Effects of neutron-irradiation-induced intergranular phosphorus segregation and hardening on embrittlement in reactor pressure vessel steels
✍ Scribed by Y. Nishiyama; K. Onizawa; M. Suzuki; J.W. Anderegg; Y. Nagai; T. Toyama; M. Hasegawa; J. Kameda
- Publisher
- Elsevier Science
- Year
- 2008
- Tongue
- English
- Weight
- 925 KB
- Volume
- 56
- Category
- Article
- ISSN
- 1359-6454
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✦ Synopsis
The effects of intergranular P segregation and hardening on the ductile-to-brittle transition temperature (DBTT) in several neutronirradiated 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.