Abstract
The paper were reviewed recent researches of parameters which control the flow and ductility of micrograin superplastic materials. Particular attention was emphasized to the strain rate sensitivity of the flow stress, m and high rate superplasticity. It has been pointed out that the origin of these characteristics is the grain boundary sliding process, which will be controlled by diffusional processes. It was discussed that the contribution of grain boundary sliding is more for the deformation having larger m value. The dependence of m value on effective stress / mean flow stress is similar to the dependence of m value on ∈gbs / ∈t. This suggests that the effective stress has a strong contribution for grain boundary sliding or related strain accommodation process. Favorable structure for the industrial application of superplastic forming will be also discussed. Those are in the relatively high deformation rate of optimum condition and having a high temperature stability of the structure.
