Journal articles on the topic 'AM metallic powder'
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1
Chike, Onuchukwu Godwin, Norhayati Binti Ahmad, and Uday Basheer Al-Naib. "Taxonomy on the production processes and characterization of powder metallurgy used in additive manufacturing process." Naukovyi Visnyk Natsionalnoho Hirnychoho Universytetu, no. 6 (December 25, 2022): 52–58. http://dx.doi.org/10.33271/nvngu/2022-6/052.
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Purpose. This article presents a concise and comprehensive review of the technologies that are typically used for manufacturing metal powders as well as the implications that particle features have on the properties of additive manufacturing (AM) techniques. Methodology. We surveyed various experiments that have taken place on the effects of the qualities of the powder and how to guarantee the dependability and reproducibility of the parts that are manufactured as well as ways of optimizing a powders performance. We classified the methods for producing metallic powders and highlighted the benefits, limitations, and image analysis of major production techniques. Findings. The usage of different approaches to metallic powder characterization for the analysis of the physical, mechanical, and chemical processes has contributed to major steps in powder optimization. The characterization of these powders is critical for ensuring adequate additive material dimensions and specifications and recording the properties of powders used in an AM and bridging the gap of comprehension concerning the end output in AM. Originality. This paper provides a thorough analysis of the efforts made in the powder characterization of AM components for the interpretation of the impact on the part materials qualities and characteristics. Metallic powder characterization has contributed to substantial progress toward powder optimization in the analysis of particle structures. Practical value. As the application of AM technology is moving away from the creation of prototypes and toward the production of finished products, it becomes important to understand the powder properties necessary to manufacture high-quality elements consistently.
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Cerejo, Fábio, Daniel Gatões, and M. T. Vieira. "Optimization of metallic powder filaments for additive manufacturing extrusion (MEX)." International Journal of Advanced Manufacturing Technology 115, no. 7-8 (May 25, 2021): 2449–64. http://dx.doi.org/10.1007/s00170-021-07043-0.
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AbstractAdditive manufacturing (AM) of metallic powder particles has been establishing itself as sustainable, whatever the technology selected. Material extrusion (MEX) integrates the ongoing effort to improve AM sustainability, in which low-cost equipment is associated with a decrease of powder waste during manufacturing. MEX has been gaining increasing interest for building 3D functional/structural metallic parts because it incorporates the consolidated knowledge from powder injection moulding/extrusion feedstocks into the AM scope—filament extrusion layer-by-layer. Moreover, MEX as an indirect process can overcome some of the technical limitations of direct AM processes (laser/electron-beam-based) regarding energy-matter interactions. The present study reveals an optimal methodology to produce MEX filament feedstocks (metallic powder, binder, and additives), having in mind to attain the highest metallic powder content. Nevertheless, the main challenges are also to achieve high extrudability and a suitable ratio between stiffness and flexibility. The metallic powder volume content (vol.%) in the feedstocks was evaluated by the critical powder volume concentration (CPVC). Subsequently, the rheology of the feedstocks was established by means of the mixing torque value, which is related to the filament extrudability performance.
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Grubbs, Jack, Bryer C. Sousa, and Danielle Cote. "Exploration of the Effects of Metallic Powder Handling and Storage Conditions on Flowability and Moisture Content for Additive Manufacturing Applications." Metals 12, no. 4 (March 31, 2022): 603. http://dx.doi.org/10.3390/met12040603.
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Metal powder-based additive manufacturing (AM) relies on consistently successful processing of feedstock powder, necessitating through-process predictability in powder properties and behavior. However, routine powder handling and storage may degrade powder performance by influencing flowability and moisture content through exposure to ambient conditions. Therefore, this study aimed to evaluate the effects of repeated environmental exposure on the flowability and moisture content of Al 5056 and Ta powders for AM applications. Using Carney Funnel flow tests, thermogravimetric analysis, and particle size/shape analysis, powder characterization helped elucidate powder property and behavioral changes with exposure. Results indicated inconsistent flowability and moisture content changes for both material types when exposure conditions were altered. Correlational statistics highlighted the most influential particle characteristics on powder behavior after exposure; particle morphology was most impactful for the semi-spherical Al 5056, whereas moisture content and particle size were most significant for the angular Ta. While exposure to laboratory conditions minimally changed powder performance in this study, caution is advised when handling and storing powders in more “extreme” environments. Powder users are urged to implement quality controls alongside powder characterization to pinpoint how specific powders should be treated, handled, and stored in a given environment for successful processing in AM.
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Grzelak, Krzysztof, Marcin Bielecki, Janusz Kluczyński, Ireneusz Szachogłuchowicz, Lucjan Śnieżek, Janusz Torzewski, Jakub Łuszczek, et al. "A Comparative Study on Laser Powder Bed Fusion of Differently Atomized 316L Stainless Steel." Materials 15, no. 14 (July 15, 2022): 4938. http://dx.doi.org/10.3390/ma15144938.
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The significant growth of Additive Manufacturing (AM), visible over the last ten years, has driven an increase in demand for small gradation metallic powders of a size lower than 100 µm. Until now, most affordable powders for AM have been produced using gas atomization. Recently, a new, alternative method of powder production based on ultrasonic atomization with melting by electric arc has appeared. This paper summarizes the preliminary research results of AM samples made of two AISI 316L steel powder batches, one of which was obtained during Ultrasonic Atomization (UA) and the other during Plasma Arc Gas Atomization (PAGA). The comparison starts from powder particle statistical distribution, chemical composition analysis, density, and flowability measurements. After powder analysis, test samples were produced using AM to observe the differences in microstructure, porosity, and hardness. Finally, the test campaign covered an analysis of mechanical properties, including tensile testing with Digital Image Correlation (DIC) and Charpy’s impact tests. A comparative study of parts made of ultrasonic and gas atomization powders confirms the likelihood that both methods can deliver material of similar properties.
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Tateno, Toshitake, Akira Kakuta, Hayate Ogo, and Takaya Kimoto. "Ultrasonic Vibration-Assisted Extrusion of Metal Powder Suspension for Additive Manufacturing." International Journal of Automation Technology 12, no. 5 (September 5, 2018): 775–83. http://dx.doi.org/10.20965/ijat.2018.p0775.
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Additive manufacturing (AM) using metal materials can be used to manufacture metal parts with complex shapes that are difficult to manufacture with subtractive processing. Recently, numerous commercial AM machines for metallic materials have been developed. The primary types of AM using metallic materials are powder bed fusion or direct energy deposition. Other types using metallic materials have not been adequately studied. In this study, the use of the material extrusion (ME) type of AM is investigated. The aim is to use metallic materials not only for fabricating metal parts but also for adding various properties to base materials, e.g., electric conductivity, thermal conductivity, weight, strength, and color of plastics. ME is appropriate for use with various materials by mixing different types of filler. However, there is a problem in that the high density of metal fillers generates unstable extrusion. Therefore, ultrasonic vibration was used for assisting extrusion. A prototype system was developed using an extrusion nozzle vibrated by an ultrasonic homogenizer. The experimental results showed that the ultrasonic vibration allows materials to be extruded smoothly. Three dimensional (3D) shapes could be built by multi-layer deposition with a thixotropic polymer containing a highly concentrated steel powder. As one application, a 3D-shaped object was fabricated as a sintered object. After the vibration effect in the extrusion process of steel powder and clay was confirmed, a 3D object built by the proposed method was sintered through a baking process.
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Koptyug, Andrey, Mikael Bäckström, Carlos Alberto Botero Vega, Vladimir Popov, and Ekaterina Chudinova. "Developing New Materials for Electron Beam Melting: Experiences and Challenges." Materials Science Forum 941 (December 2018): 2190–95. http://dx.doi.org/10.4028/www.scientific.net/msf.941.2190.
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Lack of industrially available materials for additive manufacturing (AM) of metallic materials along with the promises of materials with improved or unique properties provides a strong drive for developing new process/material combinations. As powder bed technologies for metallic materials are relatively new to the market, and to some extent are only maturing, developers of new process/material combinations have certain challenges to overcome. Firstly, basic knowledge on the behavior of materials (even those well established for other applications) under extreme conditions of melting/solidification with beam-based AM methods is far from being adequate. Secondly, manufacturing of the equipment is up to date driven by industrial application, thus optimization of the AM machines for small test batches of powders is still belongs to research and development projects. Also, majority of the powder manufacturers are primarily driven by the market development, and even they are well aware of the demands imposed by the powder bed AM machines, availability of small test batches of adequate powders may be problematic or at least quite costly for the R&D oriented users. Present paper describes the experiences in developing new materials for EBM A2 machine by Arcam EBM, modified for operating with powder batches of 100-200 ml and less. In particular it discusses achievements and challenges of working with powders from different materials with specifications far beyond the range suggested by machine manufacturer. Also it discusses the possibility of using blended rather than pre-alloyed powders for achieving both composite-like and alloyed materials in the same part by steering electron beam energy deposition strategy.
