Abstract
This paper proposes a transmission a.c. potential method for determining the position and depth of internal defects embedded in a component. Alternative currents from 100Hz to 5000Hz were applied to internally holed specimens with 0.5mm-2.0mm diameters and 2.0mm-8.0mm depths. Position and depth of internal defects were determined by two stages scans of two probes. The hole position was determined by the first scan where two probes were scanned simultaneously and hole depth was determined by the second scan where only a probe was scanned. The transmission. a.c. potential method was capable to determine the postion and depth of internal defect accurately.
