Selective laser melting of surface inoculated metal powdersWednesday (26.09.2018) 15:30 - 15:45 S1/03 - 221 Part of:
Recently, additive manufacturing has attracted substantial attention from industry and academia. Highly complex parts can be generated in a layer-wise fashion, which enables an unrivalled geometrical design freedom. One well-established additive technique is a powder bed-based technology called selective laser melting (SLM). Here, a three-dimensional computer-aided design file is sliced into thin layers, which are then successively scanned and melted by employing a high-energy laser beam directly on the powder bed.
The metallic materials available for the SLM process, however, are still limited. Large temperature gradients occurring during the SLM process result in non-equilibrium solidifications, segregations, and high residual stresses. Focusing the solidification of the melt pool, thermal stresses, in combination with solidification shrinkage, can induce the formation of hot cracks. This defect mechanism severely limits the spectrum of materials processible via SLM. A promising solution to decrease the hot crack susceptibility can be realized in the doping of the powder materials utilized for the SLM process with nanoparticles. These inoculants can than assist in the nucleation of fine, equiaxed grains rather than the common SLM columnar grain morphology. The research presented will reveal the impact of nanoparticle surface-inoculated powder materials on the microstructural evolution of SLM-fabricated parts by means of advanced microscopy and x-ray diffraction.