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, 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. The fracture mode transitioned from intergranular to transgranular fracture as the stress intensity increased.
Citation: International Journal of Fatigue
Volume: 78 (2014)
Pub Type: Journals
Fatigue, Fatigue crack growth, Hydrogen, Hydrogen embrittlement, Pipeline, Steel, X52, X100