核电管材奥氏体不锈钢热机械疲劳行为研究进展

Review of Thermomechanical Fatigue Behavior of Austenitic Stainless Steel for Nuclear Power Plant Pipes

对过去50年发表的核电管材奥氏体不锈钢热机械疲劳行为研究的文献进行综述。首先对热机械疲劳测试概念的准确定义进行阐述,并对国内外主要的热机械疲劳测试方法标准化的历程进行了系统回顾。对热机械疲劳加载下奥氏体不锈钢循环力学响应的非对称性特征进行描述。对高温疲劳加载下奥氏体不锈钢的主要变形及损伤机理,动态应变时效、氧化和蠕变的典型表现形式、微观作用机理及其与疲劳损伤的交互作用进行了详细分析。依据温度循环的最高值与材料蠕变损伤发生的临界温度间的关系,分别讨论了低温区和高温区内材料的热机械疲劳寿命行为。低温区内材料的主导失效机理是纯疲劳或氧化-疲劳交互作用,高温区内蠕变-氧化-疲劳三者间的复杂交互作用决定了材料的疲劳寿命行为。在归纳总结的基础上,对核电管材奥氏体不锈钢的热机械疲劳研究提出了几点展望。

Literatures published in the past 50 years on the thermomechanical fatigue(TMF) behavior of austenitic stainless steel(SS) for nuclear power plant pipes are reviewed. The accurate definition of TMF testing is given and its standardization processes at home and abroad are systematically reviewed. The asymmetric characteristic of cyclic mechanical response of austenitic SS under TMF loadings are described. Three main deformation and damage mechanisms of austenitic SS, namely dynamic strain aging, oxidation and creep under high temperature fatigue loadings are selected, the macroscopic manifestation, underlying physical mechanisms and interactions of which with fatigue damage are analyzed in detail. According to the relationship between the maximum temperature and the critical temperature for the occurrence of creep damage, the TMF life behavior of austenitic SS in the low and high temperature region, corresponding to different failure mechanisms are discussed respectively. The dominant failure mechanism in the low temperature region is pure fatigue or oxidation-fatigue interaction, while the complex interactions among creep, oxidation and fatigue in high temperature region determine the TMF life behavior. Based on the above discussion, several prospects for the TMF investigation of austenitic stainless steel are presented.