Process for Detecting Surface Cracks in Bars, Billets and the like

摘要

1, 194,498. Magnetographic flow detection. H TTENWERK OBERHAUSEN A. G. Oct. 15, 1968 [Nov. 15, 1967], No. 48746/68. Heading G1N. In magnetographic detection of surface cracks on magnetic solids of non-circular cross-sections, the axial magnetizing current is a pulsating direct current. Use of half-wave rectified pulses derived from an alternating current source with a frequency in the range 20-100 Hz. facilitates the detection of cracks present at or near the corners of the solids which may be bars, billets or tubes.