Hydrogen effect on fracture toughness of post-operated pipeline steel

Existing natural gas pipelines considered alternative for the transportation of hydrogen in developing hydrogen economy. Hydrogen can cause embrittlement of pipeline steels, and, therefore, an increase in a failure risk. The susceptibility of pipe steels to hydrogen embrittlement, and the assessment of crack growth resistance, in particular, fracture toughness, is an important issue for their fitness-for-service. Hydrogen effect on the fracture toughness of post-operated pipeline steel was investigated in the case of ex-situ hydrogen charging. The fracture toughness of pipe steel was determined by the J-integral method due to the high ductility. Single-edge notched beam specimens were subjected to three-point bending. Under the hydrogen pre-charging, the fracture toughness J_0,2 of the studied steel is decreased. The higher sensitivity of the J_0,2 index to hydrogen embrittlement of the steel compared to the parameter J₀, indicating crack initiation was revealed.