Advanced manufacturing approach via the combination of selective laser melting and laser metal deposition

Additive manufacturing processes are frequently discussed in a competitive manner instead of being considered synergetically. This is particularly unfavorable since advanced machining processes in combination with additive manufacturing can be brought to the point that the results could not be achieved with the individual constituent processes in isolation [K. Gupta, R. F. Laubscher, and N. K. Jain, Hybrid Machining Processes—Perspectives on Machining and Finishing (Springer, New York, 2016), p. 68]. On that basis, boundary conditions from selective laser melting (SLM) and laser metal deposition (LMD) are considered in mutual contemplation [A. Seidel et al., in Proceedings of 36th International Congress on Applications of Laser & Electro-Optics, Atlanta, GA, 22–26 October 2017 (Fraunhofer IWS, Dresden, 2017), pp. 6–8]. The present approach interlinks the enormous geometrical freedom of powder-bed processing with the scalability of the LMD process. To demonstrate the potential of this approach, two different strategies are pursued. Firstly, a hollow structure demonstrator is manufactured layer wise via LMD with powder and subsequently joined with geometrically complex elements produced via SLM. Afterward, possibilities for a microstructural tailoring within the joining zone via the modification of process parameters are theoretically and practically discussed. Therefore, hybrid sample materials have been manufactured and interface areas are subjected to microstructural analysis and hardness tests. The feasibility of the introduced approach has been demonstrated by both fields of observation. The process combination illustrates a comprehensive way of transferring the high geometric freedom of powder-bed processing to the LMD process. The adjustment of process parameters between both techniques seems to be one promising way for an alignment on a microstructural and mechanical scale.