Synthesis and characterization of 9Cr ODS F/M steel with optimized Y2O3 and Ti content and its comparison with P91 steel

Abstract

Oxide dispersion strengthened (ODS) steels are considered as potential candidates for future Gen-IV reactors core structural applications. Ti is added to this alloy to refine the dispersoid and facilitates formation of Y-Ti-O complex oxides. Optimisation of Y2O3 and Ti content in these ODS steels governs size and stoichiometry of the dispersoids. Equal amount of both Ti and Y2O3 content resulted in formation of finer and stable Y-Ti-O disper-soids. In this study two varieties of ODS alloys are synthesized: one with 0.35 wt% Ti and Y2O3 while another with 0.2 wt% Ti and Y2O3 by mechanical milling followed by SPS. The microstructure and microtexture of these two varieties of ODS steels were compared with modified 9Cr-1Mo (P91) steel. The creep-rupture studies reveal that the ODS steels have better creep-rupture life as compared to P91 steel, and the steel with 0.35 wt% Ti and Y2O3, possess superior mechanical properties.