| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and an apparatus for evaluating a defect of a tubular object, capable of not only speedily detecting even the defect whose defective volume is small, but also identifying inner and outer surfaces having the defect. SOLUTION: The method employs a sensor equipped with a DC magnetizing coil 11 and an eddy-current flaw detection coil 12. In the method, an eddy-current flaw detection is carried out for a test tube which is or is equivalent of the tubular object 100 and has a plurality of kinds of simulated defects previously disposed on its inner and outer surfaces 101, 102, while DC magnetizing the test tube by using the sensor, and then the intensity of above DC magnetization and a test frequency of the eddy-current flaw detection coil 12 are selected so that the simulated defects can be detected, and the simulated defects located on any of the inner and outer surfaces 101, 102 of the tubular object 100 can be identified, by using both effects of a magnetic permeability change and an occurrence of eddy current E, E', and then the sensor is inserted into the tubular object 100, and the eddy-current flaw detection is carried out, while DC magnetizing the tubular object 100 in the condition of the selected DC magnetization intensity and test frequency. Which one of the inner and outer surfaces 101, 102 of the tubular object 100 has the defect is identified by using a detection signal of the eddy-current flaw detection coil 12. COPYRIGHT: (C)2010,JPO&INPIT |
