| 1. |
- Dömstedt, Peter, et al.
(författare)
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Corrosion studies of a low alloyed Fe-10Cr-4Al steel exposed in liquid Pb at very high temperatures
- 2020
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Ingår i: Journal of Nuclear Materials. - : ELSEVIER. - 0022-3115 .- 1873-4820. ; 531
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the work has been to study the corrosion resistance of a new low alloyed experimental FeCrAl steel, with the potential use as corrosion barrier in high temperature lead based energy applications. The exposures were conducted in liquid lead at 800 degrees C and 900 degrees C, with controlled oxygen environment, for up to 1760 h. The results demonstrate that the new experimental alloy had formed a protective oxide in both exposures, with no indications of lead penetration. The alloy showed better corrosion properties than that of the reference materials: Kanthal APMT, Kanthal APMTT and AISI 316L. This indicates that the ductile Fe-10Cr-4Al-RE steel can be used as a corrosion barrier in liquid lead based clean energy applications, operating at very high temperatures.
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| 2. |
- Dömstedt, Peter, et al.
(författare)
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Corrosion Studies of Low-Alloyed FeCrAl Steels in Liquid Lead at 750 degrees C
- 2019
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Ingår i: Oxidation of Metals. - : SPRINGER/PLENUM PUBLISHERS. - 0030-770X .- 1573-4889. ; 91:3-4, s. 511-524
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Tidskriftsartikel (refereegranskat)abstract
- New ductile experimental FeCrAl alloys, based on the composition of Fe-10Cr-4Al, were exposed to stagnant liquid lead at 750 degrees C for up to 1970h. Two exposures with different test conditions were performed: one with addition of oxygen (as H2O) to the liquid lead and one without. The experimental alloys showed generally good oxidation and self-healing properties. The exposures showed that this specific category of steels has the potential to operate in liquid lead at very high temperatures with only minor oxidation. With this new material development, new energy technologies such as the CSP plants may be able to utilize liquid lead at very high temperatures as heat transfer fluid, thus achieving increased thermal efficiency.
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| 3. |
- Dömstedt, Peter
(författare)
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Development of Alumina Forming Alloys for High-Temperature Energy Applications
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Liquid lead as heat transfer fluid presents attractive features for future power technologies, such as next-generation nuclear reactors, thermal solar power, and thermal storage. Liquid lead has excellent heat transfer properties well suited for operating at high temperatures. While today's water-cooled reactors operate at a temperature of approximately 300°C, the next-generation lead-cooled nuclear power could operate up to 600°C, significantly increasing the energy conversion efficiency. However, it is well known that liquid lead is a corrosive medium for stainless steels, especially at temperatures above 500°C.To address the corrosion issues, aluminium oxide-forming ferritic steels have been thoroughly studied in liquid lead environments and have shown good oxidation properties. Traditionally, these steels are alloyed with 3-6 wt% aluminium and 12-24 wt% chromium, and iron as balance, hence the denotation FeCrAl steel. However, the high addition of aluminium and chromium results in poor weldability and renders them susceptible to embrittlement in the desired temperature range. Therefore, to address the welding and embrittlement issues, a new group of FeCrAl materials was developed in recent years with only 10 wt% chromium and 4 wt% aluminium, which in this work is referred to as Fe-10Cr-4Al. These alloys have shown good ductility and good corrosion properties in liquid lead up to 550°C.In this work, the Fe-10Cr-4Al steels have been further optimised and exposed to liquid lead at temperatures up to 900°C. In addition, detailed studies of the oxidation properties and structure formed on the steel surfaces were conducted using various analytical techniques. The findings showed that the most promising Fe-10Cr-4Al steel, so far, has suitable corrosion properties up to 800°C. However, although these steels have improved mechanical and welding properties, they do not meet the requirements set for the desired high-temperature energy applications.Therefore, another new family of alloys was developed, namely alumina-forming martensitic steels. This development aimed to combine the superior corrosion resistance of the aluminium oxide with the mechanical properties inherent in the martensitic structure. The development was done using thermodynamic modelling, empirical corrosion studies and detailed analytical methods. The results showed that these martensitic steels have a corrosion resistance exceeding even the best1optimised Fe-10Cr4-Al steel in liquid lead at temperatures up to at least 550°C.In parallel, alumina-forming austenitic steels were also developed. The aim was to find a suitable composition for these materials that not only provide good corrosion protection in liquid lead, but also good weldability, good phase stability, and good formability. These austenitic materials have shown, in general, good corrosion properties in liquid lead up to 600°C. However, the combination of elevated Ni, Al and Mn levels resulted in embrittlement after ageing at 600°C. In addition, a series of austenitic alumina-forming welding materials were also developed within this work. The aim was to produce a material that does not suffer from the embrittlement commonly observed in ferritic welds. Bend testing of this welding material has, so far, indicated ductile behaviour with good formability.
