PSI - Issue 38

Hugo Roirand et al. / Procedia Structural Integrity 38 (2022) 149–158 Author name / Structural Integrity Procedia 00 (2021) 000 – 000

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Fig. 7. SEM fracture surface analysis observed on (a) SLM_SR specimen (280 MPa), (b) SLM_Chess specimen (120 MPa), (d) Orlas specimen (180 MPa) . On (c), a secondary crack initiating from persistent slip band on SLM_Rot specimen (340 MPa). 4. Conclusion This paper aim was to characterize the influence of laser scan strategy on microstructure, defects, monotonic and fatigue behaviour. Following conclusions can be drawn : • The microstructure is influenced by the laser scan pattern as it modifies the thermal heat flux/gradients • A probably too thin overlap between islands of chessboard strategy generated many lacks of fusion, which are damaging for fatigue resistance. • For meander pattern strategies, the effect of rotations between layers has been investigated. Rotations remove the fine and elongated grains and they modify. They also multiply the number of small gas pores. • The consequences of these microstructural and defect results, are that the fatigue behaviour is the same for meander materials built with or without rotations between layers. It has been demonstrated that the choice of laser scan strategy must be done very consciously. This choice affect the microstructure, the defect distribution and so it could have an impact on monotonic and fatigue properties. References Afkhami, S., Dabiri, M., Piili, H., Björk, T., 2021. Effects of manufacturing parameters and mechanical post-processing on stainless steel 316L processed by laser powder bed fusion. Materials Science and Engineering: A 802, 140660. https://doi.org/10.1016/j.msea.2020.140660 AMFG report, 2020. Andreau, O., 2019. Nocivité en fatigue et contrôle de défauts produits par fabrication additive. Thèse de doctorat, ENSAM, PIMM, Paris. Andreau, O., Koutiri, I., Peyre, P., Penot, J.-D., Saintier, N., Pessard, E., De Terris, T., Dupuy, C., Baudin, T., 2019a. Texture control of 316L parts by modulation of the melt pool morphology in selective laser melting. Journal of Materials Processing Technology 264, 21 – 31. https://doi.org/10.1016/j.jmatprotec.2018.08.049 Andreau, O., Pessard, E., Koutiri, I., Penot, J.-D., Dupuy, C., Saintier, N., Peyre, P., 2019b. A competition between the contour and hatching