Fatigue crack growth of two pipeline steels in a pressurized hydrogen environment

•Fatigue crack growth measurements were made on API 5L X52 and X100 pipeline steels.•The measurements were made in pressurized hydrogen gas.•Fatigue crack growth rates were similar for X52 and X100.•The X100 material shows dependence on hydrogen gas pressure, whereas the X52 did not.

Fatigue crack growth tests were conducted on two pipeline steel alloys, API 5L X52 and X100. Baseline tests were conducted in air, and those results were compared with tests conducted in pressurized hydrogen gas. All tests were run at (load ratio) R = 0.5 and a frequency of 1 Hz, except for one test on X100, run at 0.1 Hz. Tests were conducted at hydrogen pressures of 1.7 MPa, 7 MPa, 21 MPa, and 48 MPa. Fatigue crack growth rates for both X100 and X52 were significantly higher in a pressurized hydrogen environment than in air. This enhanced growth rate appears to correlate to pressure for X100 but may not for X52.