Method of nondestructively inspecting for flaws in metal stocks including selection of detection coil diameter.

摘要

A method of nondestructively inspecting a magnetic substance such as metal pipe and bar stocks, wherein the method provides a detection coil having a diameter which is specified based on the length of existent peripheral surface flaws such that the directional sensitivity of the detection coil relative to those flaws is improved. The magnetic substance is moved along an axis thereof and has an eddy current induced therein. Relative rotation of the detection coil around the magnetic substance is effected to permit detection of surface flaws.