Figure 8. Example of scanning compliant mechanism designed and optimized for monolithic additive  manufacturing. Left: architecture overview, middle: first results without support material considerations,  right: raw result with constrained parameters to avoid overhanging structure of less than 45° from  horizontal plane.  Conclusions  After showing in 2014 the feasibility of manufacturing an elementary compliant structure made of  stainless steel with AM-SLM, CSEM successfully developed – jointly with the company 3D PRECISION –  a comprehensive end-to-end SLM-based manufacturing and post-processing production method for a  high-strength precipitation-hardened stainless steel comparable to the widely known and used 17-4PH.   The tensile properties of the material were tested for the three manufacturing directions and for two  thermal post-processing conditions, highlighting the tremendous improvement of the performances after  HIP treatment, with the conclusion that the SLM manufacturing of CL92PH powder material can lead to  tensile performance similar to a commercial grade 17-4 PH stainless steel, provided the appropriate postprocessing strategy is applied. The positive influence of the HIP treatment was also investigated at a  microscopic scale through detailed metallographic analysis which revealed the successful suppression of  macro porosity and the improvement of the microstructure for both structural and flexural segments.   The fatigue performance of the flexural segments was investigated in detail through a comprehensive  alternate bending fatigue test campaign covering four different sample groups. The collected fatigue test  data helped to highlight the contribution of the key material and surface defects on the final fatigue  performance. The beneficial effect of the HIP treatment on fatigue performance was demonstrated, with  further investigations to be carried out on the impact of the geometry of the parts versus HIP and  subsequent thermal post-processing efficiency and side effects. The percent replication of the fatigue  data collected allows us to affirm that from a lifetime point of view, SLM-manufactured compliant  structures have the potential to be eligible for demanding applications. Despite the loss in fatigue  performance, it is possible to design – provided a well-adapted sizing – a compliant structure offering  lifetime above 15 million cycles.   Similarly, the AM process for a titanium alloy has been recently optimized following the same procedure.  From the mechanical design point of view, SLM manufacturing is acknowledged to have the potential to  enable new design strategies, leading to high mass/stiffness optimized parts and simplified assemblies.  The present study demonstrates that even thin structures can offer sufficient fatigue performance and  geometrical accuracy to be foreseen for space applications. Nevertheless, it must be stressed that SLM  also brings some challenges which need to be addressed. The use of material support and the  subsequent need for material removal is foreseen to be the main source of design restrictions and needs  some additional creativity.   Another critical issue encountered during this study is the accumulation of internal mechanical stresses  during the SLM process and the necessity for annealing post-processing which avoids the emergence of  macroscopic warpage during the delicate step of separating the part from its manufacturing substrate.   NASA/CP—2018-219887 244