PSI - Issue 8

Gianni Nicoletto / Procedia Structural Integrity 8 (2018) 184–191 Author name / Structural Integrity Procedia 00 (2017) 000–000

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data are close confirming that the proposed approach using mini specimens yield representative results and it can be used for investigating the many process, material and finishing parameters involved in the SLM technology.

Fig. 6. Fatigue curves for DMLS Ti-6Al-4V for two specimen geometries.

4.2. Surface finish factor The fist influence factor on fatigue behavior is the surface finish: from as-built, to manual grinding to machining. The unnotched fatigue behavior of two sets of Type C specimens is shown in Fig. 6. Manual grinding using Emery papers of different grits has a significant effect on fatigue where the respective fatigue curves are separated by a sizable and uniform increment of about 60 % of the manually ground surface data with respect to the as-built surface data. The manual processing removed the rough surface layer of unmelted particles, typical of as-built conditions, Konečná et al. (2017).

Fig. 7. Fatigue curves of Type C specimens in as-built and in manually ground conditions (R = -1). Rotating bending test results of machined specimens are also included.