PSI - Issue 21

Taiko Aikawa et al. / Procedia Structural Integrity 21 (2019) 173–184 Taiko Aikawa/ Structural Integrity Procedia 00 (2019) 000 – 000

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4. Conclusion In order to examine the difference of brittle crack propagation arrest performance of large container ships by the change of the fracture scenarios, a series of three-sided slit Charpy test was carried out in which the sampling direction of test pieces was devised. After that, the DWTT tests processing the test specimen specially were carried out. As a result. the following knowledge was obtained. (1) In order to quantify the propagation resistance of TMCP steel in the direction of crack propagation, a three sided slit Charpy test was conducted with a modified sampling direction. The possibility of explaining the toughness difference according to the scenario was found by arranging the absorbed energy by the twist angle which is the grain boundary orientation difference in the crack propagation direction. (2) The results obtained from the three-sided slit Charpy test were also verified by the DWTT test, which is easier to purely discuss the brittle crack propagation arrest. It is difficult to say that the assumed results of the absorption energy and the crack arrest length were obtained, but regarding the fracture surface roughness, the test piece in which the crack develops in the plate thickness direction was more roughened in both visual observation and numerical index. Acknowledgements This work was supported by JSPS KAKENHI Grant Numbers, JP17H01354, JP18H05337, JP18H03811. References Broberg, K. B., Cracks and Fracture, Academic Press, 1999. Deguchi, A., Tada, M., Yaguchi, H., A Consideration on Brittle Crack Arrestability and New Impact test for 9% Ni Steel, Proceedings of the Japan Shipbuilding Association , Volume 167, 1990, Pages 271-277 Hiramatsu, H., Matsuda, H., Michiba, K., Nishiyama, G., Hirosue, T., Matsuura, M., Okamoto, K., Kawabata, T., Maeda, T., Inami, A. and Kubo, S., Investigation on the brittle crack propagation behavior of heavy thick shipbuilding steel plates (Report 1: The crack arrestability of brittle crack propagation in the thickness direction in steel plates), Conference Proceedings The Japan Society of Naval Architects and Ocean Engineers, 5(2007), 131-134. International Association of Classification Societies, “Requirements for Use of Extremely Thick Steel Plates in Container Ships,” UR S33, 2015 09. Ishikawa, T., Inoue, T., Koseki, T., Hirota, K. , Shirakihara, H. and Yajima, H., Brittle Crack Propagation Behavior in Welded Joints Using Thick Steel Plates (No.3), Poster Session in Three Society of Shipbuilding, 2004. Matsumoto, K. et al, Brittle Crack Arrest Toughness for Extremely Thick Steel Plates-Required Kca Value of Steel Plates with Thickness of 100mm Used in Ultra-Large Container Ships- Proceedings of the LASTED International Conference on Information and Knowledge Sharing, 2018, Anaheim, CA:ACTA Press., pp.122-127. Kozasu, I., Controlled rolling and controlled cooling, Tokyo, Chijinshokan, 1997. Nakanishi, D. et al, Brittle crack propagation resistance inside grain and at high angle grain boundary in 3% Si-Fe alloy, Acta Materialia , Volume 144, 2018, Pages 768-776. Yamaguchi, Y., Kitada, H.,Yajima, H, Hirota, K. and Shirakihara, H., “Development of mega container carriers – Application of new higher strength hull structural steels with heavy thickness-“, Kanrin, The Japanese Society of Navla Architects and Ocean Engineering, Vol. 3, pp.70.