Electrochemical behavior of additively manufactured AISI 316L under simulated inflammatory conditions

AISI 316L stainless steel is widely used in orthopedic applications, particularly in fracture fixation devices. However, laser powder bed fusion (LPBF) introduces a distinctive microstructure and process-related features, including melt-pool boundaries, cellular substructures, residual stresses, and defects, that may alter passivation and susceptibility to localized corrosion. Consequently, the corrosion behavior of LPBF-manufactured 316L under inflammatory conditions cannot be inferred solely from studies of wrought material. In this study, the corrosion behavior of LPBF-manufactured AISI 316L was investigated in 0.9 wt.% NaCl, with and without H₂O₂, to simulate baseline and inflammatory conditions, respectively. Electrochemical behavior was evaluated by potentiodynamic polarization and electrochemical impedance spectroscopy. The corroded surfaces were subsequently examined by scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy. The addition of H₂O₂ accelerated both anodic and cathodic reactions. The corrosion current density increased from 7.07 × 10⁻⁸ to 6.05 × 10⁻⁷ A cm⁻², whereas the polarization resistance decreased from 95.77 to 21.25 kΩ cm². The electrochemical response indicated a loss of passive-film stability and protective effectiveness, resulting in a marked reduction in corrosion resistance. This deterioration may increase the susceptibility of LPBF-manufactured 316L to localized corrosion and metal-ion release during inflammatory episodes, with potential consequences for the long-term performance of orthopedic implants. These findings support the use of physiologically relevant inflammatory environments when evaluating the corrosion performance of additively manufactured metallic biomaterials.