PSI - Issue 52

Ivo Šulák et al. / Procedia Structural Integrity 52 (2024) 143–153 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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LPBF material has n = 3.3, which indicates lower creep strength. The stress exponents of bulk Alloy material do not match either typical values for solid solutions (n = 3) or pure metals (n = 5) (Čadek, 1988) . However, for the LBPF Alloy 400 value (n = 3.3 – Fig. 9a) is close to solid solutions values. The activation energies for all creep results are of the same order. However, it can be seen that the value of the activation energy increases with the applied stress (Figs. 7b and 9b). For lower applied stresses, processes along grain boundaries become more important because these processes have lower activation energies. 4. Conclusions Experimental investigation of the high-temperature fatigue and creep behaviour of conventionally and additively manufactured NiCu-based alloy via laser powder bed fusion technique allows for the following conclusions: 1) The LPBF process for this alloy is still not optimal and needs to be improved to reduce the number of defects that have a detrimental effect on mechanical properties. 2) Finer- grained structure compensated for the negative effect of LPBF defects on fatigue life up to 550 °C . Above this temperature, the fatigue crack propagation mechanism changes from transgranular to intergranular, which entails a significant drop in the fatigue life of the LPBF Alloy 400 compared to the bulk Alloy 400. 3) LPBF Alloy 400 shows inferior creep properties in the whole range of tested temperatures and stresses. The steady strain rates for the bulk Alloy 400 are lower, and the true strain achieved is higher than for the LPBF Alloy 400. Acknowledgements The financial support from European Union’s Horizon 2020 Research and Innovation Programme under grant agreement No 958192 is acknowledged. References Babinský, T., Šulák, I., Kuběna, I., Man, J., Weiser, A., Švábenská, E., Englert, L., Guth, S., 2023. Thermomechanical fatigu e of additively manufactured 316L stainless steel. Materials Science and Engineering: A 869, 144831. https://doi.org/10.1016/j.msea.2023.144831 Čadek, J., 1988. Creep in Metallic Materials, Materials science monographs. Elsevier. Chlupová, A., Šulák, I., Kuběna, I., Kruml, T., Roth, J.P., Jahns, K., 2023. Comparison of Microstructure and Properties of N ickel-Copper Alloy Prepared by Casting and Laser Powder Bed Fusion Process. MSF 1082, 171 – 176. https://doi.org/10.4028/p-884q32 Devendranath Ramkumar, K., Arivazhagan, N., Narayanan, S., 2012. Effect of filler materials on the performance of gas tungsten arc welded AISI 304 and Monel 400. Materials & Design 40, 70 – 79. https://doi.org/10.1016/j.matdes.2012.03.024 Dobes, F., Zverina, O., Cadek, J., 1986. LOADING SYSTEM FOR CREEP TESTS AT CONSTANT COMPRESSIVE STRESS. Metallic Materials (English translation of Kovove Materialy) (Cambridge, Engl) 24, 293 – 298. Du Plessis, A., Yadroitsava, I., Yadroitsev, I., 2020. Effects of defects on mechanical properties in metal additive manufacturing: A review focusing on X-ray tomography insights. Materials & Design 187, 108385. https://doi.org/10.1016/j.matdes.2019.108385 Eckmann, S., Schweizer, C., 2017. Characterization of fatigue crack growth, damage mechanisms and damage evolution of the nickel-based superalloys MAR-M247 CC (HIP) and CM-247 LC under thermomechanical fatigue loading using in situ optical microscopy. International Journal of Fatigue 99, 235 – 241. https://doi.org/10.1016/j.ijfatigue.2017.01.015 Fintová, S., Arzaghi, M., Kuběna, I., Kunz, L., Sarrazin -Baudoux, Ch., 2017. Fatigue crack propagation in UFG Ti grade 4 processed by severe plastic deformation. International Journal of Fatigue 98, 187 – 194. https://doi.org/10.1016/j.ijfatigue.2017.01.028 Fintová, S., Dlhý, P., Mertová, K., Chlup, Z., Duchek, M., Procházka, R., Hutař, P., 2021. Fatigue properties of UFG Ti g rade 2 dental implant vs. conventionally tested smooth specimens. Journal of the Mechanical Behavior of Biomedical Materials 123, 104715. https://doi.org/10.1016/j.jmbbm.2021.104715 Fintová, S., Kuběna, I., Palán, J., Mertová, K., Duchek, M., Hutař, P., Pa storek, F., Kunz, L., 2020. Influence of sandblasting and acid etching on fatigue properties of ultra-fine grained Ti grade 4 for dental implants. Journal of the Mechanical Behavior of Biomedical Materials 111, 104016. https://doi.org/10.1016/j.jmbbm.2020.104016 Fintová, S., Kunz, L., 2015. Fatigue properties of magnesium alloy AZ91 processed by severe plastic deformation. Journal of t he Mechanical Behavior of Biomedical Materials 42, 219 – 228. https://doi.org/10.1016/j.jmbbm.2014.11.019 Hosseini, E., Popovich, V.A., 2019. A review of mechanical properties of additively manufactured Inconel 718. Additive Manufacturing 30, 100877. https://doi.org/10.1016/j.addma.2019.100877 Armstrong, R.W., 1970. The influence of polycrystal grain size on several mechanical properties of materials. Metallurgical and Materials Transactions 1, 1169 – 1176. https://doi.org/10.1007/BF02900227