Build orientation, surface roughness, and scan path influence on the microstructure, mechanical properties, and flexural fatigue behavior of Ti–6Al–4V fabricated by electron beam melting

Andrew H. Chern; Peeyush Nandwana; Robert McDaniels; Ryan R. Dehoff; Peter K. Liaw; Robert Tryon; Chad E. Duty

doi:10.1016/j.msea.2019.138740

Build orientation, surface roughness, and scan path influence on the microstructure, mechanical properties, and flexural fatigue behavior of Ti–6Al–4V fabricated by electron beam melting

Andrew H. Chern, Peeyush Nandwana, Robert McDaniels, Ryan R. Dehoff, Peter K. Liaw, Robert Tryon, Chad E. Duty

Research output: Contribution to journal › Article › peer-review

55 Scopus citations

Abstract

In the present work, microstructure and fatigue behavior of Electron Beam Melted (EBM) Ti–6Al–4V have been systematically studied. Fatigue behavior was investigated using four-point bend tests of rectangular bars with internal features fabricated with different build orientations, scan paths, and surface conditions. Microstructural variations were evaluated by optical microscopy and Vickers micro-hardness indentations, both of which were found to be consistent throughout the build and within ranges reported in the literature. The fatigue performance of the EBM material was comparable to wrought Ti–6Al–4V when the loading direction was parallel to the build direction, but severely limited when loaded perpendicular to the build direction or if surface roughness defects were present. Scanning electron microscopy and interrupted fatigue tests were utilized to characterize fracture surfaces, failure mechanisms, crack initiation, and propagation behavior. Crack initiation sites in the vertically-oriented specimens were identified to be melt-related defects formed by insufficient melting.

Original language	English
Article number	138740
Journal	Materials Science and Engineering: A
Volume	772
DOIs	https://doi.org/10.1016/j.msea.2019.138740
State	Published - Jan 20 2020

Funding

Research partially sponsored by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office, under contract DE-AC05-00OR22725 with UT-Battelle, LLC. Research also supported by the Department of the Navy in partnership with VEXTEC. We gratefully acknowledge the support provided through the Navy contract N68335-16-C-0256 and the technical collaboration with Kishan Goel, Madan Kittur, Alan Timmons of NavAir. We would also like to thank Sean Yoder and Dr. Michael M. Kirka of the Manufacturing Demonstration Facility at Oak Ridge National Laboratory for technical expertise, in addition to Zane Palmer and Dr. John Dunlap of the University of Tennessee-Knoxville. Research partially sponsored by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office , under contract DE-AC05-00OR22725 with UT-Battelle, LLC. Research also supported by the Department of the Navy in partnership with VEXTEC. We gratefully acknowledge the support provided through the Navy contract N 68335-16-C-0256 and the technical collaboration with Kishan Goel, Madan Kittur, Alan Timmons of NavAir. We would also like to thank Sean Yoder and Dr. Michael M. Kirka of the Manufacturing Demonstration Facility at Oak Ridge National Laboratory for technical expertise, in addition to Zane Palmer and Dr. John Dunlap of the University of Tennessee-Knoxville.

Keywords

Defects
Electron beam melting
Fatigue
Surface roughness
Titanium

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This output contributes to the following UN Sustainable Development Goals (SDGs)

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10.1016/j.msea.2019.138740

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Chern, A. H., Nandwana, P., McDaniels, R., Dehoff, R. R., Liaw, P. K., Tryon, R., & Duty, C. E. (2020). Build orientation, surface roughness, and scan path influence on the microstructure, mechanical properties, and flexural fatigue behavior of Ti–6Al–4V fabricated by electron beam melting. Materials Science and Engineering: A, 772, Article 138740. https://doi.org/10.1016/j.msea.2019.138740

