Metallic Biomaterials: Insights into the Microstructure and Electrochemical Properties of AISI 316L Stainless Steel

This study provides a clear assessment of the corrosion and microstructural stability of metallic biomaterials, with a focus on AISI 316L stainless steel. Electrochemical methods—such as open-circuit potential (OCP), potentiodynamic polarization, and cyclic voltammetry — show that chloride-rich and organic-acid environments progressively destabilize passive films, reducing pitting resistance and hindering repassivation. Additionally, the cold-rolling process accelerates degradation by promoting the transformation of the γ phase to ε, then to α′ martensite, thereby increasing defect density and surface heterogeneity. Comparisons with titanium and NiTi-based materials reveal similar issues related to passive layer integrity. Welded 316L also shows the formation of δ-ferrite, σ-phase, and carbides, which contribute to corrosion susceptibility. Overall, the findings highlight that microstructure-environment interactions are key drivers of degradation, underscoring the need for controlled phase stability, passive film chemistry, and surface treatments for long-term performance, particularly in biomedical and industrial applications.