Leveraging am to Better Understand Nondestructive Evaluation Using Internal Structures

In recent years, ultrasonic nondestructive evaluation (NDE) has increased in popularity as a way to detect defects and determine material properties in additively manufactured (AM) components. When completing ultrasonic scans, it can be difficult to fully resolve internal structures in a component; generally, resolution increases with frequency up to a certain point, when scattering from the microstructure causes interference. In ultrasonic transducer beam models, many assumptions are made about the beam geometry inside the sample; however, interactions with the material may result in important discrepancies between the model and the experiment. In this study, a simple internal structure, a spherical cavity, is printed through laser powder bed fusion (LPBF) inside a cubical block of SS316L. Each sample cube is printed with a different laser power and scanning speed, with a constant energy density, in order to vary the microstructure of the block. These samples allow us to compare experimental beam mapping inside the sample to preexisting ultrasonic beam models. By leveraging additive manufacturing technologies, we can validate and further our understanding of nondestructive evaluation techniques.