Assessment of a new fabrication route for Fe–9Cr–1W ODS cladding tubes

Oxide Dispersion Strengthened ferritic/martensitic steels are developed as future cladding materials for Generation IV Sodium-Cooled Fast Reactors. ODS alloys are elaborated by powder metallurgy, consolidated by hot extrusion and manufactured into tube cladding using cold rolling process. eels present low ductility and high hardness at room temperature which complicate their manufacturing. Cold working leads to the hardening of the tube which needs to be softened by heat treatment. high temperature fabrication route performed on a Fe–9Cr–1W–Ti–Y2O3-ODS martensitic steel has been designed by following the hardness values, the morphological and crystallographic anisotropy and the nano-precipitation size evolution at each step of the fabrication route. ations show that phase transformation from ferrite (α) to austenite (γ) is crucial to reduce the morphological and the crystallographic anisotropy induced by the manufacturing processes. The high temperature heat treatments permit to make the austenitic grain grow leading to an improvement of the cold workability. te Tensile Strength values obtained in the hoop direction remain about 315 MPa at 650 °C which is slightly lower compared to other Fe–9Cr ODS tubes but the new microstructure could be more favorable for creep properties.