Corrosion of Alloy 617 in high-temperature gas environments

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• 作者：Tsung-Kuang Yeh^a ; ^b ; Hao-Ping Chang^a ; Mei-Ya Wang^c ; ^{meywang@mx.nthu.edu.tw" class="auth_mail} ; Trai Yuan^a ; Ji-Jung Kai^a ; ^b
• 刊名：Nuclear Engineering and Design
• 出版年：May, 2014
• 年：2014
• 卷：271
• 期：Complete
• 页码：257-261
• 全文大小：1172 K

文摘

High-temperature gas-cooled reactors (HTGRs) with helium gas as the primary coolant have been considered as one type of the Generation IV nuclear power reactor systems. Several nickel-based superalloys, including Alloy 617, are potential structural materials to serve as pressure boundary components, such as the intermediate heat exchanger (IHX) in an HTGR. Impurities in a helium coolant, such as H₂O and O₂, can interact with structural materials at working temperatures of >900 掳C, leading to serious degradation on these materials. In addition, defects in IHX surface coatings would allow these species to reach and interact with the external surfaces of these components, leading to similar or even more serious degradation. In this study we investigated the oxidation behavior of Alloy 617 in high-temperature, gaseous environments with various levels of O₂ and H₂O. A series of general corrosion tests were conducted at test temperatures of 650 掳C, 750 掳C, 850 掳C and 950 掳C under various coolant compositions of dry air, 1% O₂, 10% relative humidity (RH), and 50% RH. Preliminary results showed that the surface morphologies of the Alloy 617 samples exhibited distinct evidence of intergranular corrosion. Compact chromium oxide layers were observed on the sample surfaces. The oxidation mechanisms of this alloy in the designated environments are discussed.