690TT合金在特殊环境下的腐蚀问题

在广泛的电厂运行及实验室研究基础上，690TT合金被证明是目前最佳的蒸汽发生器（SGs）管材之一，690TT合金的使用有效地提高了PWR蒸汽发生器的可靠性，因而成为在役第二代核电站中最常用的传热管管材，并将大量应用于第三代商用核电厂。然而在水质恶化以及随服役时间的增加，690TT合金不可避免的也会遭遇腐蚀。本文对690TT合金使用安全性造成潜在威胁的脱合金成分腐蚀（Cr贫化）、铅致应力腐蚀破裂（PbSCC）、低价硫应力腐蚀开裂（Sy-SCC）的情况加以较详细的介绍。

SOME CORROSION PROBLEMS OF ALLOY 690TT IN SPECIAL ENVIRONMENTS

In order to improve the reliability of PWR steam generators, alloy 690TT has been developed and verified as the optimum steam generators (SGs) tubing material at present, based on wide operating and laboratorial experience. Alloy 690TT is and will be one of most popular tube material of present and future commercial nuclear plants. Alloy 690TT is usually insusceptible both under acidic and alkaline conditions, but the corrosion is unavoidable under special corrosive environment in time. Dealloying (Cr depletion), lead stress corrosion cracking (PbSCC), low-valence sulfur stress corrosion cracking (S^y-CC) are considered being potential damage to Alloy 690TT and will be described in detail in this article.