基于涡流脉冲相位热成像的金属材料裂纹检测

涡流热成像可以对金属材料表面、近表面缺陷进行快速准确的检测。采用涡流热成像与脉冲相位分析相结合的方法，针对裂纹附近相位谱的分布规律及温度场对相位谱的影响关系问题，分别对带有上表面裂纹和下表面裂纹的45#钢料进行感应加热仿真和实验分析。结果表明，相位谱分布与温度大小无关，只与温度变化趋势有关，相位谱图对不均匀加热有很好的抑制作用，可以扩大裂纹的检测范围,当频率低于12.5 Hz时能够清晰地识别裂纹。结合实验验证了仿真结论的正确性，为下一步利用相位信息实现缺陷的定量检测提供参考。

Crack detection for metallic materials based on eddy-current pulsed-phase thermography

The surface and near surface crack of metallic materials can be detected efficiently and accurately by eddy current thermography. In this paper, combining with eddy current thermography and pulsed phase analysis, 45# steel with surface and subsurface cracks were studied by inductive heating simulation and experiments, which were aimed to solve the problem of the phase spectrum distribution and the influence of temperature distribution on the phase spectrum. It shows that, the phase spectrum distribution has nothing to do with temperature value, but is closely related to temperature trend. The phase image has good suppression to inhomogeneous heating, and can also broaden the detection range. Crack can be easily detected when frequency is below 12.5 Hz. The conclusions are experimentally verified, in order to provide guidance for quantitative crack detection with the phase information in the future study.