A generic method for modelling the behavior of anisotropic metallic materials : application to recrystallized zirconium alloys

TL;DR

This paper introduces a simplified polycrystalline model for simulating the anisotropic viscoplastic behavior of metallic materials, demonstrated on zirconium alloys used in nuclear fuel cladding, with a focus on predictive accuracy and minimal test data.

Contribution

A generic method for constructing simplified anisotropic textures based on pole figures, applied to zirconium alloys, requiring only a few tests for accurate modeling.

Findings

Six crystallographic orientations suffice to describe large anisotropy.

The model accurately predicts tests not used in parameter identification.

Texture parameters match experimental pole figures.

Abstract

A simplified polycrystalline model (the so-called RL model) is proposed to simulate the anisotropic viscoplastic behavior of metallic materials. A generic method is presented that makes it possible to build a simplified anisotropic material texture, based on the principal features of the pole figures. The method is applied to a recrystallized zirconium alloy, used as clad material in the fuel rods of nuclear power plants. An important database consisting in mechanical tests performed on Zircaloy tubes is collected. Only a small number of tests (pure tension, pure shear) are used to identify the material parameters, and the texture parameters. It is shown that six crystallographic orientations (6 "grains") are sufficient to describe the large anisotropy of such hcp alloy. The identified crystallographic orientations match the experimental pole figures of the material, not used in the identification procedure. Special attention is paid to the predictive ability of the model, i.e., its ability to simulate correctly experimental tests not belonging to the identification database. These predictive results are good, thanks to an identification procedure that enables to consider the contribution of each slip system in each crystallographic orientation.