SYMPOSIA PAPER Published: 05 June 2020
STP162020180111

Nondestructive Evaluation of Additive Manufactured Parts Using Process Compensated Resonance Testing

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Variations in build process parameters, post-processing parameters, and feedstock have a significant impact on the structural integrity and performance of components made with additive manufacturing (AM). Effective nondestructive testing (NDT) is critical for ensuring the structural integrity of components. Complex geometries, nonequilibrium microstructures, new process variables, and lack of clear accept or reject criteria for AM components present new challenges to NDT. Quantitative, volumetric NDT methods that can detect material defects of interest in complex geometries are required. Process compensated resonance testing (PCRT) is an NDT method that uses a swept sine input to excite the component's resonance modes of vibration. The resonance frequencies are recorded, analyzed statistically, and compared to acceptability limits established using a database of training components. The swept sine input excites whole-body vibrational modes in nearly any geometry, and the component's resonance frequencies correlate directly to its structural integrity. In this study, PCRT evaluations were performed on titanium alloy (Ti-6Al-4V) populations made with electron beam PBF and aluminum alloy (AlSi10Mg) populations made with laser PBF. The evaluations were conducted in support of ASTM round-robin testing. In the Ti-6Al-4V population, PCRT showed clear resonance frequency differences between nominal specimens and off-nominal specimens with defective material states. PCRT also quantified the effects of hot isostatic pressing (HIP). PCRT pass/fail NDT of the Ti-6Al-4V population in the pre-HIP and post-HIP states demonstrated 100% accuracy. Computed tomography scans of the post-HIP specimens showed no clear indications of porosity. Follow-up tensile testing of a subset of nominal and off-nominal specimens in the post-HIP state showed that the off-nominal specimens had lower yield stresses and ultimate tensile stresses than nominal specimens. In the AlSi10Mg population, PCRT detected differences between recycled and virgin feedstock powder. PCRT pass/fail NDT of AlSi10Mg specimens exposed to nominal and off-nominal heat treatment demonstrated 100% accuracy.

Author Information

Livings, Richard
Vibrant Corp., Albuquerque, NM, US
Biedermann, Eric
Vibrant Corp., Albuquerque, NM, US
Wang, Chen
Northrop Grumman Aerospace Systems, El Segundo, CA, US
Chung, Thomas
Northrop Grumman Aerospace Systems, El Segundo, CA, US
James, Steven
Aerojet-Rocketdyne, Newbury Park, CA, US
Waller, Jess
NASA-JSC White Sands Test Facility, Laboratories Dept., Las Cruces, NM, US
Volk, Scott
Incodema3D, Freeville, NY, US
Krishnan, Ajay
Incodema3D, Freeville, NY, US
Collins, Shane
Additive Industries North America, Inc.,, Camarillo, CA, US
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Details
Developed by Committee: F42
Pages: 165–205
DOI: 10.1520/STP162020180111
ISBN-EB: 978-0-8031-7687-4
ISBN-13: 978-0-8031-7686-7