Advances in Superplasticity from a Laboratory Curiosity to the Development of a Superplastic Forming Industry

Superplasticity refers to the ability of some materials to pull out to tensile elongations of 400% or more when the strain rate sensitivity is similar to 0.5. The first report of true superplastic flow was published in 1934 in experiments conducted in England. However, this remarkable result attracted little interest among western scientific researchers and the result remained a laboratory curiosity for many years. Later, following extensive research on superplasticity in the Soviet Union, interest developed in the west, and superplasticity became a topic of extensive scientific research. This research was further enhanced with the demonstration that the application of severe plastic deformation provided an opportunity for achieving grain refinement to the submicrometer or even the nanometer level, and these small grains were especially attractive for achieving good superplastic properties. It is now recognized that superplastic alloys provide an excellent forming capability, especially in making high quality curved parts that are not easily fabricated using more conventional processes. This has led to the development of a large superplastic forming industry that currently processes many thousands of tons of sheet metals. This report traces these developments with an emphasis on the scientific principles behind the occurrence of superplastic flow.

Automated summary

Superplasticity refers to the ability of certain materials to stretch and elongate to 400% or more when the strain rate sensitivity is close to 0.5. The first true superplastic flow experiment was published in England in 1934, but it received little attention among western researchers and remained a laboratory curiosity for many years. However, after extensive research on superplasticity in the Soviet Union, interest in the subject developed in the west and became a topic of extensive scientific research. The use of severe plastic deformation also played a role in enhancing the properties of superplastic alloys. It is now recognized that superplastic alloys have excellent forming capability, especially for making high quality curved parts.