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 316 L, 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), and uniaxial tensile tests. Our results confirm that the phase velocity depends on both pore geometry and crystallographic texture. By estimating the phase velocity from EBSD data, our measurements suggest that the measured ultrasonic phase velocity is sensitive to changes in anisotropic elastic constants, while the measured uniaxial tensile moduli are not as sensitive to the same changes. This work can be extended to other processing parameters and other anisotropic AM materials.

增材制造（AM）具有革新制造的潜力，因为它可以制造复杂的几何形状，而这是常规制造工艺无法实现的。由于凝固缺陷（例如孔隙率）和微观结构的异质性，AM零件的鉴定仍然具有挑战性，这两者都强烈取决于AM工艺参数。希望提供无损评估（NDE）技术，以便根据微观缺陷和微观结构变化及时评估AM零件。这项工作证明了超声相速度测量能够评估舱口间距变化引起的AM不锈钢316 L的缺陷和微观结构差异。我们将沿不同方向测得的相速度与AM零件的孔几何形状和织构相关联，使用X射线计算机断层扫描，电子背散射衍射（EBSD）和单轴拉伸试验。我们的结果证实，相速度取决于孔的几何形状和晶体结构。通过从EBSD数据估计相速度，我们的测量结果表明，所测量的超声相速度对各向异性弹性常数的变化敏感，而所测量的单轴拉伸模量对相同的变化不敏感。这项工作可以扩展到其他加工参数和其他各向异性AM材料。我们的测量结果表明，所测量的超声相速度对各向异性弹性常数的变化敏感，而所测量的单轴拉伸模量对相同的变化不敏感。这项工作可以扩展到其他加工参数和其他各向异性AM材料。我们的测量结果表明，所测量的超声相速度对各向异性弹性常数的变化敏感，而所测量的单轴拉伸模量对相同的变化不敏感。这项工作可以扩展到其他加工参数和其他各向异性AM材料。