Dissertation/Thesis Abstract

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Fatigue Behavior and Microstructure of Direct Laser Deposited Inconel 718 Alloy
by Johnson, Alexander Scott, M.S., Mississippi State University, 2017, 75; 10267788
Abstract (Summary)

Inconel 718 is a nickel-based superalloy with a series of superior properties, such as high strength, creep-resistance, and corrosion-resistance. Additive manufacturing (AM) is appealing to Inconel 718 because of its near-net-shape production capability to circumvent poor machinability. However, AM parts are prone to detrimental porosity, reducing their fatigue resistance. Thus, further understanding of AM fatigue behavior is required before widespread industrial use. The microstructural and fatigue properties of heat treated AM Inconel 718, produced using Laser Engineered Net Shaping (LENS™), are evaluated at room and elevated temperatures. Fully reversed, strain-controlled fatigue tests were performed on cylindrical specimens at strain amplitudes of 0.001 to 0.01 mm/mm. Fracture surfaces were inspected using a scanning electron microscope (SEM). Heat treatment caused initial dendritic microstructure to mostly re-form into an equiaxed grain structure. AM specimens experienced reduced fatigue life in testing as compared to wrought material due to inclusions or pores near the surface.

Indexing (document details)
Advisor: Stone, Tonya W., Shamsaei, Nima
Commitee: Doude, Haley R., Priddy, Matthew W.
School: Mississippi State University
Department: Mechanical Engineering
School Location: United States -- Mississippi
Source: MAI 56/04M(E), Masters Abstracts International
Source Type: DISSERTATION
Subjects: Mechanical engineering
Keywords: Additive manufacturing, Fatigue, Inconel 718, Microstructure
Publication Number: 10267788
ISBN: 9781369706222
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