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

• Published in: Metals (Basel ) Vol. 10; no. 7; p. 976
• Main Authors: Mironov, Sergey, Sato, Yutaka S., Kokawa, Hiroyuki, Hirano, Satoshi, Pilchak, Adam L., Semiatin, Sheldon Lee
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.07.2020
• Subjects: Crystallography; Defects; Electron backscatter diffraction; Friction; friction stir processing; Grain size; Heat conductivity; High temperature; Mechanical twinning; Microstructure; Misalignment; Phase transitions; Scanning electron microscopy; Texture; Ti-6Al-4V; Titanium alloys; Titanium base alloys; Japan
• ISSN: 2075-4701; 2075-4701
• DOI: 10.3390/met10070976

The present work was undertaken to shed additional light on the globular-α 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 α phase were random. Although the texture was weak, it showed a clear prevalence of the P1 and C-fiber simple-shear orientations, thus providing evidence for an increased activity of the prism- and pyramidal <c+a> slip systems. In addition, the misorientation distribution exhibited a crystallographic preference of 60° and 90° boundaries. This observation was attributed to a partial α→β→α phase transformation during/following high-temperature deformation and the possible activation of mechanical twinning.