| 摘要 |
PURPOSE:To efficiently detect the joining defect of clad steel products having a difference in the respective acoustic impedances of a base metal and a cladding metal by admitting the ultrasonic waves of longitudinal waves to the steel products by the incident angle near the angle at which the phases of the waves invert and detecting the ultrasonic waves of the longitudinal waves reflecting at the boundary face. CONSTITUTION:An oscillator 1 for signal transmission is so formed that the incident angle of the longitudinal waves incident on the cladding metal 4 via an incident point 7 from a wedge 3-1 attains, for example, 21 deg.. The incident longitudinal wave are made incident at 55 deg. incident angle to the reflecting point 8 at the boundary between the cladding metal 4 and the base metal 5 and are thereby reflected. The presence or absence of the reflected waves is efficiently detected by the output of an oscillator 2 for signal reception if a wedge 3-2 and the oscillator 2 are disposed in the position where the regular reflection is obtainable. The energy quantity of the reflected longitudinal waves is extremely small if the reflection point 8 exists in the part where the joining of the cladding metal 4 and the base m5 is defectless. The energy quantity of the reflected longitudinal waves increases extremely when the reflection point 8 exists in the non-joined part. The presence or absence of the non-joined part is, therefore, efficiently detected by detecting the reflected longitudinal waves. |
