Dislocation viscoplasticity aspects of material fracturing

Dislocation viscoplasticity, whether occurring before, during, or after the appearance of cracking, and with energy requirement additional to needed crack surface energy, has proved to be the bane of simplistic strength/energy evaluations applied to the fracturing properties of solid materials. George Irwin, in later years, turned his attention to such crack-effected viscoplasticity consideration in relation to the complex microstructural aspects of fracturing behaviors obtained for nuclear pressure vessel steels. The work is reviewed here with a broader research focus on dislocation plasticity aspects of fracturing behaviors, at ever smaller crack sizes, for a wider range of materials, especially, of relatively greater hardness.