Significance of microstructural control for superplastic deformation and forming

High tensile ductility may be achieved in metallic alloys over a Limited range of strain rates at elevated temperatures when the grain size is very small (typically less than similar to 10 mu m). These superplastic materials are often suitable for industrial forming operations. This paper considers the possibility of attaining a superplastic forming capability at lower temperatures and/or faster strain rates by a reduction of the grain size into the submicrometer range. Procedures are available for the fabrication of ultrafine-grained materials by imposing a very high plastic strain. These procedures are examined with reference to results obtained using Al-Mg solid solution alloys.