Manufacturing of functionally graded parts using 3D plasma metal deposition

Within this work, the 3D plasma-metal deposition (3DPMD) process, based on a plasma powder deposition process is introduced as an innovative additive manufacturing process. 3DPMD has several advantages compared to the established beam-based AM processes or other arc-based additive process variants, such as wire+arc additive manufacturing. For example, up to four powders, which can be different in terms of chemistry and powder fraction, can be mixed within one layer. This allows a targeted adaption of local properties (microstructure, corrosion resistance, mechanical properties, wear resistance, porosity, etc.) to the aimed load scenarios and operating conditions. For example, the localized introduction of reinforcement particles (e.g. tungsten or titanium carbides) into the component is a simple example and adds another degree of freedom to the system. Within this study, the suitability of 3DPMD for the production of functionally graded parts in layer-by-layer design was investigated. Various structures and demonstrators have been prepared and investigated. The microstructure, porosity and the mechanical properties of the different structures was characterized. Microstructure evolution was analyzed by advanced electron microscopic methods such as SEM, EDX and EBSD. In summary, 3DPMD offers the possibility to produce AM parts with high build rates and increased material flexibility. Using automated routines, it is possible to generate functionally graded metal structures using welding robots directly from the CAD drawings. Microstructures and properties are directly related to the process and therefore material-process-property relationships are discussed within this work.