PSI - Issue 68

Marcell Gáspár et al. / Procedia Structural Integrity 68 (2025) 500–505 M. Gáspár et al. / Structural Integrity Procedia 00 (2025) 000–000

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times from 800 °C to 500 °C (t 8/5 ), specifically 5 s, 15 s and 30 s. The aim was to investigate the effect of the thermal cycles on the impact toughness of the weld metal. Following conclusions were made: • Hardness test results showed that by the increase of cooling time the hardness remarkably reduced in CGHAZ and slightly decrease in ICHAZ-W. • The original weld metal and HAZ subzones surpass base material impact energy requirements, achieving over 100 J impact energy at -40 °C. • HAZ subzones consistently showed lower toughness than the original weld. ICHAZ-W had the lowest toughness, especially with longer t 8/5 cooling times. • In the registered force-displacement diagrams of instrumented Charpy impact testing and on the fracture surfaces of the specimens mostly ductile behavior of the unaffected weld metal and CGHAZ was identified, whilst ductile/brittle failure was observed in ICHAZ with instable crack propagation. Acknowledgements The authors are grateful to the funding of the research program FOSSA II (Fossil-Free Steel Applications, Dnro 5562/31/2023) funded by Business Finland. Dr. Gáspár was supported by the János Bolyai Research Scholarship of the Hungarian Academy of Sciences (Grant number: Bo/00643/22/6). Dr. Javaheri would also like to thank Jane ja Aatos Erkon säätiö (JAES) and Tiina ja Antti Herlinin säätiö (TAHS) for their financial supports on Advanced Steels for Green Planet project. References Afkhami, S., Javaheri, V., Amraei, M., Skriko, T., Piili, H., Zhao, X.-L., Björk, T., 2022. Thermomechanical simulation of the heat-affected zones in welded ultra-high strength steels: Microstructure and mechanical properties. Mater Des 213, 110336. https://doi.org/10.1016/j.matdes.2021.110336 Kang, Y., Park, G., Jeong, S., Lee, C., 2018. Correlation Between Microstructure and Low-Temperature Impact Toughness of Simulated Reheated Zones in the Multi-pass Weld Metal of High-Strength Steel. Metallurgical and Materials Transactions A 49, 177–186. https://doi.org/10.1007/s11661-017-4384-3 Laitinen, R.O., Porter, D.A., Karjalainen, L.P., Leiviskä, P., Kömi, J., 2013. Physical Simulation for Evaluating Heat-Affected Zone Toughness of High and Ultra-High Strength Steels. Materials Science Forum 762, 711–716. https://doi.org/10.4028/www.scientific.net/MSF.762.711 Mičian, M., Winczek, J., Harmaniak, D., Koňár, R., Gucwa, M., Moravec, J., 2020. Physical Simulation of Individual Heat-Affected Zones in S960MC Steel. Archives of Metallurgy and Materials 66, 81–89. https://doi.org/10.24425/amm.2021.134762 Niklas, K., Bera, A., Garbatov, Y., 2023. Impact of steel grade on a ship colliding with an offshore wind turbine monopile supporting structure. Ocean Engineering 287 Part 2, 115899 https://doi.org/10.1016/j.oceaneng.2023.115899 Rykalin, N. N., 1953. Teplovie processzi pri szvarke, Vüpuszk 2, Izdatelsztvo Akademii, Nauk SzSzSzR, Moscow Tervo, H., Gáspár, M., Kovács, J., Kaijalainena, Javaheri, V., Sainio, J., Kömi, J., 2024. The microstructure and fracture mode of physically simulated heataffected zones of a weld metal used with 500 MPa offshore steel – part 2: fractographies, inclusions and microstructures. Structural Integrity Procedia. (under publication) Tezuka, N., Shiga, C., Yamaguchi, T., Bosansky, J., Yasuda, K., Kataoka, Y., 1995. Toughness Degradation Mechanism for Reheated Mo-Ti-B Bearing Weld Metal. ISIJ International 35, 1232–1238. https://doi.org/10.2355/isijinternational.35.1232 Węglowski, M.S., Zeman, M., Lomozik, M., 2013. Physical Simulation of Weldability of Weldox 1300 Steel. Materials Science Forum 762, 551–555. https://doi.org/10.4028/www.scientific.net/MSF.762.551 Willms, R., 2009. High strength steel for steel constructions. Nordic Steel Construction Conference. Malmö, Sweden 597–604. Zhiyu, J., 2021. Installation of offshore wind turbines: A technical review. Renewable and Sustainable Energy Reviews 139, 110576. https://doi.org/10.1016/j.rser.2020.110576