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 ∼ 10 μm). 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.