title: Porosity Measurements and Analysis for Metal Additive Manufacturing Process Control.
abstract: Additive manufacturing techniques can produce complex, high-value metal parts, with potential applications as critical metal components such as those found in aerospace engines and as customized biomedical implants. Material porosity in these parts is undesirable for aerospace parts - since porosity could lead to premature failure - and desirable for some biomedical implants - since surface-breaking pores allows for better integration with biological tissue. Changes in a part's porosity during an additive manufacturing build may also be an indication of an undesired change in the build process. Here, we present efforts to develop an ultrasonic sensor for monitoring changes in the porosity in metal parts during fabrication on a metal powder bed fusion system. The development of well-characterized reference samples, measurements of the porosity of these samples with multiple techniques, and correlation of ultrasonic measurements with the degree of porosity are presented. A proposed sensor design, measurement strategy, and future experimental plans on a metal powder bed fusion system are also presented.
authors.affiliation: National Institute of Standards and Technology, Gaithersburg, MD 20899.
authors.forename: John A
authors.initials: JA
authors.lastname: Slotwinski
authors.affiliation: National Institute of Standards and Technology, Gaithersburg, MD 20899.
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Garboczi
authors.affiliation: Binghamton University, State University of New York Binghamton, NY 13902.
authors.forename: Keith M
authors.initials: KM
authors.lastname: Hebenstreit
keywords: Archimedes; Direct Metal Laser Sintering; X-ray computed tomography; additive manufacturing; cobalt-chrome; porosity; powder bed fusion; ultrasonic NDT