9-12%Cr马氏体钢蠕变-疲劳损伤机理的多尺度研究

项目名称： 9-12%Cr马氏体钢蠕变-疲劳损伤机理的多尺度研究

项目编号： No.51201097

项目类型： 青年科学基金项目

立项/批准年度： 2013

项目学科： 金属材料学科

项目作者： 纪冬梅

作者单位： 上海电力学院

项目金额： 25万元

中文摘要： 超（超）临界火电机组用钢9-12%Cr马氏体钢在服役过程中既产生蠕变损伤又产生疲劳损伤，其损伤演化过程与时间相关，随着机组服役时间的延长，损伤也随之增加，对机组安全运行的威胁也越来越严重。本项目以多尺度力学为依据，引入反映宏细观损伤演化过程的Deborah数，通过P91钢蠕变-疲劳及纯蠕变试验研究蠕变-疲劳宏观损伤与Deborah数的关系；利用金相显微镜实时监测微损伤成核及扩展过程，从细观损伤统计力学出发推导出Deborah数的数学表达式，利用寿命分数法和裂纹扩展速率模型给出宏观损伤的数学表达式，通过数值计算研究宏观损伤与Deborah的关系；将数值分析结果与试验结果作比较，根据比较结果修正宏观损伤及Deborah数的数学表达式，并将其运用于P92钢蠕变-疲劳损伤机理研究，揭示晶粒尺寸、微损伤数密度等细观尺度变量对P92钢宏观蠕变-疲劳损伤的影响，为超超临界机组蒸汽管道安全运行提供保障。

中文关键词： 9-12%Cr马氏体钢；蠕变-疲劳损伤机理；多尺度；寿命预测；裂纹扩展速率

英文摘要： 9-12%Cr martensitic steel used in the ultra supercritical thermal power units will endure not only creep damage but also fatigue damage,and the damage evolution is related with time. With the service time becoming longer and longer, the damage will increase, and brings a serious threat to the units. In this study the Deborah number is introduced based on multiscale mechanics. The Deborah number is the ratio of the characteristic time of mesoscopic damage to that of macroscopic damage, and can reflect marcoscopic and mesoscopic damage evolution process. The P91 creep-fatigue tests and pure creep tests are carried out to study the relationship between marcoscopic damage and the Deborah number. A metallurgical microscope is used to monitor the micro-damage's forming and growthing online, and the mathematic expression of the Deborah number is deduced by using statistical mesomechanics theory based on the experimental data. The mathematic expression of macroscopic damage is also proposed by using the life fraction method and the creep-fatigue crack growth model which is obtained by regressing the experimental data. The relationship of macroscopic damag and the Deborah number can be obtained by numerical calculation, which will be compared with the experimental results. According to the error between them, the mathe

英文关键词： 9-12%Cr martensitic stee；creep-fatigue damage mechanism；multiscale；life prediction；crack growth rate