Abnormal Grain Growth in Ferritic-Martensitic Eurofer-97 Steel

Abstract

Abstract. Ferritic-martensitic steels like Eurofer-97 are candidate structural materials for future fusion reactors. In the tempered state, this steel contains fine particles dispersed in the ferritic matrix. The aim of this work is to investigate abnormal grain growth in Eurofer-97 steel. The microstructural evolution was followed by isothermal annealing between 200 and 800°C (ferritic phase field) after cold rolling to 70, 80, and 90% reductions. Representative samples were characterized by scanning electron microscopy in the backscattered electron mode. Microtexture was evaluated by electron backscattered diffraction. We propose a mechanism based on the size advantage acquired by nuclei with misorientation angles above 45º relative to their nearest neighbors to explain abnormal grain growth. Abnormal grain growth textures have components belonging to the α- and γ-fibers with predominance of {111}, {111}, and {100}.