Discontinuous dynamic recrystallization in α-Zr

This study attempts to identify the type of dynamic recrystallization (DRX) occurring in hot deformed zirconium. For this, samples of Zr were uniaxially compressed at 800 degrees C and 0.1 s(-1) to varying strains. Microstructural characterization was done using electron back scatter diffraction (EBSD). The flow stress showed an initial hardening followed by softening to a steady state value. DRX grains were identified as those with a grain orientation spread of less than 2 degrees. Fine recrystallized grains were observed along grain boundaries at low to intermediate strains (0.15 and 0.6). The grain size decreased with increasing strain up to a strain of 0.6, beyond which it showed no further decrease. The degree of misorientation of boundaries was used to distinguish between discontinuous and continuous dynamic recrystallization (dDRX and cDRX, respectively). Most recrystallized grains had their boundaries of very high misorientation (> 50 degrees) suggesting that dDRX was prevalent. The evidence of cDRX was weak, although it cannot be ruled out at higher strains. It was concluded that Zr undergoes dDRX when deformed at 800 degrees C and 0.1 s(-1).