School of Engineering and Technology, Deakin University, Pigdons Rd, Geelong, VIC 3217,Australia(Received November 12, 1999)(Accepted March 9, 2000)Keywords: Steels-austenite; Dynamic recrystallization; Recrystallization1. IntroductionOne view of dynamic recrystallization is that it comprises static recrystallization occurring in the timescale of deformation. While this is clearly not true for geometric dynamic recrystallization [1] orcontinuous dynamic recrystallization [1], there is some metallographic support for it with respect to thebeginning of conventional dynamic recrystallization. The microstructure after a few volume percent ofrecrystallization by this mechanism appears very similar to that seen after a small degree of staticrecrystallization [2,3].A number of workers have constructed mathematical equations for the beginning of conventionaldynamic recrystallization (DRX) using a formulation based on the nucleation mechanisms of staticrecrystallization (SRX) [2,4,5]. These models fit the observed trends in DRX quite well. However, theydo not allow any firm conclusions to be drawn with respect to the relative kinetics of the two processes.In the present work, conventional equations for the kinetics of SRX are modified to allow “SRX” tobegin prior to the end of deformation. In this manner a critical strain for the beginning of “SRX” duringdeformation is derived. This value is then compared with observations of the critical strain required forthe initiation of DRX in steel.2. BackgroundThe static recrystallization kinetics following the hot deformation of steel are often expressed in termsof the time taken after deformation for 50% recrystallization (t