Impact property of low-activation vanadium alloy NIFS-HEAT-2 after electron beam welding and neutron irradiation

Takuya Nagasaka, Haiying Fu, Nobuyuki Kometani, Takeshi Miyazawa, Takeo Muroga, Hideo Watanabe, Masanori Yamazaki, Takeshi Toyama

Research output: Contribution to journalArticle

Abstract

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.

Original languageEnglish
Pages (from-to)645-651
Number of pages7
JournalFusion Science and Technology
Volume72
Issue number4
DOIs
Publication statusPublished - Nov 1 2017

All Science Journal Classification (ASJC) codes

  • Civil and Structural Engineering
  • Nuclear and High Energy Physics
  • Nuclear Energy and Engineering
  • Materials Science(all)
  • Mechanical Engineering

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