nondestructive measurement of degradation in aged plants and remaining life evaluation system

老化的能源工厂部件可能发生的降解机理根据部件的材料、使用环境和运行条件而有很大不同。对于设备寿命的管理和延长，基于部件在役退化的检测和定量评估来预测设备的剩余寿命。(1)开发不同类型退化的无损检测方法，分别基于退化机理；(2)开发一个原型系统，该原型系统可以确定在给定运行条件下老化设备部件的主要劣化因素。对于缺陷型退化，已成功地应用诱导电流聚焦电位降方法来确定三维形状的表面裂纹的形状和大小。在材料类型退化方面，针对尚无无损检测方法的定向凝固镍基高温合金的蠕变损伤、W变质耐热铁素体钢的蠕变损伤、镍基高温合金的高温低周疲劳损伤、双相铸造不锈钢的热时效脆化和310S不锈钢的时效脆化，发展了电化学材料表征方法。在寿命评估系统方面，引入遗传算法开发了原型系统，该系统支持识别在役退化的主要因素，并有助于预测部件的剩余寿命。该系统已成功应用于化工厂换热管腐蚀损伤评估。

Degradation mechanisms which can take place in aged energy plant components are widely varied depending on material of the component, service environment, and operating conditions. For plant life management and extension, prediction of remaining lives of the plants which is based on detection and quantitative evaluation of in-service degradation of the components.(1) development of nondestructive inspection methods for various types of degradation which are respectively based on the degradation mechanisms, and (2) development of a prototype system which can specify the dominant deterioration factors for a aged plant components under given operation conditions, have been in the scope of this research project.For defect-type degradation, Induced Current Focused Potential Drop method has been successfully applied to determine shape and size of three dimensionally shaped surface cracks. For material-type degradation, Electrochemical Materials Characterization methods have been developed for the following degradations which no nondestructive inspection methods have been available for ; creep damage in directionally solidified Ni-base super alloy for gas turbine applications, creep damage in W-modified heat-resistant ferritic steels, high-temperature low-cycle fatigue damage in Ni-base superalloys, thermally aging embrittlement of duplex stainless cast, and aging embrittlement of type 310S stainless steel.With respect to the life evaluation system, genetic algorithm has been introduced to develop the prototype system which supports identifying dominant factors for in-service degradation and helps to predict remaining lives of components. The system has been successfully applied to corrosion damage evaluation of heat-exchanger tubes of chemical plants.