| 1. |
- Mallipeddi, Dinesh, 1987, et al.
(author)
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Surface integrity of machined electron beam melted Ti6Al4V alloy manufactured with different contour settings and heat treatment
- 2020
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In: Procedia CIRP. - : Elsevier BV. - 2212-8271. ; 87:20, s. 327-332
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Conference paper (peer-reviewed)abstract
- The powder-bed-fusion-based Electron Beam Melting (EBM) is rapidly gaining interest as a feasible process in the manufacturing industry for producing intricate Ti6Al4V components. However, there is still a challenge of reducing production time and optimizing surface roughness. One way to improve surface roughness is to optimize the melting strategy, i.e. contour setting. This not only influences the obtained surface topographical features, but also the production time. Most industrial applications require subtractive post processing (machining) to obtain a desired functional surface. This paper is concerned with analysing surface and subsurface in turning of Ti6Al4V alloy, manufactured by EBM using different contour settings. Also, the effect of subsequent heat treatment, i.e. Hot Isostatic Pressing (HIP) is studied. The results indicate that avoiding of contours require a machining allowance of 1 mm to obtain surface roughness of about 0.5 µm (Sa). In case of three and five contours the machining allowance can be reduced to 0.25 mm. Microstructural differences originating from the subsequent HIP operation show no effect on machinability. Tensile residual stresses are generated when reaching down to the heat effected zone of contour settings.
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| 2. |
- Mellin, P., et al.
(author)
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Bonding EBM-built blocks of 316L steel, using hot isostatic pressing
- 2017
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In: Proceedings Euro PM 2017: International Powder Metallurgy Congress and Exhibition. - : European Powder Metallurgy Association (EPMA).
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Conference paper (peer-reviewed)abstract
- To enable production of the First Wall Beam in the ITER fusion reactor; we attempt to join EBM-built blocks of 316L, by Hot Isostatic Pressing (HIP). For highly critical components, EBM-built material is usually HIPed anyway to heal defects such as pores and cracks. Using HIP to simultaneously bond several print-jobs together into a larger component saves time and reduces manufacturing complexity. We found by carrying out this research, that fine surface roughness is an important enabler for a complete bond. The raw printed surfaces that are obtained straight from the Arcam machine (Ra = 19.2 μm) do not enable a good bond. Instead, traditional machining, which in this paper reached Ra = 2.0 μm, enabled a good bond. HIP parameters are also important. The best bond in this study was achieved after increasing holding time from 1 h to 2 h.
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| 3. |
- Roos, Stefan, 1983-
(author)
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Process Development for Electron Beam Melting of 316LN Stainless Steel
- 2019
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Licentiate thesis (other academic/artistic)abstract
- Additive manufacturing (AM) is a technology that inverts the procedure of traditional machining. Instead of starting with a billet of material and removing unwanted parts, the AM manufacturing process starts with an empty workspace and proceeds to fill this workspace with material where it is desired, often in a layer-by-layer fashion. Materials available for AM processing include polymers, concrete, metals, ceramics, paper, photopolymers, and resins. This thesis is concerned with electron beam melting (EBM), which is a powder bed fusion technology that uses an electron beam to selectively melt a feedstock of fine powder to form geometries based on a computer-aided design file input. There are significant differences between EBM and conventional machining. Apart from the process differences, the ability to manufacture extremely complex parts almost as easily as a square block of material gives engineers the freedom to disregard complexity as a cost-driving factor. The engineering benefits of AM also include manufacturing geometries which were previously almost impossible, such as curved internal channels and complex lattice structures. Lattices are lightweight structures comprising a network of thin beams built up by multiplication of a three-dimensional template cell, or unit cell. By altering the dimensions and type of the unit cell, one can tailor the properties of the lattice to give it the desired behavior. Lattices can be made stiff or elastic, brittle or ductile, and even anisotropic, with different properties in different directions. This thesis focuses on alleviating one of the problems with EBM and AM, namely the relatively few materials available for processing. The method is to take a closer look at the widely used stainless steel 316LN, and investigate the possibility of processing 316LN powder via the EBM process into both lattices and solid material. The results show that 316LN is suitable for EBM processing, and a processing window is presented. The results also show that some additional work is needed to optimize the process parameters for increased tensile strength if the EBM-processed material is to match the yield strength of additively laser-processed 316L material.
