Microstructural evolution during simple heavy warm compression of a low carbon steel: Development of a processing map

Microstructural evolution during simple heavy warm compression was studied using electron back scattering diffraction in a low carbon steel (0.15 wt.% C). Plane strain compression tests were conducted in the temperature range of 773–923 K at strain rates of 0.01 and 1 s−1 and the specimens were deformed to 25% of the original thickness. The strain rate and temperature were summarized into the Zener-Hollomon (Z) parameter and its variation with the imposed strain was studied on the basis of the grain boundary character with a view to understand the critical conditions for the formation of ultrafine grains. A processing map drawn on the axes of compressive strain (ɛ) and Z parameter was developed which makes the selection of processing variables (such as strain, strain rate and temperature) simple towards achieving tailor made microstructures in industrial components.