Improved passivation and anticorrosion behaviors of selective laser melted Inconel 718 alloy in acidic solutions

The electrochemical behaviors of Inconel 718 alloy prepared by selective laser melting (SLM) were investigated and compared with commercial rolled counterpart in 0.05 mol/L H2SO4 solution. For this purpose, open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) analyses were performed. The corrosion resistance of selective laser melted (SLMed) Inconel 718 alloy is superior to that of the rolled counterpart, which can be attributed to the difference in the microstructure and the chemical compositions of the passive film. The SLMed 718 alloy suffers from severely localized corrosion due to the micro-galvanic corrosion induced by the Laves phase. Furthermore, compared with the rolled counterpart, the passive film formed on SLMed 718 alloy has more content of Cr2O3 and less content of NiO. The significance of this study laid in the understanding of the corrosion behavior of Inconel 718 alloy prepared by SLM. These findings aided in the development of strategies to further enhance the corrosion resistance and overall performance of this alloy in various applications.

Automated summary

The corrosion resistance of Inconel 718 alloy prepared by selective laser melting (SLM) is superior to that of the rolled counterpart due to the difference in the microstructure and the chemical compositions of the passive film. The SLMed 718 alloy suffers from severely localized corrosion caused by micro-galvanic corrosion induced by the Laves phase. Furthermore, compared with the rolled counterpart, the passive film formed on SLMed 718 alloy has more content of Cr2O3 and less content of NiO.