STP1175

    The Effect of Flux on the Irradiation Hardening of Pressure Vessel Steels

    Published: Jan 1994


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    Abstract

    Hardening of low copper steels irradiated at 288°C increased with increasing flux in the range from about 0.6 to 50 × 1016 n/m2-s. In contrast, the hardening of high copper steels was generally less effected and, in some cases, decreased with increasing flux. Thus there are at least two competing effects of flux. The behavior of low copper alloys is attributed to a population of thermally unstable matrix defects that anneal during irradiation, hence, produce hardening that increases with flux. However, the unstable matrix defects also act as point defect sinks reducing radiation enhanced solute diffusion rates. In high copper steels, lower diffusion rates delay hardening due to precipitation. These conclusions were confirmed by low-temperature post-irradiation annealing treatments which produced rapid recovery of the unstable matrix defects. The observed data trends are consistent with a model that treats the unstable matrix defects as small cascade vacancy clusters.

    Keywords:

    irradiation hardening, embrittlement, pressure vessel steels, flux effects, embrittlement mechanisms


    Author Information:

    Odette, GR
    Professors of Chemical and Nuclear Engineering and Materials and PhD Candidate, University of California Santa Barbara, Santa Barbara, CA

    Mader, EV
    Professors of Chemical and Nuclear Engineering and Materials and PhD Candidate, University of California Santa Barbara, Santa Barbara, CA

    Lucas, GE
    Professors of Chemical and Nuclear Engineering and Materials and PhD Candidate, University of California Santa Barbara, Santa Barbara, CA

    Phythian, WJ
    Section Leader, Reactor Pressure Vessel Steels and Manager, Harwell Laboratory, Didcot, Oxfordshire

    English, CA
    Section Leader, Reactor Pressure Vessel Steels and Manager, Harwell Laboratory, Didcot, Oxfordshire


    Paper ID: STP23948S

    Committee/Subcommittee: E10.08

    DOI: 10.1520/STP23948S


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