PSI - Issue 80

Tomáš Vražina et al. / Procedia Structural Integrity 80 (2026) 244 – 255 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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5. Conclusion This study aimed to characterize intergranular facets within the cyclic plastic zone through fractographic analysis in BCC material FeAlOY alloy and austentitic stainless steel Sanicro 25. The key findings are as follows: • Intergranular fracture facets were identified on the fracture surfaces of both Sanicro 25 (FCC) and FeAlOY (BCC). In Sanicro 25, stage II comprised both intergranular and transgranular fracture modes, with striation progressing until the beginning of final fracture in stage III. In contrast, FeAlOY exhibited exclusively intergranular cracking in stage II, followed by a brittle final fracture zone in stage III. • The PSMs typically observed on the outer surface of fatigued specimens were also present on intergranular facets within the fracture surfaces of both Sanicro 25 and FeAlOY, extending the findings of Polák on Cu and C263 nickel-based superalloy. • In Sanicro 25, thin PSBs were confirmed by STEM and correlated HR-EBSD KAM maps, indicating that cyclic plasticity and PSM formation extend throughout the deformed volume, not just at the surface. • Although PSMs were not observed on the polished surface due to the presence of oxide nanoparticles in BCC ODS FeAlOY, the PSMs were clearly present on the fracture surface. This can be attributed to the formation of the cyclic plastic zone near the crack tip, where local stress concentrations are sufficient to overcome the nanoparticles which act as barriers and activate slip. Acknowledgements T.V ražina . and J.Svoboda gratefully acknowledge funding by the Czech Science Foundation in the frame of project 21-02203X. I. Š ulák., J. Polák gratefully acknowledge the support of the project INTER-COST No. LUC24093 funded by the Ministry of Education, Youth and Sports of the Czech Republic. Barbe, F., Benedetti, I., Gulizzi, V., Calvat, M., Keller, C., 2020. Elucidating the Effect of Bimodal Grain Size Distribution on Plasticity and Fracture Behavior of Polycrystalline Materials. J. Multiscale Modelling 11, 2050007. Blochwitz, C., Tirschler, W., 2005. Twin boundaries as crack nucleation sites. Crystal Research and Technology 40, 32 – 41. Chan, K.S., 2023. Incorporating Dislocation Mechanisms into a Phenomenological Cyclic Plasticity Model for Structural Alloys. Metall Mater Trans A 54, 3431 – 3447. Chlupová, A., Šulák, I., Babinský, T., Polák, J., 2022. Intergranular fatigue crack initiation in polycrystalline copper. Mat erials Science and Engineering: A 848, 143357. Chlupová, A., Šulák, I., Kunčická, L., Kocich, R., Svoboda, J., 2021. Microstructural aspects of new grade ODS alloy consolid ated by rotary swaging. Materials Characterization 181, 111477. Chlupová, A., Šulák, I., Svoboda, J., 2020. High Temperature Cyclic Plastic Response of New -Generation ODS Alloy. Metals 10, 804. Christ, H.-J., 1989. On the orientation of cyclic-slip-induced intergranular fatigue cracks in face-centered cubic metals. Materials Science and Engineering: A 117, L25 – L29. Essmann, U., Gösele ,U., and Mughrabi, H., 1981. A model of extrusions and intrusions in fatigued metals I. Point-defect production and the growth of extrusions. Philosophical Magazine A 44, 405 – 426. Gamanov, Š., Luptáková, N., Bořil, P., Jarý, M., Mašek, B., Dymáček, P., Svoboda, J., 2023. Mechanisms of plastic deformation and fracture in coarse grained Fe – 10Al – 4Cr – 4Y2O3 ODS nanocomposite at 20 – 1300°C. Journal of Materials Research and Technology 24, 4863 – 4874. Larrouy, B., Villechaise, P., Cormier, J., Berteaux, O., 2015. Grain boundary – slip bands interactions: Impact on the fatigue crack initiation in a polycrystalline forged Ni-based superalloy. Acta Materialia 99, 325 – 336. Li, L., Zhang, Zhenjun, Zhang, P., Zhang, Zhefeng, 2023. A review on the fatigue cracking of twin boundaries: Crystallographic orientation and stacking fault energy. Progress in Materials Science 131, 101011. Liang, F.-L., Laird, C., 1989a. Control of intergranular fatigue cracking by slip homogeneity in copper I: Effect of grain size. Materials Science and Engineering: A 117, 95 – 102. Liang, F.-L., Laird, C., 1989b. Control of intergranular fatigue cracking by slip homogeneity in copper II: Effect of loading mode. Materials Science and Engineering: A 117, 103 – 113. Mazánová, V., Heczko, M., Polák, J., 2022. On the mechanism of fatigue crack initiation in high-angle grain boundaries. International Journal of Fatigue 158, 106721. References