The Biaxial Strength and Ductility of Textured Materials

摘要

The application of the micromechanical and phenomenological yielding criteria to textured materials has been examined in reference to texture strengthening for HCP alloys and also to the brittleness problem of intermetallics. The usable micromechanical criterion has been proposed for textured industrial HCP alloys. It is based on the identification shear systems, determination of resolved shear stress values in these systems and averaging of strength for all orientations of polycrystalline grains with reference to the texture. Polycrystalline yield loci were calculated for Ti-5Al-2,5Sn and Ti-4A1-2V alloys having of nonbasal and intensive basal textures. The Tsai-Wu tensor-polynomial criterion has been extended to textured HCP polycrystalline. The principal components of strength tensor are determined by uniaxial testings and interaction component F_(12) is calculated by micromechanical criterion. It was revealed the fundamental limitation of TPC in related to textured HCP materials. The F_(12) value to calculate from biaxial tension data gives the incorrect value for biaxial compressive stress states. The brittleness problem of intermetallics is considered on the base of strain incompatibility conception for various crystalline orientations.