Predictability of elastic properties and density of 316L stainless steel manufactured by Selective-Laser-Melting

Ultrasonic investigations on 316L stainless steel manufactured by Selective-Laser-Melting (SLM) aimed to correlate elastic properties with fabrication parameters. In general, as a new technology matures, qualification is essential, especially when the technology is to be used remotely. In particular, accurate properties are required when designing prototypes. For the investigated sample set, laser power and scanning speed were varied systematically from 40 to 100 W, and 600 to 1200 mm/s, respectively. Resonant Ultrasound Spectroscopy and Pulse-Echo measurements were performed, complementarily. Numerical mode-analysis was also used to investigate the effect of void distribution, which was found inconsequential for most cases (except those of very low density). The extensive data allow for observations of specific characteristics in the elastic properties and microstructure as a function of deposited energy. Most importantly, the multi-variate data imply that standard volumetric energy density cannot be used to account for differences in the properties of the fabricated material. An effective volumetric energy density, which better accounts for the realistic non-adiabatic nature of the heating process of the melt pool, is adopted. In the new representation, the current and prior results from literature with different fabrication parameters can be compared, revealing a universal behavior of 316L produced through the SLM process. A Goldilocks region of predictability is identified.