Building Multi-Material components by Direct Laser Deposition

Most mechanical components are usually made of a single material, as a compromise between chemical, physical and functional properties. When designing an object, the choice of one material over another is driven by many reasons. Sometimes these reasons are not strictly technical, including for instance: biocompatibility, density, weldability, corrosion resistance, price, and appearance. Direct Laser Deposition (DLD) technology is an additive manufacturing process that allows the construction of objects by depositing material layer by layer. With DLD, the metal powder comes out of a nozzle conveyed by a flow of inert gas and is melted by a laser beam. One of the advantages of this technology over other AM technologies (such as SLM) is that it is possible to vary the composition of the deposited material by simply changing the metal powder. It is clear that with DLD technology, the properties of different metallic materials deposited together in a single object can be exploited. With this work the authors present two real-life case studies, in which the DLD technology is used to build multi-material components. The first case concerns a gearbox component made of C40 steel that must work in a food environment and has therefore been completely covered with a layer of stainless steel. The second case is a flange that must have a weldable base, while the internal hole must be made of a high-performance tool-steel.