| 摘要 |
PURPOSE:To measure the transformation rate and temp. distribution of a metallic material with good accuracy, by detecting the propagation time of a longitudinal ultrasonic wave and a transverse ultrasonic wave in the thickness direction of the steel material and processing the same arithmetically. CONSTITUTION:When electric current is flowed to a coil 31 for magnet from an electric power source 36, a magnet core 30 is magnetized and a magnetic flux B is generated near the surface of a thick plate 21. When pulse current is flowed to a coil 32 for generating and detecting ultrasonic waves by a pulse current generator 37, induced current I flows near the plate 21 and a transverse ultrasonic wave Ws and a longitudinal ultrasonic wave Wl are generated by Lorentz forces FH, FV. Both waves pass through alpha phase 22, gamma phase 23 and alpha phase 24 and are reflected on the bottom surface of the thick plate, whereafter the waves are detected with the coil 32. The detection signal is displayed in an oscilloscope 40 through an amplifier 45. On the other hand, the propagation velocities Tl and Ts of the longitudinal wave and the transverse wave are calculated by a calculator 42, and the transformation rate and temp. distribution of the steel material 21 are determined by the numerical computation basing on said velocities. |
