焊缝表面缺陷的涡流红外热成像检测

Eddy current infrared thermal imaging for the detection of weld surface defects

焊缝对金属结构的完整性起关键作用,而焊缝表面气孔缺陷是威胁金属结构整体性的缺陷之一。文中将涡流热成像技术与漏磁相结合,实现对人工模拟焊缝表面气孔缺陷的快速检测与全面描述。通过采用数值模拟方法分析了检测区域电磁场分布和温度分布,验证该方法可在检测区域形成相对均匀的电磁场。利用涡流热成像实验平台对不同直径与深度表面气孔缺陷进行实验检测,分析缺陷大小对温度的影响。同时与ICA图像处理算法相结合,减小焊缝边缘效应的影响,进一步增强原始图像中缺陷特征。结果表明:该方法对尺寸较小的气孔缺陷具有较高的灵敏度,可以显著提高焊缝缺陷检测能力,且相对于气孔缺陷深度,缺陷直径对于表面温度影响较大,可利用温度曲线1阶导数峰值更清楚识别不同大小的缺陷。

The Weld plays a key role in the integrity of the metal structure,and the weld surface porosity defect is one of the defects that threaten the integrity of the metal structure.In the paper,eddy current thermography is combined with leakage magnetism to achieve rapid detection and comprehensive description of porosity defects on artificially simulated weld surfaces.The electromagnetic field distribution and temperature distribution in the detection area are analyzed using numerical simulations to verify that the method can create a relatively uniform electromagnetic field in the detection area.The eddy current thermography experimental platform is used to experimentally detect surface porosity defects of different diameters and depths,and to analyze the effect of defect size on temperature.It is also combined with ICA image processing algorithm to reduce the effect of weld edge effect and further enhance the defect features in the original image.The results show that the method has a high sensitivity for detecting small size porosity defects and can significantly improve the detection of weld defects,and relative to the depth of porosity defects,the defect diameter has a greater effect on the surface temperature compared to the depth of the porosity defect,and the peak of the first order derivative of the temperature curve can be used to more clearly identify defects of different sizes.