Session: 17-01-01: Research Posters

Paper Number: 150122

150122 - Utilization of Ultrasound for Defect Detection of Additive Friction-Stir Deposition Repairs 

Metal additive manufacturing has garnered significant industry interest in the past decade due to its ability to produce complex geometries and shortening production times, but the materials selection and the end use applications are often limited. Popular metals like aluminum and magnesium alloys are often rejected for load critical additive manufacturing applications due to their significant decrease in strength from the wrought metal performance. This reduction is due to the use of localized heating to create a molten state during fabrication and thus introducing internal thermal stress gradients. A novel method that uses a solid-state additive manufacturing process, known as additive friction-stir deposition, has gained recent industry interest. Additive friction-stir deposition employs friction to heat metal sufficiently to deposit material under a shearing load without the metal changing to a liquid state. One barrier to acceptance of this manufacturing technique is potential for internal defects when the manufacturing parameters are not optimal, or impurities are inadvertently introduced to the process. Defects in additive friction stir deposits such as internal porosity and kissing bonds can function as stress concentration points due to the inability to properly transfer a load and are the often cause of premature failure. There is a need to develop methods to identify these defects so the processing can be tuned to mitigate the presence of defects. Integrating this additive manufacturing technique into industry requires the creation of appropriate nondestructive inspection methods that verify that critical application parts do not have substantial internal defects. In this study, multiple aluminum alloy repaired samples are manufactured and inspected using immersion ultrasound nondestructive testing. To simulate a metal in need of repair, a milled groove is manufactured into an aluminum plate. The goal is to manufacture repaired samples that pass visual inspection but are made with manufacturing parameters that are not optimized. The immersion ultrasonic testing setup involves placing the additive friction-stir deposited samples in a water tank, utilizing water as the coupling medium to facilitate the transmission of ultrasonic waves. Multiple ultrasound methods are tested, including conventional ultrasound over a range of frequencies up to 20 MHz. Custom signal processing techniques are utilized of the full waveform captured data sets and a visualization and quantification of the interface between the deposition and the part are presented. The ultrasound data reveals changes in material at the location of the filled groove, indicating the presence of additive friction stir deposition internal defects, and the results are compared to that of X-ray Computed Tomography and optical microscopy of sectioned samples. The results of this study prove that internal porosity can be detected in aluminum alloy additive friction-stir deposited repairs using ultrasonic nondestructive inspection. Continued research in nondestructive testing of aluminum alloy additive friction-stir deposited samples will further advance the adoption of metal additive manufacturing technologies in critical applications.

Presenting Author: Ryan Hatmaker Baylor University

Presenting Author Biography: Ryan Hatmaker is a graduate student at Baylor university in waco, texas. He is currently pursuing a PhD in mechanical engineering. His research work is focused on nondestructive testing of metal additive manufacturing, specifically ultrasonic inspection of additive friction stir deposition

Authors:

Ryan Hatmaker Baylor University
Adam Swinney Baylor University
David Jack Baylor University
Trevor Fleck Baylor University