Influence of neutron irradiation on mechanisms of viscoplastic flow of mild steel

Mechanisms of plastic flow and brittle transition are analysed. These problems are investigated for mild steel on the basis of the available experimental data. A relation between the brittle transition temperature, strain rate and grain size is derived. The suitable regions in temperature vs strain rate plane characterising the plastic deformation and brittle facture mechanism activity are discussed. Main neutron irradiation effects as well as their influence on the mechanisms of the plastic flow in the mild steel are briefly reviewed. A dependence of brittle transition temperature on the integrated neutron flux is discussed. Characteristic regions pertaining to the relative internal dissipation mechanisms in the temperature vs strain rate plane for the irradiated mild steel are then elaborated. (author)