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Santos, Cyril, Daniel Gatões, Fábio Cerejo, and Maria Teresa Vieira. "Influence of Metallic Powder Characteristics on Extruded Feedstock Performance for Indirect Additive Manufacturing." Materials 14, no. 23 (November 24, 2021): 7136. http://dx.doi.org/10.3390/ma14237136.
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Material extrusion (MEX) of metallic powder-based filaments has shown great potential as an additive manufacturing (AM) technology. MEX provides an easy solution as an alternative to direct additive manufacturing technologies (e.g., Selective Laser Melting, Electron Beam Melting, Direct Energy Deposition) for problematic metallic powders such as copper, essential due to its reflectivity and thermal conductivity. MEX, an indirect AM technology, consists of five steps—optimisation of mixing of metal powder, binder, and additives (feedstock); filament production; shaping from strands; debinding; sintering. The great challenge in MEX is, undoubtedly, filament manufacturing for optimal green density, and consequently the best sintered properties. The filament, to be extrudable, must accomplish at optimal powder volume concentration (CPVC) with good rheological performance, flexibility, and stiffness. In this study, a feedstock composition (similar binder, additives, and CPVC; 61 vol. %) of copper powder with three different particle powder characteristics was selected in order to highlight their role in the final product. The quality of the filaments, strands, and 3D objects was analysed by micro-CT, highlighting the influence of the different powder characteristics on the homogeneity and defects of the greens; sintered quality was also analysed regarding microstructure and hardness. The filament based on particles powder with D50 close to 11 µm, and straight distribution of particles size showed the best homogeneity and the lowest defects.
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Katz-Demyanetz, Alexander, Vladimir V. Popov, Aleksey Kovalevsky, Daniel Safranchik, and Andrey Koptyug. "Powder-bed additive manufacturing for aerospace application: Techniques, metallic and metal/ceramic composite materials and trends." Manufacturing Review 6 (2019): 5. http://dx.doi.org/10.1051/mfreview/2019003.
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The current paper is devoted to classification of powder-bed additive manufacturing (PB-AM) techniques and description of specific features, advantages and limitation of different PB-AM techniques in aerospace applications. The common principle of “powder-bed” means that the used feedstock material is a powder, which forms “bed-like” platform of homogeneous layer that is fused according to cross-section of the manufactured object. After that, a new powder layer is distributed with the same thickness and the “printing” process continues. This approach is used in selective laser sintering/melting process, electron beam melting, and binder jetting printing. Additionally, relevant issues related to powder raw materials (metals, ceramics, multi-material composites, etc.) and their impact on the properties of as-manufactured components are discussed. Special attention is paid to discussion on additive manufacturing (AM) of aerospace critical parts made of Titanium alloys, Nickel-based superalloys, metal matrix composites (MMCs), ceramic matrix composites (CMCs) and high entropy alloys. Additional discussion is related to the quality control of the PB-AM materials, and to the prospects of new approaches in material development for PB-AM aiming at aerospace applications.
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Liu, Jingfu, Behrooz Jalalahmadi, Y. B. Guo, Michael P. Sealy, and Nathan Bolander. "A review of computational modeling in powder-based additive manufacturing for metallic part qualification." Rapid Prototyping Journal 24, no. 8 (November 12, 2018): 1245–64. http://dx.doi.org/10.1108/rpj-04-2017-0058.
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PurposeAdditive manufacturing (AM) is revolutionizing the manufacturing industry due to several advantages and capabilities, including use of rapid prototyping, fabrication of complex geometries, reduction of product development cycles and minimization of material waste. As metal AM becomes increasingly popular for aerospace and defense original equipment manufacturers (OEMs), a major barrier that remains is rapid qualification of components. Several potential defects (such as porosity, residual stress and microstructural inhomogeneity) occur during layer-by-layer processing. Current methods to qualify AM parts heavily rely on experimental testing, which is economically inefficient and technically insufficient to comprehensively evaluate components. Approaches for high fidelity qualification of AM parts are necessary.Design/methodology/approachThis review summarizes the existing powder-based fusion computational models and their feasibility in AM processes through discrete aspects, including process and microstructure modeling.FindingsCurrent progresses and challenges in high fidelity modeling of AM processes are presented.Originality/valuePotential opportunities are discussed toward high-level assurance of AM component quality through a comprehensive computational tool.
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Ladani, Leila, and Maryam Sadeghilaridjani. "Review of Powder Bed Fusion Additive Manufacturing for Metals." Metals 11, no. 9 (September 1, 2021): 1391. http://dx.doi.org/10.3390/met11091391.
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Additive manufacturing (AM) as a disruptive technology has received much attention in recent years. In practice, however, much effort is focused on the AM of polymers. It is comparatively more expensive and more challenging to additively manufacture metallic parts due to their high temperature, the cost of producing powders, and capital outlays for metal additive manufacturing equipment. The main technology currently used by numerous companies in the aerospace and biomedical sectors to fabricate metallic parts is powder bed technology, in which either electron or laser beams are used to melt and fuse the powder particles line by line to make a three-dimensional part. Since this technology is new and also sought by manufacturers, many scientific questions have arisen that need to be answered. This manuscript gives an introduction to the technology and common materials and applications. Furthermore, the microstructure and quality of parts made using powder bed technology for several materials that are commonly fabricated using this technology are reviewed and the effects of several process parameters investigated in the literature are examined. New advances in fabricating highly conductive metals such as copper and aluminum are discussed and potential for future improvements is explored.
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del Rio, D. C., D. Juul Jensen, T. Yu, and N. S. Tiedje. "Laboratory-scale gas atomizer for the manufacturing of metallic powders." IOP Conference Series: Materials Science and Engineering 1249, no. 1 (July 1, 2022): 012034. http://dx.doi.org/10.1088/1757-899x/1249/1/012034.
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Abstract Metallic powders for additive manufacturing (AM) processes are primarily produced by gas atomization, which consists of three steps: melting, atomization and cooling. In the present work, we report on the refurbishing of a laboratory-scale gas atomizer. The equipment facilitates small-scale atomization, useful for developing powders tailored specifically to metal AM processes (e.g. binder jetting, laser powder-bed fusion and direct energy deposition). The refurbished atomizer is operated by an in-house measurement and control system, fully equipped with pressure, oxygen, gas-flow and temperature sensors that allow the user to experiment with the input parameters, and thus, understand how they affect the physical and chemical properties of powders. In this paper, the working principle of the laboratory-scale gas atomizer is presented and the main characteristics of the newly refurbished equipment are described.
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Jaenisch, Gerd-Rüdiger, Uwe Ewert, Anja Waske, and Alexander Funk. "Radiographic Visibility Limit of Pores in Metal Powder for Additive Manufacturing." Metals 10, no. 12 (December 4, 2020): 1634. http://dx.doi.org/10.3390/met10121634.
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The quality of additively manufactured (AM) parts is determined by the applied process parameters used and the properties of the feedstock powder. The influence of inner gas pores in feedstock particles on the final AM product is a phenomenon which is difficult to investigate since very few non-destructive measurement techniques are accurate enough to resolve the micropores. 3D X-ray computed tomography (XCT) is increasingly applied during the process chain of AM parts as a non-destructive monitoring and quality control tool and it is able to detect most of the pores. However, XCT is time-consuming and limited to small amounts of feedstock powder, typically a few milligrams. The aim of the presented approach is to investigate digital radiography of AM feedstock particles as a simple and fast quality check with high throughput. 2D digital radiographs were simulated in order to predict the visibility of pores inside metallic particles for different pore and particle diameters. An experimental validation was performed. It was demonstrated numerically and experimentally that typical gas pores above a certain size (here: 3 to 4.4 µm for the selected X-ray setup), which could be found in metallic microparticles, were reliably detected by digital radiography.
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Arrizubieta, Jon Iñaki, Olatz Ukar, Marta Ostolaza, and Arantza Mugica. "Study of the Environmental Implications of Using Metal Powder in Additive Manufacturing and Its Handling." Metals 10, no. 2 (February 17, 2020): 261. http://dx.doi.org/10.3390/met10020261.
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Additive Manufacturing, AM, is considered to be environmentally friendly when compared to conventional manufacturing processes. Most researchers focus on resource consumption when performing the corresponding Life Cycle Analysis, LCA, of AM. To that end, the sustainability of AM is compared to processes like milling. Nevertheless, factors such as resource use, pollution, and the effects of AM on human health and society should be also taken into account before determining its environmental impact. In addition, in powder-based AM, handling the powder becomes an issue to be addressed, considering both the operator´s health and the subsequent management of the powder used. In view of these requirements, the fundamentals of the different powder-based AM processes were studied and special attention paid to the health risks derived from the high concentrations of certain chemical compounds existing in the typically employed materials. A review of previous work related to the environmental impact of AM is presented, highlighting the gaps found and the areas where deeper research is required. Finally, the implications of the reuse of metallic powder and the procedures to be followed for the disposal of waste are studied.
