| 1. |
- Aydin, Gökçe, et al.
(författare)
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Influence of laser metal deposition process parameters on a precipitation hardening stainless steel
- 2023
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Ingår i: Welding in the World. - : Springer. - 0043-2288 .- 1878-6669. ; 67:4, s. 1067-1080
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Tidskriftsartikel (refereegranskat)abstract
- The combination of corrosion resistance and mechanical properties of martensitic precipitation hardening stainless steels (MPHSS) makes them well suited for demanding applications in aerospace, high-pressure gas bottles, or in injection molding of corrosive plastics. Directed energy deposition methods and specifically the laser metal deposition process with powder as feedstock (LMDp) have the potential to be applied in the production of such components. It is well-known that the geometrical features of the deposited beads such as aspect ratio and dilution are crucial for process efficiency and deposition quality. Therefore, this work aims at understanding the influence of the process parameters and the resulting microstructure of a MPHSS modified PH 13-8Mo alloy when using LMDp. Design of experiment (DoE) was used to plan and analyze the influence and interaction of the different LMDp process variables in the geometry of the deposits. It was found that height, width, and depth were statistically significantly influenced by speed, while height was also considerably influenced by the powder feeding rate. In terms of laser power, it was the most significant factor for the width and the depth, but it did not significantly affect the height of the beads. The results showed that the as-deposited microstructure of the modified PH 13-8Mo under the LMDp conditions investigated in this work consists of a martensitic matrix with some amount of primary δ ferrite. The presence of a low amount of retained austenite and aluminum-enriched inclusions was confirmed. This work enhances the fundamental process and material understanding of LMDp of the modified PH 13-8Mo alloy as a first stage in the fabrication of additively manufactured components.
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| 2. |
- Aydin, Gökçe, et al.
(författare)
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Towards Laser Metal Deposition of Modified PH 13-8Mo Powder
- 2023
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Ingår i: Key Engineering Materials. - 1013-9826 .- 1662-9795. ; 964, s. 85-90
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Tidskriftsartikel (refereegranskat)abstract
- Modified PH 13-8Mo alloy exhibits a good combination of corrosion resistance and mechanical properties for demanding applications in aerospace, petrochemical, and tooling industries. Additive manufacturing, specifically the laser metal deposition process with powder as feedstock (LMDp), has the potential to be utilized in these industries. However, very limited knowledge on the LMDp of this alloy currently exists. The aim of this work was, therefore, to deposit a multi-track single layer of modified PH 13-8Mo alloy as a first step towards 3D geometries, and to analyze the resulting microstructure by using Optical Microscopy, Scanning Electron Microscopy, X-Ray Diffraction, Electron Backscatter Diffraction, and micro-hardness. It was found that the multitrack single layer was free from major defects. The microstructure was heterogeneous, and it consisted of a martensitic matrix and small amounts of δ ferrite, austenite, and AlN. The results of this research will be used to tailor the microstructure and properties of future 3D additively manufactured components.
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| 3. |
- 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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| 4. |
- 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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| 5. |
- 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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| 6. |
- Hentschel, Oliver, et al.
(författare)
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Influence of the in-situ heat treatment during manufacturing on the microstructure and properties of DED-LB/M manufactured maraging tool steel
- 2023
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Ingår i: Journal of Materials Processing Technology. - : Elsevier. - 0924-0136 .- 1873-4774. ; 315
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Tidskriftsartikel (refereegranskat)abstract
- Due to high productivity, additive manufacturing (AM), and especially Directed Energy Deposition using laser and metallic powder (DED-LB/M) is attractive for manufacturing tools with integrated functionalities. This investigation was dedicated to DED-LB/M manufacturing of experimental maraging tool steel, characterization of the build microstructure with advanced electron microscopy and evaluation of hardness properties. High printability and low porosity of the final builds were observed, relative density was not lower than 99.5% for specimens manufactured with 600 W and 800 W, but microstructure and properties of the build had a gradient along the height. The characteristic hardness profile and microstructure, which were dependent on the manufacturing parameters, were observed. The top layers of manufactured maraging steel samples had a structure of martensite with precipitates presumably formed during solidification. The top layers were therefore softer to the depth of the austenitization isotherm. The higher hardness was measured in the inner regions which was a result of an in-situ heat treatment that the manufactured material was subjected to during layer-by-layer manufacturing. Thermal cycles during manufacturing resulted in precipitation hardening effect in the inner regions. Scanning and transmission electron microscopy confirmed the formation film-like and round particles in the as-build material, in top and inner regions. However, the quasicrystalline nano-sized R′-phase precipitates were observed only in the inner regions. The formation of the R′-phase precipitated during manufacturing as a result of the in-situ heat treatment was discussed as a reason for higher hardness (440 – 450 HV1) measured in the inner regions.
