STRAIN-RATE SENSITIVITY OF FLOW STRESS FOR A PEIERLS MECHANISM

Abstract The change in the flow stress Δτ resulting from an incremental change in strain rate is predicted for a Peierls mechanism. In particular, consideration is given to the effect of the mobile dislocation density on the pre-exponential term of the rate equation. The calculations show that Δτ is strongly dependent upon the temperature, base strain rate, and strain-rate ratio. In addition Δτ is a direct function of the mobile dislocation density and can be dependent on the state of deformation. Thus a Peierls mechanism does not require Δτ to be independent of the flow stress, as implied in the literature. The results of the calculation are compared with published data for iron, and suggest a change in the mechanism for iron at approximately 200°K. © 1969 Taylor & Francis Group, LLC.