| 摘要 |
PURPOSE: A non-destructive measuring method is provided to measure the crystal grain size of a ferrite from a damping change and the correlation of the average crystal grain size by using an ultrasonic damping coefficient. CONSTITUTION: A damping coefficient(alpha) of a carbon steel is measured by using an ultrasonic probe. Herein, the carbon steel has a two-phase complex structure with ferrite and perlite. The measured damping coefficient is put into a formula to calculate the crystal grain size of the ferrite. The formula is as follow. D = "1.79" + 22.97 * alpha¬1/b. Herein, the b is 2.02 to 2.04. A standard deviation is 0.95.
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