Microstructure evolution of commercial pure titanium during equal channel angular pressing

Abstract

The microstructure development of commercially pure titanium during 3 and 4 passes of equal channel angular pressing (ECAP) has been investigated in detail by optical microscopy and electron backscattered diffraction (EBSD). The flow line, texture, grain, subgrain and twinning structures along the whole length of the ECAP bar have been characterized systematically. A theoretically predicted triangular zone with a completely different flow line pattern and texture has been found at the extruded end of the sample. Details of the misorientation gradient inside grains and the continuous dynamic recrystallization (CDRX) mechanism are discussed. Low angle grain boundaries (LAGBs) in grains are seen to evolve into high angle grain boundaries (HAGBs) throughout the material. No {101¯1} twinning was detected but a low fraction of {101¯2} twins was present.