Effects of Hydrogen Embrittlement on the Fracture Toughness of High-Strength Steel Structures

Blending hydrogen into existing natural gas pipelines is being pursued as a means of delivering hydrogen to markets. However, as stated in ASME B31.12, high-strength steel pipelines under stress can be susceptible to hydrogen embrittlement, which is a phenomenon that could induce brittle fracture in steel. This study proposes a numerical framework using phase-field fracture modelling techniques to model the hydrogen embrittlement phenomenon in high-strength steels. The proposed numerical framework is validated against a Compact Tension experimental test specimen, which is deemed suitable to capture the crack-tip constraint observed in high strength steel. The finite element results show a good agreement with experimental results, which demonstrate the capability of the phase-field fracture model in reasonably predicting hydrogen embrittlement in high-strength steel. As such, the proposed numerical modelling framework could also be applicable to typical high strength steel pipelines.