A STUDY OF RESIDUAL-STRESSES IN ZIRCALOY-2 WITH ROD TEXTURE

The development of high grain-to-grain interactions in Zircaloy-2 polycrystals is due to the anisotropy of the thermal, elastic and plastic properties of the constituent grains. These residual stresses modify the mechanical performance of the material, as well as its response under neutron irradiation. Here we simulate the evolution of internal stresses in Zircaloy-2 with rod texture, when the aggregate is cooled down from the annealing temperature, and also when it is subjected to tensile and compressive deformation. We implement for that purpose an elasto-plastic self-consistent scheme that accounts for grain interactions, and compare our predictions with experimental determinations of residual strains obtained by neutron diffraction. Our results are in good quantitative agreement with the experimental evidence, and represent a qualitative improvement over the predictions of the more rigid upper-bound approach. We discuss the role that slip and twinning systems play in the macroscopic response of the aggregate and in the evolution of internal stresses.