TheARP/wARPmodel-building suite and theArpnavigatoruser interface
Tim Wiegels, S. Hazledine, Victor S. Lamzin · Acta Crystallographica Section A Foundations of Crystallography · 2012
Petch-Holl dependence σ σT o = -1 2 was establish in the middle of last century.Value "k" characterize a grain boundaries ability to pass deformation from grain to grain.However, in materials with small dimesions of grains, various grains or the different phases investigators have to do with not equilibrium structure for which value "k" is not constant.Exit a lot modern studies what show about violation Petch-Holl law and it often is not carry out exactly.Chemical composition, dislocation and fine structure, texture and the grain dimension, which exert influence on the mechanical properties of polycrystals.In the present paper have shown a new sight on the grain crystallographic orientations role in polycrystals and their influence on the mechanical properties.The main topic presented paper is a theoretical approach to crystal orientation on the basis Crystallographic Indexes Periodical System (PSCI).Crystallographic indexes may be represented in form PSCI, which consist from eight groups (G) by accordance to with square indexes sum distribution.All components of axial or planar crystallographic orientations are subdivided on the seven types (N) with different lattice direction or different lattice planes (HKL) of unit cell relatively the main external internal axes of the sample.Any crystallographic orientations can be expressed across orientation symmetry groups (GSO) as four numbers (NG 1 G 2 G 3 ) in the three-dimensional space.Quantity of crystal GSO with a different unit cell equally 230 and exactly coincidient with 230 well-know space groups crystals.Physical sense of crystallographic orientations in the polycrystalline consist in the resulting symmetry them interaction with stress field.Stress field with point of view symmetry limited only 14 second-order tensor groups.On the basis superposition principle crystals and stress field appear now perhaps for study three-dimension texture and it influence on mechanical properties of different materials.For example were carry out investigation threedimensional orientations in tube steel samples with different mechanical properties: s T = 439 MPa, s B = 557 MPa, d 10 = 27%, KCV -50 = 218 245 2 -J cm , B 7 95%, and s T = 466 MPa, s B = 579 MPa, d 10 = 25%