JP4528186B2 - Crystal grain size measuring device, crystal grain size measuring method, program, and computer-readable storage medium - Google Patents

Description

  The present invention relates to a crystal grain size measuring device, a crystal grain size measuring method, a program for causing a computer to execute processing in the crystal grain size measuring device, and a program for measuring the crystal grain size of a measurement target plate using ultrasonic waves. The present invention relates to a computer-readable storage medium that stores.

  Conventionally, as a method of measuring the crystal grain size of a material such as a steel plate, a method of measuring by taking a micrograph of the structure of the material is known. However, since this method is a destructive test, it could not be used, for example, in a manufacturing process for steel plates. Then, the measurement using the attenuation factor of an ultrasonic wave was considered as a method of measuring the crystal grain size of materials, such as a steel plate, by a nondestructive test.

  For example, as a conventional crystal grain size measuring device, an ultrasonic transmission / reception probe is used, and ultrasonic waves are radiated from the transmission / reception probe in a direction perpendicular to the surface of the measurement plate, that is, in the thickness direction of the measurement plate. In some cases, the ultrasonic wave returned from the plate to be measured is received by this transmission / reception probe, the attenuation rate for the emitted ultrasonic wave is calculated, and the crystal grain size of the plate to be measured is measured. In addition, there is one described in Patent Document 1 below that measures the crystal shape of a subject using ultrasonic waves.

JP-A-6-308100

  However, in a crystal grain size measuring device that measures the crystal grain size by emitting ultrasonic waves in the thickness direction of the plate to be measured, if the plate thickness of the plate to be measured is thin, the propagation of the ultrasonic wave in the plate thickness direction And the reflected wave from the surface of the plate to be measured became difficult, and as a result, an error occurred in the calculation of the attenuation rate of the ultrasonic wave, and the crystal grain size could not be measured with high accuracy.

  In Patent Document 1, ultrasonic waves are propagated to a subject as a surface wave and the aspect ratio of crystal grains of the subject is measured. However, in the technique of Patent Document 1, crystal grains of a target plate are measured. The absolute value of the diameter itself could not be measured.

  The present invention has been made in view of the above-described problems. When measuring the crystal grain size of a measurement target plate using ultrasonic waves, the ultrasonic attenuation rate can be accurately calculated, and the crystal The object is to enable measurement of the particle diameter with high accuracy.

The crystal grain size measuring apparatus according to the present invention includes an ultrasonic radiation unit that radiates an ultrasonic wave to a first position on a surface of a measurement target plate and generates a plate wave on the measurement target plate, and the ultrasonic radiation unit. First waveform detection means for receiving a radiated ultrasonic wave at a second position separated by a first distance from the first position and detecting a first detection waveform; and the first waveform detection A first calculation area waveform portion having a predetermined correlation with the original waveform of the ultrasonic wave radiated from the ultrasonic radiation means is extracted from the first detection waveform detected by the means; First energy calculating means for calculating and ultrasonic waves radiated from the ultrasonic radiation means are received at a third position separated from the first position by a second distance to obtain a second detection waveform. Second waveform detecting means to detect, and a second detected waveform detected by the second waveform detecting means Among them, a second energy calculating means for extracting a second calculation area waveform portion having a predetermined correlation with the original waveform of the ultrasonic wave radiated from the ultrasonic radiation means, and calculating a second energy value; Attenuation of ultrasonic waves radiated from the ultrasonic radiation means based on the first energy value calculated by the first energy calculation means and the second energy value calculated by the second energy calculation means. an attenuation factor calculating means for calculating the rate, on the basis of the ultrasonic attenuation rate calculated by the attenuation rate calculating means, have a crystalline grain diameter calculating means for calculating a crystal grain size in the target measurement plate, the first The first and second calculation area waveform portions extracted by the first and second energy calculation means are predetermined areas including the front and back of the largest amplitude .

The crystal grain size measuring method of the present invention is a crystal grain size measuring method used in a crystal grain size measuring apparatus provided with ultrasonic radiation means for radiating ultrasonic waves, from the ultrasonic radiation means to the surface of the measurement target plate. An ultrasonic radiation step for radiating an ultrasonic wave to the first position to generate a plate wave on the measurement target plate, and an ultrasonic wave radiated from the ultrasonic radiation means from the first position to the first Of the first waveform detection step detected at the first waveform detection step and the first waveform detection step for detecting the first detection waveform received at the second position separated by the distance, the ultrasonic radiation A first energy calculation step of calculating a first energy value by extracting a first calculation area waveform portion having a predetermined correlation with the original waveform of the ultrasonic wave emitted from the means; and from the ultrasonic radiation means The emitted ultrasonic wave is transmitted from the first position to the second Of the second waveform detection step that is received at a third position separated by a distance and detects a second detection waveform and the second detection waveform detected in the second waveform detection step, the ultrasonic radiation A second energy calculation step of extracting a second calculation area waveform portion having a predetermined correlation with the original waveform of the ultrasonic wave emitted from the means and calculating a second energy value; and the first energy calculation. An attenuation rate for calculating an attenuation rate of the ultrasonic wave radiated from the ultrasonic radiation means based on the first energy value calculated in the step and the second energy value calculated in the second energy calculation step. a calculation step, on the basis of the ultrasonic attenuation rate calculated by the attenuation rate calculating step, said possess a grain diameter calculating step for calculating the crystal grain size in the measurement plate, the first and the second Energy The first and second calculation region corrugations extracted with ghee calculating step, characterized in that it is a predetermined area including the front and rear largest amplitude.

A program according to the present invention is a program for causing a computer to execute processing in a crystal grain size measuring apparatus including an ultrasonic radiation unit that emits ultrasonic waves, from the ultrasonic radiation unit to a surface of a measurement target plate. An ultrasonic radiation step for radiating an ultrasonic wave to the first position to generate a plate wave on the measurement target plate, and an ultrasonic wave radiated from the ultrasonic radiation means from the first position to the first Of the first waveform detection step detected at the first waveform detection step and the first waveform detection step for detecting the first detection waveform received at the second position separated by the distance, the ultrasonic radiation A first energy calculation step of calculating a first energy value by extracting a first calculation area waveform portion having a predetermined correlation with the original waveform of the ultrasonic wave emitted from the means; and from the ultrasonic radiation means The emitted ultrasound A second waveform detecting step for detecting a second detected waveform received at a third position separated from the first position by a second distance; and a second detected waveform detected at the second waveform detecting step. A second energy calculating step of extracting a second calculation area waveform portion having a predetermined correlation with the original waveform of the ultrasonic wave radiated from the ultrasonic radiation means, and calculating a second energy value; Based on the first energy value calculated in the first energy calculation step and the second energy value calculated in the second energy calculation step, the ultrasonic wave emitted from the ultrasonic radiation means An attenuation rate calculation step for calculating an attenuation rate, and a crystal particle size calculation step for calculating a crystal particle size in the measurement target plate based on the ultrasonic attenuation rate calculated in the attenuation rate calculation step. Is executed, said first and said first and second calculation region corrugations extracted with a second energy calculating step, characterized in that it is a predetermined area including the front and rear largest amplitude.

  The computer-readable storage medium of the present invention stores the program in a computer-readable manner.

  According to the present invention, when measuring the crystal grain size of the plate to be measured, the ultrasonic waves radiated from the ultrasonic radiation means arranged at the first position are different from each other by the distance from the first position. The first and second waveform detecting means arranged at a distant position detect and receive the waveform, and from each detected waveform, the original waveform of the ultrasonic wave radiated from the ultrasonic radiation means and a predetermined correlation Since each calculation area waveform part that is related is extracted to obtain each energy value, the attenuation rate of the ultrasonic wave is calculated based on each obtained energy value, and the crystal grain size of the measurement target plate is measured. The ultrasonic attenuation rate can be calculated based on the energy values not including the waveform portion of the scattered noise, and the ultrasonic attenuation rate can be calculated accurately. As a result, the crystal grain size can be measured with high accuracy.

Embodiments according to the present invention will be described below in detail with reference to the drawings.
FIG. 1 is a block diagram showing a schematic configuration of a crystal grain size measuring apparatus according to an embodiment of the present invention. In FIG. 1, reference numeral 101 denotes a plate to be measured such as a steel plate supported by a support 102, and 100 denotes a crystal grain size measuring device that measures the crystal grain size of the plate to be measured 101.

  In the crystal grain size measuring apparatus 100, three probes are arranged on the surface of the measurement target plate 101 to measure the crystal grain size of the measurement target plate 101. Reference numeral 1 denotes a transmission probe that is arranged at a predetermined position (first position) on the surface of the measurement target plate 101 and emits ultrasonic waves to the measurement target plate 101. Reference numeral 2 denotes a first reception probe which is disposed at a second position away from the transmission probe 1 by a first distance and receives the plate wave A which has propagated through the measurement target plate 101. Reference numeral 3 denotes a second receiving probe which is disposed at a third position separated from the transmitting probe 1 by a second distance different from the first distance and receives the plate wave A which has propagated through the measurement target plate 101. .

  In FIG. 1, reference numeral 4 denotes an ultrasonic oscillator that oscillates an ultrasonic wave, which radiates the oscillated ultrasonic wave to the measurement target plate 101 via the transmission probe 1 and generates a plate wave A on the measurement target plate 101. is there. In the present embodiment, the ultrasonic oscillating unit 4 and the transmission probe 1 are collectively referred to as ultrasonic radiating means 10.

  Reference numeral 5 denotes reflection echo detection means for detecting the waveform of the ultrasonic wave B reflected by the contact surface between the transmission probe 1 and the measurement target plate 101. In the present embodiment, the waveform of the ultrasonic wave B detected by the reflected echo detection means 5 is used as the original waveform of the plate wave A radiated from the transmission probe 1.

  Reference numeral 6 denotes first waveform detecting means for detecting the waveform of the plate wave A at the second position where the first receiving probe 2 is disposed. 7 is a waveform portion having a predetermined correlation with the original waveform (waveform of the ultrasonic wave B) of the plate wave A detected by the reflected echo detection means 5 among the waveforms of the plate wave A detected by the first waveform detection means 6. Is a first energy calculating means for calculating the first energy value En1.

  Reference numeral 8 denotes second waveform detection means for detecting the waveform of the plate wave A at the third position where the second reception probe 3 is disposed. 9 extracts a waveform portion having a predetermined correlation with the original waveform of the plate wave A detected by the reflection echo detection means 5 from the waveform of the plate wave A detected by the second waveform detection means 8. It is the 2nd energy calculation means which calculates energy value En2.

  11 calculates the attenuation rate of the plate wave A based on the first energy value En1 calculated by the first energy calculating means 7 and the second energy value En2 calculated by the second energy calculating means 9. Attenuation rate calculation means. Reference numeral 12 denotes crystal grain size calculation means for calculating the crystal grain size of the plate 101 to be measured based on the attenuation rate of the plate wave A calculated by the attenuation rate calculation means 11.

  In the crystal grain size measuring apparatus 100 in the present embodiment, the reflection echo detecting means 5, the first energy calculating means 6 and the second energy calculating means 8 are constituted by a digital oscilloscope, and the first energy calculating means 7, The energy calculating means 9, the attenuation rate calculating means 11 and the crystal grain size calculating means 12 are constituted by an information processing apparatus such as a personal computer (PC).

Next, a measuring method in the crystal grain size measuring apparatus 100 will be described.
FIG. 2 is a flowchart showing an example of a crystal grain size measuring method performed by the crystal grain size measuring apparatus 100 according to the embodiment of the present invention.

  First, in step S <b> 101, after the transmission probe 1 is arranged at the first position on the surface of the measurement target plate 101, ultrasonic waves are radiated from the ultrasonic oscillator 4 through the transmission probe 1, and Wave A is generated.

  Subsequently, in step S <b> 102, the reflected echo detector 5 detects the waveform of the ultrasonic wave B reflected from the contact surface between the transmission probe 1 and the measurement target plate 101 as the original waveform of the plate wave A.

  Subsequently, in step S103, the waveform of the plate wave A propagating through the measurement target plate 101 is detected by the first waveform detection means 6 via the first reception probe 2 at the second position. An example of the waveform of the plate wave A detected by the first waveform detection means 6 (hereinafter referred to as the first detection waveform) is shown in FIG.

In the first detection waveform shown in FIG. 3, the vertical axis indicates the amplitude of the plate wave A in voltage, and the horizontal axis indicates the elapsed time. In this embodiment, the plate 101 to be measured has a plate thickness of 0.2 mm, the first receiving probe 2 is arranged at a position 60 mm away from the transmitting probe 1, and the plate wave A changes in speed due to the plate thickness change. It uses a small plate wave of S ₀ modes. As shown in FIG. 3, it can be seen that the first detected waveform is composed of a plurality of waveform portions. The largest amplitude is about 0.9V.

  Subsequently, in step S104, the first energy calculation means 7 performs a correlation operation between the first detection waveform detected in step S103 and the original waveform of the plate wave A detected in step S102, and then in step S103. Among the first detected waveforms detected in step 1, the waveform portion having the strongest correlation with the original waveform of the plate wave A detected in step S102 is extracted.

  As a result, the first calculation area waveform portion Y composed of a predetermined area including before and after the largest amplitude (about 0.9 V) is extracted from the waveform sections constituting the first detection waveform shown in FIG. Is done. The extracted first calculation area waveform portion Y is shown in FIG. As shown in FIG. 4, the first calculation region waveform portion Y is a region of about 6.0 μsec including around the largest amplitude of about 0.9V. Further, among the waveform portions constituting the first detection waveform shown in FIG. 3, the waveform portion other than the first calculation region waveform portion Y is transmitted from the transmission probe 1 to the first reception probe 2. This is a waveform portion of the scattered noise that is scattered at the crystal interface of the measurement target plate 101 and reaches the first receiving probe 2 after reaching the second position.

  Subsequently, in step S105, the first energy calculation means 7 calculates a first energy value En1 that is an energy value in the first calculation area waveform portion Y extracted in step S104. Specifically, the first energy calculation means 7 uses the integral value of the square of amplitude or the power spectrum in a specific frequency region using fast Fourier transformation (FFT), for example. The value En1 is calculated. In FIG. 5, the calculation image of the energy value En1 in the 1st calculation area waveform part Y is shown. The sum of the hatched portions in FIG. 5 is the energy value En1. Thereafter, the first receiving probe 2 is separated from the surface of the measurement target plate 101.

  Subsequently, in step S106, after the second receiving probe 3 is arranged at the second position on the surface of the measurement target plate 101, the waveform of the plate wave A propagating through the measurement target plate 101 is obtained at the third position. Detection is performed by the second waveform detection means 8 via the second reception probe 3. An example of the waveform of the plate wave A detected by the second waveform detection means 8 (hereinafter referred to as a second detection waveform) is shown in FIG.

The second detection waveform shown in FIG. 6 is similar to the first detection waveform shown in FIG. 3, and the vertical axis indicates the amplitude of the plate wave A in voltage. The horizontal axis shows the elapsed time. Further, in the present embodiment, the plate 101 to be measured has a plate thickness of 0.2 mm, the second receiving probe 3 is arranged at a position 100 mm away from the transmitting probe 1, and the plate wave A changes in speed due to plate thickness change. It uses a small plate wave of S ₀ modes. As shown in FIG. 6, it can be seen that the second detection waveform is also composed of several waveform portions. The largest amplitude is about 0.6V.

  Subsequently, in step S107, the second energy calculation means 9 performs a correlation operation between the second detected waveform detected in step S106 and the original waveform of the plate wave A detected in step S102, and step S106. Among the second detected waveforms detected in step 1, the waveform portion having the strongest correlation with the original waveform of the plate wave A detected in step S102 is extracted.

  As a result, the second calculation area waveform portion Z consisting of a predetermined region including the front and back of the largest amplitude (about 0.6 V) is extracted from the waveform portions constituting the second detection waveform shown in FIG. Is done. Further, among the waveform parts constituting the second detection waveform shown in FIG. 6, the plate wave A is transmitted from the transmission probe 1 to the second reception probe 3 except for the second calculation area waveform part Z. This is a waveform portion of the scattered noise that is scattered at the crystal interface of the measurement target plate 101 until the third position where it is disposed and arrives late with respect to the second reception probe 3.

  Subsequently, in step S108, the second energy calculation means 9 calculates the second energy value En2, which is the energy value in the second calculation area waveform portion Z extracted in step S107. The calculation method of the second energy value En2 in this case is the same as the calculation method of the first energy value En1 in step S105.

  Subsequently, in step S109, the attenuation factor calculating unit 11 attenuates the plate wave A based on the first energy value En1 calculated in step S105 and the second energy value En2 calculated in step S108. Calculate the rate.

Here, the calculation method of the attenuation factor of the plate wave A will be specifically described.
In general, the relationship between the first energy value En1 and the second energy value En2 can be expressed by Equation 1 below.

  In Equation 1, since the distance x and the plate thickness d of the plate 101 to be measured are known values, the attenuation rate α of the plate wave A is calculated based on the first energy value En1 and the second energy value En2. be able to.

  Subsequently, in step S110, the crystal grain size calculation means 12 calculates the average crystal grain size of the plate 101 to be measured based on the attenuation factor α of the plate wave A calculated in step S109.

Here, a method for calculating the average crystal grain size of the measurement target plate 101 will be specifically described.
First, the relationship between the attenuation rate of the ultrasonic wave radiated to the measurement target plate 101 at a predetermined wavelength and the average crystal grain size is calculated in advance by experiments or the like. FIG. 7 is a characteristic diagram showing the relationship between the attenuation rate and the average crystal grain size. In the characteristics shown in FIG. 7, the vertical axis indicates the attenuation factor of the ultrasonic wave, and the horizontal axis indicates the average crystal grain size. In FIG. 7, ●, ○, and * indicate the characteristics of each measured sample. Here, the attenuation rate α of the ultrasonic wave is theoretically or experimentally dependent on the crystal grain size D and the ultrasonic wavelength λ, for example, in the region where D is approximately equal to λ, as shown in Equation 2 below. It has also been verified.

  As can be seen from Equation 2, since the ultrasonic wavelength λ is a known value, the ultrasonic attenuation rate α and the crystal grain size D have a one-to-one correlation. Therefore, a calibration line can be obtained with the characteristics shown in FIG.

  Then, the average crystal grain size in step S110 is calculated based on the attenuation factor α of the plate wave A calculated in step S109 and the calibration line shown in FIG.

  By performing the processing from step S101 to step S110, the average crystal grain size of the plate 101 to be measured is calculated based on the attenuation rate of the plate wave A.

  According to the present embodiment, among the first detected waveforms detected by the first waveform detecting means 6, the correlation is strongest with the original waveform of the plate wave A at the first position where the transmission probe 1 is arranged. The first calculation area waveform portion Y is extracted to calculate the first energy value En1 at the second position, and among the second detected waveforms detected by the second waveform detecting means 8, the first energy value En1 is calculated. The second calculation area waveform portion Z having the strongest correlation with the waveform of the plate wave A at the position is extracted, the second energy value En2 at the third position is calculated, and the calculated first energy is calculated. Since the attenuation rate of the plate wave A is calculated based on the value En1 and the second energy value En2, when calculating the attenuation rate of the plate wave A, each energy not including the waveform portion of the scattered noise Calculation can be performed based on the It can be carried out in. As a result, the crystal grain size can be measured with high accuracy.

  In the crystal grain size measuring apparatus 100 of the present embodiment, two receiving probes are used to detect the original waveform of the plate wave A radiated from the transmitting probe 1 at the second position and the third position, respectively. For example, by providing only one receiving probe, the waveform of the plate wave A is first detected at the second position, and then the receiving probe is moved to the third position. The waveform of the plate wave A may be detected. In this case, one waveform detecting unit and one energy calculating unit may be provided, and a crystal grain size measuring apparatus having such a configuration is also included in the present invention.

  In addition, each means of FIG. 1 constituting the crystal grain size measuring apparatus according to the present embodiment and each step of FIG. 2 showing the crystal grain size measuring method are executed by a program stored in a RAM or ROM of a computer. It can be realized by doing. This program and a computer-readable storage medium storing the program are included in the present invention.

  Specifically, the program is recorded in a storage medium such as a CD-ROM, or provided to a computer via various transmission media. As a storage medium for recording the program, a flexible disk, a hard disk, a magnetic tape, a magneto-optical disk, a nonvolatile memory card, and the like can be used in addition to the CD-ROM. On the other hand, as the transmission medium of the program, a communication medium (wired line such as an optical fiber, etc.) in a computer network (LAN, WAN such as the Internet, wireless communication network, etc.) system for propagating and supplying program information as a carrier wave A wireless line or the like.

  Further, by executing the program supplied by the computer, not only the function of the crystal grain size measuring apparatus in the present embodiment is realized, but also an OS (operating system) or other operating system in which the program is running on the computer. When the functions of the crystal grain size measurement device in this embodiment are realized in cooperation with application software, etc., or all or part of the processing of the supplied program is performed by a computer function expansion board or function expansion unit. Even when the function of the crystal grain size measuring apparatus according to the present embodiment is realized, such a program is included in the present invention.

It is a block diagram which shows schematic structure of the crystal grain diameter measuring apparatus in embodiment of this invention. It is the flowchart which showed an example of the crystal grain size measuring method performed with the crystal grain size measuring device in embodiment of this invention. It is the figure which showed an example of the 1st detection waveform detected by the 1st waveform detection means. It is the figure which showed an example of the 1st calculation area waveform part extracted by the 1st energy calculation means. It is the figure which showed the calculation image of the energy value in a 1st calculation area waveform part. It is the figure which showed an example of the 2nd detection waveform detected by the 2nd waveform detection means. It is the characteristic view which showed the relationship between an attenuation factor and an average crystal grain diameter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transmission probe 2 1st reception probe 3 2nd reception probe 4 Ultrasonic oscillation part 5 Reflected echo detection means 6 1st waveform detection means 7 1st energy calculation means 8 2nd waveform detection means 9 2nd Energy calculating means 10 Ultrasonic radiation means 11 Attenuation rate calculating means 12 Crystal grain size calculating means 100 Crystal grain size measuring device 101 Plate to be measured 102 Support

Claims (6)

