Patent ID: 8552717
Filing Date: 2013-10-08
Classification: G01N

Abstract:
1. An eddy current testing method for detecting a flaw occurring in a columnar or cylindrical subject to be tested by conducting spinning scanning of a probe coil disposed to be opposite to the subject to be tested, relative to the subject to be tested, comprising the steps of: using a probe coil capable of obtaining a differential output about a scanning direction of a detection signal which corresponds to a detected eddy current induced in the subject to be tested as the probe coil; positioning the probe coil so that a straight line passing a spinning center of the probe coil crosses with an axial center of the subject to be tested at right angles; preparing a test piece made of the same material as that of the subject to be tested, which is provided with an axially extending artificial flaw and a circumferentially extending artificial flaw whose depth is equivalent to depth of the axially extending artificial flaw, and disposing the test piece opposite to the probe coil; setting a distance between the spinning center of the probe coil and a center of the probe coil, which is located differently from the spinning center of the probe coil, so that a difference between a maximum amplitude of a differential output at the axially extending artificial flaw provided in the test piece and a maximum amplitude of a differential output at the circumferentially extending artificial flaw provided in the test piece falls within a predetermined range; and conducting spinning scanning of the probe coil relative to the subject to be tested which is not provided with an artificial flaw at the set distance to detect a flaw occurring in the subject to be tested.