TY - JOUR
T1 - Impact property of low-activation vanadium alloy NIFS-HEAT-2 after electron beam welding and neutron irradiation
AU - Nagasaka, Takuya
AU - Fu, Haiying
AU - Kometani, Nobuyuki
AU - Miyazawa, Takeshi
AU - Muroga, Takeo
AU - Watanabe, Hideo
AU - Yamazaki, Masanori
AU - Toyama, Takeshi
N1 - Funding Information:
This study was supported by NIFS Fusion Engineering Research Project, budget code UFFF023, MEXT KAKENHI Grant number JP15K14284. This research was carried out in part at the International Research Center for Nuclear Materials Science, Institute for Materials Research, Tohoku University.
Publisher Copyright:
© American Nuclear Society.
PY - 2017/11
Y1 - 2017/11
N2 - In order to investigate the effect of post-weld heat treatment (PWHT) and post-irradiation annealing (PIA), electron-beam-weld specimens of the reference low activation vanadium alloy, NIFS-HEAT-2, were neutronirradiated to a fluence of 7.62 × 1023 neutron m-2 (E > 1 MeV) at 563 K in Belgian Reactor-2. In the present experiments, unexpected oxidation of the surface of the samples occurred during the neutron irradiation, and significantly degraded impact properties of the weld metal, while the degradation was not significant for the base metal. The removal of the oxidized layer by electro-polishing improved the impact properties of the weld metal. Although complete removal of the oxidized layer could not be confirmed, it is revealed that impact absorbed energy of the weld metal with post-weld heat treatment at 1073 K was comparable to that of the base metal after the postirradiation polishing. In other words, irradiation embrittlement of the weld metal was successfully suppressed by the PWHT. PIA at 773 K and above was effective to recover the irradiation hardening and irradiation embrittlement. Mechanisms of the irradiation hardening, irradiation embrittlement and its recovery were discussed.
AB - In order to investigate the effect of post-weld heat treatment (PWHT) and post-irradiation annealing (PIA), electron-beam-weld specimens of the reference low activation vanadium alloy, NIFS-HEAT-2, were neutronirradiated to a fluence of 7.62 × 1023 neutron m-2 (E > 1 MeV) at 563 K in Belgian Reactor-2. In the present experiments, unexpected oxidation of the surface of the samples occurred during the neutron irradiation, and significantly degraded impact properties of the weld metal, while the degradation was not significant for the base metal. The removal of the oxidized layer by electro-polishing improved the impact properties of the weld metal. Although complete removal of the oxidized layer could not be confirmed, it is revealed that impact absorbed energy of the weld metal with post-weld heat treatment at 1073 K was comparable to that of the base metal after the postirradiation polishing. In other words, irradiation embrittlement of the weld metal was successfully suppressed by the PWHT. PIA at 773 K and above was effective to recover the irradiation hardening and irradiation embrittlement. Mechanisms of the irradiation hardening, irradiation embrittlement and its recovery were discussed.
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U2 - 10.1080/15361055.2017.1352428
DO - 10.1080/15361055.2017.1352428
M3 - Article
AN - SCOPUS:85037041990
SN - 1536-1055
VL - 72
SP - 645
EP - 651
JO - Fusion Science and Technology
JF - Fusion Science and Technology
IS - 4
ER -