensively demonstrated and understood. Here, we performed WAAM experiments with 316L stainless steel under different arc modes and a constant deposition rate, and then we discussed the mechanism and impact of the arc mode on the manufacturing process stability, structural integrity, microstructures, and mechanical properties. The results indicate that the SpeedPulse and SpeedArc additive manufacturing processes are relatively stable, significantly efficient, and structurally sound. Although the deposition rate and scanning speed of SpeedPulse WAAM and SpeedArc WAAM are the same, SpeedArc WAAM has a lower heat input and a higher cooling rate. Therefore, SpeedArc WAAM produces a finer solidification structure than SpeedPulse WAAM. The ultimate tensile strengths of the SpeedPulse and SpeedArc additive manufactured specimens along the horizontal direction are greater than 540 MPa and slightly greater than previously reported results. Due to the lower heat input and finer solidification structure, a component produced by SpeedArc WAAM has greater tensile strength and hardness than a component produced by SpeedPulse WAAM.

185 citations

Journal ArticleDOI
TL;DR: In this paper, an equiatomic CoCrFeNiMn high-entropy alloy (HEA) powder is produced by vacuum induction melting gas-atomization with argon gas.

121 citations

Journal ArticleDOI
TL;DR: In this paper, the additive manufacturing process is separated into pre-process, para-process and post-process stages and a critical review of the causes and impact of repeatability found at these stages is conducted.

120 citations

Journal ArticleDOI
TL;DR: In this article, a comprehensive review of the current understanding of the structure-property correlations in AM alloys is provided, with an emphasis on the interplay between the microstructures and process attributes in determining the structural integrity of AM components in terms of properties such as near-threshold fatigue crack growth rate, fracture toughness, and fatigue strength.

110 citations

Journal ArticleDOI
TL;DR: In this paper, the authors presented an experimental study of process optimization of the pair of critical parameters (speed function (SF) and focus offset (FO)) for stainless steel 316L (SS316L) parts additively manufactured by selective electron beam melting (SEBM).

105 citations

References
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Book
01 Jan 2009
TL;DR: Gibson et al. as discussed by the authors presented a comprehensive overview of additive manufacturing technologies plus descriptions of support technologies like software systems and post-processing approaches, and provided systematic solutions for process selection and design for AM Additive Manufacturing Technologies: Rapid Prototyping to Direct Digital Manufacturing.
Abstract: Additive Manufacturing Technologies: Rapid Prototyping to Direct Digital Manufacturing deals with various aspects of joining materials to form parts. Additive Manufacturing (AM) is an automated technique for direct conversion of 3D CAD data into physical objects using a variety of approaches. Manufacturers have been using these technologies in order to reduce development cycle times and get their products to the market quicker, more cost effectively, and with added value due to the incorporation of customizable features. Realizing the potential of AM applications, a large number of processes have been developed allowing the use of various materials ranging from plastics to metals for product development. Authors Ian Gibson, David W. Rosen and Brent Stucker explain these issues, as well as: Providing a comprehensive overview of AM technologies plus descriptions of support technologies like software systems and post-processing approaches Discussing the wide variety of new and emerging applications like micro-scale AM, medical applications, direct write electronics and Direct Digital Manufacturing of end-use components Introducing systematic solutions for process selection and design for AM Additive Manufacturing Technologies: Rapid Prototyping to Direct Digital Manufacturing is the perfect book for researchers, students, practicing engineers, entrepreneurs, and manufacturing industry professionals interested in additive manufacturing.

3,087 citations

Journal ArticleDOI
TL;DR: In this paper, a mixture of different types of particles (Fe, Ni, Cu and Fe3P) specially developed for selective laser sintering (SLS) is described.

1,342 citations

Journal ArticleDOI
TL;DR: The microstructure and mechanical behavior of simple product geometries produced by layered manufacturing using the electron beam melting (EBM) process and the selective laser melting (SLM) process are compared with those characteristic of conventional wrought and cast products of Ti-6Al-4V.
Abstract: The microstructure and mechanical behavior of simple product geometries produced by layered manufacturing using the electron beam melting (EBM) process and the selective laser melting (SLM) process are compared with those characteristic of conventional wrought and cast products of Ti-6Al-4V. Microstructures are characterized utilizing optical metallography (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and included alpha (hcp), beta (bcc) and alpha(') (hcp) martensite phase regimes which give rise to hardness variations ranging from HRC 37 to 57 and tensile strengths ranging from 0.9 to 1.45 GPa. The advantages and disadvantages of layered manufacturing utilizing initial powders in custom building of biomedical components by EBM and SLM in contrast to conventional manufacturing from Ti-6Al-4V wrought bar stock are discussed.

830 citations

Journal ArticleDOI
TL;DR: In this paper, time-temperature-precipitation diagrams were determined between 400° and 900°C for up to 3000 hr as a function of carbon content, solution treatment temperature, and cold work.
Abstract: Although Type 316 austenitic stainless steel is widely used in steam generating plants and nuclear reactors the knowledge about aging reactions, nature of precipitates, and precipitation kinetics during high temperature exposure is limited. Time-temperature-precipitation (TTP) diagrams were determined between 400° and 900°C for up to 3000 hr as a function of carbon content, solution treatment temperature, and cold work. The nucleation and growth phenomena, morphology, and composition of the various carbide (M23C6, M6C) and intermetallic phases (σ, χ, η were determined. The complex sequence of phase instabilities can be explained on the basis of the carbon content, effect of molybdenum and chromium on the carbon solubility, thermodynamic stability of the phases, and the kinetics of the various precipitation reactions.

658 citations

Journal ArticleDOI
TL;DR: In this paper, a fine columnar sub-grain structure of size 0.5μm was observed inside each individual large grain of single-crystal nature and with grain sizes in the range of 10-100μm.
Abstract: Laser melting (LM), with a focused Nd: YAG laser beam, was used to form solid bodies from a 316L austenite stainless steel powder. The microstructure, phase content and texture of the LM stainless steel were characterized and compared with conventional 316L stainless steel. The crack-free LM samples achieved a relative density of 98.6±0.1%. The XRD pattern revealed a single phase Austenite with preferential crystallite growth along the (100) plane and an orientation degree of 0.84 on the building surface. A fine columnar sub-grain structure of size 0.5 μm was observed inside each individual large grain of single-crystal nature and with grain sizes in the range of 10–100 μm. Molybdenum was found to be enriched at the sub-grain boundaries accompanied with high dislocation concentrations. It was proposed that such a sub-grain structure is formed by the compositional fluctuation due to the slow kinetics of homogeneous alloying of large Mo atoms during rapid solidification. The local enrichment of misplaced Mo in the Austenite lattice induced a network of dislocation tangling, which would retard or even block the migration of newly formed dislocations under indentation force, turning otherwise a soft Austenite to hardened steel. In addition, local formation of spherical nano-inclusions of an amorphous chromium-containing silicate was observed. The origin and the implications of the formation of such oxide nano-inclusions were discussed.

526 citations