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Additive manufacturing (AM) has the potential to revolutionize manufacturing because it can fabricate complex geometries that are not possible with conventional manufacturing processes. Qualification of AM parts remains challenging due to solidification defects (e.g. porosity) and heterogeneous microstructure, both of which are strongly dependent on AM process parameters. Nondestructive evaluation (NDE) techniques are desired to provide timely evaluation of AM parts in terms of both microscopic defects and microstructure variation. This work demonstrates the capability of ultrasonic phase velocity measurements to evaluate defects and microstructural differences of AM stainless steel 316L, caused by changes in hatch spacing. We related the measured phase velocity along different directions to pore geometry and texture of AM parts, using X-ray computed tomography, electron backscatter diffraction (EBSD …