Microstructural Characterization of Friction-Stir Processed Ti-6Al-4V

The present work was undertaken to shed additional light on the globular-alpha microstructure produced during FSP of Ti-6Al-4V. To this end, the electron backscatter diffraction (EBSD) technique was employed to characterize the crystallographic aspects of such microstructure. In contrast to the previous reports in the literature, neither the texture nor the misorientation distribution in the alpha phase were random. Although the texture was weak, it showed a clear prevalence of the P(1)and C-fiber simple-shear orientations, thus providing evidence for an increased activity of the prism- and pyramidal slip systems. In addition, the misorientation distribution exhibited a crystallographic preference of 60 degrees and 90 degrees boundaries. This observation was attributed to a partial alpha ->beta ->alpha phase transformation during/following high-temperature deformation and the possible activation of mechanical twinning.