IF steel recrystallization: nucleation stage linked to internal misorientation parameters

Abstract

Microstructure evolution during deformation and recrystallization can be followed by several misorientation parameters, deduced or calculated from EBSD data, such as: BC (Band Contrast), GOS (Grain Orientation Spread), GND (Geometrically Necessary Dislocation density) and KAM (Kernel Average Misorientation). Recrystallization includes nucleation and growth of nuclei until the consumption of the deformed matrix. In this work, we propose an internal misorientation parameter, based on KAM values, to characterize recrystallization in an IF steel, especially the nucleation stage. By definition, KAM of a pixel is the mean value of misorientation between this pixel and its neighbors in a grid of (NxN) pixels in grain interior. It is well known that nucleation starts in grains that have the highest stored energy of deformation, and then progresses in grains that have lower stored energy. It was found that the new misorientation parameter is quite sensitive to the state of material. This presentation will discuss the relation between this parameter, orientation gradients and the stored energy, as well as the possibility of using its values to identify nucleation sites