金属亚表面腐蚀缺陷的脉冲调制涡流磁场梯度成像

摘要

由于工况复杂,在役金属构件极易产生亚表面腐蚀缺陷,严重影响其安全运行.脉冲调制涡流检测技术是一种新型脉冲涡流检测技术.相较传统脉冲涡流检测技术,其在金属构件缺陷检测和评估中具有优势;将其与磁场梯度测量技术有效结合,探究其在金属构件亚表面腐蚀缺陷检测中的成像方法和技术优势.通过有限元分析,发现相较脉冲涡流磁场梯度信号,脉冲调制涡流磁场梯度信号对金属亚表面腐蚀缺陷边缘识别具有更高的灵敏度.并且,搭建了相关试验系统,通过试验验证了仿真分析结论.试验结果表明,脉冲调制涡流磁场梯度检测信号对金属构件亚表面腐蚀缺陷成像具有更高的精度,有利于缺陷的检测.%Metallic structures are subj ect to subsurface corrosion due to rigorous environment.As a new inspection technique extended from Pulsed Eddy Current technique (PEC),Pulsed-modulation-based Eddy Current technique (PMEC)has been found advantageous over PEC in evaluation of conductive structures with defects.In this paper,PMEC integrated with Gradient Magnetic Field Measurement (GMFM),namely GMFM-based PMEC is proposed particularly for subsurface corrosion imaging.Through simulations,the advantages of GMFM-based PMEC for defect imaging of subsurface corrosion are investigated.A series of experiments have been conducted in a bid to verify the conclusion drawn from simulations.Through simulations and experiments,GMFM-based PMEC can carry out the imaging with high accuracy for subsurface corrosion.