Non-destructive evaluation of additively manufactured superalloy IN718 via integrating microfocus X-ray computed tomography and non-linear acoustics

Superalloy IN718 components manufactured by laser powder bed fusion (PBF-LB/M) were non-destructively evaluated by the sideband peak counting (SPC) nonlinear acoustics method and suitably validated by microfocus X-ray computed tomography (XCT). A wide-band chirp acoustic wave was used to inspect the microstructures of IN718 samples with five distinct process parameters, and the results reveal that the number of sidebands, which result from the non-linearity induced by porosity, is significantly influenced by the distribution and size of pores, in addition to the volume fraction. There was a clear correlation between extent of porosity and the corresponding value of the SPC index. XCT analysis corroborated these findings, providing quantitative insights into the porosity characteristics that affect the ensuing acoustic responses. The findings demonstrated that the porosity with varying sizes and distributions generate different SPC profiles, which were correlated to XCT results to quantitatively assess the size and spatial distributions of the porosity. Fusion of SPC and XCT characterization techniques provides a new strategic approach for non-destructive testing, where the SPC method offers rapid, qualitative evaluation, while XCT provides detailed spatial resolution for defect quantification. The integration of SPC could lead to the development of more cost-effective and advanced quality control protocols, ensuring the reliability of AM-manufactured components regardless of their geometry and composition.