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| 4. |
- Ainegren, Mats, 1963-, et al.
(author)
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The multifunctional roller ski
- 2013
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In: Science and Nordic Skiing II. - : University of Salzburg, University of Jyväskylä. - 9789513951757 ; , s. 253-261
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Book chapter (peer-reviewed)
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| 5. |
- Botero, Carlos Alberto, et al.
(author)
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Microstructural and mechanical evaluation of a cr-mo-v cold-work tool steel produced via electron beam melting (Ebm)
- 2021
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In: Materials. - : MDPI AG. - 1996-1944. ; 14:11
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Journal article (peer-reviewed)abstract
- In this work, a highly alloyed cold work tool steel, Uddeholm Vanadis 4 Extra, was manufactured via the electron beam melting (EBM) technique. The corresponding material microstructure and carbide precipitation behavior as well as the microstructural changes after heat treatment were characterized, and key mechanical properties were investigated. In the as-built condition, the mi-crostructure consists of a discontinuous network of very fine primary Mo-and V-rich carbides dispersed in an auto-tempered martensite matrix together with ≈15% of retained austenite. Adjusted heat treatment procedures allowed optimizing the microstructure by the elimination of Mo-rich carbides and the precipitation of fine and different sized V-rich carbides, along with a decrease in the retained austenite content below 2%. Hardness response, compressive strength, and abrasive wear properties of the EBM-manufactured material are similar or superior to its as-HIP forged counterparts manufactured using traditional powder metallurgy route. In the material as built by EBM, an impact toughness of 16–17 J was achieved. Hot isostatic pressing (HIP) was applied in order to further increase ductility and to investigate its impact upon the microstructure and properties of the material. After HIPing with optimized protocols, the ductility increased over 20 J.
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| 6. |
- Botero, Carlos Alberto, et al.
(author)
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Microstructure and nanomechanical behavior of modified 316L-based materials fabricated using EBM
- 2018
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Conference paper (peer-reviewed)abstract
- Stainless steel 316L based materials modified by the additions of iron-based wear-resistant alloys (Colferoloy@ 103 and 139) used for thermal spray coatings applications were fabricated by EBM. Process parameters were tailored to fabricate compact specimens of 1cm3 in an Arcam A2 (Arcam AB, Mölndal, Sweden) at Mid Sweden University. Microstructural features of the materials obtained were characterized by OM and SEM in polished and etched samples. Nanoindentation tests carried out at different penetration depths were performed on selected areas of the polished specimens to evaluate the materials micro/nano mechanical behavior and to establish correlations with the observed microstructure.
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| 7. |
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| 8. |
- Botero, Carlos, et al.
(author)
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Functionally Graded Steels Obtained via Electron Beam Powder Bed Fusion
- 2023
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In: Key Engineering Materials. - : Trans Tech Publications, Ltd.. - 1013-9826 .- 1662-9795. ; 964, s. 79-84
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Journal article (peer-reviewed)abstract
- Electron-Beam Powder Bed Fusion (EB-PBF) is one of the most important metal additive manufacturing (AM) technologies. In EB-PBF, a focused electron beam is used to melt metal powders in a layer by layer approach. In this investigation two pre-alloyed steel-based powders, stainless steel 316L and V4E, a tool steel developed by Uddeholm, were used to manufacture functionally graded materials. In the proposed approach two powders are loaded into the feeding container, V4E powder on top of 316L one, preventing their mixing. Such type of feeding yields components with two distinct materials separated by a zone with gradual transition from 316L to V4E. Microstructure and local mechanical properties were evaluated in the manufactured samples. Optical Microscopy, Scanning Electron Microscopy and EDX on the polished cross-sections show a gradual microstructural and compositional transition from characteristic 316L at the bottom of the specimens to the tool steel towards the top. Nanoindentation experiments confirmed a consequent gradient in hardness and elastic modulus, which gradually increase towards the top surface of the samples. The achieved results provide great possibilities to tailor the composition, microstructure, mechanical properties, and wear resistance by combining different powders in the powder bed AM technology. Potential applications include the tooling industry, where hard and wear-resistant materials are demanded on the surface with tougher and more ductile materials in the core of the tool.
