Manufacturing of a solid skin on porous metals using Directed Energy Deposition

Porous metals combine favorable mechanical, electrical, thermal, and acoustic properties. These properties are especially desirable for lightweight components. However, in order to realize the full potential of this material group, it is essential to develop techniques for combining them with solid parts, for example in the form of a shell-core principle. Directed Energy Deposition (DED) can be used to add solid material on top of an existing porous metal part. Due to the uneven surface topography of porous metals, several problems arise regarding a suitable manufacturing strategy. This study analyses the effect of laser remelting (LR), DED, and the combination of them on a porous surface and the deposited material. Optical micrographs were studied to evaluate the bonding to the substrate. Primary profile roughness parameters proved to be suitable to quantify the effect of the different processes on the surface topography. The combination of LR and DED led to the best results regarding the surface topography but showed bonding problems between the LR zone and the deposited material. The study also shows further potential to improve the surface topography, and the bonding of deposited material on porous metals via the optimization of LR and DED strategies.