A dislocation model of plastic yield in fuel pin cladding materials

A mechanistic understanding of plastic yield is developed using ideas of dislocation dynamics, and is applied to the interpretation of tensile test data for candidate fast reactor fuel pin cladding materials. The central ingredients of the model are rate equations describing the evolution of the mobile and static components of the dislocation density, and a physical model of the mobilisation mechanism. The model can account for the temperature, strain and strain rate dependence of the yield stress, using values for the physical parameters obtained by fitting predictions to experiment, and extension to irradiation effects and recovery/recrystallisation is straightforward. The model also offers the prospect of development to include creep plasticity. (author)