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Todai, Mitsuharu, Takeshi Nagase, Takao Hori, Hiroyuki Motoki, Shi Hai Sun, Koji Hagihara, and Takayoshi Nakano. "Fabrication of the Beta-Titanium Alloy Rods from a Mixture of Pure Metallic Element Powders via Selected Laser Melting." Materials Science Forum 941 (December 2018): 1260–63. http://dx.doi.org/10.4028/www.scientific.net/msf.941.1260.
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The powder-bed additive manufacturing (AM) process offers advantages in terms of reduced material waste, ability to create complex shape and a decrease in the lead time from design to manufacturing. Recently, custom-made implant of Ti alloys is being developed by selective laser melting (SLM) in additive manufacturing (AM) process. However, the difficulty in the fabrication of titanium alloys due to their pre-alloyed powder cost, resulting in a limited usage of titanium alloys. To overcome this disadvantage, it is effective to fabricate the Ti alloys by SLM from mixture of pure elemental powders. In this case, it is avoided the preparing of the pre-alloyed powders. Therefore, the purpose of the present study is the trying to the fabrication of the Ti-20at.%X (X = Cr, Nb) alloys from the mixture of pure elemental powders by SLM.
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Groarke, Robert, Cyril Danilenkoff, Sara Karam, Eanna McCarthy, Bastien Michel, Andre Mussatto, John Sloane, Aidan O’ Neill, Ramesh Raghavendra, and Dermot Brabazon. "316L Stainless Steel Powders for Additive Manufacturing: Relationships of Powder Rheology, Size, Size Distribution to Part Properties." Materials 13, no. 23 (December 4, 2020): 5537. http://dx.doi.org/10.3390/ma13235537.
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Laser-Powder Bed Fusion (L-PBF) of metallic parts is a highly multivariate process. An understanding of powder feedstock properties is critical to ensure part quality. In this paper, a detailed examination of two commercial stainless steel 316L powders produced using the gas atomization process is presented. In particular, the effects of the powder properties (particle size and shape) on the powder rheology were examined. The results presented suggest that the powder properties strongly influence the powder rheology and are important factors in the selection of suitable powder for use in an additive manufacturing (AM) process. Both of the powders exhibited a strong correlation between the particle size and shape parameters and the powder rheology. Optical microscope images of melt pools of parts printed using the powders in an L-PBF machine are presented, which demonstrated further the significance of the powder morphology parameters on resulting part microstructures.
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Siahmed, F., and L. Faghi. "Synthesis and Characterization of Polymer Nanocomposites Containing Fe- 40 at.% Si Powder Particles Prepared by High Energy Ball Mill." Journal of Nano Research 29 (December 2014): 65–73. http://dx.doi.org/10.4028/www.scientific.net/jnanor.29.65.
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Fe‒Si alloys are widely used as transformer magnets and magnetic cores because of their excellent soft magnetic properties. Fe60Si40 powders were milled in a high energy planetary ball mill (Rctsch PM400) under argon atmosphere at different time of milling. The metal powders obtained have an average diameter d50 of 2.5 to 6 um. The introduction of Si into Fe can result in a decrease of magnetic anisotropy (therefore leading to a decrease of coercivity). The nanocomposite magnetic cores were made from the Fe60Si40 powder obtained by high energy ball milling for different milling time. The particles of powder were mixed with unsaturated polyester (UP) to obtain toroidal cores. The polymerization process was made under a magnetic field H-500 Am. and ensured a preferential orientation of powder particles. Influences of the metallic powder fraction on soft magnetic properties as well as thermal increase under isothermal conditions were investigated along with the possibility to control these properties with the size and amount of powder fraction. It was also found that the soft magnetic properties of the polymer composites can be controlled in a wide range and depends on the mass fraction of the metallic powder Fe60Si40 in the composite, on shape and size of the powder particles and their orientation in the composite.
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Jiménez, Amaia, Prveen Bidare, Hany Hassanin, Faris Tarlochan, Stefan Dimov, and Khamis Essa. "Powder-based laser hybrid additive manufacturing of metals: a review." International Journal of Advanced Manufacturing Technology 114, no. 1-2 (March 19, 2021): 63–96. http://dx.doi.org/10.1007/s00170-021-06855-4.
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AbstractRecent advances in additive manufacturing (AM) have attracted significant industrial interest. Initially, AM was mainly associated with the fabrication of prototypes, but the AM advances together with the broadening range of available materials, especially for producing metallic parts, have broaden the application areas and now the technology can be used for manufacturing functional parts, too. Especially, the AM technologies enable the creation of complex and topologically optimised geometries with internal cavities that were impossible to produce with traditional manufacturing processes. However, the tight geometrical tolerances along with the strict surface integrity requirements in aerospace, biomedical and automotive industries are not achievable in most cases with standalone AM technologies. Therefore, AM parts need extensive post-processing to ensure that their surface and dimensional requirements together with their respective mechanical properties are met. In this context, it is not surprising that the integration of AM with post-processing technologies into single and multi set-up processing solutions, commonly referred to as hybrid AM, has emerged as a very attractive proposition for industry while attracting a significant R&D interest. This paper reviews the current research and technology advances associated with the hybrid AM solutions. The special focus is on hybrid AM solutions that combine the capabilities of laser-based AM for processing powders with the necessary post-process technologies for producing metal parts with required accuracy, surface integrity and material properties. Commercially available hybrid AM systems that integrate laser-based AM with post-processing technologies are also reviewed together with their key application areas. Finally, the main challenges and open issues in broadening the industrial use of hybrid AM solutions are discussed.
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Schindelholz, Eric J., Michael A. Melia, and Jeffrey M. Rodelas. "Corrosion of Additively Manufactured Stainless Steels—Process, Structure, Performance: A Review." Corrosion 77, no. 5 (February 6, 2021): 484–503. http://dx.doi.org/10.5006/3741.
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The corrosion of additively manufactured (AM) metallic materials, such as stainless steels (SS), is a critical factor for their qualification and reliable use. This review assesses the emerging knowledgebase of powder-based laser AM SS corrosion and environmentally assisted cracking (EAC). The origins of AM-unique material features and their hierarchal impact on corrosion and EAC are addressed relative to conventionally processed SS. The effects of starting material, heat treatment, and surface finishing are substantively discussed. An assessment of the current status of AM corrosion research, scientific gaps, and research needs with greatest impact for AM SS advancement and qualification is provided.
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Ecker, J. V., K. Dobrezberger, J. Gonzalez-Gutierrez, M. Spoerk, Ch Gierl-Mayer, and H. Danninger. "Additive Manufacturing of Steel and Copper Using Fused Layer Modelling: Material and Process Development." Powder Metallurgy Progress 19, no. 2 (December 1, 2019): 63–81. http://dx.doi.org/10.1515/pmp-2019-0007.
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AbstractFused Layer Modelling (FLM) is one out of several material extrusion (ME) additive manufacturing (AM) methods. FLM usually deals with processing of polymeric materials but can also be used to process metal-filled polymeric systems to produce metallic parts. Using FLM for this purpose helps to save costs since the FLM hardware is cheap compared to e.g. direct metal laser processing hardware, and FLM offers an alternative route to the production of metallic components.To produce metallic parts by FLM, the methodology is different from direct metal processing technologies, and several processing steps are required: First, filaments consisting of a special polymer-metal composition are produced. The filament is then transformed into shaped parts by using FLM process technology. Subsequently the polymeric binder is removed (”debinding”) and finally the metallic powder body is sintered. Depending on the metal powder used, the binder composition, the FLM production parameters and also the debinding and sintering processes must be carefully adapted and optimized.The focal points of this study are as following:1. To confirm that metallic parts can be produced by using FLM plus debinding and sintering as an alternative route to direct metal additive manufacturing.2. Determination of process parameters, depending on the used metal powders (steel and copper) and optimization of each process step.3. Comparison of the production paths for the different metal powders and their debinding and sintering behavior as well as the final properties of the produced parts.The results showed that both materials were printable after adjusting the FLM parameters, metallic parts being produced for both metal powder systems. The production method and the sintering process worked out well for both powders. However there are specific challenges in the sintering process that have to be overcome to produce high quality metal parts. This study serves as a fundamental basis for understanding when it comes to the processing of steel and copper powder into metallic parts using FLM processing technology.
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Lykov, P. A., and R. M. Baitimerov. "Selective Laser Melting of AlSi12 Powder." Solid State Phenomena 284 (October 2018): 667–72. http://dx.doi.org/10.4028/www.scientific.net/ssp.284.667.
