Ultra Grain Refinement in a Plain Carbon Steel by Means of Warm Torsion Testing

grain refinement of a plain carbon SAE-AISI 1010 steel has been obtained by means of warm torsion testing. Tests were conducted at 500 degrees C, constant strain rate of 0.1 s(-1) and total equivalent strain of 0.8, 1.6, 4.0 and 5.6. The average ferritic grain size obtained was smaller than 0.5 mu m. The steel microstructure consisted of elongated ferrite grains and fragmented and spheroidized cementite particles, similar to the microstructures found in carbon steel severely plastic deformed, like in the ARB and ECAP processes. The average ferritic grain size is reasonably predicted by the Hall-Petch equation. The mechanisms by which ultra grain refinement has been achieved here has been attributed to dynamic recovery and continuous dynamic recrystallization of the ferrite during warm plastic deformation. Warm torsion testing proved to be a suitable tool to study grain refining mechanism through severe plastic deformation.