Revealing of corrosion behavior of GH4169 under the alternate environment of intermediate temperature NaCl spraying and marine atmosphere

The corrosion behavior of Ni-based superalloy GH4169 in the marine environment was simulated and investigated by the alternation of intermediate temperature salt spraying and the marine atmosphere. The results suggested that promoted corrosion caused by intermediate temperature NaCl spraying was primary and severe in the form of an over-parabolic weight gain while a weight loss in marine atmosphere. After long-term exposure, corrosion further invaded the matrix alloy and resulted in severe internal corrosion. The corrosion preferentially occurred at the vertices of NaCl particles and led to the consumption of Cr2O3. A complex mixture of Cr2O3, NaCrO2, and Na2CrO4 was thus caused and evolved under the "active oxidation" mechanism. Accordingly, actual corrosion behavior of aircraft engine blades serviced and parked in the marine environment was revealed in the work.