Texture development and plastic deformation in a pilgered Zircaloy-4 tube

Abstract

The development of microstructure and crystallographic texture with effective strain at three through-thickness locations (near rolls, center, and near mandrel) in a partly pilgered Zircaloy-4 tube is described. Pilgering is found to eliminate through-thickness variation in grain size in the starting hot-extruded material and to generate location-dependent asymmetries in crystallographic texture. Deformation texture development during pilgering is modeled with polycrystal plasticity by idealizing the metal flow pattern as axisymmetric flow through a convergent channel. Good qualitative comparison of the predicted and experimental post-pilgering textures is obtained, provided location-dependent transverse shear component is superposed on the gross flow field, and localized deformation at grain boundaries is allowed. Frictional forces between tube and die are deduced from these observations.