Modeling mechanical response and texture evolution of α-uranium as a function of strain rate and temperature using polycrystal plasticity

We present a polycrystal plasticity model based on a self-consistent homogenization capable of predicting the macroscopic mechanical response and texture evolution of α-uranium over a wide range of temperatures and strain rates. The hardening of individual crystals is based on the evolution of dislocation densities and includes effects of strain rate and temperature through thermally-activated recovery, dislocation substructure formation, and slip-twin interactions. The model is validated on a comprehensive set of compression tests performed on a clock-rolled α-uranium plate at temperatures ranging from 198 to 573 K and strain rates ranging from 10 ^-3 to 3600 s^-1. The model is able to reproduce the stress-strain response and texture for all tests with a unique set of single-crystal hardening parameters. We elucidate the role played by the slip and twinning mechanisms and their interactions in large plastic deformation of α-uranium as a function of strain rate and temperature.