抄録
Direct metal laser sintering (DMLS) is an additive manufacturing process that uses 3D CAD data as a digital information source and a high-power laser beam which create three-dimensional metal parts by fusing fine metallic powder. DMLS was developed by the EOS firm of Munich, Germany. In this study, alloy 718 was built up by ytterbium fiber laser by fusing pre-alloyed powder in argon gas. Tensile specimens were cut from the buildup cubic. The specimens were cut along two orientations. One (0°-specimen) was cut along the building direction, another (90°-specimen) was cut perpendicular to the direction. As-deposited specimen and STA (Solution heat treatment and aged) specimen were prepared. We observed the dendrite and the coarse columnar grains which grew up along the building direction. STA improved the proof and tensile strengths at ambient temperature. Tensile properties of buildup material were comparable with conventional materials. At the ambient temperature, the buildup material showed isotropic tensile properties; however, at 650℃, 90°-specimen exhibited half ductility compared to the 0°-specimen.