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Additive manufacturing (AM) technologies make it possible to produce complex shape metallic objects from powder feedstock. AlSi12 alloy is one of the most widely used materials in selective laser melting (SLM). The large number of technological parameters involved complicate the selection of an SLM mode for obtaining a product with the required structure. The goal of this research was to determine the mode which ensures the material’s low porosity. Nine specimens were fabricated by using different SLM process parameters. The fabricated specimens have different microstructures. The lowest porosity that was achieved is about 0.5%.
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Elhattab, Karim, Mohamed Samir Hefzy, Zachary Hanf, Bailey Crosby, Alexander Enders, Tim Smiczek, Meysam Haghshenas, Ahmadreza Jahadakbar, and Mohammad Elahinia. "Biomechanics of Additively Manufactured Metallic Scaffolds—A Review." Materials 14, no. 22 (November 12, 2021): 6833. http://dx.doi.org/10.3390/ma14226833.
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This review paper is related to the biomechanics of additively manufactured (AM) metallic scaffolds, in particular titanium alloy Ti6Al4V scaffolds. This is because Ti6Al4V has been identified as an ideal candidate for AM metallic scaffolds. The factors that affect the scaffold technology are the design, the material used to build the scaffold, and the fabrication process. This review paper includes thus a discussion on the design of Ti6A4V scaffolds in relation to how their behavior is affected by their cell shapes and porosities. This is followed by a discussion on the post treatment and mechanical characterization including in-vitro and in-vivo biomechanical studies. A review and discussion are also presented on the ongoing efforts to develop predictive tools to derive the relationships between structure, processing, properties and performance of powder-bed additive manufacturing of metals. This is a challenge when developing process computational models because the problem involves multi-physics and is of multi-scale in nature. Advantages, limitations, and future trends in AM scaffolds are finally discussed. AM is considered at the forefront of Industry 4.0, the fourth industrial revolution. The market of scaffold technology will continue to boom because of the high demand for human tissue repair.
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Yang, Xinliang, Feng Gao, Fengzai Tang, Xinjiang Hao, and Zushu Li. "Effect of Surface Oxides on the Melting and Solidification of 316L Stainless Steel Powder for Additive Manufacturing." Metallurgical and Materials Transactions A 52, no. 10 (July 31, 2021): 4518–32. http://dx.doi.org/10.1007/s11661-021-06405-3.
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AbstractSurface oxidation of metallic powders may significantly affect their melting and solidification behavior and limit their service life in the additive manufacturing (AM) process. In the present work, three levels of surface oxide concentration were prepared on AM-grade 316L stainless steel powders, and their melting and solidification behavior was systematically studied through in-situ observation, advanced characterization, phase-field modeling, and theoretical analysis. Si, Mn, and Cr participated in the oxidation reaction in powder with low and medium oxygen contents, whereas Fe was involved in the oxidation reaction for the powder samples with high oxygen content. A higher full melting temperature is observed to lead to an integrated melt pool in the melting of the highly oxidized powder, which is due to the reduced permeability produced by the oxide cage effect. For the droplet samples prepared from high oxygen powders, the inclusion with increased volume fraction and coarsened size is attributed to the agglomeration of inclusion particles with the residual oxide in the melt. In the high oxygen powder fusion scenario, an undesired coarse columnar grain structure with a high aspect ratio is formed in the current nonequilibrium solidification process, and a consistent microstructure is predicted using solidification conditions with a high cooling rate and high thermal gradient similar to the conventional AM process. In contrast, fine equiaxed grains in the experiment and slim columnar grains with a small aspect ratio in the phase-field simulation are obtained for the low oxygen powder condition. This study illustrates the effect of powder oxide from a processing aspect and provides insight into the importance of improving the service life of powder feedstock by effectively reducing the surface oxidation process on the powder surface.
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Sohrabi, Navid, Jamasp Jhabvala, and Roland E. Logé. "Additive Manufacturing of Bulk Metallic Glasses—Process, Challenges and Properties: A Review." Metals 11, no. 8 (August 12, 2021): 1279. http://dx.doi.org/10.3390/met11081279.
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Bulk Metallic Glasses (BMG) are metallic alloys that have the ability to solidify in an amorphous state. BMGs show enhanced properties, for instance, high hardness, strength, and excellent corrosion and wear resistance. BMGs produced by conventional methods are limited in size due to the high cooling rates required to avoid crystallization and the associated detrimental mechanical properties. Additive manufacturing (AM) techniques are a potential solution to this problem as the interaction between the heat source, e.g., laser, and the feedstock, e.g., powder, is short and confined to a small volume. However, producing amorphous parts with AM techniques with mechanical properties comparable to as-cast samples remains a challenge for most BMGs, and a complete understanding of the crystallization mechanisms is missing. This review paper tries to cover recent progress in this field and develop a thorough understanding of the correlation between different aspects of the topic. The following subjects are addressed: (i) AM techniques used for the fabrication of BMGs, (ii) particular BMGs used in AM, (iii) specific challenges in AM of BMGs such as the control of defects and crystallization, (iv) process optimization of mechanical properties, and (v) future trends.
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Gong, Xi, Dongrui Zeng, Willem Groeneveld-Meijer, and Guha Manogharan. "Additive manufacturing: A machine learning model of process-structure-property linkages for machining behavior of Ti-6Al-4V." Materials Science in Additive Manufacturing 1, no. 1 (March 30, 2022): 6. http://dx.doi.org/10.18063/msam.v1i1.6.
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Prior studies in metal additive manufacturing (AM) of parts have shown that various AM methods and post-AM heat treatment result in distinctly different microstructure and machining behavior when compared with conventionally manufactured parts. There is a crucial knowledge gap in understanding this process-structure-property (PSP) linkage and its relationship to material behavior. In this study, the machinability of metallic Ti-6Al-4V AM parts was investigated to better understand this unique PSP linkage through a novel data science-based approach, specifically by developing and validating a new machine learning (ML) model for material characterization and material property, that is, machining behavior. Heterogeneous material structures of Ti-6Al-4V AM samples fabricated through laser powder bed fusion and electron beam powder bed fusion in two different build orientations and post-AM heat treatments were quantitatively characterized using scanning electron microscopy, electron backscattered diffraction, and residual stress measured through X-ray diffraction. The reduced dimensional representation of material characterization data through chord length distribution (CLD) functions, 2-point correlation functions, and principal component analysis was found to be accurate in quantifying the complexities of Ti-6Al-4V AM structures. Specific cutting energy was the response variable for the Taguchi-based experimentation using force dynamometer. A low-dimensional S-P linkage model was established to correlate material structures of metallic AM and machining properties through this novel ML model. It was found that the prediction accuracy of this new PSP linkage is extremely high (>99%, statistically significant at 95% confidence interval). Findings from this study can be seamlessly integrated with P-S models to identify AM processing conditions that will lead to desired material behaviors, such as machining behavior (this study), fatigue behavior, and corrosion resistance.
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Manfredi, Diego, and Róbert Bidulský. "Laser powder bed fusion of aluminum alloys." Acta Metallurgica Slovaca 23, no. 3 (September 27, 2017): 276. http://dx.doi.org/10.12776/ams.v23i3.988.
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<p class="AMSmaintext">The aim of this study is to analyze and to summarize the results of the processing of aluminum alloys, and in particular of the Al-Si-Mg alloys, by means of the Additive Manufacturing (AM) technique defined as Laser Powder Bed Fusion (L-PBF). This process is gaining interest worldwide thanks to the possibility of obtaining a freeform fabrication coupled with high mechanical strength and hardness related to a very fine microstructure. L-PBF is very complex from a physical point of view, due to the extremely rapid interaction between a concentrated laser source and micrometric metallic powders. This generate very fast melting and subsequent solidification on each layer and on the previously consolidated substrate. The effects of the main process variables on the microstructure and mechanical properties of the final parts are analyzed: from the starting powder properties, such as shape and powder size distribution, to the main process parameters, such as laser power, scanning speed and scanning strategy. Furthermore, some examples of applications for the AlSi10Mg alloy are illustrated.</p>
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Chmielewska, Agnieszka, Bartłomiej Wysocki, Piotr Kwaśniak, Mirosław Jakub Kruszewski, Bartosz Michalski, Aleksandra Zielińska, Bogusława Adamczyk-Cieślak, Agnieszka Krawczyńska, Joseph Buhagiar, and Wojciech Święszkowski. "Heat Treatment of NiTi Alloys Fabricated Using Laser Powder Bed Fusion (LPBF) from Elementally Blended Powders." Materials 15, no. 9 (May 5, 2022): 3304. http://dx.doi.org/10.3390/ma15093304.
