Modeling texture evolution during uni-axial deformation of Zircaloy-2

Abstract

Texture development in zirconium reactor components greatly affects their in-service performance, in particular influencing dimensional stability, hydride induced cracking and fracture. Understanding texture evolution in terms of micromechanical deformation mechanisms contributes to improved engineering design of the components. The texture evolution during uni-axial deformation of Zircaloy-2 obtained using neutron diffraction was interpreted with a visco-plastic self-consistent model, based on an extensive data set achieved through in situ and ex situ neutron diffraction measurements. In the model, the influences of prism, basal, pyramidal〈a〉, pyramidal〈c + a〉 slip, tensile twinning, and hardening due to dislocation interactions were considered. Model parameters were adjusted to obtain a simultaneous ‘best-fit’ to the stress–strain curves, Lankford coefficients, development of peak intensities in three dimensions and post-deformation textures, for specimens compressed or pulled in three principal directions relative to the slab texture. The texture formation was found to be directly related to the activation of different deformation mechanisms. Pyramidal〈a〉 slip was unnecessary in the modeling. Accounting for interactions between deformation modes was critical to correctly predicting texture development and stress–strain curves. This study provides further understanding on the plastic deformation of Zircaloy-2.