Hydrogen uptake from plasma and its effect on EUROFER 97 and ODS-EUROFER steels at elevated temperatures

Hydrogen effects on the mechanical properties of the ferrite-martensite EUROFER 97 and oxide dispersion strengthened ODS-EUROFER steels were studied under continuous hydrogen charging from hydrogen-enriched plasma at temperatures up to 300 °C. Hydrogen uptake measured using thermal desorption spectroscopy was found to be markedly higher in ODS-EUROFER steel in comparison to that in EUROFER 97 steel evidencing on high hydrogen trapping ability of the oxide-dispersion strengthening yttria nanoparticles. It is found that EUROFER 97 and ODS-EUROFER steels manifest rather different sensitivity to hydrogen embrittlement with increase of temperature. It is shown that increase of the temperature up to 300 °C decreases the hydrogen effects on the mechanical properties of ODS-EUROFER steel, while sensitivity to hydrogen of EUROFER 97 steel remains the same as at room temperature. FEG-SEM fractography was performed to investigate of the hydrogen-induced fracture mode at elevated testing temperatures. Possible role of the interface between yttria nanoparticles and steel matrix and the distribution of yttria nanoparticles in the hydrogen embrittlement mechanism are discussed.