Understanding and Mitigatin of Stress Corrosion Cracking of Reactor Vassel Materials in Oxidizing Supercritical Water Environments

氧化超临界水环境中反应堆容器材料应力腐蚀开裂的理解和缓解

基本信息

批准号：
13450290
负责人：
WATANABE Yutaka
金额：
$ 7.49万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

项目摘要

Corrosion morphology and rates of various corrosion resistant alloys have been examined in simulated environments of supercritical water oxidation processes. Importance of physical property of water, in particular dielectric constant, to corrosion of metals in supercritical water have been demonstrated. It has been demonstrated that corrosion rate of metals in supercritical water is strongly dependent on applied pressure and can he uniquely arranged by dielectric constant of water including both supercritical state and sub-critical liquid phase.Scale oxides formed in supercritical water environments were in good agreement with thermodynamically predicted oxide. Corrosion rate was able to be correlated with types of the scale oxides.Slow strain rate tests have been performed in neutral to acidic supercritical water up to 550℃/6OMPa to evaluate stress corrosion cracking (SCC) behavior of alloys in supercritical water environments. Effects of applied pressure (water density or dielectric … More constant effect) and sulfuric acid have been demonstrated. For sensitized stainless steel -pure water system, effects of phase state of water and applied pressure, more essentially, physical property of water, were clearly observed. SCC did not occur in the oxygenated "gas-like" supercritical water at 400℃/25MPa. Cracking occurred at 400℃/30MPa and the cracking severity was more pronounced as applied pressure was increased up to 60MPa at the same temperature. The results gave a strong evidence of the "dissolution mechanism". In contrast, for non-sensitized stainless steel -sulfuric acid water system, severe cracking with IG occurred even in a "gas-like" supercritical water and dielectric constant did not affect cracking severity. The results would indicate "dissolution mechanism" is not very likely and might suggest "oxidation cracking".Importance of aging degradation in both mechanical properties and corrosion resistance in supercritical water environments has been pointed out.A new corrosion-inhibition method for supercritical water environments has been developed, where dependence of solubility of Cr oxides on temperature and dielectric constant of water is utilized. Less

在超临界水氧化过程的模拟环境中，已经检查了各种耐腐蚀合金的腐蚀形态和速率。已经证明了水的物理特性，特别是饮食常数，对超临界水中金属的腐蚀的重要性已被证明。已经证明，超临界水中金属的腐蚀速率很大程度上取决于施加的压力，他是否可以通过水的饮食常数（包括超临界状态和亚临界液相）来唯一地排列。超临界水环境中形成的氧化物与热力学预测的氧化物非常吻合。腐蚀速率能够与量表氧化物的类型相关。Slow应变率测试已在最高550℃/6OMPA的中性至酸性超临界水中进行，以评估超临界水环境中合金的应力腐蚀裂纹（SCC）行为。已经证明了施加压力（水密度或顽固的……更恒定的效果）和硫酸的影响。对于敏感的不锈钢 - 紫水系统，水的相状和施加压力的影响，更本质上是水的物理特性。 SCC在400℃/25MPA的含氧“气状”超临界水中没有发生。裂纹发生在400℃/30MPA时，由于施加压力，结果更明显，结果给出了“溶解机制”的有力证据。相反，对于非敏感的不锈钢 - 硫酸水系统，即使在“类似气状”的超临界水和饮食常数中，与Ig发生严重的裂纹也不会影响开裂的严重程度。结果将表明“溶解机制”不是很可能，并且可能暗示了“氧化破裂”。已经指出了机械性能中衰老降解的重要性和超临界水环境中的耐腐蚀性。已开发出一种超临界水环境的新型腐蚀方法，在其中开发了氧化和氧气对温度的依赖性的氧化和氧化物的依赖性。较少的