Distinction in Anodic Dissolution Behavior of Inconel 718 Prepared by Different Forming Technologies

Abstract

Metallographic observations and electrochemical measurements were performed to investigate the anodic dissolution behavior of Inconel 718 prepared by laser solid forming (LSF) and forging. Polarization tests show that the passivation currents of the LSF-fabricated and wrought Inconel 718 are different, owing to the different properties of the surface passive films induced by element segregations. Current efficiency measurements present that the current efficiencies of the two samples at low current densities is higher than that at high current densities regardless of forming technologies, indicating that Inconel 718 suffers from stray corrosion easily. Besides, the current efficiency of the wrought sample is higher, caused by the larger quality of undissloved secondary phases than the as-deposited one. It is worth mentioning that the same surface energy level of the deposit on VS and wrought sample leads to their same dissolution rate after the surface film ruptured. These results provide an insight to obtain the required electrochemical machining results by regulating the forming technology.