On the relations between strain and strain-rate softening phenomena in some metallic materials: A computational study

It is shown that in certain materials plastic instabilities of different types may be traced back to the same physical mechanism. Depending on experimental conditions, transitions between various types of instability may take place, i.e., the classification of plastic instabilities may in those situations reflect parameters of the experimental setup rather than the intrinsic properties of the material. This is demonstrated for a theoretical model (the Ananthakrishna (AK) model) developed for the description of the Portevin-le Chatelier (PLC) effect. The results of numerical experimentation on the AK model are compared to the existing experimental data and discussed in terms of classifications of plastic instabilities that have been proposed in the literature.