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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)000503324700020 ()2-s2.0-85074019741 (Scopus ID)
Available from: 2019-11-15 Created: 2019-11-15 Last updated: 2020-01-16Bibliographically approved
Botero, C., Bäckström, M., Rännar, L.-E., Roos, S., Koptyug, A., Åsvik, K., . . . Ramsperger, M. (2019). Additive Manufacturing of a cold work steel using Electron Beam Melting. In: Proceedings of Conference:  Tooling 2019: . Paper presented at Tooling 2019, Aachen, May 2019. , May
Open this publication in new window or tab >>Additive Manufacturing of a cold work steel using Electron Beam Melting
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2019 (English)In: Proceedings of Conference:  Tooling 2019, 2019, Vol. MayConference paper, Oral presentation with published abstract (Refereed)
Keywords
Additive Manufacturing, steel, Electron Beam Melting
National Category
Other Engineering and Technologies not elsewhere specified Metallurgy and Metallic Materials Other Mechanical Engineering
Identifiers
urn:nbn:se:miun:diva-37955 (URN)
Conference
Tooling 2019, Aachen, May 2019
Available from: 2019-12-11 Created: 2019-12-11 Last updated: 2019-12-12Bibliographically approved
Botero Vega, C. A., Ramsperger, M., Selte, A., Åsvik, K., Koptioug, A., Skoglund, P., . . . Bäckström, M. (2019). Additive Manufacturing of a Cold-Work Tool Steel using Electron Beam Melting. Steel Research International, 1-6, Article ID 1900448.
Open this publication in new window or tab >>Additive Manufacturing of a Cold-Work Tool Steel using Electron Beam Melting
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2019 (English)In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, p. 1-6, article id 1900448Article in journal (Refereed) Published
Abstract [en]

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.

National Category
Other Materials Engineering
Identifiers
urn:nbn:se:miun:diva-38162 (URN)10.1002/srin.201900448 (DOI)2-s2.0-85075934124 (Scopus ID)
Funder
Interreg Sweden-Norway, 20201562
Available from: 2019-12-20 Created: 2019-12-20 Last updated: 2020-02-21Bibliographically 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), 28(12), 7290-7301
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 1544-1024, Vol. 28, no 12, p. 7290-7301Article 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)000507536600012 ()2-s2.0-85075894379 (Scopus ID)
Available from: 2019-12-02 Created: 2019-12-02 Last updated: 2020-01-31Bibliographically approved
Koptyug, A., Botero, C., Sjöström, W., Jimenez-Pique, E., Şelte, A., Asvik, K., . . . Bäckström, M. (2019). Steel-based functionally gradient materials obtained via Electron Beam Melting. In: Proc. Alloys for Additive Manufacturing Symposium AAMS2019: . Paper presented at Alloys for Additive Manufacturing Symposium, AAMS2019, Göteborg, 18-20 September, 2019.
Open this publication in new window or tab >>Steel-based functionally gradient materials obtained via Electron Beam Melting
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2019 (English)In: Proc. Alloys for Additive Manufacturing Symposium AAMS2019, 2019Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Recent developments in metal Additive Manufacturing (AM) technologies have introduced great capabilities unparalleled by conventional manufacturing, not only in achieving freeform geometries, but also in opening new possibilities to tailor the microstructure/properties of materials by controlling process parameters. Electron Beam Melting (EBM) is one of the most important members of the Powder Bed Fusion(PBF) family; it uses a focused electron beam to melt metal powder in a layer by layer approach. One of the main challenges that EBM faces nowadays is the lack of commercially available materials (most of them are Ti-based or Ni-based alloys). Therefore, there is a strong interest to further develop the process for new materials, including steel-based ones. In this investigation two steel-based powders; stainless steel 316L and a tool steel developed by Uddeholm, were used to manufacture functionally graded materials. A special hardware setup using a single powder dispenser was installed in the EBM system, where powders were placed separately to manufacture 10x10x10 mm cubes. SEM images of the specimens’ polished cross sections show a gradual microstructural transition from characteristic 316L one on 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 top surface. These results show great possibilities to tailor microstructure and mechanical properties by combining different powders in the EBM technology. Potential applications include the tooling industry, where hard and wear-resistant materials are demanded on the surface whether tougher and more ductile behavior is desirable on the core of the tool.

Keywords
Additive Manufacturing, new materials, Electron Beam Melting
National Category
Other Civil Engineering Metallurgy and Metallic Materials Composite Science and Engineering
Identifiers
urn:nbn:se:miun:diva-37956 (URN)
Conference
Alloys for Additive Manufacturing Symposium, AAMS2019, Göteborg, 18-20 September, 2019
Available from: 2019-12-11 Created: 2019-12-11 Last updated: 2019-12-12Bibliographically approved
Rännar, L.-E., Botero, C., Sjöström, W., Melin, P., Strandh, E., Ledford, C. & Harrysson, O. (2019). Surface topography development of Electron beam-melted materials - a historical review. In: Proceedings Euromat 2019: . Paper presented at Euromat 2019, Stockholm, 1-5 september, 2019. Stockholm
Open this publication in new window or tab >>Surface topography development of Electron beam-melted materials - a historical review
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2019 (English)In: Proceedings Euromat 2019, Stockholm, 2019Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Introduction/Purpose Additive manufacturing in metal is developed rapidly, with regard to both equipment and materials. A recurring question from the industry in particular is how the development has been in a historical perspective and what one can expect from the future. This study aims to make a historical overview, from the early 2000s to today, of the surface roughness of materials manufactured using the powder bed fusion technology Electron Beam Melting (EBM). Methods Surfaces of specimens manufactured in tool steel (H13) and titanium alloys (Ti6Al4V) will be characterized using different methods such as focusvariation technology and scanning electron microscopy. Results The surface roughness is presented and shows the historical development of different materials, and different EBM-systems. Conclusions Being in the middle of a constantly evolving technology as AM in metal, it can be hard to predict future developments and this study shows there has been a great improvement in surface finishes from the early 2000s to the present. These results might add some information for discussions on future developments and directions concerning the area of surface smoothness and EBM.

Place, publisher, year, edition, pages
Stockholm: , 2019
National Category
Other Materials Engineering
Identifiers
urn:nbn:se:miun:diva-38163 (URN)
Conference
Euromat 2019, Stockholm, 1-5 september, 2019
Available from: 2019-12-20 Created: 2019-12-20 Last updated: 2020-01-08Bibliographically 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
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-5954-5898

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