温度对衍射时差法超声检测结果影响
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摘要
针对温度变化引起超声衍射时差技术(time of flight diffraction,TOFD)测量结果误差的现象,以含不同预置缺陷Q235A试块为测试样品,采用TOFD超声检测技术,并结合A扫结果,研究不同温度对缺陷检测结果的影响。研究发现,当试块表面温度超过40℃时,底面小缺陷的检测难度会提高,检测结果的不稳定性提升;随着试块表面温度继续升高,TOFD测量缺陷的最小分辨率会降低到3 mm,同时小缺陷波的A扫波形已经无法从背景噪声中识别。通过比较不同温度下纵波在固体介质中传播速度,发现温度升高导致纵波速度衰减,进而导致仪器分辨力的下降和实际测量误差的增大。
Aiming at the phenomenon that the change of temperature leaded to the measurement error of the time of flight diffraction(TOFD), the TOFD ultrasonic testing technique was used to test the Q235 A specimens with different prefabricated defects, and the A-scan outcomes were used to study the effects of different temperature on defect detection. The results show that the difficulty in detecting the small defects on the bottom surface is increasing as the surface temperature of the specimens exceed 40 °C, and the instability of the testing results will increase. As the surface temperature of the specimen increasing, the minimum resolution of TOFD in measurement defects will be reduced to 3 mm, and the small defect of A-scan waveform cannot be identified from the background noise. Compared with the propagation velocity of P-wave in solid medium at different temperatures, it is found that the P-wave velocity decays with the increase of temperature, which leads to the decrease of the resolution of the instrument and the increase of the actual measurement error.
Aiming at the phenomenon that the change of temperature leaded to the measurement error of the time of flight diffraction(TOFD), the TOFD ultrasonic testing technique was used to test the Q235 A specimens with different prefabricated defects, and the A-scan outcomes were used to study the effects of different temperature on defect detection. The results show that the difficulty in detecting the small defects on the bottom surface is increasing as the surface temperature of the specimens exceed 40 °C, and the instability of the testing results will increase. As the surface temperature of the specimen increasing, the minimum resolution of TOFD in measurement defects will be reduced to 3 mm, and the small defect of A-scan waveform cannot be identified from the background noise. Compared with the propagation velocity of P-wave in solid medium at different temperatures, it is found that the P-wave velocity decays with the increase of temperature, which leads to the decrease of the resolution of the instrument and the increase of the actual measurement error.
引文
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[15]曹建树,曹振,赵龙,等.激光超声管道表面裂纹检测技术[J].光电工程,2016,43(3):1-6.
[2]洪作友,唐兴.TOFD技术在特殊结构焊缝检测中的应用[J].无损检测,2009,31(7):548-550.
[3]杨文钗.焊缝超声波衍射时差法(TOFD)的研究现状[J].工程管理,2017,10:242-243.
[4]齐杰.超声TOFD检测盲区及分辨率的计算与改善方法[C]//2008年安徽省科协年会机械工程分年会论文集,2008.
[5]于刚.高质量超声TOFD成像关键技术的研究[D].杭州:浙江大学,2013.
[6]KELLY SP,ATKINSON I,GREGOR C,et al.On-line ultrasonic inspection at elevated temperatures[C]//Proceedings of the IEEE Ultrasonics Symposium,2007:904-908.
[7]孙钟,刁海波,苏万钧,等.温度对超声波声速影响的研究[C]//全国钢结构学术年会论文集,2011.
[8]承压设备无损检测第十部分:衍射时差法超声检测:NB/T47013.10-2015[S].北京:中国质检出版社,2015.
[9]迟大钊,刚铁,袁媛,等.面状缺陷超声TOFD法信号和图像的特征与识别[J].焊接学报,2005,26(11):1-4.
[10]NEFF R,ZAKHOR A.Matching pursuit video coding:dictionary approximation[J].IEEE Transactions on Circuits and Systems for Video Technology,2002,12(1):13-26.
[11]LEYBOVICH A.Probability of detection of minute defects by ultrasonic automated testing equipment in view of Bayesian inference[J].Materialprufung,2016,58(1):27-30.
[12]李力,余新亮,张全林.超声A扫描信号建模及其缺陷识别方法研究[J].中国测试,2014,40(1):14-16.
[13]杜功焕,朱哲民,龚秀芬,等.声学基础[M].3版.南京:南京大学出版社,2012:352.
[14]董大勤,袁凤隐.压力容器与化工设备实用手册[M].北京:化学工业出版社,2000:87.
[15]曹建树,曹振,赵龙,等.激光超声管道表面裂纹检测技术[J].光电工程,2016,43(3):1-6.