The Influence of Laser Powder Bed Fusion (L-PBF) Process Parameters on 3D-Printed Quality and Stress–Strain Behavior of High-Entropy Alloy (HEA) Rod-Lattices

Laser powder bed fusion (L-PBF) additive manufacturing technology is suitable for the direct 3D printing of geometrically complex periodic micro-rod-lattices. However, controlling the geometric and performance consistency remains challenging due to manufacturability limitations, non-negligible process defects, and surface roughness, which is inconvenient to measure, affecting the mechanical properties and deformation behavior of the lattice structures. To improve the forming quality of the rod lattices and the consistency of repetitive 3D printing, we theoretically analyzed the causes of the defects and the effects of the L-PBF parameters on the process defects of CoCrFeNiMn high-entropy alloy micro-rods. The forming quality of the micro-rods was evaluated and classified with control experiments, and the surface roughness was measured and analyzed. Randomly protruding metal particles on the surface were mainly caused by the diffusion of laser energy, the incomplete melting of some metal powders, and/or “balling” process-induced defects caused by laser remelting. The tensile mechanical properties of typical L-PBF-printed micro-rods with different geometric characteristics were compared and evaluated. The influence of the geometric characteristics of the defects on the mechanical properties is discussed. The mechanical properties of the L-PBF-printed rod lattices were evaluated by compression experiments. It was found that the properties of different rod lattices have a positive relationship with the relative density.