Oxide dispersion strengthened (ODS) steels are characterized by enhanced mechanical, creep and impact toughness properties at elevated temperature. Since this group of steel are a promising candidate for first wall components, a thorough investigation of the correlation between microstructural features, mechanical and impact properties is needed.

This study focuses on characterization of 9-14% Cr with addition of W, Mn, Ni, Ti and Y2O3. The objective of the work is to investigate microstructure of selected ODS alloys, i.e. to characterize grain structure, large oxides and carbide precipitates and indicate correlations between microstructural features and impact properties.

Microstructure of the samples was analyzed using SEM/EBSD and EDS techniques. Two kinds of large particles were identified, i.e. oxides and carbides, which are visible as black dots and light flakes, respectively, as shown in Fig. 1. It was found that large oxides are rather uniformly distributed in all samples, while carbides are found at grain boundaries. It was indicated that carbides are mostly composed of Cr and W, while oxides of Cr, Mn, Ti, and Y.

Microstructural features were correlated with impact properties. A trend between carbide size, oxides number density, and DBTT was observed. DBTT achieves lower values with decreasing carbide size and increasing oxides number density. Another observed trend was for USE, which increased with increasing grain size and decreasing carbide size.