Influence of structural features on processability, microstructures, chemical compositions, and hardness of selective laser melted complex thin-walled components

Lightweight thin-walled structures are widely used in aeronautical and astronautical industries. With a further development of complexity in the structural features of components, traditional manufacturing processes cannot fully meet the high requirements of manufacturing for industrial components. In this work, thin-walled structures were processed by selective laser melting (SLM), and the influence of structural features (e.g., the dimensions, positions, and intersection of thin walls) and laser processing parameters on processability, microstructural characteristics, chemical compositions, and hardness of SLM-processed thin-walled components were investigated systematically. The simulation results show that the size and the maximum temperature of the molten pool in the intersection area were less than those in the thin wall area, while the maximum temperature gradient of the molten pool in the intersection area was larger than that in the thin wall area. The experimental results indicate that the open pores were prone to form in the intersection area of as-fabricated parts. The finer cellular microstructure was obtained in the intersection areas. Furthermore, the micro-hardness and nano-hardness in the intersection areas were relatively higher than those in the thin wall areas. With an increase of laser power to 400 W, the number of residual pores in both positions decreased significantly, the size of cells slightly coarsened, and the level of Mg element loss was more significant.