DARSTELLUNG DER UMFORMBARKElT VON METALLISCHEN WERKSTOFFEN IN EINEM UMFORMBARKEITSDIAGRAMM

Abstract

In this paper the formerly usual formability diagram has been modified on the basis of the theory of Z. Marciniak and K. Kuczynski concerning the localization of strain in shearing bands and the empirical values. The already known outer variables of state influencing the formability were extended by the term "state of strain", for the numerical designation of which the absolute value of the Lode parameter was introduced. Formability test were made with three different steels in order to confirm the relationship between the formability and the state of strain. On account of the experimental results an assumed shape of the formability diagram was taken as a basis in the whoIe region of plane stress. The assumptions valid for plane stress were extended also to spatial stress conditions on the understanding of the equivalency of the state of stress parameter in terms of the formability. A hypothesis has been formulated concerning the shearing band systems occurring in various states of strain.