Analysis of Cl⁻ corrosion resistance of Inconel 625 deposited metal

In order to study the corrosion behavior of Inconel 625 deposited metal in Cl^- corrosive solution, the corrosion behavior of deposited metal immersed in molten salt and room temperature stress corrosion cracking behavior at different temperatures were studied by means of static immersion corrosion and slow strain rate tension. X-ray diffraction (XRD) and S-3400N scanning electron microscope were used to systematically study the phase composition, corrosion morphology and element distribution of the deposited metal. The results show that: in the static immersion corrosion, the corrosion weight loss of deposited metal shows an increasing trend at both temperatures, but the increasing range is different in different time intervals. The corrosion weight loss of deposited metal increases slowly in the first 10 h, and increases sharply in the 10 ~ 60 h. It can be found that 10 h is the dividing point of corrosion behavior. The corrosion resistance of the deposited metal at 700 ℃ is better than that at 900 ℃, because the dense MgO shell appears on the surface of the deposited metal at 700 ℃, which can hinder the corrosion reaction; At 900 ℃, due to the existence of CrCl₃, the "shell breaking effect" appears, which destroys the MgO shell and reduces its corrosion resistance. For slow strain rate tensile test, the tensile strength of specimens in corrosive medium is 22.97% lower than that in air medium, and the susceptibility index of stress corrosion cracking is 30.39%, which indicates that Cl^- in corrosive medium will increase the susceptibility of specimens to stress corrosion cracking.