Abstract: Aiming at the problems of poor surface quality of additive products and difficulty of on-line detection of internal defects, the research of laser ultrasonic detection of internal defects for arc additive manufacturing test block was carried out. In order to ensure the accuracy of defect detection results, defect reflection method and synchronous movement of excitation source and receiving source way were adopted. The theoretical calculation, the simulation analysis and experimental results were contrasted, the propagation paths and detect wave type were determined. Defects in A sweeping reflection amplitude and defects in B scan reflected wave imaging were obtained respectively, according to the amplitude size and the imaging results. In depth of 10 mm, the internal defects 1 mm diameter were accurately detected, the influence laws of defect depth were obtained. The research results have a good reference value for the on-line detection of additive manufacturing.

Key words: additive manufacturing, laser ultrasound, nondestructive testing, internal defect, depth detection

摘要： 针对增材制件表面质量差、内部缺陷在线检测困难的问题，开展激光超声对电弧增材制造试块内部缺陷检测的研究。为保证缺陷检测结果的准确性，采用缺陷反射法与激发源、接收源同步移动检测方式。对比理论计算、仿真分析、实验结果，确定传播路径和检测波形，在A扫中得到缺陷反射波幅值，在B扫中得到缺陷反射波成像，根据幅值大小和成像结果，准确探测出10 mm深度内直径为1 mm的内部缺陷，得到缺陷深度影响规律。研究结果为增材制造在线检测提供了参考。

关键词: 增材制造, 激光超声, 无损检测, 内部缺陷, 深度检测