INVESTIGATION OF THE ANNEALING TEXTURE EVOLUTION IN HAFNIUM

This article presents a study of the evolution of the annealing textur e in hafnium, as measured by electron backscattering diffraction patte rns (EBSPs). It was found that the annealing texture of as-received ex truded rod depended on the annealing temperature. After low-temperatur e recrystallization, the deformation axis was parallel to [11 (2) over bar 0] or [(1) over bar 2 (1) over bar 0] and the basal planes were a pproximately parallel to the deformation axis. These orientations were deduced by the position of the points in the standard stereographic t riangle used to produce the inverse pole figure. As the annealing temp erature was raised to 1700 degrees C, the direction parallel to the ro lling direction changed to [01 (1) over bar 0] and the grain size incr eased. It appeared that the increase in grain size occurred by a proce ss of abnormal grain growth, and this abnormal grain growth appeared t o be the cause of the change in the texture. Texture was also examined in samples that had been warm rolled to thickness reductions between 10 and 90 pct and then annealed at 1700 degrees C. In these samples, t he main feature of the texture was that the basal plane became paralle l to the rolling plane as the amount of rolling increased. The maximum grain size was observed in samples that had been rolled to a reductio n in thickness of 50 pct.