Surface Texture‐Corrosion Correlation of Nickel‐Based Superalloy in Aqueous and High‐Temperature Conditions

ABSTRACT Nickel‐based superalloys are extensively used in critical and demanding applications like aerospace gas turbines. Fatigue and corrosion resistance will decide component life, which depends on surface condition. In this study, the effect of three types of surface textures—electropolished, unidirectional (parallel) and randomly oriented—on the corrosion behaviour of IN718 was studied. Surface texture was characterised using an optical profilometer. Electrochemical corrosion tests were performed in 3.5% NaCl solution. In addition, hot corrosion tests were conducted at 650°C for 80 h. The corrosion rates of the parallel and random‐textured samples were about 23% and 63% higher than electropolished samples. However, once passivated, the effect of texture was negligible during the electrochemical test. Parallel and random‐textured samples gained 50% and 150% higher weight than electropolished sample. This study shows that the overall texture of the surface is a better indicator of both electrochemical and hot corrosion behaviour in IN718.