Deformation-induced orientation spread in individual bulk grains of an interstitial-free steel

Three-dimensional X-ray diffraction was employed to characterize the lattice rotations of individual bulk grains in a 9% tensile deformed sample of interstitial-free steel. Three grains of initially close orientation that are representative of the scatter of all investigated grains with tensile axes near <522> were identified. Their rotation paths and intragranular orientation spread were analysed in detail, using crystal plasticity modelling to evaluate the nature of the orientation spread. It was found that the same set of most stressed slip systems are active in the three grains and that variations in the relative activities of the two most stressed systems account for the dominant orientation spread in the grains. The distribution of slip on these systems varies from grain to grain and also within each grain. While the grain orientation controls the identity of these slip systems, the variations are attributed to grain boundary and grain interaction effects.