Effect of Texture on Anisotropic Creep of Pressurized Zr-2.5Nb Tubes

Abstract

In this paper we report the stress dependence of the diametral and axial creep rates of cold-worked Zr-2.5Nb tubes with three different combinations of texture and microstructure in biaxial tests at 623K. One type of tube has a predominantly radial texture and it exhibits a high diametral creep rate and negative long term axial creep rate. A second type, with a predominantly transverse texture and a very fine elongated grain structure exhibits an intermediate diametral strain rate and a positive axial strain rate. The third type, with predominantly transverse texture and coarser elongated grain structure exhibits the lowest diametral creep and a positive axial strain rate. The stress exponents for the diametral creep are in the range 5-7, but those for axial creep vary from 0.7 to 7.3. The creep anisotropies were calculated with the polycrystalline model SELFPOLY-7, assuming that slip is the strain producing mechanism. The calculations give qualitative agreement with the experimental results.