Hydrogen Embrittlement of X80 Pipeline Steel

A single edge notched tensile (SENT) specimen was prepared, and hydrogen was charged in 0.5 mol/L H₂SO₄+3 g/L NH₄SCN solution at a current density of 10 mA/cm² for 4 h. The effect of hydrogen embrittlement on the fracture toughness of X80 pipeline steel was comparatively studied by tensile test and three-point bending test. The results show that the fracture toughness and bearing capacity of the hydrogen-charged SENT sample were significantly lower than those of the base material SENT sample. The fracture toughness results measured by the three-point bending test were conservative. Cracks of the hydrogen-charged SENT sample were relatively sharp, showing the characteristics of unsteady state propagation, and the plastic deformation was mainly concentrated in the localized area of the crack tip. The presence of hydrogen would reduce the energy required for crack initiation and propagation, and promote the transition from ductile tearing to brittle fracture.