Direct Metal Laser Sintering (DMLS), one of Additive Manufacturing technologies, produces layer-by-layer geometrically complex components from metal powders, such as nickel alloys, titanium alloys, aluminum alloys, etc. using a high power concentrated laser beam. The material structure created by this technology is influenced by process parameters and build orientation. The process is characterized by localized high heat inputs during very short interaction times leading to the formation of very fine structures but also to the generation of internal stresses. Therefore, the DMLS parts are heat treated to decrease or completely remove residual stresses. The DMLS manufacturing process examined here was characterized by a 400 W laser power and 60 µm layer thickness applied to a fine Ti6Al4V powder. Plane bending fatigue testing was performed on three sets of special miniature specimens prepared according to three different build orientations. A cyclic bending stress was applied to the smooth flat surface of the specimens. The surface was tested in the as-built state and in the polished state to reduce roughness of the as-built surface. The fatigue behavior of DMLS Ti6Al4V was found to be influenced by the build orientation. Fatigue specimens with polished surfaces showed better fatigue properties compared to the as-built specimens.Keywords: Ti6Al4V, DMLS, fatigue, microstructure
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