Effect of the Strain Rate on the Hydrogen Embrittlement of High Strength Austenitic Stainless Steels

Austenitic stainless steel (ASS) UNS S31603 is frequently used for hydrogen applications due to its low susceptibility to HE compared with other ASSs. If high strength is required, high strength austenitic stainless steels, like UNS S20910 and CrMnNiMoN-type, in strain-hardened condition can be used for high-pressure hydrogen applications due to their resistance against hydrogen embrittlement. In this paper, the hydrogen embrittlement susceptibility of two high strength ASS, UNS S20910 and CrMnNiMoN was investigated. Slow strain rate test (SSRT) of hydrogen precharged specimens were carried out at ambient temperature using various strain rates. These results were correlated with SSRT conducted in a hydrogen atmosphere of 100 und 1000 bar (10 und 100 MPa). The strain rate does not have a significant effect on the tensile strength of the hydrogen-charged specimens. On the other hand, the reduction of area was affected by it. The relative reduction of area (RRA) of the hydrogen-charged specimen decreases with slower strain rates. This effect is more evident on UNS S20910 than on CrMnNiMoN. Reduction of RRA was not observed on specimens tested in-situ, even at 1000 bar (100 MPa). This difference can be explained due to the hydrogen concentration behaviors of the specimens during the deformation process.