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Title: A comparative assessment of the fracture toughness behavior of ferritic-martensitic steels and nanostructured ferritic alloys

The Fe-Cr alloys with ultrafine microstructures are primary candidate materials for advanced nuclear reactor components because of their excellent high temperature strength and high resistance to radiation-induced damage such as embrittlement and swelling. Mainly two types of Fe-Cr alloys have been developed for the high temperature reactor applications: the quenched and tempered ferritic-martensitic (FM) steels hardened primarily by ultrafine laths and carbonitrides and the powder metallurgy-based nanostructured ferritic alloys (NFAs) by nanograin structure and nanoclusters. This paper aims at elucidating the differences and similarities in the temperature and strength dependences of fracture toughness in the Fe-Cr alloys to provide a comparative assessment of their high-temperature structural performance. The K JQ versus yield stress plots confirmed that the fracture toughness was inversely proportional to yield strength. It was found, however, that the toughness data for some NFAs were outside the band of the integrated dataset at given strength level, which indicates either a significant improvement or deterioration in mechanical properties due to fundamental changes in deformation and fracture mechanisms. When compared to the behavior of NFAs, the FM steels have shown much less strength dependence and formed narrow fracture toughness data bands at a significantly lower strength region. It appeared thatmore » at high temperatures ≥600 °C the NFAs cannot retain the nanostructure advantage of high strength and high toughness either by high-temperature embrittlement or by excessive loss of strength. Finally, irradiation studies have revealed, however, that the NFAs have much stronger radiation resistance than tempered martensitic steels, such as lower radiation-induced swelling, finer helium bubble formation, lower irradiation creep rate and reduced low temperature embrittlement.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4]
  1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  3. Hanbat National Univ., Daejeon (Korea, Republic of)
  4. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Report Number(s):
PNNL-SA-121145; LA-UR-17-28189
Journal ID: ISSN 0022-3115; AF5810000; NEAF225
Grant/Contract Number:
AC05-00OR22725; AC05-76RL01830; AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
Journal of Nuclear Materials
Additional Journal Information:
Journal Volume: 484; Journal ID: ISSN 0022-3115
Publisher:
Elsevier
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE Office of Nuclear Energy (NE), Fuel Cycle Technologies (NE-5). Fuel Cycle Research and Development Program
Contributing Orgs:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hanbat National Univ., Daejeon (Korea, Republic of)
Country of Publication:
United States
Language:
English
Subject:
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS; 11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
OSTI Identifier:
1335373
Alternate Identifier(s):
OSTI ID: 1339788; OSTI ID: 1398936