Surface functionalization in selective-laser-melted 17-4 PH by plasma polishing and interstitial diffusion hardening

Developments in processing technology and feedstocks are key drivers for new product innovations in the field of additive manufacturing. In the area of complex and filigree geometries, additive manufacturing technologies are often superior to conventional processes. Selective laser melting (SLM) as a powder bed process allows components of different scales to be manufactured by variation in the grain size range of the feedstocks. However, the surface quality achieved is a critical factor. The powders used as feedstock in the selective laser melting (SLM) process fundamentally limit the surface quality of these components. Particle contamination on the surfaces of the parts can remain rounded or agglomerated, contributing to a very rough surface at the microscale. Furthermore, the manufacturing advantages of a closed component design lead to limitations in the mechanical finishing process, especially regarding undercuts and cavities. In addition to corrosion protection requirements, demands for wear resistance become increasingly important. This study deals with the development of a process chain for the surface functionalization of selective-laser-melted 17-4 PH by plasma polishing and interstitial diffusion hardening. In this context, both the leveling of the surface topography and the development of graded coating properties are of particular interest. In addition, this technology can be used to protect thin films against locally acting forces by providing sufficient support for the substrate materials.