PSI - Issue 48

America Califano et al. / Procedia Structural Integrity 48 (2023) 238–243

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Califano et al / Structural Integrity Procedia 00 (2019) 000 – 000

Fig. 6. Crack-growth curve after pre-cracking for specimen n. 2 (red curve) and specimen n. 5 (blue curve).

Conclusions In this work, preliminary evaluations about the crack growth behaviour of AM 17-4 PH stainless steel were carried out. In particular, four standard C(T) specimens, manufactured through Selective Laser Melting, were equipped with a back-face strain gauge and two crack gauges each, and subjected to fatigue tests. Data from crack-gauges and strain gauge were calibrated by means of the Newman-Johnston back-face compliance equation in order to determine the Young’s modulus of the final printed material. In addition, metallographic analyses were carried out on a full specimen and showed different surface characteristics based on the considered plane, highlighting the dependence of the macrostructure from the building direction chosen for the manufacturing phase. Among the tested specimens, two of them, characterized by a different crack orientation, were selected for the results discussion. The crack-length vs. number of cycles curves highlighted that the two selected specimens have almost-overlapping crack-growth behaviour and number of cycles to failure, thus emphasizing that, in the considered cases, the selected material is barely affected by the crack orientation. References Afkhami, S., Dabiri, M., Alavi, S.H., Björk, T., Salminen, A., 2019. Fatigue characteristics of steels manufactured by selective laser melting. International Journal of Fatigue 122, 72 – 83. Alfieri, V., Giannella, V., Caiazzo, F., Sepe, R., 2022. Influence of position and building orientation on the static properties of LPBF specimens in 17-4 PH stainless steel. Forces in Mechanichs 8, 100108. ASTM E647-15e1, Standard Test Method for Measurement of Fatigue Crack Growth Rates, ASTM International, West Conshohocken, PA, 2015. Caiazzo, F., Alfieri, V., 2021. Optimization of laser beam welding of steel parts made by additive manufacturing. International Journal of Advanced Manufacturing Technology 114, 3123 – 3136. Foti, P., Razavi, M. J. S., Fatemi, A., Berto, F., 2023. Multiaxial fatigue of additively manufactured metallic components: A review of the failure mechanisms and fatigue life prediction methodologies. Progress in Materials Science 137, 101126. Gibson, I., Rosen, D., Stucker, B., Khorasani, M., 2021. Additive Manufacturing Technologies . Springer Nature Switzerland AG. Karakaş, Ö., Kardeş, F.B., Foti, P., Berto, F., 2023. An overview of factors affecting high-cycle fatigue of additive manufacturing metals. Fatigue and Fracture of Engineering Materials and Structures 46(5), 1649 – 1668. De Luca, A., Lamanna, G., Caputo, F., Borrelli, R., Franchitti, S., Pirozzi, C., Sepe, R., 2021. Effects of the Surface Finish on Thin Specimens Made by Electron Beam Melting Technology. Macromolecular Symposia 396(1). Newman, J.C.,Yamada, Y., James, M.A., 2011. Back-face strain compliance relation for compact specimens for wide range in crack lengths. Engineering Fracture Mechanics 78(15), 2707 – 2711. Sepe, R., Franchitti, S., Borrelli, R., Di Caprio, F., Armentani, E., Caputo, F., 2020. Correlation between real geometry and tensile mechanical behaviour for Ti6Al4V electron beam melted thin specimens. Theoretical and Applied Fracture Mechanics 107(1), 102519. Sepe, R., Giannella, V., Alfieri, V., Caiazzo, F., 2021. Static and fatigue behavior of laser welded additively manufactured 17-4 PH steel plates. Procedia Structural Integrity 34, 172 – 177. Sepe, R., De Luca, A., Giannella, V., Borrelli, R., Franchitti, S., Di Caprio, F., Caputo, F., 2022. Influence of dimension, building position, and orientation on mechanical properties of EBM lattice Ti6Al4V trusses. International Journal of Advanced Manufacturing Technology 122(7 – 8), 3183 – 3198.