PSI - Issue 68

Berkehan Tatli et al. / Procedia Structural Integrity 68 (2025) 1140–1146 Tatli and Yalcinkaya / Structural Integrity Procedia 00 (2024) 000–000

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(a) C 0 = 0 wt ppm,Avg. GD = 0.124mm

(b) C 0 = 0 wt ppm,Avg. GD = 1.240mm

(c) C 0 = 0 . 5 wt ppm,Avg. GD = 0.124mm

(d) C 0 = 0 . 5 wt ppm,Avg. GD = 1.240mm

(e) C 0 = 1 . 0 wt ppm,Avg. GD = 0.124mm

(f) C 0 = 1 . 0 wt ppm, Avg. GD = 1.240mm

Fig. 4: Comparison of Von Mises stress contour plots at the end state of each SGCPFEM simulation with l = 1mm

4. Conclusions

This paper integrates a potential-based mixed-mode cohesive zone model with a stress-driven hydrogen transport model, incorporating crystal plasticity and strain gradient crystal plasticity constitutive frameworks. The microstruc tural impact on the material’s macroscopic response is assessed through crystal and strain gradient plasticity simula tions, comparing stress-strain curves and microscopic insights such as hydrogen accumulation and stress localization. Strain gradient crystal plasticity simulations reveal nonlocal e ff ects on hydrogen-induced failure, validating the sig nificant role of GNDs in stress concentration, especially near the crack tip. The study also examines the grain size e ff ect, showing that, due to the well-known Hall-Petch e ff ect, smaller-sized grain specimens are more prone to hy drogen accumulation near grain boundaries and triple junction points. This is driven by increased localized stress and strain, suggesting that nonlocal plasticity formulations, which can capture size e ff ects, are crucial for micromechanical modeling of hydrogen-induced failure.