Effect of texture on the anisotropic creep of Zr-2.5Nb tubes

Zr-2.5Nb is used as the pressure-tube material in CANDU reactors. Under normal operating conditions, pressure tubes undergo dimensional changes due to the high temperature, stress and fast neutron flux. Thermal creep contributes to the deformation. In this project, the thermal creep at various temperatures, stress states, crystallographic texture and microstructures is being investigated. The research is being carried out on Zr-2.5Nb tubes with basal plane normals concentrated in the radial, axial and transverse directions, respectively. In this paper we report the results of scoping studies to determine the temperature and stress dependence of the diametral creep of tubes with a predominantly radial texture and the preparation of 'micro-pressure tubes' with a variety of textures suitable for investigating creep anisotropy. (author)