Selection of deformation modes and related texture evolution in Zircaloy-4 during one pass cold pilgering

Abstract

Zircaloy-4 is usually used as cladding tubes and structure components in nuclear reactor. Cladding tubes are manufactured mainly by hot extrusion and subsequent cold pilgering steps. The texture of cladding tubes is one of key factors influencing the final performance and becomes a hot issue in recent years. This work focuses on enclosing selection of deformation modes and related texture evolution during one-pass pilgering process. Electron backscatter diffraction (EBSD) samples of Zircaloy-4 were cut from a tapered tube with 30%, 40% and 50% area reduction respectively to find the effect of area reduction on texture evolution. The selection of deformation modes with various reduction amount was also measured with in-grain misorientation axes method. The relationship between texture evolution and deformation modes was then discussed with Schmid factor distribution calculation and activity of slip modes based on visco-plastic self-consistent (VPSC) simulation during pilgering deformation. The results show that basal slip activity indeed exists when deformation strain increases to a sufficiently high level. For low strains, the basal pole is changing from transverse direction (TD) to radial direction (RD) caused by the combination of prismatic and pyramidal slip. For higher strains, the cause of the same texture change tendency is primarily related to basal slip.