PSI - Issue 37

G. Macoretta et al. / Procedia Structural Integrity 37 (2022) 632–643 G. Macoretta, B. D. Monelli / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 10. Fractographic examinations: (a) baseline , (b) A1 , (c) A2 process parameters set.

4. Conclusions On the basis of an analytical model of the feasible region for the process parameters adopted for the SLM of the alloy Inconel 718, two sets of process parameters aimed to increase the productivity rate were selected, A1 and A2 , featuring a different combination of laser power, scan velocity and hatch distance. The layer thickness was kept constant, to preserve the nominal resolution printing process. An experimental assessment of the effects produced by the devised parameters on the material microstructure, surface roughness, and fatigue behavior was carried out by using vertically built round specimens in the as-built condition. Despite the increase in the material porosity and surface roughness, the fatigue strength of the specimens produced by adopting the parameters A1 and A2 resulted to be lower but comparable to the baseline value, defined as the standard process parameters adopted in the literature. The best results were obtained for the A2 set, which features the higher meltpool aspect ratio. Further analyses will focus on the fatigue behavior of aged specimens, featuring a higher notch sensitivity. Acknowledgements The authors wish to thank Eng. Randa Anis Ishak Nakhla for the contribution to the SEM investigations, Mr. Roberto Minelli for the mechanical tests, and Mr. Flavio Antonelli for the specimen machining. References Agazhanov, A. S., Samoshkin, D. A., & Kozlovskii, Y. M. (2019). Thermophysical properties of Inconel 718 alloy. Journal of Physics: Conference Series, 1382(1). https://doi.org/10.1088/1742-6596/1382/1/012175 Clymer, D. R., Cagan, J., & Beuth, J. (2017). Power-velocity process design charts for powder bed additive manufacturing. Journal of Mechanical Design, Transactions of the ASME, 139(10), 1 – 7. https://doi.org/10.1115/1.4037302 Guo, C., Li, S., Shi, S., Li, X., Hu, X., Zhu, Q., & Ward, R. M. (2020). Effect of processing parameters on surface roughness, porosity and cracking of as-built IN738LC parts fabricated by laser powder bed fusion. Journal of Materials Processing Technology, 285(December 2019), 116788. https://doi.org/10.1016/j.jmatprotec.2020.116788 Mendez, P. F., Lu, Y., & Wang, Y. (2018). Scaling analysis of a moving point heat source in steady-state on a semi-infinite solid. Journal of Heat Transfer, 140(8), 1 – 9. https://doi.org/10.1115/1.4039353 Moda, M. (2021). Modeling of Powder Bed Fusion Additive Manufacturing [University of Pisa]. https://doi.org/10.13131/etd/03092021-124517 Montgomery, C., Beuth, J., Sheridan, L., & Klingbeil, N. (2020). Process mapping of Inconel 625 in laser powder bed additive manufacturing. Proceedings - 26th Annual International Solid Freeform Fabrication Symposium - An Additive Manufacturing Conference, SFF 2015, 1195 – 1204.