The implications of grain boundary structure theory were considered. An analysis of deformation via the movement of a network of initially intrinsic grain-boundary dislocations which permeated the grain boundaries of a polycrystal showed that long-range strain fields arose when intrinsic grain-boundary dislocations crossed triple lines. The resultant increase in strain energy produced a back-stress which opposed further deformation. Large strains were possible due to a number of recovery mechanisms which could reduce these long-range strain fields. The strain rate at a given point was controlled by the rate at which the grain-boundary dislocations could climb under the action of the effective stress.

R.I.Todd: Materials Science Forum, 1997, 243-245, 99-108