Improvement of the properties of additively manufactured steel parts by combination of heat treatment and hard coatings

In additive manufacturing using SLM (selective laser melting), the maraging steel 1.2709 is often used to produce metallic components for various applications. The work piece properties depend on the process control in the additive process, but also on the heat treatment and the final processing. Here, the heat treatment and the used finishing processes lead to changes in the work piece and material properties (e.g. residual stresses, strength). As part of the international "Ad-Proc-Add" project, the presented work took into account individual process steps of the process chain with consideration of: additive manufacturing - pre-treatment - functionalization - final processing when using different materials. In investigations of additive manufacturing of the material 1.2709, it could be proven that the thermal treatment determines the mechanical properties of the components. A PVD coating process was used to replace the usual heat treatment. Similar temperature-time regimes during the coating resulted in mechanical properties comparable to conventionally heat-treated additively manufactured components. In addition to modifying the microstructure and the component properties, the PVD coatings improve the surface wear resistance up to more than 60%. Further investigations to improve the adhesion strength of the coatings are planned.