Mechanical and microstructural properties of a hipped RAFM ODS-steel

Oxide dispersion strengthened (ODS) materials for structural applications in future fusion power reactors would allow to increase the operating temperature to approximately 650 deg. C. Two ODS variants of the 9%CrWVTa-RAFM steel EUROFER 97 with Y2O3 contents of 0.3 and 0.5 wt% have been produced. The microstructure of both powder and compacted material has been characterised by means of optical and electron microscopy (SEM, TEM). Tensile tests performed between RT and 850 deg. C show an increase of yield strength and ultimate tensile strength by 50% and more compared to the basic steel. The ductility values are sufficiently high. Creep tests between 600 and 700 deg. C up to test times of 5000 h confirm the superior creep strength of ODS-EUROFER. Impact tests reveal a similar impact behaviour to comparable ODS alloys, but the ductile-to-brittle transition temperature is substantially higher than that of EUROFER 97. Preliminary results of low-cycle fatigue show a promising fatigue behaviour of ODS-EUROFER