Magnetic Flux Leakage Testing Method using Rotating Field for Detection of All-directional Surface Flaw

摘要

In magnetic leakage flux testing (MFLT) it is difficult to detect flaws parallel to the direction of magnetization because there is minimal of leakage flux. However, the direction of flaws cannot be known prior to the examination. There is a possibility, therefore, that several flaws may remain in the test specimen if the examination is executed by conventional MFLT with one directional magnetization. To resolve this, the authors developed a new MFLT method that can detect all-directional surface flaws without overlooking any. Testing the new method by applying the rotating field for magnetization of materials and detecting the leakage flux using a cross type differential sensor (coil) confirmed that this is a highly sensitive means of detecting all-directional surface flaws.