Study on the Magnetic Flux Leakage (MFL) for Fillet Weld

Abstract

The magnetic flux leakage (MFL) technique is widely used as a Non-Destructive Testing (NDT) method for welds [1]. Because of the specialty of fillet weld structure, the defect may not be in the location suitably detected, which is normally at the center of yoke poles, and the rate of detect-ability would decline. In this paper, we focus on the yoke-magnetization testing for a fillet weld, and it is studied the influences of air gap between magnetic poles and specimen surface on MFL density at an artificial flaw by Finite Element Method (FEM), and also the influences of distance between magnetic poles and fillet weld on MFL density. The results show that the MFL density observably decreases as the air gap and the distance increase.