Understanding the role of grain boundaries was impeded by continued adoption of power law equations for identification of the processes governing creep and creep fracture of metals and alloys. In contrast, the dominant mechanisms could be clarified through new relationships which involve normalisation of the applied stress by the yield and ultimate tensile strengths determined from high strain rate tests at the creep temperatures.

Grain Boundaries: their Influence on Creep Strain Accumulation. B.Wilshire, M.T.Whittaker: Materials Science and Technology, 2010, 26[7], 793-6