SEDL / STP / STP1366-EB / STP12407S

Two-Step Recovery Process of Irradiation Hardening in 1%Ni Doped 9%Cr-2%W Martensitic Steel

Kasada, R
Graduate student, Institute of Advanced Energy, Kyoto University, Kyoto,

Morimura, T
Graduate student, Institute for Materials Research, Tohoku University, Sendai,

Matsui, H
Professor, Institute for Materials Research, Tohoku University, Sendai,

Narui, M
Assistant researcher, Institute for Materials Research, Tohoku University, Sendai,

Kimura, A
Professor, Institute of Advanced Energy, Kyoto University, Kyoto,

Pages: 12    Published: Jan 2000

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Abstract

The effect of nickel addition on irradiation-induced hardening has been investigated for reduced-activation martensitic steel (RAMS). Specimens were irradiated in the JMTR at 80°C and 220°C up to 0.15 dpa. There was no significant difference in the tensile properties between the steels with and without Ni addition after the irradiation at 220°C, while in the case of the irradiation below 170°C, the Ni-added RAMS showed a more than four times larger irradiation hardening than the steel without Ni addition. The recovery behavior of the irradiation hardening of Ni-added steel on post-irradiation annealing showed two-step recovery behavior; the first step was around 200°C and the second one was around 350°C, while only the single step of recovery was observed around 350°C in the steel without Ni addition. The mechanism of the recovery process of the tremendous irradiation hardening in Ni-added steel is discussed along with the behavior of vacancies, carbon atoms and their complexes investigated by means of positron annihilation lifetime spectrometry.