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Koptioug, A., Popov, V. V. ., Botero Vega, C. A., Jiménez-Piqué, E., Katz-Demyanetz, A., Rännar, L.-E. & Bäckström, M. (2020). Compositionally-tailored steel-based materials manufactured by electron beam melting using blended pre-alloyed powders. Materials Science & Engineering: A, 771, Article ID 138587.
Open this publication in new window or tab >>Compositionally-tailored steel-based materials manufactured by electron beam melting using blended pre-alloyed powders
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2020 (English)In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 771, article id 138587Article in journal (Refereed) Published
Abstract [en]

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". 

Keywords
Additive manufacturing, Blended powder, EBM, Electron beam melting, Graded material, In situ alloying
National Category
Materials Engineering
Identifiers
urn:nbn:se:miun:diva-37689 (URN)10.1016/j.msea.2019.138587 (DOI)2-s2.0-85074019741 (Scopus ID)
Available from: 2019-11-15 Created: 2019-11-15 Last updated: 2019-11-15Bibliographically approved
Roos, S., Botero Vega, C. A., Danvind, J., Koptioug, A. & Rännar, L.-E. (2019). Macro- and Micromechanical Behavior of 316LN Lattice Structures Manufactured by Electron Beam Melting. Journal of materials engineering and performance (Print)
Open this publication in new window or tab >>Macro- and Micromechanical Behavior of 316LN Lattice Structures Manufactured by Electron Beam Melting
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2019 (English)In: Journal of materials engineering and performance (Print), ISSN 1059-9495, E-ISSN 1544-1024Article in journal (Refereed) Published
Abstract [en]

This work focuses on the possibility of processing stainless steel 316LN powder into lightweight structures using electron beam melting and investigates mechanical and microstructural properties in the material of processed components. Lattice structures conforming to ISO13314:2011 were manufactured using varying process parameters. Microstructure was examined using a scanning electron microscope. Compression testing was used to understand the effect of process parameters on the lattice mechanical properties, and nanoindentation was used to determine the material hardness. Lattices manufactured from 316L using EBM show smooth compression characteristics without collapsing layers and shear planes. The material has uniform hardness in strut shear planes, a microstructure resembling that of solid 316LN material but with significantly finer grain size, although slightly coarser sub-grain size. Grains appear to be growing along the lattice struts (e.g., along the heat transfer direction) and not in the build direction. Energy-dispersive x-ray spectroscopy analysis reveals boundary precipitates with increased levels of chromium, molybdenum and silicon. Studies clearly show that the 316LN grains in the material microstructure are elongated along the dominating heat transfer paths, which may or may not coincide with the build direction. Lattices made from a relatively ductile material, like 316LN, are much less susceptible to catastrophic collapse and show an extended range of elastic and plastic deformation. Tests indicate that EBM process for 316LN is stable allowing for both solid and lightweight (lattice) structures.

Keywords
316L additive manufacturing electron beam melting ISO 13314:2011 lattice nanoindentation
National Category
Other Mechanical Engineering Other Mechanical Engineering
Identifiers
urn:nbn:se:miun:diva-37818 (URN)10.1007/s11665-019-04484-3 (DOI)
Available from: 2019-12-02 Created: 2019-12-02 Last updated: 2019-12-04Bibliographically approved
Olsén, J., Shen, Z., Liu, L., Koptyug, A. & Rännar, L.-E. (2018). Micro- and macro-structural heterogeneities in 316L stainless steel prepared by electron-beam melting. Materials Characterization, 141, 1-7
Open this publication in new window or tab >>Micro- and macro-structural heterogeneities in 316L stainless steel prepared by electron-beam melting
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2018 (English)In: Materials Characterization, ISSN 1044-5803, E-ISSN 1873-4189, Vol. 141, p. 1-7Article in journal (Refereed) Published
Abstract [en]

This is a study of the micro- and macrostructural variations in samples of stainless steel with the overall composition of the grade 316L, produced using electron beam melting. Electron beam melting is one of the processing methods under consideration for manufacturing some of the International Thermo- Nuclear Experimental Reactor In-Vessel components. Therefore further studies of the homogeneity of the material were conducted. Electron beam melting results in a complicated thermal history of the manufactured part giving a significant impact on the microstructure. A cellular structure that is often observed in samples prepared by selective laser melting was found in the top layers of the specimens. Further down, the structure changed until the cellular structure was almost non-existing, and the grain boundaries had become more pronounced. This revelation of a heterogeneous structure throughout the entire part is crucial for large-scale industrial applications like the Thermo- Nuclear Experimental Reactor to make sure that it is understood that the properties of the material might not be the same at every point, as well as to assure that the correct post-treatment is done. It is also exposed that a significant part of this change is due to molybdenum redistribution inside the sample when it diffuses from the cell boundaries into the cells, and into bigger agglomerates in the grain boundaries. This diffusion seems not to affect the microhardness of the samples. 

