Experimental data for constant strain rate and creep tests in the temperature and stress regime expected during dry storage of spent fuel were presented and modelled. The model used follows the approach of Kocks and Mecking in which the dislocation density was considered as the governing internal variable. The model was extended in a phenomenological manner, to take into account the incompatibility stress that developed as a consequence of the anisotropy of the hexagonal close-packed zirconium. An equation that accounted for the evolution of the incompatibility stress with strain was used in conjunction with the evolution equation for dislocation density thus providing a full description of the deformation behavior. A set of parameters determined experimentally enables the prediction of the mechanical response under constant strain rate and creep conditions. A reasonably good predictive capability of the model was demonstrated.

Dislocation Density-Based Modelling of Plastic Deformation of Zircaloy-4. J.W.Dunlop, Y.J.M.Bréchet, L.Legras, Y.Estrin: Materials Science and Engineering A, 2007, 443[1-2], 77-86