Generation of 3D micro-lattices by PBF-LB/M using broadened hatch distance

Abstract 316L stainless steel micro-lattices have been designed and manufactured by laser powder bed fusion using a particular approach consisting in generating the strut-based architecture by adopting a particularly wide hatch distance that prevents the overlap of the individual scan lines. Microlattices featuring a cell size of the order of 400 μm have been successfully produced with a microstructure characterized by the presence of columnar grains crossing several melt pools, ensuring the continuity of the lattice structure also at the nodes of the intersecting struts. The mechanical performance of the lattices was evaluated by compression tests. The lattices generally showed compression curves with an horizontal plateau and fluctuations of the load, which suggested a bending-dominated-like behavior, which was assumed to be also affected by the buckling of the rectangular section of the struts, showing their elongated sides aligned along the loading direction. The approach allowed the successful generation of micro-lattices with fairly good geometrical resolution and controllable mechanical properties, while dramatically limiting the geometrical details to be included in the digital model of complex lattices since only the external profile of the sample is needed, while the 3D lattice is automatically produced by the specific setup of the printing process.