The geometry and material properties of additively manufactured (AM) parts are closely related in a way that any alteration in geometry of the part will change the underlying manufacturing strategy. This in turn, affects the microstructure and consequently, the mechanical behavior of material. This paper aims to evaluate the effect of the AM part’s thickness and geometry on microstructure, surface roughness, and mechanical properties under quasi-static and fatigue loading conditions by performing experimental tests. A series of Ti-6Al-4V specimens with three different thicknesses and two different geometries were fabricated using electron beam melting (EBM). The results of microstructural analyses revealed that specimens with lower build thickness experience finer grain size, higher microhardness, and lower elongation at failure. Although the microstructure of the produced parts was strongly affected by the build thickness, different surface to volume ratios eliminated the effect of microstructural differences and governed the fatigue properties of the parts. The size effect on the microstructural features, geometrical appearance, mechanical properties of the AM parts should be considered for the design and failure analysis of complex structures.

增材制造（AM）零件的几何形状和材料属性密切相关，以这种方式改变零件的几何形状将改变基本的制造策略。反过来，这会影响材料的微观结构，进而影响材料的机械性能。本文旨在通过进行实验测试，评估准静态和疲劳载荷条件下AM零件的厚度和几何形状对显微组织，表面粗糙度和机械性能的影响。使用电子束熔化（EBM）制作了一系列具有三种不同厚度和两种不同几何形状的Ti-6Al-4V标本。显微组织分析的结果表明，厚度较小的试样的晶粒尺寸较小，显微硬度较高，断裂伸长率较低。尽管所生产零件的微观结构受构造厚度的强烈影响，但是不同的表面体积比消除了微观结构差异的影响并控制了零件的疲劳性能。对于复杂结构的设计和失效分析，应考虑尺寸对AM零件的微观结构特征，几何外观，机械性能的影响。