ISSN: 1546-962X
CODEN: JAIOAD
Published Online: 28 July 2009
Page Count: 8

Irradiation-Induced Grain-Boundary Solute Segregation and Its Effect on Ductile-to-Brittle Transition Temperature in Reactor Pressure Vessel Steels

Nishiyama, Yutaka
Nuclear Safety Research Center, Japan Atomic Energy Agency, Tokai-mura, Ibaraki-ken

Yamaguchi, Masatake
Center for Computational Science and e-Systems, Japan Atomic Energy Agency, Tokai-mura, Ibaraki-ken

Onizawa, Kunio
Nuclear Safety Research Center, Japan Atomic Energy Agency, Tokai-mura, Ibaraki-ken

Iwase, Akihiko
Dept. of Materials Science, Osaka Prefecture Univ., Sakai-shi, Osaka

Matsuzawa, Hiroshi
Japan Nuclear Energy Safety Organization, Tokyo, Minato-ku

(Received 24 June 2008; accepted 2 June 2009)

Abstract

A study on grain-boundary segregation and embrittlement in terms of the Charpy ductile-to-brittle transition temperature (DBTT) has been performed for the neutron-irradiated A533B steels with typical contents of impurities of Japanese reactor pressure vessel ones. The neutron irradiation was conducted at 563 K to a fluence of 1.3× 10²⁴n/m² (E>1 MeV) using material testing reactors. The neutron irradiation induced the P and Ni segregation and the reduction in C in some cases at grain-boundaries. The increase in the P segregation at high fluence (>5×10 ²³n/m², E>1 MeV) was less than 0.1 in monolayer coverage for the steels with the bulk content of P not exceeding 0.02 wt%. The hardening more strongly affected the DBTT shift than the P segregation for those steels. The reduction in segregated C that enhances the grain-boundary cohesion by neutron fluence is not large enough to cause the DBTT shift.

Keywords:
reactor pressure vessel, phosphorus segregation, carbon segregation, grain-boundary, neutron irradiation, embrittlement, ductile-to-brittle transition temperature (DBTT), intergranular fracture

Paper ID: JAI101959
DOI: 10.1520/JAI101959
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