Issue 77

S. Spiller et alii, Fracture and Structural Integrity, 77 (2026) 386-404; DOI: 10.3221/IGF-ESIS.77.22

present work, the majority of the failures initiated from surface defects. In particular, a very frequent crack initiation point (5 cases observed, which means less than 30% of the total number of failed specimens) was located at one of the bottom corners of the specimens. Those significantly deformed corners presented an acute angle, and thus are believed to act as major stress intensifiers. The deformation was probably caused by different factors: first, the bottom layers must bear the weight of the part during printing, which provokes a relaxation of the bottom parts, a defect usually referred to as elephant foot [28]. Moreover, due to the constant contact with the warm printing platform, the first layers have a more intense thermal history. Thus, the bottom part of a print is generally exposed to high temperatures for longer times, both during the printing and during the sintering process, and this condition favors the deformation.

Figure 9: Fractography analysis of the smooth specimens. S1-2: SEM image of the whole fracture surface a) and crack initiation point a1), morphological IFM image b). S1-4: images c), c1), and d), same description as S1-2. Following: SEM images of the whole fracture surfaces and magnifications for S3-3 e), and e1); S3-6 f), f1), and f2); S5-4 g) and g1).

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