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The use of elemental metallic powders and in situ alloying in additive manufacturing (AM) is of industrial relevance as it offers the required flexibility to tailor the batch powder composition. This solution has been applied to the AM manufacturing of nickel-titanium (NiTi) shape memory alloy components. In this work, we show that laser powder bed fusion (LPBF) can be used to create a Ni55.7Ti44.3 alloyed component, but that the chemical composition of the build has a large heterogeneity. To solve this problem three different annealing heat treatments were designed, and the resulting porosity, microstructural homogeneity, and phase formation was investigated. The heat treatments were found to improve the alloy’s chemical and phase homogeneity, but the brittle NiTi2 phase was found to be stabilized by the 0.54 wt.% of oxygen present in all fabricated samples. As a consequence, a Ni2Ti4O phase was formed and was confirmed by transmission electron microscopy (TEM) observation. This study showed that pore formation in in situ alloyed NiTi can be controlled via heat treatment. Moreover, we have shown that the two-step heat treatment is a promising method to homogenise the chemical and phase composition of in situ alloyed NiTi powder fabricated by LPBF.
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Costa, José, Elsa Sequeiros, Maria Teresa Vieira, and Manuel Vieira. "Additive Manufacturing." U.Porto Journal of Engineering 7, no. 3 (April 30, 2021): 53–69. http://dx.doi.org/10.24840/2183-6493_007.003_0005.
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Additive manufacturing (AM) is one of the most trending technologies nowadays, and it has the potential to become one of the most disruptive technologies for manufacturing. Academia and industry pay attention to AM because it enables a wide range of new possibilities for design freedom, complex parts production, components, mass personalization, and process improvement. The material extrusion (ME) AM technology for metallic materials is becoming relevant and equivalent to other AM techniques, like laser powder bed fusion. Although ME cannot overpass some limitations, compared with other AM technologies, it enables smaller overall costs and initial investment, more straightforward equipment parametrization, and production flexibility.This study aims to evaluate components produced by ME, or Fused Filament Fabrication (FFF), with different materials: Inconel 625, H13 SAE, and 17-4PH. The microstructure and mechanical characteristics of manufactured parts were evaluated, confirming the process effectiveness and revealing that this is an alternative for metal-based AM.
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Cook, Olivia, Nancy Huang, Robert Smithson, Christopher Kube, Allison Beese, and Andrea Argüelles. "Ultrasonic Characterization of Porosity in Components Made by Binder Jet Additive Manufacturing." Materials Evaluation 80, no. 4 (April 1, 2022): 37–44. http://dx.doi.org/10.32548/2022.me-04266.
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Binder jet metallic additive manufacturing (AM) is a popular alternative to powder bed fusion and directed energy deposition because of lower costs, elimination of thermal cycling, and lower energy consumption. However, like other metallic AM processes, binder jetting is prone to defects like porosity, which decreases the adoption of binder-jetted parts. Binder-jetted parts are sometimes infiltrated with a low melting temperature metal to fill pores during sintering; however, the infiltration is impacted by the part geometry and infiltration environment, which can cause infill nonuniformity. Furthermore, using an infiltration metal creates a complicated multiphase microstructure substantially different than common wrought materials and alloys. To bring insight to the binder jet/infiltration process toward part qualification and improved part quality, spatially dependent ultrasonic wave speed and attenuation techniques are being applied to help characterize and map porosity in parts made by binder jet AM. In this paper, measurements are conducted on binder-jetted stainless steel and stainless steel infiltrated with bronze samples. X-ray computed tomography (XCT) is used to provide an assessment of porosity.
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Caravella, Ilaria, Daniele Cortis, Luca Di Angelo, and Donato Orlandi. "Experimental Data Collection of Surface Quality Analysis of CuCrZr Specimens Manufactured with SLM Technology: Analysis of the Effects of Process Parameters." Materials 16, no. 1 (December 22, 2022): 98. http://dx.doi.org/10.3390/ma16010098.
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Selective laser melting (SLM) is the most widely used laser powder-bed fusion (L-PBF) technology for the additive manufacturing (AM) of parts from metallic powders. The surface quality of the SLM parts is highly dependent on many factors and process parameters. These factors include the powder grain size, the layer thickness, and the building angle. This paper conducted an experimental analysis of the effects of SLM process parameters on the surface quality of CuCrZr cubic specimens. Thanks to its excellent thermal and mechanical properties, CrCrZr has become one of the most widely used materials in SLM technology. The specimens have been produced with different combinations of layer thickness, laser patterns, building angles, and scanning speed, keeping the energy density constant. The results show how different combinations of parameters affect the surface quality macroscopically (i.e., layer thickness, building angle, and scanning speed); in contrast, other parameters (i.e., laser pattern) do not seem to have any contributions. By varying these parameters within typical ranges of the AM machine used, variations in surface quality can be achieved from 10.4 µm up to 40.8 µm. These results represent an important basis for developing research activities that will further focus on implementing a mathematical/experimental model to help designers optimize the surface quality during the AM pre-processing phase.
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Eichler, Fabian, Marco Skupin, Laura Katharina Thurn, Susanne Kasch, and Thomas Schmidt. "Operating limits for beam melting of glass materials." MATEC Web of Conferences 299 (2019): 01004. http://dx.doi.org/10.1051/matecconf/201929901004.
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Laser-based Additive Manufacturing (AM) processes for the use of metals out of the powder bed have been investigated profusely and are prevalent in industry. Although there is a broad field of application, Laser Powder Bed Fusion (LPBF), also known as Selective Laser Melting (SLM) of glass is not fully developed yet. The material properties of glass are significantly different from the investigated metallic material for LPBF so far. As such, the process cannot be transferred, and the parameter limits and the process sequence must be redefined for glass. Starting with the characterization of glass powders, a parameter field is initially confined to investigate the process parameter of different glass powder using LPBFprocess. A feasibility study is carried out to process borosilicate glass powder. The effects of process parameters on the dimensional accuracy of fabricated parts out of borosilicate and hints for the post-processing are analysed and presented in this paper.
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Ladani, Leila, Jafar Razmi, and Maryam Sadeghilaridjani. "Fabrication of Cu-CNT Composite and Cu Using Laser Powder Bed Fusion Additive Manufacturing." Powders 1, no. 4 (October 12, 2022): 207–20. http://dx.doi.org/10.3390/powders1040014.
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Additive manufacturing (AM) as a disruptive technique has offered great potential to design and fabricate many metallic components for aerospace, medical, nuclear, and energy applications where parts have complex geometry. However, a limited number of materials suitable for the AM process is one of the shortcomings of this technique, in particular laser AM of copper (Cu) is challenging due to its high thermal conductivity and optical reflectivity, which requires higher heat input to melt powders. Fabrication of composites using AM is also very challenging and not easily achievable using the current powder bed technologies. Here, the feasibility to fabricate pure copper and copper-carbon nanotube (Cu-CNT) composites was investigated using laser powder bed fusion additive manufacturing (LPBF-AM), and 10 × 10 × 10 mm3 cubes of Cu and Cu-CNTs were made by applying a Design of Experiment (DoE) varying three parameters: laser power, laser speed, and hatch spacing at three levels. For both Cu and Cu-CNT samples, relative density above 90% and 80% were achieved, respectively. Density measurement was carried out three times for each sample, and the error was found to be less than 0.1%. Roughness measurement was performed on a 5 mm length of the sample to obtain statistically significant results. As-built Cu showed average surface roughness (Ra) below 20 µm; however, the surface of AM Cu-CNT samples showed roughness values as large as 1 mm. Due to its porous structure, the as-built Cu showed thermal conductivity of ~108 W/m·K and electrical conductivity of ~20% IACS (International Annealed Copper Standard) at room temperature, ~70% and ~80% lower than those of conventionally fabricated bulk Cu. Thermal conductivity and electrical conductivity were ~85 W/m·K and ~10% IACS for as-built Cu-CNT composites at room temperature. As-built Cu-CNTs showed higher thermal conductivity as compared to as-built Cu at a temperature range from 373 K to 873 K. Because of their large surface area, light weight, and large energy absorbing behavior, porous Cu and Cu-CNT materials can be used in electrodes, catalysts and their carriers, capacitors, heat exchangers, and heat and impact absorption.
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Bissett, H., M. Makhofane, and S. Lötter. "Reduction of copper oxide powder by an inductively coupled thermal plasma." Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 40, no. 1 (January 24, 2022): 79–83. http://dx.doi.org/10.36303/satnt.2021cosaami.16.
