Evidence for contributions of lack-of-fusion defects and dislocations to acoustic nonlinearity and loss in additively manufactured aluminum

Published

February 2, 2024

Author(s)

Ward L. Johnson, Paul R. Heyliger, Jake Benzing, Orion Kafka, Newell Moser, Derek Harris, Jeremy Iten, Nik Hrabe

Abstract

Resonant acoustic nonlinearity and loss have previously been found to be correlated with porosity in additively manufactured (AM) commercially pure aluminum and stainless steel, and this effect offers a potential basis for rapid nondestructive qualification of AM metal parts with complex geometries in industrial settings. This study explores possible physical mechanisms for this correlation and its observed anisotropy, using a combination of measurements and modeling. Acoustic anisotropy and porosity dependence are characterized with nonlinear reverberation spectroscopy (NRS) and Ritz modeling of resonant modes that would be degenerate in isotropic material. Information on pore geometries, crystallographic texture, and densities of geometrically necessary dislocations (GNDs) is obtained from Xray-CT and SEM-based measurements. The results are consistent with two physical mechanisms dominating the acoustic nonlinearity and loss in this material: 1) an anisotropic and porosity-dependent mechanism involving hysteretic motion within lack-of-fusion defects under acoustic stress and 2) bulk dislocation nonlinearity/anelasticity that is approximately independent of porosity.

Citation

Ndt & E International

Issue

143

Pub Type

Journals

Download Paper

https://doi.org/10.1016/j.ndteint.2024.103068

Local Download

Keywords

Additively manufactured aluminum, Anisotropy, Acoustic nonlinearity and anelasticity, Ritz vibrational analysis, X-ray computed tomography, Electron backscatter diffraction

Citation

Johnson, W. , Heyliger, P. , Benzing, J. , Kafka, O. , Moser, N. , Harris, D. , Iten, J. and Hrabe, N. (2024), Evidence for contributions of lack-of-fusion defects and dislocations to acoustic nonlinearity and loss in additively manufactured aluminum, Ndt & E International, [online], https://doi.org/10.1016/j.ndteint.2024.103068, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=956721 (Accessed October 10, 2025)