Long-term corrosion behavior of ODS-Eurofer in flowing Pb-15.7Li at 550 °C

Highlights: • Long term corrosion testing of ODS-Eurofer was successfully performed in PICOLO loop. • The compatibility behavior of ODS-Eurofer was tested for the first time. • Corrosion rate is about 200 µm/year at 0.1 m/s flow velocity at 550 °C. • ODS particles have no visible impact on the corrosion behavior. • Corrosion behavior of both steels (ODS and 'classical' Eurofer) is similar. • Dominating corrosion mechanism is dissolution with an amount of ca. 2 kg/m²year. • Dissolved material is a serious risk for formation of precipitates and line pluggings. • Managing corrosion attack and precipate risk needs coatings. - Abstract: Low activation ferritic-martensitic steels (RAFM-steels) are foreseen as structural materials in different blanket designs (HCLL, DCLL, WCLL) with Pb-15.7Li as breeding and partly also as cooling medium. In HCLL and WCLL designs the structural material will be in direct contact with the flowing liquid breeder at operating temperatures up to 550 °C. In the past, investigations concerning the corrosion behavior of RAFM-steels like F82H-mod. and Eurofer showed that these alloys are attacked by the flowing breeder. These corrosion tests pointed out, that the corrosion attack depends mainly on flow velocity and temperature. All these alloys were 'single' phase ferritic-martensitic steels without any additions. However, structural materials with better strength and creep resistance like ODS-Eurofer or ferritic steels are gathering interest in blanket development and will be required at least for DCLL application due to higher operation temperatures. Nevertheless, reliable data concerning compatibility with Pb-15.7Li are missing until now. In this paper results from long-term corrosion testing of ODS-Eurofer will be reported for exposure times up to 1.5 years at a flow velocity of 0.1 m/s. The evaluated data for ODS-Eurofer corrosion will be compared with values of 'single' phase 'classical' Eurofer. The observed corrosion attack and mechanisms will be discussed in detail considering the testing conditions and the microstructure of the RAFM-steels.