Process Signature for Porosity-Dominant Fatigue Scattering of Materials Processed by Laser Fusion.

The functionality of load-bearing parts remains a central challenge for laser-powder bed fusion (L-PBF). However, the understanding and quantification of the process–quality–fatigue (P-Q-F) causal relationship are still lacking. The variable fatigue behavior is randomized by the PBF process variations and the subsequent quality uncertainty, e.g., random geometrical defects. In particular, the bulk literature is limited to gross fatigue fracture, while the fatigue initiation and development process is poorly understood due to the constraint of available online fatigue monitoring techniques. Addressing these challenges is critical to qualify L-PBF as a standard industrial process for fabricating load-bearing metal parts. From the scientific point of view, the effect of a wide range of porosity on fatigue performance is yet to be studied to understand the P-Q-F causal relationship even though low porosity more completely is desired in L-PBF parts. This work focuses on resonance-based fatigue testing of as-PBFed SS-316L material with random porosity. The results have shown that frequency and power are process signatures for fatigue initiation, development, and gross fracture. The porosity-induced fatigue life and fatigue limit scattering show normal distributions. [ABSTRACT FROM AUTHOR]