Comparison of low cycle fatigue data of X52 pipeline steel in air and gaseous hydrogen using conventional and hollow specimen

The present work compares low cycle fatigue results in high pressure gaseous hydrogen and in ambient air using hollow (HS) and conventional specimens (CS). For the given X52 pipeline steel and test conditions (ambient air and 20 MPa hydrogen gas pressure, Rε = 0.1, f = 0.1 Hz), the presence of a borehole had no significant influence on the elastic–plastic deformation behavior of the HS compared to CS. Test results in ambient air were comparable. Data for CS tested in hydrogen gas was not available but was approximated by fatigue crack growth results from the open literature at comparable test conditions. Hydrogen-assisted reduction of fatigue life was sufficiently similar in both, HS and CS. For the HS tested in H2 gas, fatigue cracks always initiated at the inner bore gauge surface.