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. 5. Metallographic examinations in the longitudinal direction, inner region of the specimen gauge length, (a) baseline , (b) A1, and (c) A2 process parameters set, respectively

3.2. Surface roughness measurement The measurements of the surface roughness carried out by the profilometer and by the extraction of the specimen profile along the longitudinal direction show the same trend both for the arithmetical mean deviation of the assessed profile ( R a ), Fig. 6 (a) and for the maximum height of the profile ( R z ), Fig. 6 (). The A1 and A2 sets markedly increase the surface roughness, as they produce an undulation in the specimen profile that results in a stack of larger rings and steep valleys, acting a severe notch and causing an important stress concentration. The results obtained from the specimen profile are constantly greater than the ones measured by the profilometer, with the greater relative difference when the roughness is greater, suggesting that the step valleys typical of the SLM process in the A1 and A2 conditions are better investigated by the detailed investigation of the specimen profile.

Fig. 6. Surface roughness measurement, black and gray columns represent data extracted by longitudinal sections and profilometer, respectively