Self-organization of plastic shears in localized deformation macrobands in the neck of high-strength polycrystals, its role in material fracture under uniaxial tension

Based on the television-optical measurements of displacement vector fields, we study the distribution of shear and linear strain components as well as plastic flow intensity in the neck of flat high-strength polycrystals of steel VKS-12, submicrocrystalline armco-iron and titanium under uniaxial tension. The leading deformation mechanism in the neck is related to the development of two stationary localized plastic flow macrobands in it. The macrobands are self-organized as a cross along the conjugate directions of maximum tangential stresses. The self-consistency of plastic shears in these macrobands governs the specific character of material deformation and fracture in the neck.