Theory of the effect of dynamic strain aging on mechanical properties

Dynamic strain aging (DSA) in solid solutions is described as diffusion of solute atoms to mobile dislocations, temporarily arrested at obstacles. As a consequence the solute concentration experienced locally by the dislocations depends on the time of arrest and the solute diffusion coefficient. Starting from this idea the dependence of the flow stress on strain rate, temperature, and strain in the presence of DSA is calculated. A criterion for the onset of serrated yielding is formulated. Finally the change in strain rate sensitivity due to DSA is calculated. The theory allows a qualitative and in some respects a quantitative comparison with experimental results of which some examples are given.