Characterization of microstructural and mechanical properties of a reduced activation ferritic oxide dispersion strengthened steel

For specific blanket and divertor applications in future fusion power reactors a replacement of presently considered Reduced Activation Ferritic Martensitic (RAFM) steels as structural material by suitable oxide dispersion strengthened (ODS) ferritic martensitic steels would allow a substantial increase of the operating temperature from ∼823 K to about 923 K. Temperatures above 973 K in the He cooled modular divertor concept necessitate the use of Reduced Activation Ferritic (RAF)-ODS-steels, which are not limited by a phase transition. The development concentrates on the ferritic ODS-steel Fe–13Cr–1W–0.3Ti–0.3Y2O3. The microstructures of a mechanically alloyed powder particle are observed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Ageing experiments for 1000 h and 3000 h at 1123.5 K and 1223.5 K of compacted Fe–13Cr–1W–0.3Ti–0.3Y2O3 were executed. The impact especially on the oxide particles in terms of segregation and decomposition effects were monitored by electron energy loss spectroscopy (EELS). Long term vacuum creep experiments have been performed with rolled Fe–13Cr–1W–0.3Ti–0.3Y2O3 at 923.5 K and 1023.5 K, which will be compared to reference alloys.