Study of failure for unstable austenitic steel in a hydrogen atmosphere

1. A reduction in the mechanical properties of steel 12Kh18N10T under the action of hydrogen proceeds in the pressure range 0–3 MPa both with static tests and with loading in the low-cycle fatigue region. 2. The presence of hydrogen leads to a change in failure micromechanism from ductilepitted with cyclic tension, and fatigue-grooved with low-cycle loading, to a brittle micromechanism. 3. A brittle failure mechanism occurs as result of a reduction in crack initiation energy along martensite platelet interfaces (deformation α′-phase) in the presence of hydrogen. 4. By promoting formation of microcracks in volumes where deformation martensite transformation has occurred, hydrogen prevents its continuous propagation in the rest of the volume, as a result of which its transformation is suppressed.