A Study on Microstructural Evolution and Dynamic Recrystallization During Isothermal Deformation of a Ti-Modified Austenitic Stainless Steel

Dynamic recrystallization (DRX) behavior in hot deformed (by uniaxial compression in a thermomechanical simulator in the temperatures range 1173 K to 1373 K [900 A degrees C to 1100 A degrees C]) Ti-modified austenitic stainless steel was studied using electron back scatter diffraction. Grain orientation spread with a cut off of 1 deg was a suitable criterion to partition dynamically recrystallized grains from the deformed matrix. The extent of DRX increased with strain and temperature, and a completely DRX microstructure with a fine grain size similar to 4 mu m (considering twins as grain boundaries) was obtained in the sample deformed to a strain of 0.8 at 1373 K (1100 A degrees C). The nucleation of new DRX grains occurred by the bulging of the parent grain boundary. The DRX grains were twinned, and a linear relationship was observed between the area fraction of DRX grains and the number fraction of I 3 pound boundaries. The deviation from the ideal misorientation of I 3 pound boundaries decreased with an increase in the fraction of I 3 pound boundaries (as well as the area fraction of DRX) signifying that most I 3 pound boundaries are newly nucleated during DRX. The generation of these I 3 pound boundaries could account for the formation of annealing twins during DRX. The role of I 3 pound twin boundaries on DRX is discussed.