A crystallographic study of the deformation mechanisms during small punch testing of 14wt%Cr oxide dispersion steel

With their excellent resistance to high-temperature creep and irradiation swelling, the oxide dispersion strengthened (ODS) ferritic steels are considered promising structural materials for future reactors. The characteristic anisotropy of these materials, imposed by their fabrication processes, is considered both beneficial and harmful, depending on the specific application. Current research has addressed the effect of anisotropy on mechanical properties by analyzing deformation mechanisms operating during the small punch testing (SPT). As a case study, 14wt%Cr ODS steel rod was studied before and post SPT along and perpendicular to the extrusion direction. In order to assess the effect of the anisotropy, this study incorporates extensive microstructural characterization alongside quantitative textural analysis. Nucleation of cracks and their subsequent propagation are discussed, taking grain boundary characteristics, grain morphology, texture, and the effect of dispersed particles into account.