Approach to the microstructural control of two medium carbon microalloyed steels under hot forming conditions

Abstract

The main aim of the present investigation was to study the flow behaviour of two medium carbon microalloyed steels under hot forming conditions, and to analyse their microstructural evolution. The dependence of recrystallized grain size (Drec) on the Zener-Hollomon parameter Z shows a bimodal behaviour with transition from single to cyclic dynamic recrystallization. We also observed that the variation of Drec) normalized by the Burgers vector (b) with the steady state stress σss normalized by shear modulus (μ) shows the same bimodal behaviour cited above. The Derby's universal equation reported in the literature for recrystallized grain sizes was not followed; it seems that the presence of fine precipitated particles has a clear effect on this disagreement.