A comparative study of clock rolling and unidirectional rolling on deformation/recrystallization microstructure and texture of high purity tantalum plates

Clock rolling, which rotates a sample 135° with respect to the previous rolling direction, was used to study the effect of strain path change on deformation and recrystallization microstructure and texture in high purity tantalum plates in the present work. High purity tantalum plates were unidirectional and clock rolled to 87% reduction then annealed at various temperatures. The texture and microstructure in the surface layer of the rolled and annealed plates were characterized using X-ray diffraction (XRD), light microscopy (LM), electron backscatter diffracting (EBSD) and electron channeling contrast imaging (ECCI). The hardness values of the annealed plates were measured using Vickers hardness testing. The results show that the unidirectional- and clock-rolled materials exhibit different textures. The unidirectional rolled plate recrystallized more quickly than that of the clock rolled plate. After annealing at 1200 °C, pronounced γ-fiber in the unidirectional rolled plate while strong cube texture mixed with less strong γ-fiber in the clock rolled plate was found. The annealed clock rolled plate had smaller grain size and less variation than that of the annealed unidirectional rolled plate. The change of strain path plays an important role in the recrystallization kinetics and microstructure of high purity tantalum plates.