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Evaluation of Crack Growth Rates and Microstructures Near the Crack Tip of Neutron-Irradiated Austenitic Stainless Steels in Simulated BWR Environment

  • Yasuhiro ChimiEmail author
  • Shigeki Kasahara
  • Hitoshi Seto
  • Yuji Kitsunai
  • Masato Koshiishi
  • Yutaka Nishiyama
Conference paper
Part of the The Minerals, Metals & Materials Series book series (MMMS)

Abstract

In order to understand irradiation-assisted stress corrosion cracking (IASCC) growth behavior, crack growth rates (CGRs), locally deformed microstructure, and oxide film properties for neutron-irradiated austenitic stainless steels (SSs) are investigated. Crack growth rate tests have been performed in simulated Boiling Water Reactor (BWR) water conditions (at ~288 ℃) on a neutron-irradiated 316L SS at ~12–14 dpa. After the crack growth rate tests, the microstructures near the crack tip of the CT specimens are examined with scanning transmission electron microscope (FE-STEM). In comparison with a previous study at <~2 dpa, the irradiated 316L SS at ~12 dpa shows a less benefit of low electrochemical corrosion potential (ECP) conditions on CGR. An inactive crack tip immersed over 1000 h was filled with oxides, while almost no oxide film was observed near the active crack front in the low-ECP conditions. In addition, a high density of deformation twins and dislocations were found near the fracture surface of the crack front. It is considered that both localized deformation and oxidation are possible dominant factors for the SCC crack growth in highly irradiated SSs.

Keywords

IASCC Crack growth rate Microstructure Localized deformation Oxide film Austenitic stainless steel Neutron irradiation BWR 

Notes

Acknowledgements

A part of this study was conducted under a contract with the Nuclear Regulation Authority of Japan.

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Copyright information

© The Minerals, Metals & Materials Society 2019

Authors and Affiliations

  • Yasuhiro Chimi
    • 1
    Email author
  • Shigeki Kasahara
    • 1
  • Hitoshi Seto
    • 2
  • Yuji Kitsunai
    • 2
  • Masato Koshiishi
    • 2
  • Yutaka Nishiyama
    • 1
  1. 1.Japan Atomic Energy Agency (JAEA)IbarakiJapan
  2. 2.Nippon Nuclear Fuel Development (NFD)IbarakiJapan

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