Abstract
Excellent weldability and high temperature stability make Inconel 718 (IN718) one of the most desired alloys to be produced by additive manufacturing (AM). Within the flourishing field of AM technology, laser powder bed fusion (LPBF) is a popular prospective candidate capable of fabricating complex and near net-shape engineering components that traditional manufacturing methods cannot accomplish. In this study, the effects of processing parameters on the relative density and microstructure was investigated. Gas atomized IN718 powders were used to fabricate cuboidal specimens via LPBF for metallographic characterization. The specimens were printed with independently varied laser power (125 - 350 W), laser scan speed (200 - 2200 mm/s), and laser scan rotation (0 - 90 degrees). Archimedes' method, optical microscopy, and scanning electron microscopy were employed to assess the influence of LPBF parameters on part density and microstructure, respectively. In general, relative density greater than 99.5% was achieved for a wide range of energy density between 50 and 100 J/mm^3. At higher laser powers, larger processing windows to produce high density parts were documented. Microstructural features including melt pool geometry, lack of fusions defects, keyhole porosity, and grain structure were examined and correlated to a wide range of LPBF parameters. The cellular microstructure within grains was observed to decrease with increasing laser scan speed. Based on the measurement of cellular structures and Rosenthal models, cooling rate in LPBF was estimated to be in the order of 10^5 - 10^7 K/s.
Notes
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Graduation Date
2020
Semester
Fall
Advisor
Sohn, Yongho
Degree
Master of Science in Materials Science and Engineering (M.S.M.S.E.)
College
College of Engineering and Computer Science
Department
Materials Science and Engineering
Degree Program
Materials Science and Engineering
Format
application/pdf
Identifier
CFE0008336; DP0023773
URL
https://purls.library.ucf.edu/go/DP0023773
Language
English
Release Date
12-15-2020
Length of Campus-only Access
None
Access Status
Masters Thesis (Open Access)
STARS Citation
Huynh, Thinh, "Parametric Investigation and Optimization for Inconel 718 Nickel-Based Superalloy in Laser Powder Bed Fusion" (2020). Electronic Theses and Dissertations, 2020-2023. 365.
https://stars.library.ucf.edu/etd2020/365