Strain Hardening and ‘Strain-Rate Hardening’

The limitations of power-law strain hardening and 'strain-rate hardening' descriptions are reviewed. It is found that significant advantages can be gained by using, instead, the Voce relation, especially in the proposed modification that accounts for the rate sensitivities of flow stress and of strain hardening. Considerable further predictive value can be derived from differential constitutive relations, which can be integrated over arbitrary paths. The material parameters to be measured are the (linear) strain-hardening rate and the rate sensitivity of the flow stress, both as a function of (pre)stress and (current) strain rate. These are history independent over substantial regimes of unidirectional deformation, where a mechanical equation of state exists.