Pulsed Eddy Current Technique for Testing of Stainless Steel Plates

Pulsed eddy current (PEC) technique is attractive for detection of surface defects and wall-thinning in covered electrically conductive materials. This paper discusses development of PEC technique and two different types of self-nulling probes (differential Hall sensors and Double-D differential coils) for detection of surface notches in a thick stainless steel plate. PEC testing of covered objects is attempted. In this regard, the influence of lift-off on the PEC signal due to insulation shims and thin aluminum layer is studied using the peak amplitude and the performance of the two probes is compared. The results showed that the PEC instrument, probes and scanner developed can be used for detection as well as imaging of defects in stainless steel plates covered with insulation.