Strain Mode Dependence of Deformation Texture Developments: Microstructural Origin
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PLASTIC deformation in metallic materials often is studied either from the classical crystal plasticity[1–24] or from the perspective of microstructure developments.[25–56] The former tend to focus on the requirement of stress equilibrium and strain compatibility of adjacent grains and its effect on plastic anisotropy, whereas the latter involve topics ranging from substructure developments to dislocation interactions. Arguably, both are important and interrelated. It is, however, fair to admit that the two approaches have been used rarely, in reasonable conjunction, for common scientific goals. As an example, let us consider predictions of deformation textures. All texture prediction models are based on crystal plasticity. They describe plastic deformation S. RAVEENDRA, formerly Research Scholar at Indian Institute of Technology Bombay, Mumbai 400076, India, is now Research Engineer at Sandvik Asia Pvt. Ltd., Pune 411012, India. A.K. KANJARLA, formerly Doctoral Student at KU Leuven, BE-3001 Leuven, Belgium, is now Postdoctoral Researcher at Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545. H. PARANJAPE, formerly B. Tech Student at Indian Institute of Technology Bombay, is now Graduate Research Associate at The Ohio State University, Columbus, OH 43210. S.K. MISHRA, formerly Research Scholar at Indian Institute of Technology Bombay, is now Researcher at General Motors R&D, Bangalore 560002, India. S. MISHRA, Assistant Professor, is with the Indian Institute of Technology Bombay. L. DELANNAY, Professor, is with the Universite´ Catholique de Louvain (UCL), BE-1348 Louvain-la-Neuve, Belgium. I. SAMAJDAR, Professor, is with the Indian Institute of Technology Bombay. Contact e-mail: [email protected] P. VAN HOUTTE, Professor, is with KU Leuven. Manuscript submitted July 7, 2010. Article published online January 4, 2011 METALLURGICAL AND MATERIALS TRANSACTIONS A
of a crystallite or part of a crystallite by relating velocity gradient tensors, slip rates, lattice rotation rates, and deviatoric stress. In the full constraint Taylor (FCT) model,[1,10,25] the velocity gradient tensor is homogenous. This is, of course, in conflict with microstructural observations of strain heterogeneities and geometrically necessary boundaries.[27–29] The subsequent relaxed constraint models offer ‘‘limited’’ strain heterogeneity, involving only certain components of velocity gradient tensor. Although relaxed constraint models led to improvements in deformation texture prediction, the choice of the type of relaxation is, at best, artificial. The classical full and relaxed constraints models are often termed ‘‘one-point’’—taking, at a time, a single grain in account. An extension is possible through generalized relaxed constraints[10] and viscoplastic self-consistent[10,22,23,57] methods, which are ‘‘one-point’ models taking the macroscopic polycrystal properties into account. These ‘‘one-point’’ models do not consider interactions among neighboring grains. The multipoint models, however, consider two or more grains inter
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