文献类型：期刊文献

英文题名：Thermal Degradation Evaluation of HP40Nb Alloy Steel After Long Term Service Using a Nonlinear Ultrasonic Technique

作者：Xiang, Yanxun[1];Deng, Mingxi[2];Xuan, Fu-Zhen[1]

机构：[1]E China Univ Sci & Technol, Sch Mech & Power Engn, Key Lab Pressure Syst & Safety MOE, Shanghai 200237, Peoples R China;[2]Logist Engn Univ, Dept Phys, Chongqing 400016, Peoples R China

年份：2014

卷号：33

期号：2

起止页码：279

外文期刊名：JOURNAL OF NONDESTRUCTIVE EVALUATION

收录：;EI(收录号：20142717907441);WOS:【SCI-EXPANDED(收录号:WOS:000337168800013)】；

基金：The authors are grateful for the supports provided by National Natural Science Foundations of China (Grant Nos. 51325504, 11004056 and 11274388).

语种：英文

外文关键词：Ultrasonic nonlinearity; Thermal degradation; HP40Nb alloy steel; Precipitation kinetics

摘要：Nonlinear ultrasonic analysis has been proposed to characterize the thermal degradation of HP40Nb steel associated with microstructure evolution. Measurements of ultrasonic nonlinear signals were performed in the thermally degraded damaged HP40Nb specimens and the results showed a clear change of increase-plateau-decrease tendency of the normalized nonlinear parameter with respect to the different thermal loading time. Based on metallographic studies, the variation in the measured acoustic nonlinearity reveals that the normalized acoustic nonlinearity increases due to the increases of the second phase precipitates and dislocation density in the early stage and it decreases as a combined result of the reduction of dislocation density, coarsening of precipitates and initiation of micro-voids after long-term high temperature exposure. Moreover, an analytical model calculation of precipitate-dislocation interaction has been performed to interpret the correlation between microstructural evolutions and the measured ultrasonic nonlinearity. Consequently, ultrasonic nonlinearity is found to be strongly sensitive to the microstructure evolutions during thermal degradation of HP40Nb steels.