Additively manufactured 316L stainless steel as a potential alternative implant material

The microstructural features, electrochemical corrosion behavior, and biocompatibility with Locke's solution were evaluated for 316L stainless steel (SS) samples fabricated by selective laser melting (SLM) with understudied processing conditions providing low residual stress - 800, 1000 and 1200 mm/s laser scan speed with a laser power of 100 W. Confocal images and scanning electron microscopy found fewer SLM processing induced surface flaws at samples fabricated at 800 mm/s. Electrochemical impedance spectroscopy and potentiodynamic polarization measurements indicated samples fabricated at 800 mm/s developed a more compact and thicker passive oxide film resulting in greater corrosion resistance, relative to samples prepared at the higher laser scan speeds. The surface characteristics of SLM 316L SS samples fabricated at 800 mm/s also promoted substantial biocompatibility that was observed via cell attachment and differentiation of osteoblasts, as well as high collagen 1A coverage indicating strong potential as a alternative implant material. • Corrosion resistance and biocompatibility of SLM 316L SS samples made made under low residual stress conditions was investigated. • The relationship between SLM processing and corrosion behavior was correlated with microscopic surface characteristics. • The impedance response revealed that ion transport through the passive oxide layer governed the surface electrochemistry. • Potentiodynamic polarization measurements were taken to assess localized pitting behavior and corrosion tendencies. • Corrosion and biocompatibility data were analyzed to determine shared benefits and incompatible behavior.