Laser ultrasonic technique for surface defects detection of 6061 aluminum alloy

LI Hai-yang1, WEI Zhuang-zhuang1, PAN Qiang-Hua2

（1. School of Information and Communication Engineering, North University of China， Taiyuan 030051, China； 2. China Special Equipment Inspection and Research Institute, Beijing 100029, China）

Abstract： In order to estimate and detect the surface defect depth of metals, the transmission method of laser ultrasonic surface waves is used in this work. The laser ultrasonic detection platform taking use of thermoelastic mechanism as acoustic signal excitation method and interference receiver as acoustic signal receiver method was built, by which B-scan images of detected specimens with surface defects were collected to establish the relationship between the transmission coefficient and depth of the surface defect. Experimental results show that the amplitude of transmitted acoustic signal is related to the depth of surface defect. At last, a fitted curve of transmission coefficient using measured experimental data is obtained to estimate depth of surface defect on the 6061 aluminum alloy. Furthermore, a surface defect depth of 0.3 mm is estimated by the fitting curve with an estimated error of 16%. Therefore, a experimental method using the transmission method by laser ultrasonic is presented in this paper.

Key words： laser ultrasonics; transmission method; surface defect; depth detection

CLD number： TH878; TN247  Document code： A

Article ID： 1674-8042（2019）03-0293-06  doi： 103969/jissn1674-8042201903013

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针对6061铝合金材料表面缺陷的激光超声检测

李海洋1， 魏壮壮1， 潘强华2

（1. 中北大学 信息与通信工程学院， 山西 太原 030051； 2. 中国特种设备检测研究院， 北京 100029）

摘要： 为了完成对金属材料表面缺陷深度的检测， 提出了透射法检测与估计表面缺陷深度的方法。 基于热弹机制和干涉接收方式， 搭建了激光超声检测实验平台， 实现了工件表面缺陷的非接触检测， 完成了缺陷处的B-scan信号采集和成像， 建立了透射系数与表面缺陷深度之间的关系。 实验结果表明， 由B-scan信号可见缺陷处透射声信号的幅值与表面缺陷深度有关； 采用透射系数-表面缺陷深度拟合曲线估计了深度0.3 mm 表面缺陷， 估计误差为16%， 实现了表面缺陷深度的测量。

关键词： 激光超声； 透射法； 表面缺陷； 深度检测

引用格式：LI Hai-yang, WEI Zhuang-zhuang, PAN Qiang-hua. Laser ultrasonic technique for surface defects detection of 6061 aluminum alloy. Journal of Measurement Science and Instrumentation, 2019, 10（3）： 293-298. ［doi： 103969／jissn1674-8042201903013］

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