Keywords
316L stainless steel, Additive manufacturing, Electron beam melting, Heterogeneous material, Microstructure
National Category
Other Mechanical Engineering
Identifiers
urn:nbn:se:miun:diva-33692 (URN)10.1016/j.matchar.2018.04.026 (DOI)000435428100001 ()2-s2.0-85046110254 (Scopus ID)
Available from: 2018-06-01 Created: 2018-06-01 Last updated: 2018-08-10Bibliographically approved
Botero, C. A., Koptyug, A., Jiménez-Piqué, E. & Rännar, L.-E. (2018). Microstructure and nanomechanical behavior of modified 316L-based materials fabricated using EBM. In: : . Paper presented at 2:nd International Conference on Electron Beam Additive Manufacturing, Nuremberg, Germany, April 11, 2018.
Open this publication in new window or tab >>Microstructure and nanomechanical behavior of modified 316L-based materials fabricated using EBM
2018 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

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.

National Category
Other Materials Engineering
Identifiers
urn:nbn:se:miun:diva-35341 (URN)
Conference
2:nd International Conference on Electron Beam Additive Manufacturing, Nuremberg, Germany, April 11, 2018
Available from: 2018-12-21 Created: 2018-12-21 Last updated: 2019-01-10Bibliographically approved
Botero Vega, C. A., Jiménez-Piqué, E., Roos, S., Skoglund, P., Koptioug, A., Rännar, L.-E. & Bäckström, M. (2018). Nanoindentation: a suitable tool in metal Additive Manufacturing. In: : . Paper presented at Materials Science & Technology, MS&T 2018, October 14-18, Columbus, USA.
Open this publication in new window or tab >>Nanoindentation: a suitable tool in metal Additive Manufacturing
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2018 (English)Conference paper, Oral presentation only (Refereed)
National Category
Other Materials Engineering
Identifiers
urn:nbn:se:miun:diva-35342 (URN)
Conference
Materials Science & Technology, MS&T 2018, October 14-18, Columbus, USA
Available from: 2018-12-21 Created: 2018-12-21 Last updated: 2019-01-09Bibliographically approved
Skoglund, P., Botero Vega, C. A., Koptioug, A., Rännar, L.-E. & Bäckström, M. (2018). Possibility of the “cold start” of the build in Electron Beam Melting. In: : . Paper presented at Materials Science & Technology, MS&T 2018, October 14-18, Columbus, USA.
Open this publication in new window or tab >>Possibility of the “cold start” of the build in Electron Beam Melting
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2018 (English)Conference paper, Oral presentation only (Refereed)
National Category
Other Mechanical Engineering
Identifiers
urn:nbn:se:miun:diva-35345 (URN)
Conference
Materials Science & Technology, MS&T 2018, October 14-18, Columbus, USA
Available from: 2018-12-21 Created: 2018-12-21 Last updated: 2019-01-09Bibliographically approved
Olsén, J., Koptioug, A., Rännar, L.-E., Saedi, K. & Shen, Z. J. (2018). The Heterogenic Structure Formed During Electron Beam Melting of 316L Stainless Steel. In: : . Paper presented at International Conference on Powder Metallurgy and Particulate Materials, (PowderMet), San Antonio, USA, June 17-20, 2018.
Open this publication in new window or tab >>The Heterogenic Structure Formed During Electron Beam Melting of 316L Stainless Steel
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2018 (English)Conference paper, Poster (with or without abstract) (Refereed)
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:miun:diva-35346 (URN)
Conference
International Conference on Powder Metallurgy and Particulate Materials, (PowderMet), San Antonio, USA, June 17-20, 2018
Available from: 2018-12-21 Created: 2018-12-21 Last updated: 2019-01-10Bibliographically approved
Koptioug, A., Rännar, L.-E., Botero Vega, C. A., Bäckström, M. & Popov, V. (2018). Unique material compositions obtained by Electron beam melting of blended powders. In: Euro PM2018 Proceedings: . Paper presented at Euro PM2018 Congress & Exhibition, Bilbao, Spain, 14-18 October, 2018. European Powder Metallurgy Association, EPMA
Open this publication in new window or tab >>Unique material compositions obtained by Electron beam melting of blended powders
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2018 (English)In: Euro PM2018 Proceedings, European Powder Metallurgy Association, EPMA , 2018Conference paper, Published paper (Refereed)
Abstract [en]

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.  