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| 7. |
- Mussa, Abdulbaset, et al.
(författare)
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Development of a new PM tool steel for optimization of cold working of advanced high-strength steels
- 2020
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Ingår i: Metals. - : MDPI AG. - 2075-4701. ; 10:10
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Tidskriftsartikel (refereegranskat)abstract
- In the present study, Uddeholm Vancron SuperClean cold work tool steel was investigated concerning wear resistance and fatigue strength, using laboratory and semi-industrial tests. The Uddeholm Vancron SuperClean was designed with the help of ThermoCalc calculations to contain a high amount of a carbonitride phase, which was suggested to improve tribological performance of this tool steel. In order to investigate the tested steel, galling tests with a slider-on flat-surface tribotester and semi-industrial punching tests were performed on an advanced high-strength steel, CP1180HD. Uddeholm Vanadis 8 SuperClean containing only a carbide phase and Uddeholm Vancron 40 containing a mixture of carbides and carbonitrides were also tested to compare the performance of the tool steels. The microstructure and wear mechanisms were characterized with scanning electron microscopy. It was found that the carbonitrides presented in Uddeholm Vancron SuperClean improved its resistance to material transfer and galling. Semi-industrial punching tests also confirmed that Uddeholm Vancron SuperClean cold work tool steel also possesses enhanced resistance to chipping and fatigue crack nucleation, which confirms the beneficial role of the carbonitride phase in wear resistance of cold work tool steel.
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| 8. |
- Şelte, Aydın, et al.
(författare)
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Industrial Development and Verification of Cr-Mo-V Based Cold Work Tool Steel Parts Produced Via Electron Beam Melting (EBM)
- 2022
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Ingår i: World PM 2022 Congress Proceedings. - : European Powder Metallurgy Association (EPMA). - 9781899072552
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Being a fast, powerful and crack-free manufacturing process, electron beam melting (EBM) has been gaining importance for tooling industry for the recent years. EBM allows processing high melting materials under vacuum atmosphere with high building rates, which offers less residual stresses caused by the complex thermal history and high cooling rates during the manufacturing. Uddeholms AB has previously shown on a pilot scale the performance capabilities of the EBM process in respect to the high alloyed and commercially available tool steel powder grade Vanadis® 4 Extra AM. In this study, industrial scale demonstrators and application tools were produced from Vanadis® 4 Extra AM powder. Industrialization of the concept studies was completed. Verification of the parts were conducted by using a slider-on-flat-surface (SOFS) wear tester and a semi-industrial punching test. Moreover, the dimensional tolerances, need of post processing treatments and product qualities were emphasized within the scope of this investigation. © European Powder Metallurgy Association (EPMA)
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| 9. |
- Sjöström, William, et al.
(författare)
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Steel-based multi-material configurations by PBF-EB
- 2023
-
Konferensbidrag (refereegranskat)abstract
- Most Powder Bed Fusion (PBF) methods for the Additive Manufacturing (AM) of metals are based on manufacturing components by the melting of powder feedstock of one kind; either of pure-elemental or pre-alloyed compositions. Although the AM of multi-materials has recently gained a lot of attention, it is still not commercially available for metal PBF. In Electron-beam based PBF (EB-PBF) it is possible to control precisely the beam parameters such as speed, spot size and current in each site of the build area. By doing this for each manufactured layer, the melting and solidification process can be steered throughout the build. This opens great possibilities for adaptive processes that allows melting of feedstock powders of different nature in the same build. In this investigation, different steel-based powders are used to create metal-metal multimaterials, including stainless-, hot-work and cold-work tool steels. In the proposed approach, each of the two hoppers is loaded with different metal feedstock so that the fetching can be steered to dispense each specific powder into the bed layer-by-layer. By doing so, the process was steered to obtain multimaterials with lamellar, sandwich-like, and compositionally graded configurations. The microstructure and micromechanical properties of the obtained specimens were characterized by microscopic techniques and nanoindentation.
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