LAUSR

Abstract The superplastic forming process has many industrial applications; however the slow nature of the process is impeding its popularity. In theory, it should be possible to design an optimum pressure profile that generates a strain rate path with the highest possible strain rates while at the same time mitigating necking. This can be accomplished by incorporating certain sheet stability criteria in a model of the process. As a first step towards this goal, in this study, the target is to determine the limit strain in a sheet being superplastic formed at a constant strain rate taking into consideration the friction at the sheet-die interface. The geometry of the formed part was chosen to be a long rectangular box, in order to benefit from the plane strain state that exists in most of the sheet during the forming process. The results show that the limit strain highly depends on the dimensions of the assumed non-homogeneity.