Hydrogen-Accelerated Fatigue Crack Growth in Arc Welded X100 Pipeline Steel

Fatigue crack growth rate (da/dN) versus stress intensity factor range (ΔK) relationships were measured for arc welded X100 pipeline steel in high pressure hydrogen gas. Tests were performed at a load ratio (R) of 0.5, a frequency of 1 Hz, and pressures of 21 MPa H₂. Tests were also conducted in a reference environment (e.g. air) at 295 K. Hydrogen-accelerated fatigue crack growth rates were observed to be higher in the weld compared to the base metal. The results from the welded X100 pipeline steel tests are compared to lower strength pipeline grades (e.g. X52 and X65 steels) along with their respective welds to observe the effects that microstructure and strength have on hydrogen accelerated fatigue crack growth.