Abstract: In this paper, based on the basic theory of the plastic mechanics for continuous media and using the superplastic constitutive equations with varying m value, the hight limit coefficient D for free bulging at constant pressure, the radius limit coefficient for filling the grooves at constant pressure and a simple method of deciding the limit hight and the limit radius by D and D' are presented. The theoretical conclusion have been proved to be identical to test results, so D and can be taken as the important technical parameters for superplastic bulging.

Key words: 超塑胀形, 胀形极限系数, Active control, Grinding residual stress, Induction heating, Metal powder bonded magnetic flux concentrator (MPB-MFC) , Nickel-based superalloy