PSI - Issue 54

Martin Matušů et al. / Procedia Structural Integrity 54 (2024) 135 – 142 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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powder overpowered the positive act of adding the new powder (from ECKART instead of the commonly used GE powder). The decline in fatigue performance is mainly visible for T200 and T300 heat treatments. The decline in fatigue performance is present, and it is not negligible for all the tested platforms regardless of heat treatment. The differences between HTs in platform n°3 are not huge regarding the fatigue strength at 10 6 cycles (using K&V regression), but the k exponent of the S-N curve slope differs. The generally low levels of the k slopes, which are close to values observed for notched specimens, also indicate that the defects in the specimen’s structure act as micro notches leading to the failure of the specimen. Notably, higher-stabilized temperature of HT’s (T240 and T300) led to increased temperature responses above the fatigue limit due to their influence on ductility and silicon network disintegration. In contrast, the T200 heat treatment, resembling artificial aging, reduced plastic strain impact, and lowered thermal responses. When analyzing identical heat treatments across platforms, no significant effects on the shape and position of the S-N curves were observed in the thermal responses, except for the T200 case. Here, platform n°4 displayed a notably lower fatigue curve and self-heating response, suggesting a potentially more defective microstructure. These unexpected findings challenge our initial expectations, prompting further exploration of thermal responses . Acknowledgements The authors acknowledge the support by the Czech Ministry of Education, Youth and Sports within the LUABA22071 project, by the Bavarian-Czech Academic Agency (BTHA-JC-2022-30 project), by the Grant Agency of the Czech Technical University in Prague within the SGS23/156/OHK2/3T/12 project and by ESIF, EU Operational Programme Research, Development and Education, from the Center of Advanced Aerospace Technology (CZ.02.1.01/0.0/0.0/16_ 019/0000826), Faculty of Mechanical Engineering, Czech Technical University in Prague is appreciated by the Škoda Auto a.s. for the instrumentation provided for research in the field of fractographic analysis is appreciated. The support by Czech Science Foundation (grant No. 23-05338S) is also acknowledged. References Khan, H., Karabulut, Y., Kitay, O., Kaynak Y., and Jawahir. I., 2021, Influence of the post-processing operations on surface integrity of metal components produced by laser powder bed fusion additive manufacturing: a review. Machining Science and Technology. vol, 25, 118-176. https://doi:10.1080/10910344.2020.1855649 Matušů , M., Dimke, K., Šimota, J., Papuga, J., Rosenthal, J., Mára, V., Beránek, L., 2023, Energy-based method for analyzing fatigue properties of additively manufactured AlSi10Mg. Journal of Mechanical Science and Technology, vol. 37. https://doi.org/10.1007/s12206-022 2110-6. Kohout, J. , Věchet , S., 2001, A new function for fatigue curves characterization and its multiple merits. International Journal of Fatigue, vol. 23:175-183. https://doi.org/10.1016/S0142-1123(00)00082-7. Haibach, E., 2006, Betriebsfestigkeit Verfahren und Daten zur Bauteilberechnung. 3rd rev. ed. Springer, 2006. ISBN 978-3540293637. La Rosa G., 2000, Thermographic methodology for rapid determination of the fatigue limit of materials and mechanical components. International Journal of Fatigue, vol. 22, 65-73. https://doi.org/10.1016/S0142-1123(99)00088-2. Fargione G., 2001, Rapid determination of the fatigue curve by the thermographic method. International Journal of Fatigue, vol. 24:11-19. https://doi.org/10.1016/S0142-1123(01)00107-4. Luong, M., 1998, Fatigue limit evaluation of metals using an infrared thermographic technique. Mechanics of Materials vol. 28, 155-163, https://doi.org/10.1016/S0167-6636(97)00047-1 Amiri, M., Khonsari, M.M., 2010, Rapid determination of fatigue failure based on temperature evolution: Fully reversed bending load. International Journal of Fatigue. 2010, vol. 32, 382-389. https://doi:10.1016/j.ijfatigue.2009.07.015 Matušů , M., Papuga, J. , Mžourek , M., 2022, Fatigue strength estimation of 42CrMo4 QT from the temperature evolution during cyclic loading. Procedia Structural Integrity, vol. 42:102-109. https://doi.org/10.1016/j.prostr.2022.12.012. Wang, X.G., Crupi, V., et al., 2017, Energy-based approach for fatigue life prediction of pure copper. International Journal of Fatigue. 2017, vol. 104, 243-250. https://doi:10.1016/j.ijfatigue.2017.07.025 Papuga, J., Mžourek, M., Matušů, M., Mára, M., and Čapek, J., 2023, Investigation of the size effect on 42CrMo4 QT steel in the high-cycle fatigue domain part I: Experimental campaign. International Journal of Fatigue vol.175. https://doi:10.1016/j.ijfatigue.2023.107743