Correlation between the deformation and post-deformation softening behaviours in hot worked austenite

Abstract

The relation between the deformation and post-deformation softening behaviours of austenite is examined in a 304 stainless steel. This correlation has been exploited in the modelling of hot rolling and it is argued here that the key to this understanding lies in the deformation structure. The latter is characterized in the present work by the fraction of dynamic recrystallization. The value of this fraction at the peak in the flow stress curve is found to decrease with increasing stress (i.e. with decreasing temperature and increasing strain rate). By contrast, the fraction of dynamic recrystallization at the strain corresponding to the point where post-deformation softening becomes strain independent is found to be constant. These observations are used to explain the nature of the important difference between the flow curve peak and the onset of strain independent post-deformation softening. © 2008 ISIJ.