超音波測定によるアルミニウム合金ダイカストの表面近傍に内在する人工欠陥の検出

抄録

  Surface acoustic wave (SAW, or Rayleigh wave) measurement was carried out with specimens containing artificial holes of different diameters at different depths to develop a nondestructive method of detecting casting defects existing near the surface of castings. SAW intensity was measured at different distances from the hole position, and that reflected from holes was found to increase with decreasing distance from the hole, peaking before the hole. Just before maximizing, the SAW intensity takes a local minimum. These results confirm that ultrasonic measurement is able to detect holes with a diameter of 0.5mm or larger existing at a depth of 0.5mm or less. In addition, the position of the hole was roughly evaluated, without fixing the hole depth. The results obtained by the SAW measurement were compared with those by surface SH wave measurement.