Structural and mechanical characteristics of porous 316L stainless steel fabricated by indirect selective laser sintering

Selective laser sintering (SLS) technique is capable of rapidly fabricating customized implants with porous structure. A simple encapsulation process was developed to coat 316L stainless steel (316L SS) powder with ethylene-vinyl acetate copolymer (EVA). Subsequently, porous 316L SS was prepared by SLS preforming of EVA-coated metal powders, debinding and sintering in hydrogen atmosphere. The effects of processing parameters on pore characteristics and mechanical properties were analyzed. The results indicate that the porosity of green body mainly depends on laser energy density, while the pore features and mechanical properties of sintered specimens are largely dominated by sintering temperature. After sintering at 1100–1300 °C, the average pore size and porosity are 160–35 μm and 58–28%, respectively. In addition, the elastic modulus and compressive yield strength are 1.58–6.64 GPa and 15.5–52.8 MPa, respectively. It is revealed that the pore structural parameters and mechanical properties of the as-sintered porous 316L SS can be controlled readily to match with those of cancellous bone by modification of SLS processing parameters and subsequent sintering temperature.