1997 Volume 83 Issue 4 Pages 245-250
A measurement system has been developed in which the sound velocity of thin steel sheet is measured quickly and displayed as a two-dimensional distribution. In the system the velocity is obtained from the peak amplitude of ultrasonic wave (multiple interfered echo reflected from the specimen). This system is characterized by the use of ultrasonic tone burst wave being transmitted through specimen to eliminate the disturbance of the first surface echo. This measurement system was applied to the observation of the growth of secondary recrystallized grain in grainoriented electrical steel sheet. The results were as follows.
1) The amplitude of multiple echo increases with the number of burst waves up to about 50 waves.
2) The relation between the amplitude of multiple echo and the sound velocity shows a typical resonance curve in which half-width is about 450m/s and the maximum inclination is 0.34% per lm/s.
3) The two-dimensional display of the secondary recrystallized structure by the ultrasonic wave method shows a good agreement with that by the conventional macro-etching technique.
4) This ultrasonic wave method is applicable for the observation of the growth of secondary recrystallized grain in grainoriented electrical steel sheet.