Direct ink writing of porous structures in 316L stainless steel: Printable window construction and sintering performance evaluation

This work develops a Direct Ink Writing (DIW)-based additive manufacturing route for fabricating 316L stainless steel components with internal hollow and porous architectures. By tailoring the metal solid loading and binder ratio, combined with rheological characterization and printing trials, a printable window governed jointly by extrusion continuity and shape retention is established. A dual-parameter criterion-effective viscosity ( ) and storage modulus -is proposed to evaluate printability, and is further introduced to estimate the self-supportable span of printed lattices. Sintering experiments reveal a competitive relationship between densification and grain evolution. At 1400 °C for 240 min, the material reaches a relative density of 98.9 ± 1.3% of the theoretical density and exhibits an excellent strength–ductility synergy (≈550 MPa and ≈53%). Further heating or prolonged holding leads to strength degradation due to grain coarsening and localized σ-phase formation, indicating that the performance peak arises from a balance between pore elimination-induced strengthening and grain/interface evolution-induced softening. Overall, multiple irregular porous samples were fabricated, demonstrating the application potential of DIW for forming complex metallic structures and providing a basis for printable-window determination and sintering optimization.