IWPDF2023

Technical Sessions

Hydrogen Assisted Cracking Through Mixed-Mode Hydrogen-Sensitive Cohesive Zone Model

B. Tatli ∗ , I. E. Unsal, T. Yalçinkaya

Department of Aerospace Engineering, Middle East Technical University, Ankara 06800, Türkiye

∗ btatli@metu.edu.tr

Keywords: hydrogen induced fracture, cohesive zone modeling, hydrogen diffusion.

Metals, particularly high-strength steels, are susceptible to the phenomenon known as hydrogen embrittlement. Hydrogen embrittlement is observed when the metal interacts with a hydrogen producing environment, particularly intensified under conditions of high pressure and humidity. This interaction allows small hydrogen particles to readily diffuse into the metallic material and relocate within the crystal lattice. Consequently, under stresses below the yield point of metallic materials, both ductility and load-bearing capacity are significantly reduced, resulting in cracking and potentially catastrophic brittle failures. While extensive documentation exists on the micro mechanical and physical aspects of the hydrogen-assisted fracture, a complete understanding is yet to be achieved. In this study, the constitutive J2 plasticity model is integrated with both a mixed-mode cohesive zone formulation, see [1] for an example study, and a multi-trap hydrogen transport model [2] to simulate the failure process. Unlike some of the literature studies [3], the presented model effectively couples the hydrogen transport model with the cohesive zone formulation to account for the effects resulting from the hydrogen redistribution during crack tip propagation. This approach also allows for the prediction of intergranular fracture and the precise representation of the material’s sensitivity to hydrogen content. To validate the results obtained from the integrated framework, numerical examples from the literature are analyzed, and comparisons are made with experimental data. References [1] Aydiner, I. U., Tatli, B., and Yalçinkaya, T. (2023). Micromechanical modeling of failure in dual phase steels. Material Research Proceedings, 28, 1443-1452. [2] Fernández-Sousa, R., Betegón, C., and Martínez-Pañeda, E. (2020). Analysis of the influence of microstructural traps on hydrogen assisted fatigue. Acta Mater., 199, 253-263. [3] Lin, M., Yu, H., Wang, X., Wang, R., Ding, Y., Alvaro, A., and Zhang, Z. (2022). A microstructure informed and mixed-mode cohesive zone approach to simulating hydrogen embrit tlement. Int. J. Hydrog. Energy, 47(39), 17479-17493.

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