作者：王亮1,2,3,4, 刘帅1,2,3,4, 杨洋1,2,3,4
作者单位：1. 航空材料检测与评价北京市重点实验室，北京 100095;
2. 材料检测与评价航空科技重点实验室，北京 100095;
3. 中国航空发动机集团材料检测与评价重点实验室，北京 100095;
4. 中国航发北京航空材料研究院，北京 100095
关键词：高温合金材料;直流电位法;疲劳裂纹长度;勾线法
摘要：
航空发动机设计用材料的疲劳裂纹扩展速率测量是其性能测试的重要环节，而金属材料在600 ℃以上温度时合金表面由于氧化或者高温热辐射，无法使用基于光学原理的测量方法测量裂纹长度，所以需要使用自动测量方法——直流电位法。在室温条下使用铝合金对电位法系统进行测试，通过直流电位法与目测法测量的裂纹长度进行对比，发现使用参考试样测量的裂纹长度测量要好于没有使用参考试样的测量结果，说明参考试样可以很好地消除温度波动对测量结果的影响；同时在高温实验中，使用勾线法标定电位法测量的裂纹长度数据。结果表明，电位法测量的裂纹长度与勾线法测量平均裂纹长度之间的平均相对误差为1.79%，说明在高温实验环境下，试样出现表面氧化，可以使用直流电位法进行裂纹长度的测量。应用电位法技术完成650~800 ℃实验环境下，获得钛合金材料负应力比疲劳裂纹扩展试验数据。
Technology and application of fatigue crack length measurement based on DC potential drop method
WANG Liang1,2,3,4, LIU Shuai1,2,3,4, YANG Yang1,2,3,4
1. Beijing Key Laboratory of Aeronautical Materials Testing and Evaluation, Beijing 100095, China;
2. Aviation Key Laboratory of Science and Technology on Materials Testing and Evaluation, Beijing 100095, China;
3. Key Laboratory of Aeronautical Materials Testing and Evaluation, Aero Engine Corporation of China, Beijing 100095, China;
4. AECC Beijing Institute of Aeronautical Materials, Beijing 100095, China
Abstract: The measurement of fatigue crack growth rate of materials for aero engine design is an important part of its performance test. When the temperature of metal materials is above 600 ℃, the alloy surface cannot use the measurement method based on optical principle to measure the crack length due to oxidation or high-temperature heat radiation, so it is necessary to use the automatic measurement method - DC potential drop method. The DC potential drop system was tested with aluminum alloy at room temperature. By comparing the crack length measured by DC potential drop method with that measured by visual method, it was found that the crack length measured with reference sample was better than that without reference sample, indicating that the reference sample can well eliminate the influence of temperature fluctuation on the measurement results; at the same time, in the high temperature experiment, the crack length data measured by the overload method and the calibration potential method are used. The results show that the average relative error between the crack length measured by the potential method and the average crack length measured by the hook method is 1.79%, indicating that the surface oxidation of the sample occurs in the high temperature experimental environment, and the DC potential drop method can be used to measure the crack length. The negative stress ratio fatigue crack growth test data of titanium alloy were obtained under the experimental environment of 650- 800 ℃ by potential drop method.
Keywords: super alloy material;DC potential method;fatigue crack length;overload method
2022, 48(5):56-64 收稿日期: 2021-09-23;收到修改稿日期: 2021-12-01
基金项目:
作者简介: 王亮（1975-），男，北京市人，高级工程师，主要从事金属力学性能试验技术研究
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