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title = "Build orientation, surface roughness, and scan path influence on the microstructure, mechanical properties, and flexural fatigue behavior of Ti–6Al–4V fabricated by electron beam melting",

abstract = "In the present work, microstructure and fatigue behavior of Electron Beam Melted (EBM) Ti–6Al–4V have been systematically studied. Fatigue behavior was investigated using four-point bend tests of rectangular bars with internal features fabricated with different build orientations, scan paths, and surface conditions. Microstructural variations were evaluated by optical microscopy and Vickers micro-hardness indentations, both of which were found to be consistent throughout the build and within ranges reported in the literature. The fatigue performance of the EBM material was comparable to wrought Ti–6Al–4V when the loading direction was parallel to the build direction, but severely limited when loaded perpendicular to the build direction or if surface roughness defects were present. Scanning electron microscopy and interrupted fatigue tests were utilized to characterize fracture surfaces, failure mechanisms, crack initiation, and propagation behavior. Crack initiation sites in the vertically-oriented specimens were identified to be melt-related defects formed by insufficient melting.",

keywords = "Defects, Electron beam melting, Fatigue, Surface roughness, Titanium",

author = "Chern, {Andrew H.} and Peeyush Nandwana and Robert McDaniels and Dehoff, {Ryan R.} and Liaw, {Peter K.} and Robert Tryon and Duty, {Chad E.}",

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doi = "10.1016/j.msea.2019.138740",

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Chern, AH, Nandwana, P, McDaniels, R, Dehoff, RR, Liaw, PK, Tryon, R & Duty, CE 2020, 'Build orientation, surface roughness, and scan path influence on the microstructure, mechanical properties, and flexural fatigue behavior of Ti–6Al–4V fabricated by electron beam melting', Materials Science and Engineering: A, vol. 772, 138740. https://doi.org/10.1016/j.msea.2019.138740

Build orientation, surface roughness, and scan path influence on the microstructure, mechanical properties, and flexural fatigue behavior of Ti–6Al–4V fabricated by electron beam melting. / Chern, Andrew H.; Nandwana, Peeyush; McDaniels, Robert et al.
In: Materials Science and Engineering: A, Vol. 772, 138740, 20.01.2020.

Research output: Contribution to journal › Article › peer-review

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T1 - Build orientation, surface roughness, and scan path influence on the microstructure, mechanical properties, and flexural fatigue behavior of Ti–6Al–4V fabricated by electron beam melting

AU - Chern, Andrew H.

AU - Nandwana, Peeyush

AU - McDaniels, Robert

AU - Dehoff, Ryan R.

AU - Liaw, Peter K.

AU - Tryon, Robert

AU - Duty, Chad E.

PY - 2020/1/20

Y1 - 2020/1/20

N2 - In the present work, microstructure and fatigue behavior of Electron Beam Melted (EBM) Ti–6Al–4V have been systematically studied. Fatigue behavior was investigated using four-point bend tests of rectangular bars with internal features fabricated with different build orientations, scan paths, and surface conditions. Microstructural variations were evaluated by optical microscopy and Vickers micro-hardness indentations, both of which were found to be consistent throughout the build and within ranges reported in the literature. The fatigue performance of the EBM material was comparable to wrought Ti–6Al–4V when the loading direction was parallel to the build direction, but severely limited when loaded perpendicular to the build direction or if surface roughness defects were present. Scanning electron microscopy and interrupted fatigue tests were utilized to characterize fracture surfaces, failure mechanisms, crack initiation, and propagation behavior. Crack initiation sites in the vertically-oriented specimens were identified to be melt-related defects formed by insufficient melting.

AB - In the present work, microstructure and fatigue behavior of Electron Beam Melted (EBM) Ti–6Al–4V have been systematically studied. Fatigue behavior was investigated using four-point bend tests of rectangular bars with internal features fabricated with different build orientations, scan paths, and surface conditions. Microstructural variations were evaluated by optical microscopy and Vickers micro-hardness indentations, both of which were found to be consistent throughout the build and within ranges reported in the literature. The fatigue performance of the EBM material was comparable to wrought Ti–6Al–4V when the loading direction was parallel to the build direction, but severely limited when loaded perpendicular to the build direction or if surface roughness defects were present. Scanning electron microscopy and interrupted fatigue tests were utilized to characterize fracture surfaces, failure mechanisms, crack initiation, and propagation behavior. Crack initiation sites in the vertically-oriented specimens were identified to be melt-related defects formed by insufficient melting.

KW - Defects

KW - Electron beam melting

KW - Fatigue

KW - Surface roughness

KW - Titanium

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Build orientation, surface roughness, and scan path influence on the microstructure, mechanical properties, and flexural fatigue behavior of Ti–6Al–4V fabricated by electron beam melting

Abstract

Funding

Keywords

UN SDGs

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