Grain growth depending on strain is generally observed during structural superplasticity. A new deformation model is proposed in order to explain this grain growth.
This model is based on grain switching by Ashby and Verrall. The modification is to introduce grain size irregularity. The grain structure with minimum irregularity consists of one 5–7 pair in hexagonal array, which corresponds to edge dislocation. While the tensile stress oblique to the pair results the grain switching described by dislocation glide, the stress parallel to it results the grain switching which transforms the pentagon into the quadrilateral and then removes it. The latter can be described by dislocation climb and results the enhancement of grain growth. The expansion into three dimensions is discussed.