MICROSTRUCTURAL DEVELOPMENT DURING WARM ROLLING OF AN IF STEEL

Wedge-shaped slab rolling was employed to investigate the microstructu ral evolution of an interstitial-free (IF) steel during warm working i n the temperature range 500-800 degrees C. Mean flow stress-strain cur ves calculated from load-time data of rolling tests reasonably corresp ond to work hardening and dynamic recovery behaviour. The development of substructures in the deformed material was investigated using optic al and electron microscopy. A close correlation was observed between m echanical behaviour and microstructural development during deformation . Microbands in directions of +/-35 degrees with respect to the rollin g direction, independent of strain, temperature and initial grain orie ntations are the most noticeable features in the microstructural obser vations. The sequences of substructural changes from the appearance of early microbands at very low strains, their development with strain, to the formation of equiaxed subgrains at higher strains and temperatu res were followed by TEM. (C) 1997 Acta Metallurgica Inc.