Development of Environment‐Time‐Dependent Material Selection Maps for Alloy 718 Under Crevice Conditions in Aerated Seawater

Material selection practices and standards that rely on the so‐called pitting corrosion resistance equivalent (PRE) might be both risky and over‐conservative. This paper introduces material selection maps, that is, charts indicating crevice corrosion resistance as a function of temperature and electrochemical potential, illustrating their applicability using nickel‐based alloy 718 as a case study. The results showed that alloy 718 could sustain crevice corrosion at temperatures as low as 10°C and 100 mVSSC for 30 days. The most extensive crevice attack was observed at 20°C and 200 mVSSC. Microstructure precipitates were found to cause preferential dissolution of the surrounding matrix. The crevice corrosion susceptibility maps developed in this study represent a new approach that demonstrates how environmental parameters can be used to determine the material suitability under certain conditions.