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Additive manufacturing (AM) methods can be utilised to manufacture complex, custom Ti6Al4V components for medical implants. Infection at the bone-implant interface is a key reason for implant rejection. Advanced titanium implants with biocompatibility and antibacterial properties can be manufactured by modifying the titanium alloy with copper, which in small concentrations (< 1 at % copper) is a proven, non-toxic antibacterial agent. Copper can be embedded into the titanium implant during the AM process creating antibacterial functionality. In order to produce sufficiently fine metallic copper powder, copper oxide can be reduced, either by chemical reduction or thermal treatment methods. These include thermal decomposition or reduction of the oxide in the presence of a reactive gas at elevated temperatures. Making use of thermal treatment methods such as thermal plasma reduction, the process conditions can be tuned to manipulate the morphology and average particle size of the powders. The purpose of this study was to investigate the thermal plasma reduction of copper oxide to copper metal making use of the Tek-15 radio-frequency inductively coupled thermal plasma system at Necsa. In the presence of hydrogen, the black copper (II) oxide powder was converted to a dark red powder, while a yellow / orange coloured powder was obtained without hydrogen being present. A change in composition was observed using SEM-EDS and was confirmed by XRD analysis.
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Nemati, Saber, Hamed Ghadimi, Xin Li, Leslie G. Butler, Hao Wen, and Shengmin Guo. "Automated Defect Analysis of Additively Fabricated Metallic Parts Using Deep Convolutional Neural Networks." Journal of Manufacturing and Materials Processing 6, no. 6 (November 13, 2022): 141. http://dx.doi.org/10.3390/jmmp6060141.
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Laser powder bed fusion (LPBF)-based additive manufacturing (AM) has the flexibility in fabricating parts with complex geometries. However, using non-optimized processing parameters or using certain feedstock powders, internal defects (pores, cracks, etc.) may occur inside the parts. Having a thorough and statistical understanding of these defects can help researchers find the correlations between processing parameters/feedstock materials and possible internal defects. To establish a tool that can automatically detect defects in AM parts, in this research, X-ray CT images of Inconel 939 samples fabricated by LPBF are analyzed using U-Net architecture with different sets of hyperparameters. The hyperparameters of the network are tuned in such a way that yields maximum segmentation accuracy with reasonable computational cost. The trained network is able to segment the unbalanced classes of pores and cracks with a mean intersection over union (mIoU) value of 82% on the test set, and has reduced the characterization time from a few weeks to less than a day compared to conventional manual methods. It is shown that the major bottleneck in improving the accuracy is uncertainty in labeled data and the necessity for adopting a semi-supervised approach, which needs to be addressed first in future research.
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Riza, Syed H., Ashish M. Ashok, Syed H. Masood, and Igor Sbarski. "Sub-Zero Temperature Effect on Impact Properties of 17-4PH Stainless Steel Processed by Selective Laser Melting." Solid State Phenomena 266 (October 2017): 3–7. http://dx.doi.org/10.4028/www.scientific.net/ssp.266.3.
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The Selective Laser Melting (SLM) process has been proved as the most effective method among Additive Manufacturing (AM) technologies to produce hard, dense and strong metallic structures with intricate shapes and profiles from wide range of metallic alloys. The SLM generated structures from 17-4PH stainless steel high strength alloys involve layer by layer building up through laser melting of successively deposited powder layers. Therefore, the mechanical properties of such structures need to be thoroughly checked and investigated before putting these materials to practical applications. This research mainly investigates the cryogenic impact properties of SLM generated 17-4PH specimen. These characteristics are very important in applications requiring high strength customized structures that could maintain their mechanical properties at sub-zero temperatures. The experimental analysis proves that SLM is a very reliable technology to produce high strength metallic structures and these specimens can function efficiently in extreme conditions.
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Nastac, Laurentiu. "3D Modeling of the Solidification Structure Evolution and of the Inter Layer/Track Voids Formation in Metallic Alloys Processed by Powder Bed Fusion Additive Manufacturing." Materials 15, no. 24 (December 12, 2022): 8885. http://dx.doi.org/10.3390/ma15248885.
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A fully transient discrete-source 3D Additive Manufacturing (AM) process model was coupled with a 3D stochastic solidification structure model to simulate the grain structure evolution quickly and efficiently in metallic alloys processed through Electron Beam Powder Bed Fusion (EBPBF) and Laser Powder Bed Fusion (LPBF) processes. The stochastic model was adapted to rapid solidification conditions of multicomponent alloys processed via multi-layer multi-track AM processes. The capabilities of the coupled model include studying the effects of process parameters (power input, speed, beam shape) and part geometry on solidification conditions and their impact on the resulting solidification structure and on the formation of inter layer/track voids. The multi-scale model assumes that the complex combination of the crystallographic requirements, isomorphism, epitaxy, changing direction of the melt pool motion and thermal gradient direction will produce the observed texture and grain morphology. Thus, grain size, morphology, and crystallographic orientation can be assessed, and the model can assist in achieving better control of the solidification microstructures and to establish trends in the solidification behavior in AM components. The coupled model was previously validated against single-layer laser remelting IN625 experiments performed and analyzed at National Institute of Standards and Technology (NIST) using LPBF systems. In this study, the model was applied to predict the solidification structure and inter layer/track voids formation in IN718 alloys processed by LPBF processes. This 3D modeling approach can also be used to predict the solidification structure of Ti-based alloys processes by EBPBF.
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Evans, Samuel, Eric Jones, Peter Fox, and Chris Sutcliffe. "Photogrammetric analysis of additive manufactured metallic open cell porous structures." Rapid Prototyping Journal 24, no. 8 (November 12, 2018): 1380–91. http://dx.doi.org/10.1108/rpj-05-2017-0082.
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PurposeThis paper aims to introduce a novel method for the analysis of open cell porous components fabricated by laser-based powder bed metal additive manufacturing (AM) for the purpose of quality control. This method uses photogrammetric analysis, the extraction of geometric information from an image through the use of algorithms. By applying this technique to porous AM components, a rapid, low-cost inspection of geometric properties such as material thickness and pore size is achieved. Such measurements take on greater importance, as the production of porous additive manufactured orthopaedic devices increases in number, causing other, slower and more expensive methods of analysis to become impractical.Design/methodology/approachHere the development of the photogrammetric method is discussed and compared to standard techniques including scanning electron microscopy, micro computed tomography scanning and the recently developed focus variation (FV) imaging. The system is also validated against test graticules and simple wire geometries of known size, prior to the more complex orthopaedic structures.FindingsThe photogrammetric method shows an ability to analyse the variability in build fidelity of AM porous structures for use in inspection purposes to compare component properties. While measured values for material thickness and pore size differed from those of other techniques, the new photogrammetric technique demonstrated a low deviation when repeating measurements, and was able to analyse components at a much faster rate and lower cost than the competing systems, with less requirement for specific expertise or training.Originality/valueThe advantages demonstrated by the image-based technique described indicate the system to be suitable for implementation as a means of in-line process control for quality and inspection applications, particularly for high-volume production where existing methods would be impractical.
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Dass, Adrita, Ashlee Gabourel, Darren Pagan, and Atieh Moridi. "Laser based directed energy deposition system for operando synchrotron x-ray experiments." Review of Scientific Instruments 93, no. 7 (July 1, 2022): 075106. http://dx.doi.org/10.1063/5.0081186.
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The adoption of metal additive manufacturing (AM) has tremendously increased over the years; however, it is still challenging to explain the fundamental physical phenomena occurring during these stochastic processes. To tackle this problem, we have constructed a custom metal AM system to simulate powder fed directed energy deposition. This instrument is integrated at the Cornell High Energy Synchrotron Source to conduct operando studies of the metal AM process. These operando experiments provide valuable data that can be used for various applications, such as (a) to study the response of the material to non-equilibrium solidification and intrinsic heat treatment and (b) to characterize changes in lattice plane spacing, which helps us calculate the thermo-mechanical history and resulting microstructural features. Such high-fidelity data are made possible by state-of-the-art direct-detection x-ray area detectors, which aid in the observation of solidification pathways of different metallic alloys. Furthermore, we discuss the various possibilities of analyzing the synchrotron dataset with examples across different measurement modes.
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Navarro, Miguel, Amer Matar, Seyid Fehmi Diltemiz, and Mohsen Eshraghi. "Development of a Low-Cost Wire Arc Additive Manufacturing System." Journal of Manufacturing and Materials Processing 6, no. 1 (December 24, 2021): 3. http://dx.doi.org/10.3390/jmmp6010003.
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Due to their unique advantages over traditional manufacturing processes, metal additive manufacturing (AM) technologies have received a great deal of attention over the last few years. Using current powder-bed fusion AM technologies, metal components are very expensive to manufacture, and machines are complex to build and maintain. Wire arc additive manufacturing (WAAM) is a new method of producing metallic components with high efficiency at an affordable cost, which combines welding and 3D printing. In this work, gas tungsten arc welding (GTAW) is incorporated into a gantry system to create a new metal additive manufacturing platform. Design and build of a simple, affordable, and effective WAAM system is explained and the most frequently seen problems are discussed with their suggested solutions. Effect of process parameters on the quality of two additively manufactured alloys including plain carbon steel and Inconel 718 were studied. System design and troubleshooting for the wire arc AM system is presented and discussed.
