Determination of the value of the threshold stress for superplastic flow

A robust method to determine threshold stresses from experimental superplasticity data is described in this paper. The method suggested does not require any special investigations to be carried out (e.g. low strain rate tests or the load relaxation). It is based upon the results of standard tensile tests. Experimental implementation of the method suggested is carried out for a number of aluminum-based alloys. It is shown that the method involved enables one to obtain stable results with various choices of data points used in the process of extracting the threshold stress value. The fact that no assumptions are needed to extract a meaningful threshold stress from data obtained in a convenient manner is the main advantage of the method suggested.