STP725: Tensile, Creep, and Fatigue Properties of Low-Fluence Neutron-Irradiated Welded Joints DIN 1.4948

    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),

    Pages: 18    Published: Jan 1981


    Abstract

    Welded joints 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). Tension and creep tests show considerable irradiation embrittlement, depending on fluence, test temperature, and strain rate. Creep strain values at 823 K reduce to 0.3 percent. The embrittlement is attributed to helium promoted intergranular fracture of the parent metal, the helium being formed mainly by the 10B reaction.

    Low-cycle fatigue tests show considerable scatter (standard deviation 25 percent) of the fatigue life (Nf) due to weld inhomogeneities, and therefore no significant difference between irradiated and unirradiated welded joints could be observed. Fracture is located in the weld.

    Fatigue life is reduced to 0.2 Nf after more than 1000 h creep exposure, due to enhanced initiation of large intergranular cracks in the heat-affected zone below the root weld of irradiated specimens. Tensile and creep properties deteriorate after prior fatigue loading up to a relatively high number of cycles (> 0.7 Nf). Residual creep strain values of irradiated welded joints reduce from 0.5 percent to zero.

    Keywords:

    radiation, stainless steels, welded joints, neutron irradiation, tension tests, creep, fatigue tests, embrittlement, elevated temperature, strain rate, ductility, elongation, fatigue life


    Paper ID: STP28220S

    Committee/Subcommittee: E10.08

    DOI: 10.1520/STP28220S


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