Enhanced detection of deep seated flaws in 316 stainless steel plates using integrated EC-GMR sensor

Eddy current electromagnetic non-destructive evaluation technique is widely used for detection and sizing of flaws in electrically conducting materials within a depth of 5.0 mm. In order to extend the application of EC technique for detection of deep seated flaws (>5.0 mm), an integrated sensor comprising of EC coil and a Giant magnetoresistive sensor has been developed. The experimental measurements and Finite Element Model based studies on 8.0 mm thick AISI type 316 stainless steel plate having machined surface and subsurface notches at different depth location have been investigated. The paper discusses the detection sensitivity of components of induced magnetic field for deep seated flaws under varying lift-off condition.