| 1. |
- Balachandramurthi, Arun Ramanathan, 1989-, et al.
(författare)
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On the microstructure of laser beam powder bed fusion alloy 718 and its influence on the low cycle fatigue behaviour
- 2020
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Ingår i: Materials. - : MDPI AG. - 1996-1944. ; 13:22
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Tidskriftsartikel (refereegranskat)abstract
- Additive manufacturing of Alloy 718 has become a popular subject of research in recent years. Understanding the process-microstructure-property relationship of additively manufactured Alloy 718 is crucial for maturing the technology to manufacture critical components. Fatigue behaviour is a key mechanical property that is required in applications such as gas turbines. Therefore, in the present work, low cycle fatigue behaviour of Alloy 718 manufactured by laser beam powder bed fusion process has been investigated. The material was tested in as-built condition as well as after two different thermal post-treatments. Three orientations with respect to the building direction were tested to evaluate the anisotropy. Testing was performed at room temperature under controlled amplitudes of strain. It was found that defects, inclusions, strengthening precipitates, and Young’s modulus influence the fatigue behaviour under strain-controlled conditions. The strengthening precipitates affected the deformation mechanism as well as the cycle-dependent hardening/softening behaviour. The defects and the inclusions had a detrimental effect on fatigue life. The presence of Laves phase in LB-PBF Alloy 718 did not have a detrimental effect on fatigue life. Young’s modulus was anisotropic and it contributed to the anisotropy in strain-life relationship. Pseudo-elastic stress vs. fatigue life approach could be used to handle the modulus-induced anisotropy in the strain-life relationship. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.
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| 2. |
- Balachandramurthi, Arun Ramanathan, et al.
(författare)
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On the microstructure of laser beam powder bed fusion alloy 718 and its influence on the low cycle fatigue behaviour
- 2020
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Ingår i: Materials. - : MDPI AG. - 1996-1944. ; 13:22, s. 1-21
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Tidskriftsartikel (refereegranskat)abstract
- Additive manufacturing of Alloy 718 has become a popular subject of research in recent years. Understanding the process-microstructure-property relationship of additively manufactured Alloy 718 is crucial for maturing the technology to manufacture critical components. Fatigue behaviour is a key mechanical property that is required in applications such as gas turbines. Therefore, in the present work, low cycle fatigue behaviour of Alloy 718 manufactured by laser beam powder bed fusion process has been investigated. The material was tested in as-built condition as well as after two different thermal post-treatments. Three orientations with respect to the building direction were tested to evaluate the anisotropy. Testing was performed at room temperature under controlled amplitudes of strain. It was found that defects, inclusions, strengthening precipitates, and Young’s modulus influence the fatigue behaviour under strain-controlled conditions. The strengthening precipitates affected the deformation mechanism as well as the cycle-dependent hardening/softening behaviour. The defects and the inclusions had a detrimental effect on fatigue life. The presence of Laves phase in LB-PBF Alloy 718 did not have a detrimental effect on fatigue life. Young’s modulus was anisotropic and it contributed to the anisotropy in strain-life relationship. Pseudo-elastic stress vs. fatigue life approach could be used to handle the modulus-induced anisotropy in the strain-life relationship.
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| 3. |
- Danielsson, Mats, et al.
(författare)
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Temperature dependent material properties of MaterialA used for quenching simulations
- 2012
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Rapport (refereegranskat)abstract
- This report describes the experimental and computational programs that were used to extract material properties required for finite-element-based quenching simulations. Several metallurgical phases appear prior to, during, and after the quenching operation. The experimental program was designed so as to provide both temperature-dependent thermal and temperature-dependent elastic-plastic material properties for every appearing phase. One thermal property, enthalpy, was calculated using computational thermodynamics. In addition to material properties, metallurgical transformations (diffusion-governed and diffusionless) were quantified experimentally. The obtained data in this work was used to calibrate material models and models for phase transformation kinetics in the finite element software Sysweld.
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| 4. |
- Frisk, Karin, et al.
(författare)
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Simulation of oxygen reduction in PM-HIP materials
- 2010
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Ingår i: Proceedings of the World Powder Metallurgy Congress and Exhibition, World PM 2010. - : European Powder Metallurgy Association (EPMA). - 9781899072194
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Konferensbidrag (refereegranskat)abstract
- A challenge in the development of powder based materials is to limit the oxygen contents. In the present work reduction of oxygen/oxides in a duplex stainless steel powder was studied. The main mechanisms ruling the reduction of oxygen in a hydrogen atmosphere have been established. A combination of experiments and mathematical modelling was used. Experiments were performed on small samples of powder, as well as powder encapsulated in a 200x200 mm canister. FEM calculations of the heat transfer in the canister, combined with thermodynamic calculations of the stability, and heat of reduction of oxides were used for the modelling. The experimental features: oxide reduction, heat transfer, and hydrogen transport, are reproduced by the calculations. A high-oxygen powder was used for the experiments, and the oxygen content was reduced from 200 ppm O in the powder, to less than 100 ppm O in the compacted material. The results from the modelling could conclude that this was due to a reduction of Fe-oxides at low temperatures, and Cr-oxides at high temperatures.
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| 5. |
- Goel, Sneha, 1993-, et al.
(författare)
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Microstructure evolution-based design of thermal post-treatments for EBM-built Alloy 718
- 2020
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Ingår i: Journal of Materials Science. - : Springer Science and Business Media LLC. - 0022-2461 .- 1573-4803. ; 56:2, s. 5250-5268
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Tidskriftsartikel (refereegranskat)abstract
- Alloy 718 samples were fabricated by electron beam melting (EBM) additive manufacturing process. The work focused on systematic investigation of response of the material to various thermal post-treatments, involving hot isostatic pressing (HIPing), solution treatment (ST) and two-step aging, to tailor post-treatment procedure for EBM-built Alloy 718. Results showed that HIPing at lowered temperature can be used for attaining desired defect closure while preserving grain size. Subjecting the material to ST, with or without prior HIPing, mainly caused precipitation of δ phase at the grain boundaries with prior HIPing decreasing the extent of δ phase precipitation. Moreover, results suggest that the utility of ST, with prior HIPing, could be dictated by the need to achieve a certain δ phase content, as the typically targeted homogenization after ST had already been achieved through HIPing. Detailed investigation of microstructural evolution during subsequent aging with and without prior HIPing showed that a significantly shortened aging treatment (‘4 + 1’ h), compared to the ‘standard’ long treatment (‘8 + 8’ h) traditionally developed for conventionally produced Alloy 718, might be realizable. These results can have significant techno-economic implications in designing tailored post-treatments for EBM-built Alloy 718.
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| 6. |
- Gutkin, Renaud, et al.
(författare)
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Slutrapport för det koncernstrategiska projektet Swerea Virtual Lab
- 2016
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Simulering som verktyg för utveckling, tillverkning och provning av produkter i avancerade material är en stor och betydande del av Swereas ordinarie verksamhet. Swerea Virtual Lab är ett fokusområde inom Swerea AB. Swerea Virtual Lab är en kraftsamling för att hjälpa industrin att utöka sin virtuella produktutveckling. Swerea Virtual Lab är en unik samarbetspartner genom sin storlek, kompetens, materialbredd och förmåga att generera indata till beräkningsmodell, genomföra simuleringar och verifiera resultat i laboratorieskala. Swerea Virtual Lab är ett välkänt begrepp, en prioriterad samarbetspartner och den självklara forskningspartnern i EU projekt och i industriella utvecklingsprojekt i Europa och Sverige. Swerea Virtual Lab kännetecknas av tydlig kontaktstruktur, transparent process, hög kvalité och hög leveranssäkerhet. Swerea Virtual Lab vänder sig till alla branscher som har ett intresse av virtuell produktutveckling.
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