| 摘要 |
A method and apparatus are provided which are based upon a discovery that regardless of the type of ferromagnetic material of a part and its shape, there is a certain direct, uniform and constant relationship between the level of magnetization required for satisfactory testing by the magnetic particle method and the response which is obtained from an eddy current instrument which has been properly calibrated and which is used under proper conditions. After removal of scale from a surface portion of a part and after demagnetization of the part, a probe of the eddy current instrument is simply placed against such surface portion and the part is magnetized at a level which produces a certain target eddy current indication. The instrument may be readily calibrated through the use of a test block which has a milled slot of a certain size. Preferably, the probe is of a crossed coil type permitting a rapid scanning operation with respect to a plurality of surface areas of a part of irregular shape.
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