A study combining EBSD and x-ray synchrotron diffraction using generalized pole figures

Abstract

The development of advanced materials with optimum structural and mechanical properties requires a detailed control of their microstructures, textures and crystalline defects. Different techniques can be used for the characterization of those microstructures and defects, but it is their combination that could result in an exhaustive understanding of the microstructural and orientational developments on these materials.X-Ray Diffraction (XRD) can be employed to obtain a “global” characterization of microstructure and texture, since the presence of defects in the sample produces shift and broadening of diffraction peaks. Different models have been developed to quantify these defects, some of which require fitting the complete diffraction pattern while others just individual peaks. These techniques can be extended to texture measurements, often represented through pole figures (PFs), wherein diffraction patterns are obtained for different sample orientations. This allows the determination of defect density in function of orientations and their representation in Generalized Pole Figures (GPFs).On the other hand, for a more “local” characterization, Electron Backscatter Diffraction (EBSD) has proven to be extremely useful for microstructural and orientational analysis, allowing to assess defect accumulation in individual grains and orientations.In this work, a set of 32,205 duplex steel samples cold-rolled up to 79 % reduction (in steps of approximately 20 %) are studied, aiming to investigate the evolution of defect storage with deformation in different orientations and texture components. For this purpose, Laue diffraction patterns have been obtained for these samples in P07 beamline in Petra III station (DESY), from which PFs and GPFs were obtained. This information is complemented with EBSD results, where dislocation arrays and grain and subgrain structures for particular orientations are studied. This paper not only aims at describing the microstructural evolution of a cold rolled duplex steel with increasing deformation, providing both a local and a global characterization of this microstructure, but also at exploring the capabilities of the diffraction techniques used for this purpose. The combination of both techniques allowed for an exhaustive analysis of defect storage and microstructural orientations developed with increasing deformation.