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| 9. |
- Botero, Carlos, et al.
(author)
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PBF-EB For Manufacturing Of 3D Metal-Metal Multi Material Assemblies
- 2023
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In: Euro Powder Metallurgy 2023 Congress and Exhibition, PM 2023. - : European Powder Metallurgy Association.
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Conference paper (peer-reviewed)abstract
- Most Powder Bed Fusion (PBF) methods for the Additive Manufacturing (AM) of metals are based on the melting of powder of one specific metallic material; either of pure-elemental or pre-alloyed composition. Although the potential to build components from different materials in AM has recently gained a lot of attention, it is still not feasible in the current metal PBF systems. In the specific case of Electron beam- based PBF (PBF-EB), it is possible to precisely control the beam parameters in each site of the build area, which opens great possibilities for adaptive processes that allows melting powders of different nature in the same build. In this investigation, different steel-based and Ti6Al4V alloy powders are used to create metal-metal assemblies. By steering the fetching of two powders loaded in different hoppers it was possible to build different metal-metal assemblies. The microstructure and mechanical properties of the final materials were evaluated.
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| 10. |
- Botero Vega, Carlos Alberto, et al.
(author)
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Additive Manufacturing of a Cold-Work Tool Steel using Electron Beam Melting
- 2020
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In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 19:5, s. 1-6
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Journal article (peer-reviewed)abstract
- Metal additive manufacturing (AM) is on its way to industrialization. One of the most promising techniques within this field, electron beam melting (EBM), is nowadays used mostly for the fabrication of high‐performance Ti‐based alloy components for the aerospace and medical industry. Among the industrial applications envisioned for the future of EBM, the fabrication of high carbon steels for the tooling industry is of great interest. In this context, the process windows for dense and crack‐free specimens for a highly alloyed (Cr–Mo–V) cold‐work steel powder are presented in this article. High‐solidification rates during EBM processing lead to very fine and homogeneous microstructures. The influence of process parameters on the resulting microstructure and the chemical composition is investigated. In addition, preliminary results show very promising mechanical properties regarding the as‐built and heat‐treated microstructure of the obtained material.
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| 11. |
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| 12. |
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| 13. |
- Ek, Rebecca, 1985-, et al.
(author)
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The Effect of EBM Process Parameters upon Surface Roughness
- 2016
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In: Rapid prototyping journal. - 1355-2546 .- 1758-7670. ; 22:3, s. 495-503
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Journal article (peer-reviewed)abstract
- Purpose-The surface roughness of products manufactured using the additive manufacturing (AM) technology of electron beam melting (EBM) has a special characteristic. Different product applications can demand rougher or finer surface structure, so the purpose of this study is to investigate the process parameters of EBM to find out how they affect surface roughness. Design/methodology/approach-EBM uses metal powder to manufacture metal parts. A design of experiment plan was used to describe the effects of the process parameters on the average surface roughness of vertical surfaces. Findings-The most important electron beam setting for surface roughness, accorDing to this study, is a combination of speed and current in the contours. The second most important parameter is contour offset. The interaction between the number of contours and contour offset also appears to be important, as it shows a much higher probability of being active than any other interaction. The results show that the line offset is not important when using contours. Research limitations/implications-This study examined contour offset, number of contours, speed in combination with current and line offset, which are process parameters controlling the electron beam. Practical implications-The surface properties could have an impact on the product's performance. A reduction in surface processing will not only save time and money but also reduce the environmental impact. Originality/value-Surface properties are important for many products. New themes containing process parameters have to be developed when introducing new materials to EBM manufacturing. During this process, it is very important to understand how the electron beam affects the melt pool.
