PSI - Issue 77

A. Hell et al. / Procedia Structural Integrity 77 (2026) 41–48 Author name / Structural Integrity Procedia 00 (2026) 000–000

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further embrittling phenomena. Finally, reminding the calculated concentration profile, no clear connection between hydrogen-related damaging and the location on the fracture surface has been visible. Intergranular failure and cleavage facet enlargement in fatigue (Fig. 6) occur in areas over the entire sample thickness, indicating that the approximation of D eff = 2.5*10 -11 m 2 /s is too conservative. This is also supported with the fracture mechanical data, where hydrogen effects on crack growth are observed even for high crack extensions. The apparently larger penetration depth of hydrogen is advantageous in a way that it leads to a sufficient H-reservoir in the microstructure, which ensures the testability of the precharged specimens despite the competing hydrogen desorption processes. As hydrogen uptake and diffusion in steel is a process influenced by several factors, local hydrogen distribution remains difficult to access. 4. Conclusion The influence of hydrogen on crack growth resistance of the pressure vessel steel grade P355NH was investigated. The main findings of this work are summarized as follows: • Cathodic charging of reference sheet samples with 1.4 mm thickness, leads to a hydrogen uptake of about 0.8 wt.- ppm in the steel. D eff for this process is estimated to 2.5*10 -11 m 2 /s and used to calculate the charging profile of compact tension specimens (CT50) in a first approximation. • Saturation of the CT50 samples is difficult to achieve. A steep decline in c H is calculated for D eff = 2.5*10 -11 m 2 /s with increasing depth of the specimen volume. However, results from SEM fractography and mechanical testing reveal that the diffusion calculation parameters are too conservative. • Accelerated FCG is obtained in precracking of H-charged samples due to internal hydrogen for high stress intensities and low frequencies. SEM fractography reveals an increase in intergranular failure ratio and the formation of a flatter morphology with larger (quasi-)cleavage facets. • The stable crack growth resistance of the steel is lowered after hydrogen precharging, indicated by facilitated ductile crack extension and a reduced slope of J- ∆ a -curves for H-charged CT50 specimen geometries. Acknowledgements The authors thank AG der Dillinger Hüttenwerke and the German Research Foundation for funding their research. This work made use of the resources of the Correlative Microscopy and Tomography (CoMiTo) core facility at Saarland University. Funding for nanoCT by German Research Foundation, grant number 316923640, is gratefully acknowledged. References Barrera, O., Bombac, D., Chen, Y., Daff, T.D., Galindo-Nava, E., Gong, P., Haley, D., Horton, R., Katzarov, I., Kermode, J.R., Liverani, C., Stopher, M., Sweeney, F., 2018. Understanding and mitigating hydrogen embrittlement of steels: a review of experimental, modelling and design progress from atomistic to continuum. Journal of Materials Science 53, 6251–6290. Bolzoni, F., Paterlini, L., Casanova, L., Ormellese, M., 2024. Hydrogen charging of carbon and low alloy steel by electrochemical methods. Journal of Applied Electrochemistry 54, 103–114. Ghosh, G., Rostron, P., Garg, R., Panday, A., 2018. Hydrogen induced cracking of pipeline and pressure vessel steels: A review. Engineering Fracture Mechanics 199, 609–618. Hoschke, J., Chowdhury, M.F.W., Venezuela, J., Atrens, A., 2023. A review of hydrogen embrittlement in gas transmission pipeline steels. Corrosion Reviews 41, 277–317. Müller, C., Zamanzade, M., Motz, C., 2019. The Impact of Hydrogen on Mechanical Properties; A New In Situ Nanoindentation Testing Method. Micromachines (Basel) 10. Nagumo, M., Yoshida, H., Shimomura, Y., Kadokura, T., 2001. Ductile Crack Growth Resistance in Hydrogen-Charged Steels. Materials Transactions 42, 132–137. Rosen, M.A., Koohi-Fayegh, S., 2016. The prospects for hydrogen as an energy carrier: an overview of hydrogen energy and hydrogen energy systems. Energy, Ecology and Environment 1, 10–29. Tau, L., Chan, S., 1996. Effects of ferrite/pearlite alignment on the hydrogen permeation in a AISI 4130 steel. Materials Letters 29, 143–147. Yue, M., Lambert, H., Pahon, E., Roche, R., Jemei, S., Hissel, D., 2021. Hydrogen energy systems: A critical review of technologies, applications, trends and challenges. Renewable and Sustainable Energy Reviews 146, 111180. Zafra, A., Álvarez, G., Benoit, G., Henaff, G., Martinez-Pañeda, E., Rodríguez, C., Belzunce, J., 2023. Hydrogen-assisted fatigue crack growth: Pre-charging vs in-situ testing in gaseous environments. Materials Science and Engineering: A 871, 144885.