STP824

    Analytical Approaches and Experimental Verification to Describe the Influence of Cold Work and Heat Treatment on the Mechanical Properties of Zircaloy Cladding Tubes

    Published: Jan 1984


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    Abstract

    Well-controlled laboratory heat treatments were performed in the range from 460 to 610°C (733 to 883 K) and from 1 to 8 h at temperature on Zircaloy-4 cladding tubes with three different degrees of initial cold work (40%, 64%, and 76%). Within this range the influence of annealing temperature T and time t and of cold work on the yield strength Rp0.2 at 400°C (673 K) and on the degree R of recrystallization was experimentally determined.

    This data base was used to verify a semi-empirical approach to describe analytically the dependence of yield strength and recrystallization on the aforementioned technological parameters T and t for the annealing and φ = ln 1/lo as a measure for the applied cold work.

    Using a “growing function” y=lnRp0.2maxRp0.2Rp0.2Rp0.2min to correlate the normalized annealing temperature A = t·exp(-Q/RT) with the change of the yield strength Rp0.2 between the values Rp0.2max and Rp0.2min, the correlation Rp0.2=Rp0.2min+ΔRp0.2·11+k·A can be obtained, where ΔRp0.2=Rp0.2min.

    It was found as a good expirical approach that ΔRp0.2=c·ω4

    and the yield strength can be described as Rp0.2=Rp0.2min+c·φ41+k1·φ2·A

    The influence of the same mentioned technological parameters on the recrystallization can be described as R1R=k2·ω2·A

    This leads to the correlation Rp0.2=RP0.2min+c·φ41+k1k2·R1R

    between yield strength and recrystallization.

    Keywords:

    zirconium, zirconium alloys, cladding tubes, mechanical properties, elevated temperature, yield strength, recrystallization, annealing time, annealing temperature, cold work


    Author Information:

    Steinberg, E
    Engineer and physicist, Fuel Technology Division, Kraftwerk Union AG, Erlangen,

    Weidinger, HG
    Engineer and physicist, Fuel Technology Division, Kraftwerk Union AG, Erlangen,

    Schaa, A
    Engineer, Nuklearrohr GmbH, Duisburg,


    Paper ID: STP34465S

    Committee/Subcommittee: B10.02

    DOI: 10.1520/STP34465S


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