Significantly Enhanced Biocompatibility and Performance of 3d-Printed Porous 316l Stainless Steel Via a Simple and Efficient Surface Polishing Approach

Abstract

Residual powder on 3D-printed porous 316L stainless steel implants detrimentally impacts cell growth and biocompatibility, thereby increasing the risk of clinical implant failure. This study introduces a high-voltage anodic oxidation (AO) technique designed to polish gyroid-structured porous 316L stainless steel implants, fabricated via selective laser melting, for residual powder removal and bioactivity enhancement. Mechanical testing of 316L-50 samples revealed properties resembling natural bone. Polished 316L-AU-50 samples exhibited reduced roughness, slightly larger pore size, and retained compressive strength, with an elastic modulus of 5.31 GPa, compressive yield strength of 79.91 MPa, ultimate strength >2000 MPa, plateau stress of 168.65 MPa, and energy absorption of 85.48 MJ/m³. While the overall mechanical performance showed minor reductions, the improved plateau stress and energy absorption enhanced the material's impact-buffering capabilities, thereby offering superior bone protection. The polishing process removed internal powder, creating ripple-like, fish-scale, and dendritic surface patterns that promote cell adhesion, proliferation, and differentiation. The findings demonstrate that reverse high-voltage AO not only effectively removes residual powder but also preserves the mechanical integrity of 316L stainless steel. This technique minimizes implant failure risks and generates bioactive surface textures, providing substantial potential for advancing clinical applications of porous 316L stainless steel implants.

Keywords: 316L stainless steel, Selective laser melting, Residual powder, High-voltage anodic oxidation, Bioactivity