Anisotropic creep behaviour of zirconium alloys in a fast neutron flux

Abstract During fabrication, zirconium alloys develop strong crystallographic textures, which give the materials anisotropic properties. To derive the anisotropic factors which apply to creep deformation at relatively low stresses, temperatures of 260° to 300°C and fast neutron flux from 0.6 × 1013 to 3.5 × 1013 n/cm2s (>1 MeV), test results are analyzed using the effective stress and effective strain relations. The analysis is an extension of the conventional method representing the multiaxial stress state based on the generalized Von Mises yield function proposed by Hill.For the tubes evaluated the ratio of transverse creep in a closed-end tube to a uniaxial creep rate in the axial direction at the same stress, flux and temperature is about 0.3. The ratio of uniaxial creep rates in the transverse and axial directions is about 0.5. Tentative values for the anisotropic factors are determined for pressure tube materials which allow one to calculate strain behaviour under any stress state. The factors are b...