Abstract Microstructural features and defects arising from selective laser melting (SLM) determine the in-service performance of additively manufactured near-net-shape components. Here the grain type, shape, size and distribution were characterized using electron backscattered diffraction (EBSD). High-resolution synchrotron radiation X-ray computed tomography (CT) was used to quantify the population, morphology and dimensions of porosity and lack of fusion defects. For SLM Ti-6Al-4V alloy, the larger-sized defects in comparison with the α grains are more important for crack initiation, typically leading to poor fatigue resistance and a pronounced variation in fatigue life. The fatigue strength was then evaluated in terms of the defect population using a combination of the statistics of extremes and the Murakami model. Finally, an extended Kitagawa-Takahashi fatigue diagram was established within the framework of defect-tolerant design, which includes a classical safe-life region and the defect-determined lifetime in the finite life region.

中文翻译：

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一种将缺陷数量与选择性激光熔化 Ti-6Al-4V 疲劳寿命相关联的新方法

摘要 选择性激光熔化 (SLM) 产生的微观结构特征和缺陷决定了增材制造的近净成形部件的在役性能。在这里，使用电子背散射衍射 (EBSD) 表征晶粒类型、形状、尺寸和分布。高分辨率同步辐射 X 射线计算机断层扫描 (CT) 用于量化孔隙度和缺乏融合缺陷的数量、形态和尺寸。对于 SLM Ti-6Al-4V 合金，与 α 晶粒相比，较大尺寸的缺陷对于裂纹萌生更为重要，通常会导致较差的抗疲劳性和疲劳寿命的显着变化。然后结合使用极端统计数据和村上模型，根据缺陷数量评估疲劳强度。最后，