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Strauß, A., P. Quadbeck, O. Andersen, S. Riecker, H. D. Böhm, and T. Weißgärber. "Gas Analysis and Optimization of Debinding and Sintering Processes for Metallic Binder-Based AM*." HTM Journal of Heat Treatment and Materials 77, no. 6 (December 1, 2022): 437–48. http://dx.doi.org/10.1515/htm-2022-1033.
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Abstract Binder-based additive manufacturing processes for metallic AM components in a wide range of applications usually use organic binders and process-related additives that must be thermally removed before sintering. Debinding processes are typically parameterized empirically and thus far from the optimum. Since debinding based on thermal decomposition processes of organic components and the subsequent thermochemical reactions between process atmosphere and metal powder materials make uncomplicated parameterization difficult, in-situ instrumentation was introduced at Fraunhofer IFAM. This measurement method relies on infrared spectroscopy and mass spectrometry in various furnace concepts to understand the gas processes of decomposition of organic components and the subsequent thermochemical reactions between the carrier gas atmosphere and the metal part, as well as their kinetics. This method enables an efficient optimization of the temperature-time profiles and the required atmosphere composition to realize dense AM components with low contamination. In the paper, the optimization strategy is presented, and the achievable properties are illustrated using a fused filament fabrication (FFF) component example made of 316L stainless steel.
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Neils, Andrew, Liang Dong, and Haydn Wadley. "The small-scale limits of electron beam melt additive manufactured Ti–6Al–4V octet-truss lattices." AIP Advances 12, no. 9 (September 1, 2022): 095021. http://dx.doi.org/10.1063/5.0094155.
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The emergence of powder-based additive manufacturing (AM) processes, such as electron beam melting (EBM), enables the one step manufacture of microarchitected metamaterials from topology optimized models. However, many applications are optimized by low relative density lattices with slender trusses whose diameter approaches small multiples of largest powder particles, potentially resulting in surface roughness. The thermal history experienced by alloy powders also modifies the alloy microstructure, and thus mechanical behavior, posing a significant challenge to metallic metamaterial designs and fabrication. We therefore build and characterize the multiscale structure and mechanical properties of EBM manufactured Ti–6Al–4V octet truss lattices with strut diameters approaching the particle diameter-imposed fabrication limit. We measure the dependence of their relative density, elastic modulus, and compressive strength on the fabrication process-controlled truss topology and microstructure, and compare them to identical smooth surface structures made from an annealed, wrought version of the same alloy built using a snap-fit assembly method. Micro-x-ray tomography confirmed that the lattice strut surfaces were covered with partially melted powder particles, resulting in about 29% of the lattice mass that inefficiently supported the applied loads. The use of a powder bed held at a temperature of 600–700 °C also resulted in a lamellar α/β phase microstructure with an elastic modulus, yield strength, and a ductility that were less than the equiaxed α/β microstructure of snap-fit assembled structures. However, the higher tangent modulus of the lamellar AM processed alloy resulted in significant strengthening of EBM lattices that failed by inelastic buckling during compression. The ability to increase the alloy tangent modulus during an EBM build process therefore provides a promising approach for increasing lattice compressive strength and therefore compensates for surface roughness induced losses.
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Cañadilla, Antonio, Ana Romero, Gloria P. Rodríguez, Miguel Á. Caminero, and Óscar J. Dura. "Mechanical, Electrical, and Thermal Characterization of Pure Copper Parts Manufactured via Material Extrusion Additive Manufacturing." Materials 15, no. 13 (July 1, 2022): 4644. http://dx.doi.org/10.3390/ma15134644.
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Material Extrusion Additive Manufacturing (MEAM) is a novel technology to produce polymeric, metallic, and ceramic complex components. Filaments composed of a high-volume content of metal powder and a suitable binder system are needed to obtain metallic parts. Thermal and energetic controversies do not affect MEAM technology, although common in other additive manufacturing (AM) techniques. High thermal conductivity and reflectivity of copper to high-energy beams are the most challenging properties. A material extrusion technique to produce high density and quality copper parts is deeply studied in this research. Characterization of the filament, printed parts, brown parts and final sintered parts is provided. The sintering stage is evaluated through density analysis of the sintered copper parts, as well as their dimensional accuracy after part shrinkage inherent to the sintering process. The mechanical behavior of sintered parts is assessed through tensile, hardness and impact toughness tests. In addition, the measured electrical and thermal conductivities are compared to those obtained by other AM technologies. High-density components, with 95% of relative density, were successfully manufactured using MEAM technology. Similar or even superior mechanical, thermal and electrical properties than those achieved by other 3D printing processes such as Electron Beam Melting, Selective Laser Melting and Binder Jetting were obtained.
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D’Accardi, Ester, Davide Palumbo, Vito Errico, Andrea Fusco, and Umberto Galietti. "A first quantitative approach for detecting volumetric defects in additive manufactured metal samples by using active thermographic technique." IOP Conference Series: Materials Science and Engineering 1214, no. 1 (January 1, 2022): 012015. http://dx.doi.org/10.1088/1757-899x/1214/1/012015.
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Abstract This work is focused on the quantitative analysis of defects produced in metal samples of AISI 316L with Laser Powder Bed Fusion (L-PBF) additive manufacturing (AM) process by means of active thermographic techniques. A simple and common set-up with 2 flash lamps and a cooled sensor has been used to analyse the differences between planar and volumetric defects. In particular, the presence of imprinted spheres containing inside non-sintered metallic powder has been compared with those of similar cylinders in size and depth, induced in similar samples. Furthermore, the differences in terms of thermal contrasts have been studied between the cylinder manufactured as an internal defect with powder inside, against the same geometry, but with a small channel for the discharge of the non-melted material. The analysis of the thermal signal and the application of post processing algorithms allowed us to identify the thermal features suitable for describing the behaviour of different kind of defects, typical of the process.
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Mohta, Kaustubh Anand, Vaishnav Madhavadas, Dibyarup Das, Nevan Nicholas Johnson, and S. Senthur Prabu. "Comparative Study on Thermal Properties of 3D Printed and Conventional Fins." ECS Transactions 107, no. 1 (April 24, 2022): 14555–74. http://dx.doi.org/10.1149/10701.14555ecst.
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Fins are a type of heat exchanger that is attached to a part of the product and is mainly used to enhance the heat transfer rates. Fins are generally manufactured using conventional manufacturing (CM) methods such as extrusion, die casting, and forging. Additive manufacturing (AM) is a modern manufacturing technique that is one of the emerging methods to manufacture metallic components such as fins. Some of the advantages of using AM is that it is much more cost-efficient, reduces a lot of material wastage than CM methods, as well as more time-efficient. The AM process, which will be used for the manufacture of fins, is either Directed Energy Deposition (DED) or Powder Bed Fusion (PBF). AM printed fins can even be used in applications that require components to operate at very high temperatures. In this research paper, the effect on heat transfer rates of the fins manufactured using different AM techniques is carried. Furthermore, an analysis of the thermal properties and heat transfer rates of multiple 3D printable materials will be conducted using the ANSYS Workbench Mechanical 2018 software. These will then be compared with fins manufactured with CM techniques. The expected research outcomes are that the fins manufactured using AM techniques will show better thermal properties than the CM method, and hence AM will be a great replacement for CM techniques given the introduction of more 3D printable materials in near future.
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Zerbst, Uwe, Mauro Madia, Giovanni Bruno, and Kai Hilgenberg. "Towards a Methodology for Component Design of Metallic AM Parts Subjected to Cyclic Loading." Metals 11, no. 5 (April 26, 2021): 709. http://dx.doi.org/10.3390/met11050709.
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The safe fatigue design of metallic components fabricated by additive manufacturing (AM) is still a largely unsolved problem. This is primarily due to (a) a significant inhomogeneity of the material properties across the component; (b) defects such as porosity and lack of fusion as well as pronounced surface roughness of the as-built components; and (c) residual stresses, which are very often present in the as-built parts and need to be removed by post-fabrication treatments. Such morphological and microstructural features are very different than in conventionally manufactured parts and play a much bigger role in determining the fatigue life. The above problems require specific solutions with respect to the identification of the critical (failure) sites in AM fabricated components. Moreover, the generation of representative test specimens characterized by similar temperature cycles needs to be guaranteed if one wants to reproducibly identify the critical sites and establish fatigue assessment methods taking into account the effect of defects on crack initiation and early propagation. The latter requires fracture mechanics-based approaches which, unlike common methodologies, cover the specific characteristics of so-called short fatigue cracks. This paper provides a discussion of all these aspects with special focus on components manufactured by laser powder bed fusion (L-PBF). It shows how to adapt existing solutions, identifies fields where there are still gaps, and discusses proposals for potential improvement of the damage tolerance design of L-PBF components.
