Eddy current inversions of defects in rough welds using a simplified computational model

This study demonstrates that the profiles of defects in Inconel welds with a rough surface can be sufficiently evaluated by eddy current testing with the aid of computational inversion techniques. A plate specimen with Inconel welding is fabricated and artificial notches are introduced between the welding metal and base material. Eddy current inspections are performed to measure signals caused by the artificial notches, and their profiles are reconstructed from the measured signals using a computational inversion algorithm based on the conjugate gradient method. Since it is difficult to model the specimen exactly, simulations to calculate eddy current signals due to a reconstructed profile are performed in a simplified configuration. The lengths and maximum depths of the notches are well estimated, which validates the applicability of eddy current testing to not only the detection but also evaluation of defects in Inconel welds.