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 °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 °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 °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.