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| 14. |
- Hirsch, J. M., et al.
(author)
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Additive manufacturing and 3D printing
- 2020
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In: Lasers in Oral and Maxillofacial Surgery. - Cham : Springer International Publishing. - 9783030296049 - 9783030296032 ; , s. 227-237
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Book chapter (other academic/artistic)abstract
- This chapter discusses recent applications and findings in additive manufacturing (AM), or 3D printing, applied in oral and maxillofacial surgery. The reader will get an introduction to the basics of AM technology followed by oral and maxillofacial applications like printing of anatomical models and the design and manufacturing of customised implants. Recent research on the biological response of some AM metal alloys is also discussed at the end of the chapter. © Springer Nature Switzerland AG 2020. All rights reserved.
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| 15. |
- Hosseini, Seyed, et al.
(author)
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Comparison of machining performance of stainless steel 316L produced by selective laser melting and electron beam melting
- 2022
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In: Procedia CIRP. - : Elsevier B.V.. - 2212-8271. ; , s. 72-77
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Conference paper (peer-reviewed)abstract
- Powder bed fusion processes based additively manufactured SS 316L components fall short of surface integrity requirements needed for optimal functional performance. Hence, machining is required to achieve dimensional accuracy and to enhance surface integrity characteristics. This research is focused on comparing the material removal performance of 316L produced by PBF-LB (laser) and PBF-EB (electron beam) in terms of tool wear and surface integrity. The results showed comparable surface topography and residual stress profiles. While the hardness profiles revealed work hardening at the surface where PBF-LB specimens being more susceptible to work hardening. The investigation also revealed differences in the progress of the tool wear when machining specimens produced with either PBF-LB or PBF-EB. .
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| 16. |
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| 17. |
- Klingvall Ek, Rebecca, 1985-
(author)
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Electron beam melting: Impact of part surface properties on metal fatigue and bone ingrowth
- 2019
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Doctoral thesis (other academic/artistic)abstract
- AbstractThe aim of this thesis is to investigate aspects on how additive manufacturing (AM) contributes to functional bone implants with the use of the electron beam melting (EBM) technology. AM manufactures parts according to computer-aided design, and the EBM technology melts powder using an electron beam, which acts similar to a laser beam. The topics discussed in this thesis are related to surface roughness that originate from the melted metal powder, and the thesis tries to define some aspects that affect implant functionality. Process parameters steering the electron beam and biocompatibility arising from the surface texture were the initial parts of the PhD studies, and the other half focused on post-processing and fatigue, which are important for medical and industrial applications. There are six studies in this compilation thesis. They are abbreviated as P - process parameters, M - medical applications, and F - fatigue. Studies P, M2, F2, and F3 are journal articles, and M1 and F1 are conference proceedings.Study P used design of experiments to investigate how process parameters affect the surface roughness of as-built EBM-manufactured parts and concluded that beam speed and energy (current) were the most important parameters that influence the surface roughness.In studies M1 and M2, EBM-manufactured specimens of cobalt-chromium and titanium alloys were used to evaluate biocompatibility. The blood chamber method quantified the reactions of the human whole blood in contact with the metal surfaces, and the results showed how the as-built EBM surface roughness contributed to coagulation and bone healing.Rotating beam fatigue equipment was used in studies F1–F3 and study F1 discussed the size effect on fatigue loaded as-built specimens and included specimens with different sizes and with or without hot isostatic pressing (HIP). Study F2 compared as-built and machined specimens and study F3 investigated how Hirtisation, which is a patented electrochemical surface treatment, and HIP affect the fatigue properties that originate from the electrochemical polishing surface topography. The studies showed that a decreased surface roughness increased the fatigue resistance while the stress concentrations (Kt) in the surface of EBM-manufactured specimens decreased.The thesis concludes that EBM-manufactured as-built surfaces are suitable for direct contact with the bone, and that HIP does not improve the fatigue resistance of parts with as-built surfaces, where crack initiation starts at notches.
