Layer-by-layer additive manufacturing (AM) by means of laser-powder bed fusion (L-PBF) offers many prospects regarding the design of lattice structures used, for example, in gas turbines. However, defects such as bulk porosity, surface roughness, and re-entrant features are exacerbated in nonvertical structures, such as tilted struts. The characterization and quantification of these kinds of defects are essential for the correct estimation of fracture and fatigue properties. Herein, cylindrical struts fabricated by L-PBF are investigated by means of X-ray computed tomography (XCT), with the aim of casting light on the dependence of the three kinds of defects (bulk porosity, surface roughness, and re-entrant features) on the build angle. Innovative analysis methods are proposed to correlate shape and position of pores, to determine the angular-resolved surface roughness, and to quantify the amount of re-entrant surface features, q. A meshing of the XCT surface enables the correlation of q with the classical surface roughness P _a. This analysis leads to the conclusion that there is a linear correlation between q and P _a. However, it is conjectured that there must be a threshold of surface roughness, below which no re-entrant features can be build.

中文翻译：

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3D 计算机断层扫描量化了增材制造的 IN625 晶格支柱中体积孔隙率、表面粗糙度和重入特征对构建角度的依赖性

通过激光-粉末床熔合 (L-PBF) 的逐层增材制造 (AM) 为例如燃气轮机中使用的晶格结构的设计提供了许多前景。然而，在非垂直结构（如倾斜支柱）中，诸如体积孔隙率、表面粗糙度和凹入特征等缺陷会加剧。这些缺陷的表征和量化对于正确估计断裂和疲劳特性至关重要。在此，通过 X 射线计算机断层扫描 (XCT) 研究了由 L-PBF 制造的圆柱支柱，目的是揭示三种缺陷（体积孔隙率、表面粗糙度和凹入特征）的依赖性。 ) 在构建角度上。提出了创新的分析方法来关联孔隙的形状和位置，问。XCT 表面的网格化使q与经典表面粗糙度P _a相关联。该分析得出的结论是q和P _a之间存在线性相关性。然而，推测必须有一个表面粗糙度的阈值，低于该阈值就不能构建可重入特征。