PSI - Issue 43

Tibor Varmus et al. / Procedia Structural Integrity 43 (2023) 184–189 Tibor Varmus / Structural Integrity Procedia 00 (2022) 000 – 000

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Fig. 4. S-N curves of as-built specimens compared to polished specimens.

4. Conclusions The investigation of microstructure, as-built surface characteristics and directional fatigue performance of as-built L-PBF Al2024-RAM2 alloy after T6 heat treatment provided the following results: • The microstructure is characterized by coarse and fine grain regions of α -Al phase with ceramic nanoparticles based on Ti and La, and alloying elements Cu, Mg, Mn, distributed in both fine and coarse grains. • Surface roughness on as-built specimens is dependent on their orientation during L-PBF building. It ranged from Rz = 34.1 ± 7 µm (the worst case is specimen orientation C) to Rz = 5. 7 ± 3 µm (the best case for specimen orientation A-). • The fatigue behavior (for loading with R = 0) of specimens with as-built surfaces is only slightly influenced by the building orientation. The highest fatigue strength of 120 MPa (for the fatigue life 2 x10 6 cycles) was found for specimen orientation A- and the lowest, about 100 MPa, for specimen with C orientation. • Hand polishing of the specimen surface resulted in the considerable improvement of the fatigue strength to about 200 MPa. Acknowledgements The authors acknowledge the company BEAM-IT srl, Fornovo Taro, Italy for providing the specimens and the VEGA grant agency for partial support by the grant No. 1/0463/19. References Kumar M., Gibbons G. J, Das A., Manna I., Tanner D., Kotadia H. R., 2021, Additive manufacturing of aluminium alloy 2024 by laser powder bed fusion: microstructural evolution, defects and mechanical properties, Rapid Prototyping Journal, Vol. 27 No. 7, pp. 1388-1397 Mair, P., Goettgens, V. S., Rainer T., Weinberger N., Letofsky-Papst I., Mitsche S., Leichtfried G., 2021, Laser powder bed fusion of nano-CaB6 decorated 2024 aluminum alloy, Journal of Alloys and Compounds, Volume 863, 158714. Tan Q., Zhang J., Sun Q., Fan Z., Li G., Yin Y., Liu Y., Zhang M.X., 2020, Inoculation treatment of an additively manufactured 2024 aluminium alloy with titanium nanoparticles, Acta Mater. 196, pp. 1 – 16. FIA, 2022, 2022 Formula one sporting regulations, information on: https://www.fia.com/sites/default/files/formula_1_-_sporting_regulations_- _2022_-_iss_4_-_2022-02-18.pdf. Nicoletto, G., Anisotropic high cycle fatigue behavior of Ti – 6Al – 4V obtained by powder bed laser fusion, International Journal of Fatigue, 94, 2017, pp. 255 – 262. Gu, T., Chen, B., Tan, C. and Feng, J., 2019, Microstructure evolution and mechanical properties of laser additive manufacturing of high strength Al-Cu-Mg alloy, Optics & Laser Technology, Vol. 112, pp. 140-150. Information on https://www.elementum3d.com, Sep. 2022.