Development of constitutive equations for modelling of hot rolling

Constitutive equations which describe the flow stress behaviour of material s during hot deformation are used to model forming processes. Since the flo w stress depends on both temperature and strain rate, the Zener-Hollomon pa rameter which combines these factors, is frequently used to describe the sh ape of such curves. For materials which dynamically recover, (only) the flo w stress reaches a steady state value at high strains and methodologies whi ch enable such behaviour to be modelled have previously been presented. Bey ond the onset of dynamic recrystallisation, the flow stress of materials, s uch as steels, reach a peak in flow stress before gradual softening. The re lative position of the peak in the how stress shifts as a function of the Z ener-Hollomon parameter further complicating such analyses. The present pap er describes the development and application of a methodology for modelling the flow stress of microalloyed steels: materials which exhibit dynamic re crystallisation behaviour.