Effects of neutron-irradiation-induced intergranular phosphorus segregation and hardening on embrittlement in reactor pressure vessel steels

TitleEffects of neutron-irradiation-induced intergranular phosphorus segregation and hardening on embrittlement in reactor pressure vessel steels
Publication TypeJournal Article
Year of Publication2008
AuthorsNishiyama Y, Onizawa K, Suzuki M, Anderegg JW, Nagai Y, Toyama T, Hasegawa M, Kameda J
Journal TitleActa Materialia
Volume56
Pages4510-4521
Date PublishedSep
Type of ArticleArticle
ISBN Number1359-6454
Accession NumberISI:000259931300037
KeywordsALPHA-IRON, carbon, CU, evolution, fe, FERRITIC ALLOYS, fracture, Grain-boundary segregation, Hardening, Irradiation embrittlement, MICROSTRUCTURAL, Precipitate, Reactor pressure vessel steels, SOLUTE SEGREGATION
Abstract

The effects of intergranular P segregation and hardening on the ductile-to-brittle transition temperature (DBTT) in several neutron-irradiated reactor pressure vessel steels with different bulk contents of P and Cu have been investigated using a scanning Auger microbe, a local electrode atom probe and positron annihilation spectroscopy. Increasing the neutron fluence at 563 K promotes intergranular P segregation, particularly in steels with high levels of P. The content of P (<570 ppm) more significantly affects irradiation-hardening than that of Cu (<0.17 wt.%) due to distinct formation of P-rich precipitates arising from the stabilization of vacancies. Analyzing the correlations between P segregation, hardening. fraction of intergranular fracture and DBTT, it is found neutron irradiation mitigates the embrittling effect of segregated P. and therefore the hardening more strongly affects the DBTT shift than the P segregation, with the exception of highly P-doped steel irradiated to high neutron fluence. (C) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

DOI10.1016/j.actamat.2008.05.026
Alternate JournalActa Mater.