Assessment of neutron irradiation-induced grain boundary embrittlement by phosphorous segregation in a reactor pressure vessel steel

Akihiko Kimura, Masaaki Shibata, Ryuta Kasada, Katsuhiko Fujii, Kohji Fukuya, Hayato Nakata

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)


The materials used were two sorts of reactor pressure vessel steels (RPVSs), which contain different amounts of impurity phosphorous (P) and copper (Cu). The specimens for Charpy V-notch impact tests and Auger electron spectroscopy (AES) were irradiated in the Japan Materials Test Reactor (JMTR) at 290°C up to fluences of 6 × 1021 and 1 × 10 24 n/m2 using a multi-division temperature control capsule which enables removal of a part of the sub-capsules during operation of the reactor. Neutron irradiation resulted in a significant shift in the ductile-brittle transition temperature (DBTT) accompanied by a large irradiation hardening in the high P and high Cu steel. The AES measurements following the irradiations revealed that almost no phosphorous segregation occurred at grain boundaries. The DBTT shifts by neutron irradiation were reasonably interpreted in terms of a so-called hardening mechanism. The SEM observations of the fractured surface indicated that a very small amount of grain boundary fracture was induced at the irradiation conditions, and resultantly no grain boundary embrittlement was observed. Based on the results of irradiation experiments as well as long-term thermal aging experiments beyond 16 000 h, neutron irradiation-induced grain boundary embrittlement is considered to rarely happen to the RPVS that contains 110 wppm of phosphorous.

Original languageEnglish
Title of host publicationEffects of Radiation on Materials
Subtitle of host publication22nd Symposium
PublisherAmerican Society for Testing and Materials
Number of pages13
ISBN (Print)0803134010, 9780803134010
Publication statusPublished - 2006 Jan 1
Externally publishedYes
Event22nd Symposium on Effects of Radiation on Materials - Boston, MA, United States
Duration: 2004 Jun 82004 Jun 10

Publication series

NameASTM Special Technical Publication
Volume1475 STP
ISSN (Print)0066-0558


Other22nd Symposium on Effects of Radiation on Materials
Country/TerritoryUnited States
CityBoston, MA


  • DBTT shift
  • Grain boundary fracture ratio
  • Non-hardening embrittlement
  • Phosphorous segregation

ASJC Scopus subject areas

  • Materials Science(all)


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