A comparative study about the hydrogen embrittlement susceptibility of Eurofer'97 and conventional 9%cr ferritic/martensitic steels

Constant displacement rate tests have been performed in conjunction with the electrochemical hydrogen charging technique to evaluate the relative susceptibility to hydrogen embrittlement of the martensitic steels: Eurofer'97, T91 and EM10. Mechanical property and failure mode results associated with any specific hydrogenation condition were fairly reproducible in the conventional alloys, showing a minor tendency to hardening and a major resistance to embrittlement effect at high hydrogen content of T91 compared to EM10. The underlying mechanism for damage could be identified and tentatively explained, based on fractographic evidences and microstructural arguments. Conversely, the results of replicated tests on Eurofer were significantly scattered and gave rise to embrittlement behaviours fitting those of either T91 or EM10, probably due to local heterogeneity of grain boundary chemistry.