Dislocation Hardening in a New Manufacturing Route of Ferritic Oxide Dispersion-Strengthened Fe-14Cr Cladding Tube
Résumé
The microstructure evolution associated with the cold forming sequence of an Fe-14Cr1W-0.3Ti-0.3Y2O3 grade ferritic stainless steel strengthened by dispersion of nano oxides (ODS) was investigated. The material, initially hot extruded at 1100 ◦C and then shaped into cladding tube
geometry via HPTR cold pilgering, shows a high microstructure stability that affects stress release heat
treatment efficiency. Each step of the process was analyzed to better understand the microstructure
stability of the material. Despite high levels of stored energy, heat treatments, up to 1350 ◦C, do not
allow for recrystallization of the material. The Vickers hardness shows significant variations along
the manufacturing steps. Thanks to a combination of EBSD and X-ray diffraction measurements, this
study gives a new insight into the contribution of statistically stored dislocation (SSD) recovery on
the hardness evolution during an ODS steel cold forming sequence. SSD density, close to 4.1015 m−2 after cold rolling, drops by only an order of magnitude during heat treatment, while geometrically necessary dislocation (GND) density, close to 1.1015 m−2, remains stable. Hardness decrease during heat treatments appears to be controlled only by the evolution of SSD.
Domaines
MatériauxOrigine | Fichiers éditeurs autorisés sur une archive ouverte |
---|---|
Licence |