  This paper starts with a systematic rederivation of the statistical
thermodynamic equations of motion for dislocation-mediated plasticity proposed
in 2010 by Langer, Bouchbinder and Lookman. It then uses that theory to explain
the anomalous rate-hardening behavior reported in 1988 by Follansbee and Kocks,
and to explore the relation between hardening rate and grain size reported in
1995 by Meyers et al. A central theme is the need for physics-based,
nonequilibrium analyses in developing predictive theories of the strength of
polycrystalline materials.
