DEFECT RECOGNITION IN CONDUCTIVE MATERIALS BY LOCAL MAGNETIC-FIELD MEASUREMENT

Among the various nondestructive testing methods, the electric potenti al method requires relatively simple device and measurement. However, because of the high electrical contact resistance, sometimes it is dif ficult to measure the correct local electric potentials by direct cont act. In order to overcome this difficulty, method is proposed which in volves substituting the local magnetic field for electric potential me asurements. The comparison with the conventional electric potential me thod demonstrates the usefulness this method, especially for materials with low resistivity.