A method to characterise superplastic materials in comparison with alternative methods

Superplastic materials show a very high ductility, i.e. maximum elongation of about 5000%, even if they are lowly stressed. This is due to both peculiar process conditions and material intrinsic characteristics. The aerospace industry has shown that, in order to produce complex parts requiring large tensile elongations that cannot be formed by conventional processes, superplastic forming can be used. A detailed design of technological process is necessary so as to exploit at best the peculiar potentialities of superplastic forming. The aim of the present work is to show a method to characterise superplastic materials. This method is based on the approximate analysis of a superplastic forming process in a triangular indefinite prismatic-shaped die. It has been experimentally validated through laboratory samples on material formed by room temperature; moreover, it has been compared to several methods proposed by other authors.