Insights of NaCl water vapor coupling induced hot corrosion behaviors of IN718 superalloy

Abstract

The hot corrosion behavior of Ni-based superalloys induced by NaCl at 600°C, 650°C, and 700°C in a marine-like environment was investigated. The results show that the corrosion scale on the IN718 alloy includes two distinct layers, of which the outer layer is mainly composed of NiFe 2 O 4 and NiO, while the inner layer contains FeCr 2 O 4 and NiCr 2 O 4 . The HCl (g) as a catalyst significantly accelerated the corrosion of the samples. The formation of the Cr-depletion layer was analyzed. The O 2 in the atmosphere can diffuse to the substrate surface through the corrosion product layer, leading to internal corrosion. The hot corrosion behaviors of the corroded samples have been discussed in detail.