Effects of texture of zirconium alloy and multi-axial stress on iodine SCC susceptibility.

Abstract

An analytical model of iodine stress corrosion cracking (SCC) of hexagonal close packed metals is developed. The SCC susceptibility is represented in the model by the elastic strain energy in the single crystals with tensile strain toward the axis of the crystal. The model incorporates the effect of crystallographic textures and multi-axial stress states. The SCC susceptibilities of the Zr and Zr alloy fuel claddings with three different textures are calculated based on the model. It is found that the stress for the tangential tensile loading of cladding is about 40% of that for longitudinal tensile loading with the same SCC susceptibility. Measurements are made on the number of microcracks on the inner surface of the Zircaloy-2 fuel claddings. These cracks are produced during the iodine SCC tests performed at 350°C under the biaxial stress state with a constant Mises' effective stress. The SCC susceptibility obtained by the proposed model was found to agree with the experimental results. The SCC susc...