Date of Completion

5-7-2016

Embargo Period

5-6-2017

Advisors

Dr. Mark Aindow, Dr. Bi Zhang, Dr. Vito Moreno

Field of Study

Mechanical Engineering

Degree

Master of Science

Open Access

Campus Access

Abstract

Laser powder bed melting process is an additive manufacturing process that uses laser beam energy to melt metallic powder particles in a powder bed and form a desired shape. This process is being adapted by aerospace industry, specifically for high strength, high temperature materials such as Inconel and titanium used in high temperature applications such as jet engines. However, there are countless variables that could affect the final quality of the parts including microstructure, defect density and final mechanical strength. Laser power and laser speed have been found to be most important parameters in these processes. In order to examine the microstructure evolution caused by varying these process parameters and ultimately improve parts manufactured in this way, a systematic experiment is designed (DoE) and implemented on the process in which laser power and speed are varied at multiple levels to fabricate line scans of Inconel 718. DoE contained 24 runs of single block specimens, each containing 10 scanned lines. Extensive and systematic microstructural analysis are conducted on these specimens including measurement of melt pool dimensions, a qualitative analysis on line quality, and analysis of grain size and orientations using electron backscatter diffraction analysis to relate the process parameters to the final microstructure. Statistical analysis is conducted to quantitatively relate the results to the main effect of the initial process parameters and detect distinguishable trend.

Major Advisor

Dr. Leila Ladani

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