Session: MF-02-09 Materials for Hydrogen Service (Joint with C&S)-9

Paper Number: 154683

154683 - Testing and Simulation of Gaseous Hydrogen Embrittlement in Pipeline Steels Using Sub-Sized Fracture Toughness Specimens 

Abstract: 

The transportation of hydrogen through pipelines is essential for its integration into a decarbonized energy landscape. However, the degradation of mechanical properties in pipeline steels, driven by Hydrogen Embrittlement (HE), remains a significant challenge. This work combines experimental testing and finite element (FE) simulations to better understand the mechanisms behind HE.

Sub-sized fracture toughness specimens were used to assess hydrogen embrittlement in steels. Mini Disk Shaped Compact Tensile (mDCT) specimens, with dimensions of 10 mm width and 5 mm thickness, were extracted from E355 modified steel (hot rolled tube) and X52 steel (vintage pipeline). The specimens were tested in a controlled environment with gaseous hydrogen at pressures of 30, 100, and 200 bar, using the Edge Tracing (ET) technique to monitor Load Line Opening Displacement (LLOD) and Opening Angle during tests. The results revealed a decrease in toughness in E355 mod. steel at 100 and 200 bar H2, with a further reduction at lower Stress Intensity Factor Rates (K̇). X52 steel exhibited consistent toughness reduction at 100 and 200 bar H2, with no loss at 30 bar. Scanning Electron Microscopy (SEM) was employed to evaluate the fracture surfaces, providing insights into the varying behaviors of the two steel grades under hydrogen exposure.

The FE method was then used to model hydrogen embrittlement in these steels. The model incorporates hydrogen diffusion, trapping by dislocations, and mechanisms like Hydrogen Enhanced Localized Plasticity (HELP), Hydrogen Enhanced Decohesion (HEDE), and Hydrogen Enhanced Strain-Induced Vacancy (HESIV). A damage variable evolution, dependent on local hydrogen concentration, principal stress, and accumulated plastic strain, was introduced to simulate HEDE. The model was enhanced with a nonlocal formulation to address mesh dependency and used a mixed formulation to avoid spurious pressure fluctuations. The simulation was applied to replicate crack propagation in both air and hydrogen environments.

Presenting Author: Yazid Madi Centre des Matériaux, Mines Paris, CNRS UMR 7633, PSL Research University

Presenting Author Biography: Pr. Yazid Madi is an HDR-qualified researcher and educator at MINES Paris - PSL University, currently serving as an Associate Professor at the Centre des Matériaux (CMAT). With over 25 years of experience in mechanical engineering and materials science, Dr. Madi has a profound expertise in the durability and fracture of metallic materials, particularly focusing on hydrogen embrittlement and the use of mini-specimens for material characterization. He leads several high-impact research projects, including the ANR industrial chair MESSIAH and the European HYWAY project, both aimed at advancing hydrogen technologies. In addition to his research, Dr. Madi is deeply involved in teaching and mentoring, coordinating engineering projects and contributing to the education of future engineers.

Authors:

Yazid Madi Centre des Matériaux, Mines Paris, CNRS UMR 7633, PSL Research University
Luciano M.-Santana Centre des Matériaux, Mines Paris, CNRS UMR 7633, PSL Research University
Daniela L.-Pinto Centre des Matériaux, Mines Paris, CNRS UMR 7633, PSL Research University
Jader Furtado Air Liquide, Innovation Campus Paris
Pierre-Jean Marchais Mannesmann Precision Tubes France SAS
Nicolae Osipov Transvalor S.A.
Jacques Besson Centre des Matériaux, Mines Paris, CNRS UMR 7633, PSL Research University