Hot deformation behavior of an industrially cast large grained low density austenitic steel

Hot compression testing was performed on specimens of an Fe-30Mn-9Al-1Si-0.9C-0.5Mo wt.% low density steel which were extracted from an industrial casting with large grain size (320 +/- 50 mu m). Grain boundaries act as nucleation sites for dynamic recrystallization in the present material and the large grain size results in fewer nucleation sites, which delays dynamic recrystallization to larger strains and/or higher temperatures and causes higher rates of work hardening relative to similar materials but with smaller grain sizes. A relatively high activation energy for hot deformation of 470 +/- 90 kJ mol- 1 was determined from a Zener-Hollomon analysis of the flow stresses at different temperatures and strain rates, attributed in part to the large grain size.