Effect of Different Manufacturing Routes on the Microstructural, Mechanical, and Corrosion Behavior of Inconel 625 Alloy

In this study, the effects of different manufacturing routes on the microstructural, mechanical, and electrochemical corrosion behavior of Inconel 625 alloy were comparatively investigated. Three types of specimens were evaluated: commercially supplied Inconel 625, wire arc additively manufactured (WAAM) Inconel 625, and laser-cladded (LC) Inconel 625. The specimens were characterized by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), nanoindentation, microhardness, open circuit potential (OCP), and potentiodynamic polarization tests in 3.5 wt.% NaCl solution. SEM observations showed that the commercial specimen had a relatively homogeneous microstructure, whereas the WAAM specimen exhibited a directional dendritic morphology due to repeated thermal cycles. The laser-cladded specimen presented a finer dendritic structure. EDS analyses indicated that Nb and Mo segregation was more pronounced in the WAAM and LC specimens, particularly in interdendritic regions. XRD results confirmed that the dominant phase in all specimens was the FCC γ-Ni solid solution. Hardness measurements showed that WAAM and commercial specimens had similar values, while the LC specimen exhibited slightly lower hardness. Electrochemical results revealed that the commercial specimen showed the most noble OCP value, whereas the WAAM specimen exhibited the lowest corrosion current density, highest polarization resistance, and lowest corrosion rate. The corrosion resistance ranking was WAAM > LC > commercial. These results indicate that the manufacturing route significantly affects the corrosion performance of Inconel 625 alloy.