PSI - Issue 52

Ben M B Sargeant et al. / Procedia Structural Integrity 52 (2024) 472–479 Ben M B Sargeant , Catrin M Davies and Paul A Hooper / Structural Integrity Procedia 00 (2023) 151-158

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4. Conclusion The fracture behaviour of small-scaled single edge notch bend, SEN(B), samples have been examined for 508 Steel at room temperature and compared to that of larger samples. Data from 10 mm and 25 mm thick square cross-section samples analysed and compared. The crack growth of the 10 mm thick sample was monitored using a potential drop (PD) technique and an approximate linear relationship between PD and crack length was observed. The PD technique underestimated crack growth during the fracture test due to significant crack tunnelling effects and the electrical current taking a path of least resistance. Though PD was not able to accurately measure crack growth, it was useful to determine crack growth initiation. The larger sample was able to withstand an approximately 40% increase in bending stress than the smaller sample, indicating significant differences in their stress state. The larger sample demonstrates over 3 times higher elastic toughness component, making the larger sample response closer to plane strain conditions. Therefore, the use of small samples for this material and temperature for fracture toughness testing need careful consideration for real components. Acknowledgements Sponsorships acknowledgments to EPSRC (EP/S023844/1), the Nuclear Energy Futures CDT and industrial sponsor, AWE. Thanks to the Imperial College Department of Mechanical Engineering for ongoing support, sample manufacture and experimental facilities. Finally, the authors appreciate permission for use of materials by Rolls Royce and historical results by Dr Geena Rait. References [2] A.R. Shahani, M. Rastegar, M. Botshekanan Dehkordi, H. Moayeri Kashani, Experimental and numerical investigation of thickness effect on ductile fracture toughness of steel alloy sheets, Eng. Fract. Mech. 77 (2010) 646 – 659. https://doi.org/10.1016/J.ENGFRACMECH.2009.12.017. [3] ASTM, ASTM E1820 - 22: Standard Test Method for Measurement of Fracture Toughness, West Conshohocken, 2022. [4] K. Wallin, The size effect in KICresults, Eng. Fract. Mech. 22 (1985) 149 – 163. https://doi.org/10.1016/0013-7944(85)90167-5. [5] G.K. Rait, The Effects of Constraint on the Fracture Toughness of Reactor Pressure Vessel Steels, Imperial College London, 2019. [6] COMSOL Multiphysics®, (2023). https://www.comsol.com/ (accessed May 7, 2023). [7] A.N. O’Connor, C.M. Davies, S.J. Garwood, The influence of constraint on fracture toughness: Comparing theoretical T0 shifts in master curve analyses with experimental data, Eng. Fract. Mech. 275 (2022) 108857. https://doi.org/10.1016/J.ENGFRACMECH.2022.108857. [1] T.L. Anderson, Fracture mechanics : fundamentals and applications, 4th ed., Boca Raton, 2017.