| 1. |
- Mallipeddi, Dinesh, 1987, et al.
(författare)
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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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Ingår i: Procedia CIRP. - : Elsevier BV. - 2212-8271. ; 87:20, s. 327-332
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Konferensbidrag (refereegranskat)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.
(författare)
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Bonding EBM-built blocks of 316L steel, using hot isostatic pressing
- 2017
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Ingår i: Proceedings Euro PM 2017: International Powder Metallurgy Congress and Exhibition. - : European Powder Metallurgy Association (EPMA).
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Konferensbidrag (refereegranskat)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-
(författare)
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Process Development for Electron Beam Melting of 316LN Stainless Steel
- 2019
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)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.
(författare)
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The multifunctional roller ski
- 2013
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Ingår i: Science and Nordic Skiing II. - : University of Salzburg, University of Jyväskylä. - 9789513951757 ; , s. 253-261
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Bokkapitel (refereegranskat)
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| 5. |
- Botero, Carlos Alberto, et al.
(författare)
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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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Ingår i: Materials. - : MDPI AG. - 1996-1944. ; 14:11
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Tidskriftsartikel (refereegranskat)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.
(författare)
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Microstructure and nanomechanical behavior of modified 316L-based materials fabricated using EBM
- 2018
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Konferensbidrag (refereegranskat)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.
(författare)
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Functionally Graded Steels Obtained via Electron Beam Powder Bed Fusion
- 2023
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Ingår i: Key Engineering Materials. - : Trans Tech Publications, Ltd.. - 1013-9826 .- 1662-9795. ; 964, s. 79-84
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Tidskriftsartikel (refereegranskat)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.
(författare)
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PBF-EB For Manufacturing Of 3D Metal-Metal Multi Material Assemblies
- 2023
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Ingår i: Euro Powder Metallurgy 2023 Congress and Exhibition, PM 2023. - : European Powder Metallurgy Association.
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Konferensbidrag (refereegranskat)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.
(författare)
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Additive Manufacturing of a Cold-Work Tool Steel using Electron Beam Melting
- 2020
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Ingår i: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 19:5, s. 1-6
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Tidskriftsartikel (refereegranskat)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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