PSI - Issue 72

Péter Ungár et al. / Procedia Structural Integrity 72 (2025) 265–269

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Fig. 4. Failure probability comparison with measurements using optimized values for mini CT.

4. Conclusion This study successfully demonstrates the applicability of the Beremin model for assessing brittle fracture in 15Kh2MFAA steel using sub-sized compact tensile test specimens. The optimization of the Beremin parameters, particularly for the -130°C ( m = 23.1 and σ u = 2585MPa ) and -120°C ( m=20.96 and σ u = 2656MPa ) conditions, yielded results that align well with experimental measurements, highlighting the model’s effectiveness in predicting failure probabilities. While the findings for the other analyzed materials were less satisfactory, they underscore the complexities involved in characterizing materials with high plasticity. This research emphasizes the potential for using small specimens in nuclear power plants, where material availability is limited. Weibull stresses can be accurately calculated with the developed code, and a T 0 reference temperature can be determined in the future for materials where data is sufficient. Future work should focus on refining the optimization techniques and exploring the underlying factors affecting the discrepancies observed in the other materials. The Weibull parameter determination could be enhanced with the use of AI if sufficient data is available. Acknowledgements This project has received funding from the Euratom research and training programme 2019-2020 under grant agreement No 900018 (ENTENTE project). References Beremin, F.M., 1983, A Local Criterion for Cleavage Fracture of a Nuclear Pressure Vessel Steel, Metallurgical Transactions A 14a, 2287 Andrieu, A., Pineau, A., Besson, J., Ryckelynck, D., Bouaziz, O., 2012, Beremin model: Methodology and application to the prediction of the Euro toughness data set, Engineering Fracture Mechanics 9, 102 – 117, Elsevier Ltd., http://dx.doi.org/10.1016/j.engfracmech.2011.10.019 Jin, W., Li, Y., Li Y., Zhou, M., 2022, Scaled Fracture Toughness Based on the Weibull Stress for the Ferritic Steel Used in Nuclear Power Plants, Frontiers in Materials 9, Article 927806, doi: 10.3389/fmats.2022.927806 Moattari, M., Sattari-Far, I., Bonora, N., 2016, The effect of subcritical ductile crack growth on cleavage fracture probability in the transition regime using continuum damage mechanics simulation, Theoretical and Applied Fracture Mechanics 82, 125 – 135, Elsevier Ltd., http://dx.doi.org/10.1016/j.tafmec.2015.12.010 Najafabadi, A.M., Biglari, F.R., Nikbin, K., 2019, Probability of brittle failure in different geometries using a simplified constraint based local criterion method, Theoretical and Applied Fracture Mechanics 104, 102331, Elsevier Ltd., https://doi.org/10.1016/j.tafmec.2019.102331 Barbosa, V.S., Ruggieri, C., 2020, A simplified estimation procedure for the Weibull stress parameter, m, and applications to predict the specimen geometry dependence of cleavage fracture toughness, International Journal of Pressure Vessels and Piping 188, 104228, Elsevier Ltd., https://doi.org/10.1016/j.ijpvp.2020.104228 Tiryakioğlu, M., 2008 On estimating Weibull modulus by moments and maximum likelihood methods, J Mater Sci 2008, 43: 793 – 798., Springer Science+Business Media, LLC 2007, DOI 10.1007/s10853-007-2095-7