Nuclear Engineering and Technology

Korean Nuclear Society (한국원자력학회)
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A comprehensive study of the effects of long-term thermal aging on the fracture resistance of cast austenitic stainless steels

  • Collins, David A. (Materials Science and Technology Division, Oak Ridge National Laboratory) ;
  • Carter, Emily L. (Earth Systems Science Division, Pacific Northwest National Laboratory) ;
  • Lach, Timothy G. (Materials Science and Technology Division, Oak Ridge National Laboratory) ;
  • Byun, Thak Sang (Materials Science and Technology Division, Oak Ridge National Laboratory)
  • Received : 2021.05.04
  • Accepted : 2021.08.17
  • Published : 2022.02.25
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Abstract

Loss of fracture resistance due to thermal aging degradation is a potential limiting factor affecting the long-term (80+ year) viability of nuclear reactors. To evaluate the effects of decades of aging in a practical time frame, accelerated aging must be employed prior to mechanical characterization. In this study, a variety of chemically and microstructurally diverse austenitic stainless steels were aged between 0 and 30,000 h at 290-400 ℃ to simulate 0-80+ years of operation. Over 600 static fracture tests were carried out between room temperature and 400 ℃. The results presented include selected J-R curves of each material as well as K0.2mm fracture toughness values mapped against aging condition and ferrite content in order to display any trends related to those variables. Results regarding differences in processing, optimal ferrite content under light aging, and the relationship between test temperature and Mo content were observed. Overall, it was found that both the ferrite volume fraction and molybdenum content had significant effects on thermal degradation susceptibility. It was determined that materials with >25 vol% ferrite are unlikely to be viable for 80 years, particularly if they have high Mo contents (>2 wt%), while materials less than 15 vol% ferrite are viable regardless of Mo content.

Keywords

Acknowledgement

This manuscript has been authored in part by UT-Battelle LLC under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan).

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