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| 4. |
- Dömstedt, Peter, et al.
(författare)
-
High Temperature Corrosion of a Lean Alloyed FeCrAl-steel and the Effects of Impurities in Liquid Lead
- 2020
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Ingår i: Proceedings - 2020 IEEE International Conference on Environment and Electrical Engineering and 2020 IEEE Industrial and Commercial Power Systems Europe, EEEIC / I and CPS Europe 2020. - : Institute of Electrical and Electronics Engineers (IEEE).
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Konferensbidrag (refereegranskat)abstract
- A lean-alloyed FeCrAl steel have been developed by KTH and Kanthal and tested in liquid lead environments at 800°C and 900°c, as well as at 550°C with and without impurities and varying oxygen activates. The results demonstrate that the lean alloyed FeCrAl steel shows superior oxidation performance up 800°C. Also, lead impurities can accelerate corrosion.
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| 5. |
- Dömstedt, Peter, et al.
(författare)
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New Alumina Forming Martensitic Steels
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The work presents a new category of alloys, Alumina Forming Martensitic (AFM) steels, developed for new clean energy power applications such as thermal solar power and Gen IV nuclear power. The aim was to combine the superior corrosion resistance of the alumina scale with the excellent creep properties of the martensitic structure. The alloys were exposed to liquid lead at 550°C for 1824 hours to evaluate their oxidation properties. In addition, the microstructures were analysed in annealed conditions and after the exposure to assess phase stabilities. Using a variety of characterisation techniques, the studies identified Al-rich oxides formed on the surfaces of both specimens after the exposure with no lead penetration. Moreover, martensite, NiAl precipitates, and different carbides were observed in both alloys.
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| 6. |
- Lindgren, Kristina, 1989, et al.
(författare)
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The Nanostructure of the Oxide Formed on Fe-10Cr-4Al Exposed in Liquid Pb
- 2022
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Ingår i: Microscopy and Microanalysis. - : Cambridge University Press (CUP). - 1435-8115 .- 1431-9276. ; 28:4, s. 1321 -1334
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Tidskriftsartikel (refereegranskat)abstract
- An Fe-10Cr-4Al alloy containing reactive elements developed for application in high-temperature liquid lead environments was analyzed after exposure in 600 and 750°C lead with dissolved oxygen for 1,000-2,000 h. Atom probe tomography, transmission electron microscopy, and X-ray scattering were all used to study the protective oxide formed on the surface. Exposure at 750°C resulted in a 2-μm thick oxide, whereas the 600°C exposure resulted in a 100-nm thick oxide. Both oxides were layered, with an Fe-Al spinel on top, and an alumina layer toward the metal. In the 600°C exposed material, there was a Cr-rich oxide layer between the spinel and the alumina. Metallic lead particles were found in the inner and middle parts of the oxide, related to pores. The combination of the experimental techniques, focusing on atom probe tomography, and the interpretations that can be done, are discussed in detail.
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