Electrochemical Investigation of Hydrogen Embrittlement in Steels for Oil & Gas Applications

Hydrogen embrittlement (HE) represents one of the major challenges for the safe use of gaseous hydrogen in existing Oil & Gas (O&G) infrastructures, particularly in transport and storage applications. This study focuses on the characterization of the hydrogen embrittlement behavior of two high-strength steels, T95 and P110, compliant with the API 5CT specification and commonly employed in high-severity drilling environments. The experimental investigation includes microstructural analysis, hardness measurements, tensile testing, and fracture mechanics assessments, performed on specimens in both the “as-received” condition and after hydrogen pre-charging. Controlled hydrogen introduction was achieved through electrochemical charging, with process parameters optimized via Finite Element Method (FEM) simulations aimed at modelling hydrogen diffusion within the samples. Hydrogen diffusivity was experimentally determined using the Devanathan–Stachurski technique to evaluate the permeation behavior of the steels under investigation. Subsequent mechanical testing on hydrogen-charged specimens revealed the impact of hydrogen on mechanical properties and fracture toughness. The results were interpreted in relation to the fracture surface morphology, allowing for the assessment of the susceptibility of the studied materials to HE under service-representative conditions.