ANISOTROPIC YIELD AND PLASTIC-FLOW OF POLYCRYSTALLINE SOLIDS

Deformation induced anisotropy in polycrystalline solids results mainl y from crystallographic slip due to dislocation motion at the grain le vel and texture development due to grain rotation at the aggregate lev el. To describe these characteristics, the so-called scale invariance approach is adopted which allows information and constitutive relation s pertaining to single slip to be cast in a form of macroscopic consti tutive equations. An orientation distribution function (ODF) and a tex ture tensor are introduced into the earlier version (based on the hypo theses of single slip at the grain level and isotropic distribution of the crystallites at the aggregate level) of the scale invariance fram ework to describe texture effects in plastically deformed polycrystals . The texture tensor is calculated either directly through the solutio n of ODF, or indirectly through an appropriate set of evolution equati ons for the orientation tensors and the use of a closure approximation . Theoretical predictions for anisotropic yield and plastic flow behav ior compare well with available experimental data. (C) 1997 Elsevier S cience Ltd.