METHOD AND APPARATUS FOR CALIBRATING SENSITIVITY OF HOT EDDY CURRENT FLAW DETECTOR

摘要

PURPOSE: To accurately detect a crack flaw, a pitlike flaw, etc., caused in a wire material, a bar-in-coil, a pipe-in-coil, etc., by efficiently, accurately calibrating the sensitivity of a hot eddy current flaw detector. ;CONSTITUTION: A test piece 1 for calibrating sensitivity in which a circumferentially uniform annular flaw is processed is heated to the temperature of a test specimen by a heater 5 at the time of hot eddy current flaw detecting. The piece 1 is passed through a plurality of detecting coils 7 which are annularly disposed. In this case, since circumferentially uniformly annular flaw is processed at the piece 1, uniform eddy current is generated in the circumferential direction of the piece 1. Since the piece 1 is heated to the temperature of the test specimen, the sensitivity of the coil 7 calibrated by the piece 1 becomes the same as the sensitivity at the time of detecting the flaw of the test specimen. Thus, the plurality of the coils 7 can be accurately calibrated in a short time.;COPYRIGHT: (C)1996,JPO