Mechanistic Understanding of Creep-Fatigue led Degradation of ODS Steels in Tension and Compression Hold

The Oxide Dispersion Strengthening (ODS) Steels are candidate materials for future nuclear reactors such as in the cladding and tubing of high-temperature Gen IV fission reactors, and in the blanket surrounding the vessel of fusion reactors. The ODS steels with added nano-size yttrium oxides (Y2O3) provide resistance against irradiation, creep, and swelling. Continuous exposure of high dose neutron irradiation and combined cycle loading at high temperatures transform the nanoparticles into new complex oxides which degrades the mechanical properties and irradiation resistance. In this work, the effects of tensile and compressive creep hold on the ODS steels produced from mechanical alloying are being investigated to underpin the consolidation process capable of safeguarding the use of ODS steel in the nuclear reactor life cycle resisting ageing without altering the mechanical properties. The insitu lattice strain data in creep-fatigue loading will enable us to understand the root cause of the different degradation mechanisms in ODS steels in tensile and compressive creep hold environments.