γ-Fibre recrystallization texture in IF-steel: an investigation on the recrystallization mechanisms

Abstract

Development of recrystallization texture in cold-rolled Ti-bearing IF-steel was investigated using X-ray diffraction, Electron Back Scattered Diffraction/Orientation Imaging Microscopy (EBSD/OIM) and TEM. During cold-rolling, both the α (RD//〈110〉) and the γ (ND//〈111〉) fibres were observed to be strengthened, although the increase in α was more pronounced. Simulations of the cold-rolling using Taylor type theories demonstrated an approximate predictability of the textural changes. Recrystallization strengthened the γ, as F (={111}〈112〉) increased but E (={111}〈110〉) remained essentially unchanged. A corresponding decrease in α, more in H (={001}〈110〉) than in I (={112}〈110〉), was also observed. The strong γ-fibre recrystallization texture was mainly due to the larger numbers (i.e. `frequency advantage') of the γ-oriented grains, as the γ grains were no larger than grains of other orientations. TEM studies showed an increase in cell size and a decrease and cell misorientation (which means an increase in stored energy) from H⇒ I⇒ E⇒ F. With the exception of a slight drop from E to F, increase in the Taylor factor always corresponded to an increase in the stored energy. The spread of stored energies, corresponding to inhomogeneities in dislocation substructure, were observed to increase from I⇒ H⇒ E⇒ F. A combination of the higher stored energy and the stronger inhomogeneities in dislocation substructure is possibly responsible for the preferred nucleation behavior causing the frequency advantage for the γ grains.