Research activities around additive manufacturing at SIMaP rely mainly on the Electron Beam Melting (EBM) technology. This technology enables to manufacture new designs and sophisticated geometries. This process is particularly suitable for the production of architectured materials such as lattice structures or metallic foams. A significant part of the activity is devoted to material development and especially to materials that show a poor weldability. Tailoring microstructures by playing with process parameters is the aim of undergoing research efforts.
The biggest challenge of architectured materials was the processing route. With the recent development of additive manufacturing, it is now much easier to produce sophisticated geometries. SIMaP is now equipped with two EBM machines.
Illustration of the concept of mechanical efficiency. In red is highlighted the mechanical equivalent cylinder, i.e. a perfect cylinder having a stiffness equal to the as-built structure.
Lattice structures were produced by EBM and characterized structurally as well as mechanically. X-ray tomography was extensively used in order to characterize lattice structures in 3D. The discrepancies between the ideal properties (those of the CAD file) and the effective properties of the produced structure were investigated based on the concept of mechanical efficiency. This concept allows to discriminate the material that transmit loads with the one which doesn't.
Effect of chemical etching on a single vertical strut as a function of the etching time.
Significant surface defects can be observed on as-built structures and are not considered as mechanically efficient. The effect of chemical etching on the surface defects was investigated. The chemical etching clearly improves the mechanical efficiency of the lattice structures. This is further illustrated in the above figure that shows the evolution of the strut morphology as a function of etching time. The surface profile after a 30 min etching time appears much smoother than the as-built profile.
mise à jour le 9 octobre 2019