Performance of LFR structural materials in the oxygen-controlled lead at 480°C

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F26722445%3A_____%2F22%3AN0000140" target="_blank" >RIV/26722445:_____/22:N0000140 - isvavai.cz</a>

Result on the web

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DOI - Digital Object Identifier

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Result language

angličtina

Original language name

Performance of LFR structural materials in the oxygen-controlled lead at 480°C

Original language description

The long-term corrosion tests of austenitic and ferritic-martensitic (F-M) steels were conducted in a non-isothermal loop MATLoo with active oxygen control target 1x10-7wt.% O. While the F-M steels steadily oxidize in time, the austenitic steels were protected by an 80 – 250 nm protective film, consisting of (Ni, Mn, Fe2+) (Cr, Fe3+)2O4 spinel with variable cation ratio depending on steel and exposure time, effectively blocking further oxidation. The thin film can be maintained for at least 18 000 h, but with prolonged exposure, there was an increased probability of local failure and deeper oxidation with minor Pb penetration. The metal recession or the depth of localized damage of both steel types was less than 20 μm over 16 000 h. A decreased corrosion resistance on frequently replaced specimens was observed. The 4 000 h old specimens extracted every ~ 1000 h exhibited greater corrosion damage than specimens exposed for 8 – 16 000 h, indicating that thermal cycling leads to cracking of protective film, thus opening pathways for accelerated oxidation and lead penetration, especially in combination with slightly increased oxygen levels at the beginning of the corrosion test. Detailed analyses revealed that the work-hardened layer on austenitic specimens created by lathe turning of specimen surface is the most likely responsible for enhanced corrosion resistance. A similar effect was observed on 9Cr-1Mo steel specimens where the presence of the fine-grain layer near the surface promoted thin film formation and increased resistance against oxidation, but the effect seems to be only temporary. When the work-hardened layer was removed from austenitic steel specimens by electropolishing, the specimens were a subject of localized dissolution attack on the grain boundary. The main corrosion product found in the loop purification system was the iron, despite its low solubility in the liquid lead and the fact that the loop itself was fabricated from austenitic steel consisting of highly soluble Ni. Presented at Sixth International Workshop on Structural Materials for Innovative Nuclear Systems (SMINS-6), 12 - 15 September 2022, Idaho Falls (ID, US), Idaho National Laboratory, USA.

Czech name

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Czech description

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Type

O - Miscellaneous

CEP classification

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OECD FORD branch

20501 - Materials engineering

Project

<a href="/en/project/TK04030082" target="_blank" >TK04030082: Pretty Fast Flow</a><br>

Continuities

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Publication year

2022

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů