Effect of texture and grain shape on anisotropy

An attempt is made to summarize the different ways of modelling the anisotropy of a polycrystalline material. At the single crystal level, the formulation based on Schmid law or viscoplasticity shows clearly the microscopic anisotropy due to the hardening and the orientation changes. It is also shown how viscoplasticity leads to a unique slip system activity irrespectively of the rate sensitivity. Macroscopic properties are derived from the microscopic ones via models that are a picture of the grain-matrix interaction. It is shown that low interaction models should be investigated for large strain descriptions. It is also shown how grain shapes explicitely affec the interaction. Finally, yield surfaces are predicted, and it is demonstrated that flat grain shapes can induce vertices on the overall yield surface. Revue Phys. Appl. 23 (1988) 533-548 AVRIL 1988, Classification Physics Abstracts 81.40E 81.40J 81.40L Most industrial applications dealing with e.g. metal forming (at low and high strain rates) like deep drawing, or simply the rolling operation have to deal with a preexisting or induced anisotropy--w-71ch affects the material behavior and wich can be associated with some problems (earing, plastic instabilities...) or with some properties that the engineer wants to optimize. In this summary paper, we want to assess the description of the anisotropy of a polycrystalline material. The overall materi al anisotropy is, first of all, affected by the single crystal behavior. The Schmid law is assumed to hold in the following treatment and is used to describe the preexisting anisotropy of the single crystal. The induced anisotropy can be affected by different microscopic hardening laws and by the lattice rotations. Both effects will be described. Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/rphysap:01988002304053300