Anisotropic deformation of 316L stainless steel overhang structures built by material extrusion based additive manufacturing

Metal components with complex structures can be fabricated via additive manufacturing (AM) technologies benefited from the geometrically free of design. A fused filament fabrication (FFF)-debinding-sintering method has emerged within the past five years owing to the low cost, moderate energy consumption, and promising scalability. However, recent studies failed to address the capability and limitations of FFF for the fabrication of metals with complex structures, such as foam, lattice, and other functional hollow structures. Herein, we comprehensively revealed the dimensional change (shrinkage and change of angle) of the FFF-built overhang pillars using analytical modeling, finite element (FE) simulation, and experimental verification approaches. Six groups of pillars with overhang angles from 40° to 90° were designed and fabricated. The effect of gravity on the bending of overhang pillars was involved in the modeling and simulation. The gravity accelerated the shrinkage in the z-direction and results of shrinkage and deflection ratio exhibited a good consistency within the analytical, numerical, and experimental approaches. An extended application to predict the shrinkage of a lattice structure was also provided. This study provides the fundamental understanding of the sintering behavior of the metallic overhang structure fabricated by AM, and will significantly contribute to the future research efforts of FFF-built three-dimensionally complex metallic parts without support structures.