PSI - Issue 53

S. Leonardi et al. / Procedia Structural Integrity 53 (2024) 327–337

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S. Leonardi et al. / Structural Integrity Procedia 00 (2023) 000–000

Fig. 4. Results of the topological analysis onto the Inconel 625 cellular test samples: (a-c) optical micrographs and probability distributions of the pore aspect ratio (d-f) and radius (g-i). The mean value µ and the standard deviation σ are also reported. Specifically, (a,d,g), (b,e,h) and (c,f,i) correspond respectively to the experimental micrograph and the resulting topological descriptors for test samples In-30, In-40 and In-50 in Table 4. For porous architectures designed to contain equisized circular pores, the nominal pore radius is highlighted with a dotted red line. Scale bar : 3mm.

Notably, they show that this additive manufacturing process results into topological pore features that may di ff er, both in size and shape, from those designed numerically. In this study, the geometrical mismatch between the as-designed and as-manufactured pores is quantified in terms of two main topological descriptors, i.e. the pore ellipticity and average radius. Interestingly, comparing pairwise AlSi10Mg and Inconel 625 test samples corresponding to identical numerical models (i.e. Figure 3e,h with Figure 4d,g, and Figure 3f,i with Figure 4e,h) reveals that the use of a single laser contour produces pores whose average radius is closer to its nominal as-designed value, which is indicated with a dotted red line in Figures 3,4. On the other hand, when two contours are employed to manufacture the test samples, the manufactured pores are found to be several tens of µ m smaller then the target value (see Figures 4g,h). While this observed di ff erence is likely to depend also on other factors (such as, e.g., the base metallic powder and the value of the energy density), our results confirm the findings of a recent study investigating the role of the contour strategy on the geometrical accuracy of cellular lattices produced by LPBF (Vra´na et al. (2022)). Likewise, it is reasonable to expect that the observed pore downsizing has a direct implication on the total (geometrical) porosity of the Inconel 625 printed parts. Figure 5a confirms this intuition. Notably, it gives a comparison between the amount of internal porosity featured by the numerical model (Table 1) with that measured onto the LPBF-manufactured test samples. It