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

Louise Toualbi (1) , Cyril Cayron (2) , Patrick Olier (1) , Joël Malaplate (1) , Mathilde Praud (1) , Marie-Helene Mathon (3) , Didier Bossu (1) , Elodie Rouesne (1) , Alexandre Montani (2) , Roland E. Logé (4) , Yann de Carlan (1)

1 SRMA - Service des Recherches Métallurgiques Appliquées
2 LITEN - Laboratoire d'Innovation pour les Technologies des Energies Nouvelles et les nanomatériaux
3 LLB - UMR 12 - Laboratoire Léon Brillouin
4 CEMEF - Centre de Mise en Forme des Matériaux

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. ODS steels 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. A new high temperature fabrication route performed on a Fe-9Cr-1W-Ti-Y 2O 3-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. Observations 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. Ultimate 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.

Mots clés: ODS; phase transformation; cold rolling; texture measurements

Domaines: Sciences de l'ingénieur [physics]; Matériaux

Louise Toualbi, Cyril Cayron, Patrick Olier, Joël Malaplate, Mathilde Praud, et al.. Assessment of a new fabrication route for Fe-9Cr-1W ODS cladding tubes. Journal of Nuclear Materials, 2012, 428 (1-3), pp.47-53. ⟨10.1016/j.jnucmat.2011.12.013⟩. ⟨hal-00679120⟩