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Title: Thermal annealing recovery of fracture toughness in HT9 steel after irradation to high doses

The HT9 ferritic/martensitic steel with a nominal chemistry of Fe(bal.)–12%Cr–1%MoVW has been used as a primary core material for fast fission reactors such as FFTF because of its high resistance to radiationinduced swelling and embrittlement. Both static and dynamic fracture test results have shown that the HT9 steel can become brittle when it is exposed to high dose irradiation at a relatively low temperature 430 °C). This article aims at a comprehensive discussion on the thermal annealing recovery of fracture toughness in the HT9 steel after irradiation up to 3–148 dpa at 378–504 °C. A specimen reuse technique has been established and applied to this study: the fracture specimens were tested Charpy specimens or broken halves of Charpy bars (13 3 4 mm). The post-anneal fracture test results indicated that much of the radiation-induced damage can be recovered by a simple thermal annealing schedule: the fracture toughness was incompletely recovered by 550 °C annealing, while nearly complete or complete recovery occurred after 650 °C annealing. This indicates that thermal annealing is a feasible damage mitigation technique for the reactor components made of HT9 steel. The partial recovery is probably due to the non-removable microstructural damages such as void or gasmore » bubble formation, elemental segregation and precipitation.« less
 [1] ;  [2] ;  [3] ;  [3] ;  [4]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Korea Atomic Energy Research Inst., Daejeon (South Korea)
  3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  4. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 0022-3115; AF5810000
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Nuclear Materials; Journal Volume: 449; Journal Issue: 1-3
Research Org:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org:
Country of Publication:
United States
22 GENERAL STUDIES OF NUCLEAR REACTORS; 36 MATERIALS SCIENCE HT-9; neutron irradiation; fracture toughness; thermal annealing; FFTF