Cold-rolling & annealing process for nuclear grade wrought FeCrAl cladding alloy to enhance the strength and ductility

摘要

FeCrAl alloy is a good candidate as accident-tolerant fuel (ATF) cladding material. While cold-working is a preferred routine for fabricating thin-wall FeCrAl tubes, the effects of cold-rolling treatment on the micro-structural features and the tensile properties are still unclear. In this study, a successive process containing hotrolling and annealing at 800°C, cold-rolling at room temperature and final annealing at 750°C were developed for a wrought Fe-13Cr-4.5Al-2Mo-2.5Nb-0.1Ti-0.1V-0.05Y alloy. The alloy with 60% hot-rolling and 40% cold-rolling reductions exhibited an ultimate tensile strength of 869MPa and a total elongation of 20.9%. The good mechanical properties were attributed to the recovery microstructure with much refined grain size, the dense dislocation network forming the sub-grain boundaries and the Laves precipitates distributed both along the grain or sub-grain boundaries and in the ferritic matrix. The alloy also exhibited a weak deformation texture. The satisfactory mechanical properties together with the nearly isotropic grain morphology and the weak rolling texture provide it good potential for application as ATF cladding materials.