Fatigue Behavior of Direct Metal Laser Sintered (DMLS) Inconel 718
Abstract: 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 pr... read moreocess. This research focused on characterizing the
high cycle fatigue (HCF) behavior of Inconel 718 produced via the Direct Metal Laser
Sintering (DMLS) process. Material anisotropy in three orthogonal build orientations was
evaluated along with the influence of the as-fabricated surface quality on fatigue
performance. In addition to fatigue testing, surface roughness characterization, tensile
testing, and fractography were performed on the additive manufactured specimens.
Measured fatigue strength of specimens built in horizontal orientations was found to be
greater than that of specimens built in the vertical orientation. Furthermore, fatigue
lives of specimens with a machined surface were significantly greater (10 to nearly 1000
times) than those of specimens left as-fabricated by the DMLS process. Results showed
that specimens produced in an optimal build orientation for the particular loading
condition and with improved surface quality via machining correlated well with published
fatigue data for traditionally processed and polished Inconel 718
Thesis (M.S.)--Tufts University, 2016.
Submitted to the Dept. of Mechanical Engineering.
Advisor: Anil Saigal.
Committee: Gary Leisk, and Anthony DiCarlo.
Keyword: Mechanical engineering.read less