Place, publisher, year, edition, pages
European Powder Metallurgy Association, EPMA, 2018
Keywords
powder bed, additive manufacturing, electron beam melting, new materials, powder belnds, composite materials
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:miun:diva-35137 (URN)978-1-899072-50-7 (ISBN)
Conference
Euro PM2018 Congress & Exhibition, Bilbao, Spain, 14-18 October, 2018
Available from: 2018-12-10 Created: 2018-12-10 Last updated: 2018-12-11Bibliographically approved
Koptioug, A., Bäckström, M. & Rännar, L.-E. (2017). 3D-printing: a future “magic wand” for global manufacturing. How can we benefit from it today for sports and health care?. In: Jan Cabri, Pedro Pezarat Correia (Ed.), Proceedings of the 5th International Congress on Sport Sciences Research and Technology Support, icSPORTS: . Paper presented at 5th International Congress on Sport Sciences Research and Technology Support, icSPORTS, Portugal, 30-31 October 2017. INSTICC Press
Open this publication in new window or tab >>3D-printing: a future “magic wand” for global manufacturing. How can we benefit from it today for sports and health care?
2017 (English)In: Proceedings of the 5th International Congress on Sport Sciences Research and Technology Support, icSPORTS / [ed] Jan Cabri, Pedro Pezarat Correia, INSTICC Press, 2017Conference paper, Published paper (Refereed)
Abstract [en]

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.

Place, publisher, year, edition, pages
INSTICC Press, 2017
Keywords
Additive Manufacturing, Sports Technology, Active Lifestyle, Research and Development, Education
National Category
Other Engineering and Technologies not elsewhere specified Manufacturing, Surface and Joining Technology Other Materials Engineering
Identifiers
urn:nbn:se:miun:diva-32506 (URN)2-s2.0-85055289834 (Scopus ID)978-98-97-58269-1 (ISBN)
Conference
5th International Congress on Sport Sciences Research and Technology Support, icSPORTS, Portugal, 30-31 October 2017
Projects
STII
Funder
VINNOVA
Available from: 2017-12-19 Created: 2017-12-19 Last updated: 2018-12-07Bibliographically approved
Zhong, Y., Rännar, L.-E., Liu, L., Koptyug, A., Wikman, S., Olsen, J., . . . Shen, Z. (2017). Additive manufacturing of 316L stainless steel by electron beam melting for nuclear fusion applications. Journal of Nuclear Materials, 486, 234-245
Open this publication in new window or tab >>Additive manufacturing of 316L stainless steel by electron beam melting for nuclear fusion applications
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2017 (English)In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 486, p. 234-245Article in journal (Refereed) Published
Abstract [en]

A feasibility study was performed to fabricate ITER In-Vessel components by one of the metal additive manufacturing methods, Electron Beam Melting® (EBM®). Solid specimens of SS316L with 99.8% relative density were prepared from gas atomized precursor powder granules. After the EBM® process the phase remains as austenite and the composition has practically not been changed. The RCC-MR code used for nuclear pressure vessels provides guidelines for this study and tensile tests and Charpy-V tests were carried out at 22 °C (RT) and 250 °C (ET). This work provides the first set of mechanical and microstructure data of EBM® SS316L for nuclear fusion applications. The mechanical testing shows that the yield strength, ductility and toughness are well above the acceptance criteria and only the ultimate tensile strength of EBM® SS316L is below the RCC-MR code. Microstructure characterizations reveal the presence of hierarchical structures consisting of solidified melt pools, columnar grains and irregular shaped sub-grains. Lots of precipitates enriched in Cr and Mo are observed at columnar grain boundaries while no sign of element segregation is shown at the sub-grain boundaries. Such a unique microstructure forms during a non-equilibrium process, comprising rapid solidification and a gradient ‘annealing’ process due to anisotropic thermal flow of accumulated heat inside the powder granule matrix. Relations between process parameters, specimen geometry (total building time) and sub-grain structure are discussed. Defects are formed mainly due to the large layer thickness (100 μm) which generates insufficient bonding between a few of the adjacently formed melt pools during the process. Further studies should focus on adjusting layer thickness to improve the strength of EBM® SS316L and optimizing total building time.

Keywords
316L stainless steel, Additive manufacturing, Electron beam melting, Mechanical properties, Microstructure, Nuclear fusion
National Category
Other Mechanical Engineering Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:miun:diva-30111 (URN)10.1016/j.jnucmat.2016.12.042 (DOI)000397373600027 ()2-s2.0-85010310479 (Scopus ID)
Available from: 2017-02-14 Created: 2017-02-14 Last updated: 2017-06-09Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-5954-5898

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