STP1325

    Anomalous Hardening in Model Alloys and Steels Thermally Aged at 290°C and 350°C: Implications to Low Flux Irradiation Embrittlement

    Published: Jan 1999


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    Abstract

    Age hardening at 290°C and 350°C in five simple ferritic alloys with systematic variations in Cu and Mn and four A533B-type split melt steels with systematic variations in Cu and Ni was evaluated for times up to 7200h. Significant yield stress increases were found in alloys containing high copper and nickel. The hardening is consistent with formation of copper-rich precipitates. However, the precipitation kinetics are accelerated relative to estimates based on extrapolations of the high temperature copper diffusion coefficient. Further the observed high sensitivity to both copper and nickel content is not understood. The rapid thermal kinetics suggest that embrittlement due to age hardening could occur in sensitive pressure vessel steels during extended service. Further, high thermal diffusion rates must be considered in models of the effect of flux on hardening and embrittlement. Anomalously high diffusion would also introduce a new rate-dependent regime at very low fluxes. Hence, the peak irradiation hardening from copper-rich precipitates may occur at much lower fluences than predicted by current data correlations.

    Keywords:

    pressure vessels steels, hardening, embrittlement, flux effects, thermalaging, composition effects


    Author Information:

    Odette, GR
    University of California, Santa Barbara, Santa Barbara, CA

    Lucas, GE
    University of California, Santa Barbara, Santa Barbara, CA

    Klingensmith, D
    University of California, Santa Barbara, Santa Barbara, CA


    Paper ID: STP13859S

    Committee/Subcommittee: E10.07

    DOI: 10.1520/STP13859S


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