文章摘要
项延训.HP40Nb合金钢高温劣化的非线性超声评价[J].声学技术,2012,(6):578~582
HP40Nb合金钢高温劣化的非线性超声评价
Nonlinear ultrasonic evaluation of thermal degradation in HP40Nb alloy steels
投稿时间:2012-08-08  修订日期:2012-10-28
DOI:10.3969/j.issn1000-3630.2012.06.009
中文关键词: 超声非线性  高温劣化  HP40Nb合金钢
英文关键词: ultrasonic nonlinearity  thermal degradation  HP40Nb alloy steel
基金项目:国家自然科学基金资助项目(11004056)
作者单位E-mail
项延训 华东理工大学机械与动力工程学院,上海 200237 yxxiang@ecust.edu.cn 
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中文摘要:
      耐高温合金材料在服役过程中会发生高温劣化,主要表现为微观组织结构的变化,从而导致在其中传播的超声波能产生显著的高次谐波.针对HP40Nb合金钢材料高温劣化的检测及评价,提出采用归一化超声纵波非线性参量来表征材料的高温损伤状态.对HP40Nb损伤试样进行了非线性超声信号的测量结果显示,归一化超声纵波的非线性参量随着材料高温加载时间呈现出显著的上升-平稳-下降趋势.对材料微观组织演化过程进行了扫描电镜(SEM)的观察和分析,结果表明,超声非线性参量在早期阶段的上升与HP40Nb材料高温加载过程中η相等第二相的析出和聚集密切相关;其在后期阶段的下降归因于析出相的减少和脱落以及微孔洞的产生.由此可见,非线性超声对HP40Nb材料高温劣化后微观组织的变化非常敏感.
英文摘要:
      The thermal degradation associated with microstructure evolution would happen to the heat-resistance alloy materials while experiencing high temperature in service. This would lead to an obvious high order ultrasonic harmonics propagating in it. Normalization of ultrasonic nonlinear parameter is proposed in this paper to characterize the thermal degradation of HP40Nb steel for damage testing and evaluation. Measurements of ultrasonic nonlinear signals are performed in HP40Nb specimens with different thermal damages. The results show clear changes of increasing-plateau-decreasing tends of the normalized nonlinear parameter with respect to the thermal loading time. A scanning electron microscope (SEM) has also been utilized to observe the microstructure evolution of the damaged specimens. The results indicate that the normalized acoustic nonlinearity in HP40Nb alloy increases due to the second phase precipitation and coalescence, such as the h phases, in the early stage. And it decreases as a result of the precipitations reduction and the microviods initiation in the late stage. Therefore, ultrasonic nonlinearity is found to be strongly sensitive to the microstructure evolutions during thermal degradation of HP40Nb steel.
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