Influence of the effective thermal conductivity of the powder bed on the properties of overhanging areas in Laser-based Powder Bed Fusion of Ti-6Al-4V

In this paper the influence of a variation of the effective thermal conductivity of the powder bed on the properties and manufacturability of overhanging component areas in laser-based powder bed fusion (PBF-LB/M) of Ti-6Al-4V is investigated. The variation of the effective thermal conductivity of the powder bed is realized by contactless support structures under the over-hanging test specimens. The downskin angle between the overhanging test specimens and the base plate as well as the distance between the overhanging area and the test specimens are varied in a full factorial experimental design. The test specimens are examined with regard to the properties of relative density, surface roughness and geometric accuracy. In addition, a key figure is introduced which makes the results comparable with those obtained with other system configurations and parameters such as laser spot diameter, hatch distance and layer thickness.