Weld Crack Detection Based on Region Electromagnetic Sensing Thermography

Nondestructive inspection for fatigue cracks is a critical and challenge task in both science and industry fields. This paper investigates the sensing effect of region electromagnetic performance as well as thermal intensity and uniformity on weld crack detection. The uniformity variation caused by vertical and horizontal lift-off distance between sensing and defect has been studied. In particular, a new AT metric has been proposed to present the thermal contrast and evaluate the detectability for weld natural cracks. This has been conducted by detail interpreting the region sensing for electromagnetic and thermal fields. Results have shown that the crack can be detected with a higher thermal contrast as it lies in a region sensing with relatively high uniformity and eddy current intensity.