Dynamic Strain Aging in Single Crystal Vanadium: Material Characterization and Dislocation-Based Crystal Plasticity Framework

In this study, we investigate the mechanical behavior of single-crystal vanadium and introduce an enhanced dislocation-based crystal plasticity framework to model its response under various loading conditions. Our experiments, conducted over a wide range of temperatures and strain rates on single-crystal vanadium samples, reveal progressive thermal hardening at low strain rates and elevated temperatures. This behavior is indicative of dynamic strain aging (DSA), a phenomenon previously observed in polycrystalline vanadium. Because of DSA, conventional single-crystal plasticity models—effective for other body-centered cubic (BCC) metals such as tantalum or molybdenum—cannot accurately capture the mechanical response of vanadium within the DSA regime. To overcome this limitation, we refined the saturation dislocation density formulation to incorporate DSA effects while maintaining predictive capability for other BCC crystals. Our approach remains relatively simple yet robust, providing satisfactory predictions of the material’s strength behavior both inside and outside of the DSA regime. It successfully predicts the reported temperature dependence of polycrystalline vanadium flow stress. In addition, it also predicts stress adjustments associated with negative strain-rate sensitivity in rate-jump tests.