PSI - Issue 42

B.Aydin Baykal et al. / Procedia Structural Integrity 42 (2022) 1350–1360 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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5. Conclusion In this paper, we have examined the current state of the art in accounting for the effects of scaling in standardized CT specimens in detail and showed that it was valid in a very narrow K range, as previously reported in literature. Instead of simply restricting the range of validity of the same calculation by changing the parameter M, we proposed a way to improve the approximation by including a second correction factor to account for constraint loss and subsequent overestimation of fracture toughness in miniaturized specimens. This new combined correction factor extended the range of validity to much higher K values, with a significantly better fit. As a result, it is conceivable that in demanding applications with high stress intensity, the proposed combined miniaturization factor k M should provide a significantly better approximation of full-sized specimen behavior compared to the current state of the art. Acknowledgements The authors are grateful for the financial support for PROACTIV project (Contract No. CTR-00489) provided by the Swiss Federal Nuclear Safety Inspectorate (ENSI). References ASTM E1921-21a Standard Test Method for Determinationof Reference Temperature, To, for Ferritic Steels in the Transition Range. (2021). In. Bonadé, R., Mueller, P., & Spätig, P. (2008). Fracture toughness behavior in the ductile – brittle transition region of the tempered martensitic Eurofer97 steel: Experiments and modeling. Engineering Fracture Mechanics , 75 (13), 3985-4000. https://doi.org/https://doi.org/10.1016/j.engfracmech.2008.01.016 Joyce, J. A., & Tregoning, R. L. (2005). Determination of constraint limits for cleavage initiated toughness data. Engineering Fracture Mechanics , 72 , 1559-1579. Mueller P., S. P., Bonadé R., Odette G. R., Gragg D. (2009). Fracture toughness master curve analysis of the tempered martensitic steel Eurofer97. Journal of Nuclear Materials , 386-388 , 323-327. Mueller, P. F. (2009). Finite element modeling and experimental study of brittle fracture in tempered martensitic steels for thermonuclear fusion applications (Publication Number No. 3405) PhD-4518 EPFL]. Lausanne. Odette, G. R., Yamamoto, T., Kishimoto, H., Sokolov, M., Spätig, P., Yang, W. J., Rensman, J. W., & Lucas, G. E. (2004). A master curve analysis of F82H using statistical and constraint loss size adjustments of small specimen data. Journal of Nuclear Materials , 329-333 , 1243 1247. https://doi.org/https://doi.org/10.1016/j.jnucmat.2004.04.255 Odette, G. R., Yamamoto, T., Rathbun, H. J., He, M. Y., Hribernik, M. L., &Rensman, J. W. (2003). Cleavage fracture and irradiation embrittlement of fusion reactor alloys: mechanisms, multiscale models, toughness measurements and implications to structural integrity assessment. Journal of Nuclear Materials , 323 , 313-340. Rathbun H. J., O. G. R., He M. Y., Yamamoto T. (2006). Inluence of statistical and constraint loss size effects on cleavage fracture toughness in the transition - A single variable experiment and database. Engineering Fracture Mechanics (73), 134-158. Spätig, P., Stoenescu, R., Mueller, P., Odette, G. R., & Gragg, D. (2009). Assessment of irradiation embrittlement of the Eurofer97 Steel after 590 MeV proton irradiation. Journal of Nuclear Materials , 386-388 , 245-248. van der Schaaf B., T. F., Fazio C., Rigal E., Diegele E., Lindau R., LeMarois G. (2003). The development of EUROFER reduced activation steel. Fusion Engineering and Design , 69 , 197-203. Wallin, K. (1993). Irradiation damage effects on the fracture toughness transition curve shape for reactor pressure vessel steels. International Journal of Pressure Vessels and Piping , 55 , 61-79. Wallin, K. (1999). The master curve method: a new concept for brittle fracture. International Journal of Materials and Product Technology , 14 (2 4), 342-354. https://doi.org/10.1504/IJMPT.1999.036276