铝合金薄板不同走向焊缝缺陷的脉冲涡流热成像检测

Pulsed Eddy Current Thermography for Weld Defects with Different Orientation in Aluminum Alloy Sheet

针对铝合金薄板不同走向焊缝缺陷的高效以及可视化成像检测要求,进行了涡流热成像检测方法试验研究。基于麦克斯韦方程、焦耳定律与热传导方向,分析了铝合金涡流热成像的基本原理,在此基础上搭建了不同走向焊缝缺陷的涡流热成像检测试验系统。试验分析了不同角度缺陷处的最大温差变化规律曲线,以及激励电流强度与激励时间对检测效果的影响。结果表明:红外涡流热成像检测方法能够有效检测出铝合金薄板的不同走向缺陷,并且最大温差随着缺陷角度的增加而增加,最后趋于平稳;改变电流大小与激励时长对最大温差的影响不明显。该研究为铝合金焊缝不同走向缺陷的检测提供了一种有效途径。

In order to inspect and image the weld defects with different orientation in aluminum alloy sheet,the feasibility of pulsed eddy current thermography(ECPT)is investigated.Based on the Maxwell’s equations,Joule’s laws and heat conduction equation,the fundamental principle of ECPT for aluminum alloy is analyzed.Based the testing principle,the ECPT system is built for the weld defects with different orientations.Experimental results show that the proposed ECPT system can effectively detect the defects with different orientations in aluminum alloy sheet.The maximum thermal response increases with the increase of the defect orientation,and finally stabilizes.The excitation current density and the excitation duration has little influence on the response.The study provides an alternative for the weld defects of aluminum alloy.