Final report on in-reactor creep-fatigue deformation behaviour of a CuCrZr alloy: COFAT 1

B.N. Singh, Seppo Tähtinen, Pekka Moilanen, P. Jacquet, J. Dekeyser, D.J. Edwards, M. Li, J.F. Stubbins

    Research output: Book/ReportReport


    At present, practically nothing is known about the deformation
    behaviour of materials subjected simultaneously to external cyclic
    force and neutron irradiation. The main objective of the present
    work is to determine experimentally the mechanical response and
    resulting microstructural changes in CuCrZr(HT1) alloy exposed
    concurrently to flux of neutrons and creep-fatigue cyclic loading
    directly in a fission reactor. Special experimental facilities were
    designed and fabricated for this purpose. A number of in-reactor
    creep-fatigue experiments were successfully carried out in the BR-2
    reactor at Mol (Belgium). In the present report we first describe the
    experimental facilities and the details of the in-reactor creep-fatigue
    experiments carried out at 363 and 343K at a strain amplitude of
    0.5% with holdtimes of 10 and 100s, respectively. For comparison
    purposes, similar creep-fatigue tests were performed outside of the
    reactor. (i.e. in the absence of neutron irradiation).

    During in-reactor tests, the mechanical response was continuously
    registered throughout the whole test. The results are first presented
    in the form of hysteresis loops confirming that the nature of
    deformation during these tests was truly cyclic. The temporal
    evolution of the stress response in the specimens is presented in the
    form of the average maximum stress amplitude as a function of the
    number of cycles as well as a function of displacement dose
    accumulated during the tests. The results illustrate the nature and
    magnitude of cyclic hardening as well as softening as a function of
    the number of cycles and displacement dose. Details of the
    microstructure were investigated using TEM and STEM techniques.
    The fracture surface morphology was investigated using SEM
    technique. Both mechanical and microstructural results are briefly
    discussed. The main conclusion emerging from the limited amount
    of present results is that neither the irradiation nor the duration of
    the holdtime have any significant effect on the lifetime (in terms of
    number of cycle to failure) of the material.
    Original languageEnglish
    Number of pages45
    Publication statusPublished - 2007
    MoE publication typeD4 Published development or research report or study

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