Lithography-based additive manufacturing of steel metamaterials: Effect of sintering temperature on shape distortion, microstructure and mechanical properties

Lithography metal manufacturing (LMM) is an emerging sinter-based additive manufacturing (AM) technology for support-free 3D printing of extremely complex parts with micrometric resolution on a decimeter scale. Although the printing phase of LMM is well-established, the sintering stage is challenging due to either high porosity or melting-induced deformation, particularly in thin-walled lattices and metamaterials. This study investigates the effects of sintering temperature on shape distortion, surface morphology, chemistry, porosity, microstructure, and mechanical properties of 316L stainle b steel auxetic metamaterials 3D printed using LMM and sintered in a furnace customized for precise temperature control. Our results show that the fully dense grain microstructure with high plasticity can be sintering within 1300 - 1325 °C range. Going beyond this temperature results in shape distortion and embrittlement of the steel metamaterials. The previously recommended range of sintering temperatures for 316L steel, 1360 - 1380 °C need revision.