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Milhomme, Sarah, Julie Lartigau, Charles Brugger, Catherine Froustey, and Ludovic Dufau. "Influence of Machine Parameters on Ti-6Al-4V Small Sized Specimens Made by Laser Metal Powder Deposition." Advanced Materials Research 1161 (March 2021): 113–19. http://dx.doi.org/10.4028/www.scientific.net/amr.1161.113.
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The present work is focused on one Additive Manufacturing (AM) process – Laser powder Metal Deposition (LMD-p) – and on one metallic alloy – Ti-6Al-4V. State of the art on LMD-p on Ti-6Al-4V alloy shows that three kinds of process parameters influence mechanical properties of building parts: raw materials (powder and substrate), machine parameters (Laser Power (P), Powder Flow (F) and Building Speed (V)), and building strategies (part orientation, waiting time between layers, etc.). Thus, this paper relates to first manufacturing investigations on small sized specimens (bead, wall and block) with the aim of providing a better knowledge about the first steps of manufacturing. Particularly, this paper is dedicated to the study of machine parameters (P, F and V). First, the influence of each machine parameter on 28 beads is studied separately. The geometrical aspect (high, width, dilution) of each bead is microscopically measured. Similarly, combinations of parameters (P/F, Energy Density and Powder Density) are introduced to increase parameters degree of freedom. First results show that P, V and F have a major influence on the beads’ geometry. In addition, a window process map is plotted and allows determining functional areas of machine parameters. From this map, walls (vertical superposition of one bead) are manufactured and microscopically observed. Functional sets of parameters from walls are selected and blocks can be built.
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Dadkhah, Mehran, Mohammad Hossein Mosallanejad, Luca Iuliano, and Abdollah Saboori. "A Comprehensive Overview on the Latest Progress in the Additive Manufacturing of Metal Matrix Composites: Potential, Challenges, and Feasible Solutions." Acta Metallurgica Sinica (English Letters) 34, no. 9 (May 23, 2021): 1173–200. http://dx.doi.org/10.1007/s40195-021-01249-7.
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AbstractNowadays, as an emerging technology, additive manufacturing (AM) has received numerous attentions from researchers around the world. The method comprises layer-by-layer manufacturing of products according to the 3D CAD models of the objects. Among other things, AM is capable of producing metal matrix composites (MMCs). Hence, plenty of works in the literature are dedicated to developing different types of MMCs through AM processes. Hence, this paper provides a comprehensive overview on the latest research that has been carried out on the development of the powder-based AM manufactured MMCs from a scientific and technological viewpoint, aimed at highlighting the opportunities and challenges of this innovative manufacturing process. For instance, it is documented that AM is not only able to resolve the reinforcement/matrix bonding issues usually faced with during conventional manufacturing of MMCs, but also it is capable of producing functionally graded composites and geometrically complex objects. Furthermore, it provides the opportunity for a uniform distribution of the reinforcing phase in the metallic matrix and is able to produce composites using refractory metals thanks to the local heat source employed in the method. Despite the aforementioned advantages, there are still some challenges needing more attention from the researchers. Rapid cooling nature of the process, significantly different coefficient of expansion of the matrix and reinforcement, processability, and the lack of suitable parameters and standards for the production of defect-free AM MMCs seem to be among the most important issues to deal with in future works.
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Safavi, Mir Saman, Aydin Bordbar-Khiabani, Jafar Khalil-Allafi, Masoud Mozafari, and Livia Visai. "Additive Manufacturing: An Opportunity for the Fabrication of Near-Net-Shape NiTi Implants." Journal of Manufacturing and Materials Processing 6, no. 3 (June 14, 2022): 65. http://dx.doi.org/10.3390/jmmp6030065.
Full textAbstract:
Nickel–titanium (NiTi) is a shape-memory alloy, a type of material whose name is derived from its ability to recover its original shape upon heating to a certain temperature. NiTi falls under the umbrella of metallic materials, offering high superelasticity, acceptable corrosion resistance, a relatively low elastic modulus, and desirable biocompatibility. There are several challenges regarding the processing and machinability of NiTi, originating from its high ductility and reactivity. Additive manufacturing (AM), commonly known as 3D printing, is a promising candidate for solving problems in the fabrication of near-net-shape NiTi biomaterials with controlled porosity. Powder-bed fusion and directed energy deposition are AM approaches employed to produce synthetic NiTi implants. A short summary of the principles and the pros and cons of these approaches is provided. The influence of the operating parameters, which can change the microstructural features, including the porosity content and orientation of the crystals, on the mechanical properties is addressed. Surface-modification techniques are recommended for suppressing the Ni ion leaching from the surface of AM-fabricated NiTi, which is a technical challenge faced by the long-term in vivo application of NiTi.
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Borrelli, R., S. Franchitti, C. Pirozzi, L. Carrino, L. Nele, W. Polini, L. Sorrentino, and A. Corrado. "Ti6Al4V Parts Produced by Electron Beam Melting: Analysis of Dimensional Accuracy and Surface Roughness." Journal of Advanced Manufacturing Systems 19, no. 01 (March 2020): 107–30. http://dx.doi.org/10.1142/s0219686720500067.
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Additive manufacturing (AM), applied to metal industry, is a family of processes that allows complex shape components to be realized from raw materials in the form of powders. Electron beam melting (EBM) is a relatively new additive manufacturing (AM) technology. Similar to electron-beam welding, EBM utilizes a high-energy electron beam as a moving heat source to melt metal powder, and 3D parts are produced in a layer-building fashion by rapid self-cooling. By EBM, it is possible to realize metallic complex shape components, e.g. fine network structures, internal cavities and channels, which are difficult to make by conventional manufacturing means. This feature is of particular interest in titanium industry in which numerous efforts are done to develop near net shape processes. In the field of mechanical engineering and, in particular, in the aerospace industry, it is crucial for quality certification purpose that components are produced through qualified and robust manufacturing processes ensuring high product repeatability. The contribution of the present work is to experimentally identify the EBM job parameters (sample orientation, location of the sample in the layer and height in the build chamber) that influence the dimensional accuracy and the surface roughness of the manufactured parts in Ti6Al4V. The repeatability of EBM is investigated too.
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Soares Barreto, Erika, Volker Uhlenwinkel, Maximilian Frey, Isabella Gallino, Ralf Busch, and Andreas Lüttge. "Influence of Processing Route on the Surface Reactivity of Cu47Ti33Zr11Ni6Sn2Si1 Metallic Glass." Metals 11, no. 8 (July 23, 2021): 1173. http://dx.doi.org/10.3390/met11081173.
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Recently, laser additive manufacturing (AM) techniques have emerged as a promising alternative for the synthesis of bulk metallic glasses (BMGs) with massively increased freedom in part size and geometry, thus extending their economic applicability of this material class. Nevertheless, porosity, compositional inhomogeneity, and crystallization display themselves to be the emerging challenges for this processing route. The impact of these “defects” on the surface reactivity and susceptibility to corrosion was seldom investigated but is critical for the further development of 3D-printed BMGs. This work compares the surface reactivity of cast and additively manufactured (via laser powder bed fusion—LPBF) Cu47Ti33Zr11Ni6Sn2Si1 metallic glass after 21 days of immersion in a corrosive HCl solution. The cast material presents lower oxygen content, homogeneous chemical distribution of the main elements, and the surface remains unaffected after the corrosion experimentation based on vertical scanning interferometry (VSI) investigation. On the contrary, the LPBF material presents a considerably higher reactivity seen through crack propagations on the surface. It exhibits higher oxygen content, heterogeneous chemical distribution, and presence of defects (porosity and cracks) generated during the manufacturing process.
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Nurel, Bar, Moshe Nahmany, Adin Stern, Nahum Frage, and Oren Sadot. "Study on the dynamic properties of AM-SLM AlSi10Mg alloy using the Split Hopkinson Pressure Bar (SHPB) technique." EPJ Web of Conferences 183 (2018): 04005. http://dx.doi.org/10.1051/epjconf/201818304005.
Full textAbstract:
Additive manufacturing by Selective Laser Melting of metals is attracting substantial attention, due to its advantages, such as short-time production of customized structures. This technique is useful for building complex components using a metallic pre-alloyed powder. One of the most used materials in AMSLM is AlSi10Mg powder. Additively manufactured AlSi10Mg may be used as a structural material and it static mechanical properties were widely investigated. Properties in the strain rates of 5×102–1.6×103 s-1 and at higher strain rates of 5×103 –105 s-1 have been also reported. The aim of this study is investigation of dynamic properties in the 7×102–8×103 s-1 strain rate range, using the split Hopkinson pressure bar technique. It was found that the dynamic properties at strain-rates of 1×103–3×103 s-1 depend on a build direction and affected by heat treatment. At higher and lower strain-rates the effect of build direction is limited. The anisotropic nature of the material was determined by the ellipticity of samples after the SHPB test. No strain rate sensitivity was observed.