Rail flaw detection is at present an important research and development area. Technological developments augmented the circulating speed of trains, improved their comfort and increased the use of railway transportation in Europe making the safety of railway networks a paramount issue. One item associated with today's rail track assessment is inspection speed. This paper presents a contribution to attain a solution for this problem. It proposes a testing method whose sensitivity increases with the moving speed of the probe in relation with the material to be tested.

In the approach described in this paper a nondestructive technique (NDT) based on velocity induced eddy currents is used to inspect a machined plate. The induction of the eddy currents in the plate is performed with a DC magnetic field provided by a magnet moving in the vicinity of the plate. Very sensitive magnetoresistors (GMR) are used to measure the magnetic field resulting from the perturbation originated in the currents flow pattern by the presence of cracks.