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 °C to 1100 °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 ∼4 μm (considering twins as grain boundaries) was obtained in the sample deformed to a strain of 0.8 at 1373 K (1100 °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 ∑3 boundaries. The deviation from the ideal misorientation of ∑3 boundaries decreased with an increase in the fraction of ∑3 boundaries (as well as the area fraction of DRX) signifying that most ∑3 boundaries are newly nucleated during DRX. The generation of these ∑3 boundaries could account for the formation of annealing twins during DRX. The role of ∑3 twin boundaries on DRX is discussed. © 2010 The Minerals, Metals & Materials Society and ASM International.