FLAW DETECTOR FOR SQUARE BILLETS USING MAGNETIC TAPE HELICALLY MOVED ABOUT SAID BILLETS

A method and apparatus for inspecting an elongated magnetic object for structural flaws includes a magnetic tape entrained for movement on a support structure, and the support structure and the object are moved relative to one another about a longitudinal axis of the object. The tape is moved through a predetermined path relative to the support structure and into pressure engagement with a peripheral surface of the object to be inspected so that a magnetic flux pattern along the peripheral surface of the object is recorded on the tape during relative rotation of the support structure and the object. A pick-up head disposed at a remote location along the path of movement of the tape reads the flux pattern recorded on the tape, and an erase head erases the recorded flux pattern after it is read from the tape by the pick-up head.