Study of the influence of large shear strains and vortex flow of metal on the formation of an equiaxed ultrafine-grained structure of the E110 zirconium alloy by X-ray diffraction analysis

Abstract

In this work, the task was to investigate the processes of microstructure change occurring in relatively large bulk bars under the action of large plastic deformations. Such large levels of deformation are usually achievable in high pressure twisting of small flat disks, but are difficult to achieve in large bulk bars. The method of radial shear rolling makes it possible to achieve comparable ultrahigh degrees of deformation (~ 45 mm/mm) in combination with the vortex flow of the metal. Sequential rolling of the E110 zirconium alloy was carried out under extreme conditions on 2 radial shear rolling mills with a total reduction in diameter ε = 185% and a maximum accumulated deformation = 46 mm/mm. To assess the level of deformation and its distribution over the section, FEM modeling was carried out in Deform-3D. The resulting structure was studied by electron microscopy (TEM/SEM). A detailed cross-sectional study of the EBSD structure was performed with a resolution of 1 mm. A gradient structure with a predominance of an equiaxed ultrafine-grained structure was found, which was not very pronounced compared to the use of smaller deformations.