Cyclic stress-strain behavior and load sharing in duplex stainless steels: Aspects of modeling and experiments

From cyclic experimental tests, it has been found that the cyclic stress-strain behavior of duplex stainless steels (DSSs) is largely dependent on the applied load/strain amplitude. It is believed that the difference in the elastoplastic properties between the austenite and ferrite phases as well as the load sharing between the phases, are responsible for the dependence. In order to examine this hypothesis, three different DSSs, where the difference in the elastoplastic properties between the phases varies between them, are studied in this paper. The examinations are performed both experimentally and by simulations using multiscale material modeling. Since multiscale material modeling is used, it is possible to study in more detail the stress-strain evolution in the two phases during cycling. It is found that the difference in the elastoplastic properties between the phases affects the amount of plastic deformation occurring in the austenite and ferrite phases of the three steels. As a consequence, the cyclic stress-strain behavior is different in the three steels. A more detailed analysis of the dislocation structures formed in the two phases is also performed, and it is found that the slip band formation and the dislocation structures strongly depend on the elastoplastic properties of the individual phases as well as on the load sharing between the phases. (c) 2007 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved