Method for evaluating the mixed grain ratio of crystal grains of metal structure

摘要

PROBLEM TO BE SOLVED: To provide a method capable of evaluating the mixing ratio of crystal grains of a metal structure of a material to be evaluated formed from a metal material with respect to the total length and the total number of the materials to be evaluated. According to the method for evaluating a mixed particle ratio according to the present invention, a bottom surface in which an ultrasonic wave is incident on a material P to be evaluated from an ultrasonic probe 1 to acquire a first bottom surface echo signal B1 and a second bottom surface echo signal B2. The echo detection step, the frequency spectrum calculation step of calculating the frequency spectrum SB1 of the first bottom surface echo signal and the frequency spectrum SB2 of the second bottom surface echo signal, the frequency spectrum of the first bottom surface echo signal, and the second bottom surface echo. A frequency spectrum ratio calculation step of calculating the frequency spectrum ratio SB1 / SB2, which is the ratio of the signal to the frequency spectrum, a feature amount calculation step of calculating the feature amount S of a predetermined frequency band in the frequency spectrum ratio, and a large feature amount. Based on the above, the step of evaluating the mixing ratio of the crystal grains of the metal structure of the material to be evaluated is included. [Selection diagram] Fig. 3