Abstract
This work highlighted that a ground surface finish and the exposure to a pressurised water reactor (PWR) environment result in a decreased low-cycle fatigue lifetime, an enhanced fatigue crack initiation and an accelerated fatigue crack growth rate of 304 L austenitic stainless steel. A ground surface finish promotes fatigue crack initiation and short crack growth especially in a water environment, due to the highly deformed underlying microstructure with high-angle grain boundaries and the grinding marks on surface. Martensite was observed in the vicinity of secondary crack tips in specimens tested in a simulated PWR primary side environment. The aggregated presence of α′- and ε-martensite in the vicinity of the fatigue crack tip can enhance the material's susceptibility to hydrogen-assisted fatigue cracking. Martensite formation was rarely observed in specimens exposed to high temperature air. The phase transformation from γ-austenite to αꞌ-martensite in the PWR primary environment occurred via the intermediate ε-martensite phase.
| Original language | English |
|---|---|
| Article number | 153399 |
| Journal | Journal of Nuclear Materials |
| Volume | 558 |
| DOIs | |
| Publication status | Published - Jan 2022 |
| MoE publication type | A1 Journal article-refereed |
Funding
The project was funded by EU Horizon 2020 project INCEFA-PLUS from the Euratom research and training programme 2014-2018 under grant agreement N662320. The authors would like to sincerely thank M. Bruchhausen (JRC), M. Vankeerberghen (SCK-CEN), L. de Baglion (Framatome), J.C. le Roux (Electricité de France), L. Doremus (Framatome), A. McLennan (Jacobs), K. Mottershead (Jacobs), T. Lehtikuusi (VTT), J. Lukin (VTT) and all participants in the INCEFA-PLUS Project for their valuable contributions to this work.
Keywords
- Environmentally assisted fatigue
- Hydrogen
- Martensite formation
- Stainless steels
- Surface finish