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| 18. |
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| 19. |
- Klingvall Ek, Rebecca, 1985-, et al.
(author)
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Fatigue properties of Ti-6Al-4V manufactured using electron beam melting
- 2017
-
In: Proceedings Euro PM 2017: International Powder Metallurgy Congress and Exhibition 2017. - Brussels : EPMA European Powder Metallurgy Association. - 9781899072491
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Conference paper (peer-reviewed)abstract
- The interest in powder bed fusion additive manufacturing methods, such as electron beam melting (EBM), is increasing constantly and main business areas driving the development are aerospace and implant manufacturers. EBM manufactured parts have a rather coarse surface roughness mainly originating from the layer thickness and the powder grains melted by the electron beam. Thus, there is an interest in understanding how the surface properties influences the fatigue performance of the material. In this study, EBM manufactured Ti-6Al-4V was investigated at high cycle fatigue using rotating beam and different types of specimens regarding geometry, as-built and hot isostatic pressing (HIP) post-processing were evaluated. The results confirm that as-built surfaces affect the fatigue limit and a small size specimen geometry for rotating beam fatigue testing is proposed as a part of material and process verification.
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| 20. |
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| 21. |
- Klingvall Ek, Rebecca, 1985-, et al.
(author)
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Micro- to Macroroughness of Additively Manufactured Titanium Implants in Terms of Coagulation and Contact Activation
- 2017
-
In: International Journal of Oral & Maxillofacial Implants. - : Quintessence Publishing. - 0882-2786 .- 1942-4434. ; 32:3, s. 565-574
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Journal article (peer-reviewed)abstract
- Purpose: This study aimed to evaluate how as-built electron beam melting (EBM) surface properties affect the onset of blood coagulation. The properties of EBM-manufactured implant surfaces for placement have, until now, remained largely unexplored in literature. Implants with conventional designs and custom-made implants have been manufactured using EBM technology and later placed into the human body. Many of the conventional implants used today, such as dental implants, display modified surfaces to optimize bone ingrowth, whereas custom-made implants, by and large, have machined surfaces. However, titanium in itself demonstrates good material properties for the purpose of bone ingrowth. Materials and Methods: Specimens manufactured using EBM were selected according to their surface roughness and process parameters. EBM-produced specimens, conventional machined titanium surfaces, as well as PVC surfaces for control were evaluated using the slide chamber model. Results: A significant increase in activation was found, in all factors evaluated, between the machined samples and EBM-manufactured samples. The results show that EBM-manufactured implants with as-built surfaces augment the thrombogenic properties. Conclusion: EBM that uses Ti6Al4V powder appears to be a good manufacturing solution for load-bearing implants with bone anchorage. The as-built surfaces can be used "as is" for direct bone contact, although any surface treatment available for conventional implants can be performed on EBM-manufactured implants with a conventional design.
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| 22. |
- Koptioug, Andrei, 1956-, et al.
(author)
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3D-printing: a future “magic wand” for global manufacturing. How can we benefit from it today for sports and health care?
- 2017
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In: Proceedings of the 5th International Congress on Sport Sciences Research and Technology Support, icSPORTS<em></em>. - : INSTICC Press. - 9789897582691
-
Conference paper (peer-reviewed)abstract
- 3D-printing, or as it is also known, additive manufacturing (AM), is promising to be one of the determining manufacturing technologies of the present century. It is not a single technology but a family of rather different ones common in the way components are made, adding materials layer by layer. Additive manufacturing is already quite competitive to existing and well established technologies, but it also can provide unprecedented flexibility and complexity of shapes making components from the materials as different as cheese, chocolate and cream, live cells, concrete, polymers and metal. Many more materials we were not even thinking about few years ago are also becoming available in additive manufacturing, making it really believable that “only the sky is the limit”. During the time available for the keynote lecture, we will analyze the present position of AM in relation to other technologies, the features that make it so promising and its influence upon the part of our life we call sports and health, using the examples relevant to the Congress areas from computer systems to sports performance. Out of all enormities of materials available for different representatives of this manufacturing family we will concentrate at polymers and metals. AM technologies working with these two material families are already providing some unique solutions within the application areas relevant to the Congress' scope. We will also talk about some limitations inherent to the AM in polymers and metals to have the awareness that though the limit is somewhere “high in the sky”, it still exists.
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| 23. |
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| 24. |
- Koptioug, Andrei, 1956-, et al.
(author)
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Compositionally-tailored steel-based materials manufactured by electron beam melting using blended pre-alloyed powders
- 2020
-
In: Materials Science & Engineering. - : Elsevier BV. - 0921-5093 .- 1873-4936. ; 771
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Journal article (peer-reviewed)abstract
- The paper presents the prospects of additive manufacturing (AM) in metal, using the powder bed fusion (PBF) method Electron Beam Melting (EBM) in fabrication specific steel-based alloys for different applications. The proposed approach includes manufacturing of metals from blended pre-alloyed powders for achieving in situ alloying and the material microstructure tailoring by controlling electron beam energy deposition rate EBM tests were conducted with the blends of 316L stainless steel and Colferoloys 103 and 139, corrosion- and abrasion-resistant iron based materials commonly used for plasma spray coating. Thorough microstructure analysis of the manufactured sample was carried out using electron microscopy and measurements of microhardness and elastic modulus was carried out using nanoindentation. It is concluded that implementation of blended powder pathway in PBF AM allows to widen the scope of available materials through diminishing the dependence on the availability of pre-alloyed powders. Together with beam energy steering this pathway also allows for an effective sample microstructure control at different dimensional scales, resulting in components with unique properties. Therefore, the implementation of ‘blended powder pathway’ in PBF AM provides a possibility of manufacturing components with the composite-like and homogeneous zones allowing for the microstructure control and effectively adding a “4th dimension” to “3D printing".
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| 25. |
- Koptioug, Andrei, 1956-, et al.
(author)
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Unique material compositions obtained by Electron beam melting of blended powders
- 2018
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In: Euro PM2018 Proceedings. - : European Powder Metallurgy Association, EPMA. - 9781899072507
-
Conference paper (peer-reviewed)abstract
- Today powder bed fusion based (PBF) additive manufacturing (AM) methods in metallic materials mainly employ pre-alloyed precursor powders. It was even somehow assumed that in situ alloying of the blended powders will not be effective and such PBF processing will not yield any valuable materials. Recent studies carried out both for laser- and electron beam- based PBF have demonstrated possibilities of using precursors blended from both elemental and alloyed powders. We also demonstrate that composites and alloys indeed can be manufactured from a range of different pre-blended powders with Electron Beam Melting (EBM). It is also possible achieving both composites and alloys by design in different parts of the manufactured components by varying the beam energy deposition strategy. Using sequentially fed precursor powders together with a new powder delivery system also allows manufacturing of the functionally graded materials with gradual composition variation. Blended powder precursors and sequential powder feeding should provide opportunities of manufacturing components with changing composition and material properties in a single manufacturing process. It makes possible modern industrial manufacturing of materials similar to Damascus steels, and other composites and composite-like materials in combinations with alloyed and gradient sections by choice in different parts of components.
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