STP683

    Effects of Neutron Irradiation and Fatigue on Ductility of Stainless Steel DIN 1.4948

    Published: Jan 1979


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    Abstract

    Test specimens of stainless steel DIN 1.4948, which is similar to AISI Type 304, have been irradiated at 723 and 823 K up to fluences of 1 × 1023 neutrons (n)∙m-2 and 5 × 1024 n.m-2 (E > 0.1 MeV). These are representative conditions for the reactor vessel and inner components of the liquid metal fast breeder reactor SNR-300 after 16 years of operation. High-temperature (723 to 1023 K) tension tests at strain rates (ϵ) from 10-7 to 10 s-1 show a considerable decrease of tensile ductility. The extent depends on helium content, test temperature, and strain rate. The atomic helium fractions of 3 × 10-7 and 7 × 10-6 result from the reactions of thermal neutrons with the 14 ppm boron present in the steel. Helium embrittlement sets in at strain rates below 1 to 10 s-1 (the range of interest for Bethe-Tait accident analyses). A minimum total elongation value of 6 percent is shown at 923 K. The postirradiation fatigue life is reduced by up to about 50 percent due to intergranular cracking. The combination of irradiation and fatigue causes a decrease of ductility after a smaller number of prior fatigue cycles than in the case of unirradiated material.

    Keywords:

    radiation, stainless steels, neutron irradiation, ductility, elongation, embrittlement, strain rate, fatigue tests


    Author Information:

    de Vries, MI
    Research scientists, Netherlands Energy Research Foundation ECN, Petten (N-H),

    van der Schaaf, B
    Research scientists, Netherlands Energy Research Foundation ECN, Petten (N-H),

    Staal, HU
    Research scientists, Netherlands Energy Research Foundation ECN, Petten (N-H),

    Elej, LD
    Research scientists, Netherlands Energy Research Foundation ECN, Petten (N-H),


    Paper ID: STP38183S

    Committee/Subcommittee: E10.07

    DOI: 10.1520/STP38183S


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