Investigation of the microstructure of additively manufactured Inconel 738LC
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Date
2020-05
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Publisher
The Ohio State University
Abstract
Additive manufacturing (AM) offers fast, customizable, near-net production of metallic parts, especially when sophisticated part geometries are required. However, the microstructures of these AM parts often vary from those produced by traditional manufacturing, and AM structureprocessing relationships are not fully understood. Here, a sample of Inconel 738LC manufactured via electron beam melting powder bed fusion technique with a random electron beam scanning strategy is characterized to create a microstructural baseline of comparison for similarly printed samples and to establish a framework for the characterization of future samples. Optical microscopy, scanning electron microscopy, electron dispersive X-ray spectroscopy, and microhardness testing were used to analyze porosity, phase distributions, and mechanical strength. It was found that spherical pores, gamma prime (γ') precipitates, and heavy metal carbides were uniformly distributed within each build plane. Along the build direction, γ' precipitates were smaller and more monodisperse at the top compared to the bottom. The sample had a slightly lower hardness at the top. Carbide sizes remained unchanged throughout the build.
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Keywords
Additive Manufacturing, Inconel 738LC, Powder Bed Fusion, Electron Beam Melting, Characterization, Microscopy