Mechanistic Understanding of Ageing led Degradation of ODS Steels produced from different Manufacturing Methods

The Oxide Dispersion Strengthening (ODS) Steels are candidate material for future nuclear reactors such as in cladding and tubing of high-temperature Gen IV fission reactors, and in 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 at extremely high temperature transform the nanoparticles into new complex oxides which degrades the mechanical properties and irradiation resistance; both conditions in nuclear reactor applications are ill characterised. In this work we are correlating the effects of ageing led degradation and nanoparticles coarsening on the mechanical properties of two different ODS steels to underpin the consolidation process capable of safeguarding the use of ODS steels in the nuclear reactor life cycle by resisting against ageing. The insitu and exsitu SANS data from thermally aged ODS samples will develop mechanistic understanding of the rate of grain coarsening at different temperatures to underpin the stability of ODS nanoprecipitates that preserve their internal dispersion network and material properties.