Tensile and Fatigue Behavior of Direct Metal Laser Sintered (DMLS) Inconel 718

In the rapidly growing field of additive manufacturing (AM), the focus in recent years has shifted from prototyping to manufacturing fully functional, end-use parts, particularly using metals. In order for these parts to be designed to function both safely and effectively, it is necessary to have a thorough understanding of the mechanical behavior of materials produced via the AM process.This research focuses on characterizing Inconel 718 produced via the Direct Metal Laser Sintering (DMLS) process. Specimens from three orthogonal build orientations were tested as both machined and as-fabricated specimens. Surface roughness was evaluated using non-contact profilometry. Tensile testing was performed in order to characterize material yield strength. Finally, high cycle fatigue (HCF) testing was conducted on a rotating beam apparatus.Results show that the measured elastic modulus of the as-fabricated material was 162.7 GPa for the in-plane build orientation and 72.1 GPa for the vertical build orientation. In addition, the measured fatigue strength of horizontal build orientations was greater than that of specimens built in a vertical orientation. Furthermore, it was found that the fatigue lives of the machined specimens were at least 7 times greater than those of as-fabricated specimens.Copyright © 2015 by ASME