Dynamic recrystallisation kinetics of GCr15 bearing steel

Abstract The dynamic recrystallisation (DRX) behaviour of GCr15 bearing steel with various initial grain sizes has been investigated by isothermal compression tests on a Gleeble 3800 thermomechanical simulator. The tests have been carried out in the temperature range 950–1150°C and strain rate range 0˙01–10 s–1. Experimental results show that the flow stress and the DRX critical strain of GCr15 bearing steel decrease with increasing temperature and decreasing strain rate, and the stress–strain curves at low strain rate display a typical DRX characteristic. The refinement of initial grains can promote the occurrence of the DRX, but the variety has no effect on the peak stress. The present paper proposes a relationship to predict the critical strain. And based on the stress–strain curves, the effects of initial grain size, deformation temperature and strain rate on the DRX fraction have been studied. At last, the fraction data have been used to fit an Avrami equation.