Dynamic Recrystallization in Sintered Cobalt during High-Temperature Deformation

The constitutive flow behavior of sintered cobalt in the temperature range 873 to 1473 K (600 to 1200 A degrees C) and at strain rates from 0.001 to 10 s(-1) has been studied using constant true strain rate hot compression tests. On the basis of these data, a processing map has been generated that depicts the variation of strain rate sensitivity with temperature and strain rate. The processing map reveals a domain of dynamic recrystallization (DRX) with an optimum condition of processing at 1273 K (1000 A degrees C) and at 10(-3) s(-1). When deformed within the domain, the stress-strain curves exhibit a single peak followed by flow softening, leading to steady-state behavior. In addition to this, a recently developed approach based on flow curve analysis is used to study the DRX kinetics, which is found to follow an Avrami-type relation.