Abstract Comparison of the microstructure and the phase composition of the Ti-6Al-4V alloy parts built by various additive manufacturing technologies was carried out by optical and transmission scanning electron microscopy, as well as X-ray diffraction analysis. It was shown that the martensitic αʹ phase, formed due to the melt pool fast cooling rate, determined the accommodation mechanisms of shear deformation of the as-built Ti-6Al-4V AM fabricated samples under uniaxial quasi-static tension and impact bending (and, accordingly, their mechanical properties). The effect of microstructure on impact toughness, ultimate impact strength, as well as the crack initiation and propagation energy was investigated by the impact bending tests with recording impact load diagram (force-displacement graph). It was concluded that impact toughness of the Ti-6Al-4V samples built by wire-feed electron beam additive manufacturing was significantly higher than that of ones manufactured by selective laser melting and electron beam melting of a powder. Matching the mechanical properties and SEM micrographs of the fracture surfaces of the as-built Ti-6Al-4V AM fabricated samples enabled to reveal the crack initiation and propagation mechanisms during their quasi-static and dynamic loading. Discussion of the results was carried out using the concept of scale levels of plastic deformation.

中文翻译：

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通过各种增材制造方法制造的 Ti-6Al-4V 零件的准静态和动态断裂行为的尺度水平

摘要 通过光学和透射扫描电子显微镜以及 X 射线衍射分析，对采用各种增材制造技术制造的 Ti-6Al-4V 合金零件的显微组织和相组成进行了比较。结果表明，由于熔池快速冷却速度而形成的马氏体 αʹ 相决定了 Ti-6Al-4V AM 制造样品在单轴准静态拉伸和冲击弯曲（和，因此，它们的机械性能）。通过记录冲击载荷图（力-位移图）的冲击弯曲试验研究了微观结构对冲击韧性、极限冲击强度以及裂纹萌生和扩展能量的影响。结果表明，采用送丝电子束增材制造的Ti-6Al-4V样品的冲击韧性显着高于选择性激光熔化和粉末电子束熔化制造的样品。匹配已建成的 Ti-6Al-4V AM 制造样品的断裂表面的机械性能和 SEM 显微照片，能够揭示其准静态和动态加载过程中的裂纹萌生和扩展机制。使用塑性变形尺度水平的概念对结果进行了讨论。匹配已建成的 Ti-6Al-4V AM 制造样品的断裂表面的机械性能和 SEM 显微照片，能够揭示其准静态和动态加载过程中的裂纹萌生和扩展机制。使用塑性变形尺度水平的概念对结果进行了讨论。匹配已建成的 Ti-6Al-4V AM 制造样品的断裂表面的机械性能和 SEM 显微照片，能够揭示其准静态和动态加载过程中的裂纹萌生和扩展机制。使用塑性变形尺度水平的概念对结果进行了讨论。