An ultrasonic radiation means for radiating an ultrasonic wave to a first position on the surface of the measurement target plate and generating a plate wave on the measurement target plate;
First waveform detection means for receiving the ultrasonic wave emitted from the ultrasonic radiation means at a second position separated from the first position by a first distance and detecting a first detection waveform;
From the first detection waveform detected by the first waveform detection means, a first calculation area waveform portion having a predetermined correlation with the original waveform of the ultrasonic wave radiated from the ultrasonic radiation means is extracted. First energy calculating means for calculating a first energy value;
Second waveform detection means for detecting the second detection waveform by receiving the ultrasonic wave radiated from the ultrasonic radiation means at a third position separated from the first position by a second distance;
From the second detected waveform detected by the second waveform detecting means, a second calculation area waveform portion having a predetermined correlation with the original waveform of the ultrasonic wave radiated from the ultrasonic radiation means is extracted. Second energy calculating means for calculating a second energy value;
Attenuation of ultrasonic waves radiated from the ultrasonic radiation means based on the first energy value calculated by the first energy calculation means and the second energy value calculated by the second energy calculation means. An attenuation rate calculating means for calculating a rate;
On the basis of the ultrasonic attenuation rate calculated by the attenuation rate calculating unit, said possess a grain diameter calculating means for calculating a crystal grain size in the measurement plate,
Said first and said first and second calculation region corrugations extracted by the second energy calculating means, the crystal grain size measuring device comprising a predetermined area der Rukoto including front and rear largest amplitude . The first and second energy calculation means are configured to contact the ultrasonic radiation means and the measurement target plate as an original waveform of the ultrasonic wave used when extracting the first and second calculation area waveform portions. 2. The crystal grain size measuring apparatus according to claim 1, wherein an ultrasonic waveform reflected by the surface is used. A crystal grain size measuring method used in a crystal grain size measuring apparatus equipped with an ultrasonic radiation means for emitting ultrasonic waves,
An ultrasonic radiation step of radiating an ultrasonic wave from the ultrasonic radiation means to a first position on the surface of the measurement plate to generate a plate wave on the measurement plate;
A first waveform detection step of receiving an ultrasonic wave radiated from the ultrasonic radiation means at a second position separated from the first position by a first distance and detecting a first detection waveform;
From the first detection waveform detected in the first waveform detection step, a first calculation area waveform portion having a predetermined correlation with the original waveform of the ultrasonic wave radiated from the ultrasonic radiation means is extracted. A first energy calculating step for calculating a first energy value;
A second waveform detecting step for receiving the ultrasonic wave radiated from the ultrasonic radiation means at a third position separated from the first position by a second distance and detecting a second detected waveform;
From the second detection waveform detected in the second waveform detection step, a second calculation area waveform portion having a predetermined correlation with the original waveform of the ultrasonic wave radiated from the ultrasonic radiation means is extracted. A second energy calculating step for calculating a second energy value;
Attenuation of ultrasonic waves emitted from the ultrasonic radiation means based on the first energy value calculated in the first energy calculation step and the second energy value calculated in the second energy calculation step. An attenuation rate calculating step for calculating a rate;
On the basis of the ultrasonic attenuation rate calculated by the attenuation rate calculating step, said possess a grain diameter calculating step for calculating the crystal grain size in the measurement plate,
It said first and said first and second calculation region corrugations extracted with a second energy calculating step, the crystal grain size measuring method comprising predetermined areas der Rukoto including front and rear largest amplitude . In the first and second energy calculation steps, as the original waveform of the ultrasonic wave used for extraction of the first and second calculation area waveform portions, contact between the ultrasonic radiation means and the measurement target plate is performed. 4. The crystal grain size measuring method according to claim 3 , wherein an ultrasonic waveform reflected by the surface is used. A program for causing a computer to execute processing in a crystal grain size measuring device including an ultrasonic radiation means for radiating ultrasonic waves,
An ultrasonic radiation step of radiating an ultrasonic wave from the ultrasonic radiation means to a first position on the surface of the measurement plate to generate a plate wave on the measurement plate;
A first waveform detection step of receiving an ultrasonic wave radiated from the ultrasonic radiation means at a second position separated from the first position by a first distance and detecting a first detection waveform;
From the first detection waveform detected in the first waveform detection step, a first calculation area waveform portion having a predetermined correlation with the original waveform of the ultrasonic wave radiated from the ultrasonic radiation means is extracted. A first energy calculating step for calculating a first energy value;
A second waveform detecting step for receiving the ultrasonic wave radiated from the ultrasonic radiation means at a third position separated from the first position by a second distance and detecting a second detected waveform;
From the second detection waveform detected in the second waveform detection step, a second calculation area waveform portion having a predetermined correlation with the original waveform of the ultrasonic wave radiated from the ultrasonic radiation means is extracted. A second energy calculating step for calculating a second energy value;
Attenuation of ultrasonic waves radiated from the ultrasonic radiation means based on the first energy value calculated in the first energy calculation step and the second energy value calculated in the second energy calculation step. An attenuation rate calculating step for calculating a rate;
Based on the attenuation rate of the ultrasonic wave calculated in the attenuation rate calculation step, a computer executes a crystal grain size calculation step for calculating a crystal grain size in the measurement target plate ,
The first and second calculation area waveform portions extracted in the first and second energy calculation steps are predetermined areas including before and after the largest amplitude. A computer-readable storage medium storing the program according to claim 5 in a computer-readable manner.

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