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Neutron interferometry detection of early crack formation caused by bending fatigue in additively manufactured SS316 dogbones

Authors :
Daniel S. Hussey
Shengmin Guo
Ali Haghshenas
Michael M. Khonsari
Adam J. Brooks
Caroline G. Lowery
Leslie G. Butler
David L. Jacobson
Jumao Yuan
Jacob M. LaManna
Hong Yao
Nikolay Kardjilov
Source :
Materials & Design, Vol 140, Iss, Pp 420-430 (2018)
Publication Year :
2018
Publisher :
Elsevier BV, 2018.

Abstract

Fatigue in selective laser melted (SLM) and conventionally manufactured stainless steel (SS) 316 dogbones was studied with neutron imaging methods for attenuation, diffraction, and scattering. Neutron attenuation tomography and Bragg edge imaging did not reveal crack formation. Conversely, to efficiently detect the microcrack evolution, two methods of grating-based neutron interferometry, Talbot-Lau and far-field, were employed. Both interferometry methods detect early crack formation via the dark-field (scattering) images, especially for porous microstructures in the range of 0.6 μm to 2 μm. The dark-field image combines sensitivity to micrometer-sized scattering centers at crack formation with sub-millimeter imaging resolution. The crack formation observed with neutron interferometry dark-field was validated post-imaging with additional fatigue cycles to fracture. Further inspection was performed by scanning electron microscopy (SEM) and optical photography. In the two fatigued dogbones, SLM and conventional crack formation was identified to within 1 mm. Keywords: Additive manufacturing, Neutron interferometry, Bragg edge spectroscopy, Fatigue

Details

ISSN :
02641275
Volume :
140
Database :
OpenAIRE
Journal :
Materials & Design
Accession number :
edsair.doi.dedup.....01fdc3c3dda745734e266457c62ba60d
Full Text :
https://doi.org/10.1016/j.matdes.2017.12.001