Assoz. Prof. Dr. Susanne Michelic - Advanced inclusion analytics for the detailed characterization of micro and sub-micro multiphase particles
©EUROMAT 2021, 13 Sep 2021, Today steelmaking is driven by specific demands regarding material properties for high-quality applications, often involving the precise adjustment of non-metallic inclusion populations in the surrounding steel matrix. On the one hand, fine dispersed inclusions below 1 µm in size can improve the final microstructure by e.g. grain boundary pinning or by acting as nucleation sites for phase transformations. On the other hand, to achieve requirements of super clean steels for high performance applications, the amount and size of undesirable particles needs to be as low as possible, even for small particle sizes. Thus, also analytics are constantly facing new challenges for a representative and comprehensive characterization of non-metallic inclusions. Although automated SEM/EDS analyses are a well approved and state of the art method for inclusion characterization, the described developments also require an ongoing effort in the optimization of the measurement itself as well as in the subsequent data evaluation. The present paper outlines different improvement approaches in the application of automated SEM/EDS analyses covering the aspects matrix correction in dependence of inclusion size and composition, as well as the accurate representation of inclusion morphology. Using an adapted form for inclusion categorization based on so called morphology factors and next neighbor relations, stereological effects of cross-section preparation as well as different cluster situations can be evaluated. For three-dimensional particle investigation, different techniques for inclusion extraction from the steel matrix are applied. For all aspects, special focus is put on the characterization of multiphase inclusions.