800、600和690合金的铅致应力腐蚀破裂

在很多核电站的蒸汽发生器中都发现了金属态铅或氧化态铅，因而蒸汽发生器传热管的铅诱导（铅致）应力腐蚀破裂（PbSCC)已引起广泛的注意，已证实在压水堆的蒸汽／水系统，特别对管材，存在着铅的许多可能的来源，本文介绍了PbSCC的现场事例，讨论在压水堆（PWR）二回路条件（碱性，酸性和近中性）下铅对镍合金SCC的影响及其作用机理研究的进展。

LEAD-INDUCED STRESS CORROSION CRACKING OF ALLOYS 800, 600 AND 690

Lead, either in metallic form or the form of lead oxide, is found in the steam generator of many nuclear power plants. The lead induced stress corrosion cracking (PbSCC) has received extensive attention. Many potential sources of lead have been identified in PWR steam water system, mainly at the tube level. In this review, the field occurrence of PbSCC and the mechanisms through which lead affects the SCC susceptibility of nickel alloys under PWR secondary side conditions (caustic, acidic and near neutral) are discussed. Lead induced cracking occurs across the whole feasible range of pH and is the main type of tube degradation for which there is unequivocal evidence that it occurs in the mid range, moderately alkaline pH, a target of secondary water chemistry treatment to minimize general corrosion. However, whether the minor amounts of lead found in practically every steam generator have a critical influence on nickel alloys as distinct from aggravating another underlying degradation mechanism remains unresolved.