Corrosion of Nickel and Iron-based Superalloys in High Temperature Gas Environments

摘要

High-temperature gas-cooled reactors (HTGRs) with helium gas as the primary coolant have been considered as Generation Ⅳ nuclear power reactor systems. Several iron- and nickel-based superalloys, including Incoloy 800H, Hastelloy X, and Inconel 617, are potential structural materials in pressure boundary components, such as the intermediate heat exchanger (IHX) in an HTGR. Impurities in a helium coolant, such as H_2O and O_2, can interact with structural materials at working temperatures of ＞900 ℃, causing serious degradation. This study investigates the oxidation behavior of three selected alloys (Hastelloy X, Incoloy 800H, and Inconel 617) in high-temperature, gaseous environments with various levels of O_2 and H_2O. A series of corrosion tests were conducted at test temperatures of 650 ℃, 750 ℃, 850 ℃ and 950 ℃ under various coolant compositions of dry air, 1% O_2, 10% humidity, and 50% humidity.