Crystal orientation evaluation method and crystal orientation evaluation apparatus

Abstract

This invention provides a crystal orientation evaluation method that allows for the simple evaluation of the crystal orientation of a metal material under test over a wide range. [Solution] The crystal orientation evaluation method includes a wall-to-wall dimension acquisition step in which the dimension L between opposing wall surfaces Wa and Wb of the object to be measured W is obtained as the ultrasonic propagation distance; a propagation time measurement step in which ultrasonic waves are incident into the object to be measured W from an ultrasonic probe 10 positioned opposite wall surface Wa, and the reflected or transmitted ultrasonic waves are detected to measure the ultrasonic propagation time T between the pair of wall surfaces Wa and Wb; and a sound velocity value calculation step in which the sound velocity value C is calculated from the wall-to-wall dimension L and propagation time T of the object to be measured W. These steps are performed at multiple measurement points on the object to be measured W, and the tendency of the crystal orientation in the object to be measured W is evaluated based on the sound velocity value C at each measurement point.

Description

Technical Field

[0001] This invention relates to a crystal orientation evaluation method for evaluating the tendency of crystal orientations in a metallic material and a crystal orientation evaluation apparatus used for this method.

Background Art

[0002] As a method for evaluating crystal orientations in a metallic material, there is the EBSD method (Electron BackScatter Diffraction pattern) using a scanning electron microscope. This EBSD method is a technique for irradiating an electron beam onto a sample and obtaining the crystal orientations in the vicinity of the fracture surface of the sample by backscattering of electrons (see, for example, Patent Document 1 below). This EBSD method enables highly accurate crystal orientation analysis for each crystal. However, since the sample needs to be accommodated in a chamber and measured in a vacuum environment, the range that can be analyzed at one time is narrow (about several mm to 10 mm), and there are problems such as long measurement time.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] This invention is based on the above circumstances, and an object thereof is to provide a crystal orientation evaluation method capable of easily evaluating the crystal orientations of a measurement object made of a metallic material over a wide range, and a crystal orientation evaluation apparatus used for this method.

Means for Solving the Problems

[0005] Thus, the crystal orientation evaluation method of this invention is defined as follows. That is, A wall-to-wall dimension acquisition step in which the distance between opposing wall surfaces of an object to be measured, made of a metal material, is obtained as the ultrasonic propagation distance, A propagation time measurement step involves injecting ultrasonic waves into the body to be measured from an ultrasonic probe positioned opposite the wall surface, detecting the reflected or transmitted waves of the ultrasonic waves, and measuring the propagation time of the ultrasonic waves between the pair of wall surfaces. A sound velocity calculation step, which calculates the sound velocity value from the wall-to-wall dimension of the object to be measured and the propagation time, The process involves performing these steps at multiple measurement locations on the object to be measured, Based on the sound velocity values ​​at each measurement point, the tendency of the crystal orientation in the object being measured is evaluated.

[0006] In this defined crystal orientation evaluation method, the tendency of crystal orientation is evaluated based on the sound velocity value when ultrasound is incident into the body being measured. Therefore, unlike the conventionally known EBSD method, it is not necessary to house the sample in a chamber and measure it in a vacuum environment. Even large samples can be easily evaluated over a wide range of crystal orientation tendencies without cutting them. This type of crystal orientation evaluation method is particularly suitable for cases where it is necessary to roughly grasp the presence or absence of orientation in the crystal orientation at each measurement point.

[0007] The apparatus used in this crystal orientation evaluation method is: A support portion for the object to be measured, The ultrasonic probe is positioned opposite the wall surface of the supported object to be measured, A relative movement mechanism is provided that allows the ultrasonic probe or at least one of the object to be measured to be movable, and the position of the measurement point to be changed. A crystal orientation evaluation device equipped with the following can be used.

[0008] This crystal orientation evaluation apparatus can be further configured to include a dimensional measuring means positioned adjacent to the ultrasonic probe, which is capable of measuring the dimensions between the walls at the measurement point of the object to be measured. [Brief explanation of the drawing]

[0009] [Figure 1] This is an explanatory diagram of the crystal orientation evaluation method for one embodiment of the present invention. [Figure 2] This is an explanatory diagram illustrating an example of evaluating the crystal orientation of a billet material using the crystal orientation evaluation method of the same embodiment. [Figure 3] This figure shows an example of evaluation results using the crystal orientation evaluation method of the same embodiment. [Figure 4] This figure shows a comparison between the evaluation results using the crystal orientation evaluation method of this embodiment and the evaluation results using the conventionally known EBSD method. [Figure 5] This diagram shows a schematic configuration of a crystal orientation evaluation device used to evaluate rod-shaped objects under test. [Figure 6] This diagram shows a schematic configuration of a crystal orientation evaluation device used for evaluating plate-shaped objects to be measured. [Modes for carrying out the invention]

[0010] Next, embodiments of the present invention will be described in detail. For cubic metallic materials, it is known that there are differences in Young's modulus depending on the crystal orientation. For example, Young's modulus <111> Largely in direction, <100> It is known that the value decreases in the direction. Here, there is a relationship between the Young's modulus of a metallic material and the propagation speed of ultrasonic waves propagating within the metallic material (speed of sound in the metallic material), as shown in equation (1) below. In the crystal orientation evaluation method of this embodiment, the speed of sound when ultrasonic waves are incident on the metallic material is measured, and the tendency of the crystal orientation is determined from the relationship between the magnitudes of the obtained speed of sound values.

number

[0011] Figure 1 is an explanatory diagram of the crystal orientation evaluation method for one embodiment of the present invention. In FIG. 1(A), W is a cubic object to be measured made of a metal material, and the dimension between the upper wall surface Wa and the lower wall surface Wb is L. Reference numeral 10 shown in FIG. 1(B) is an ultrasonic probe arranged to contact the upper wall surface Wa side of the object to be measured W through a contact medium such as glycerin. The ultrasonic probe 10 is configured to make ultrasonic waves incident on the upper wall surface Wa in a perpendicular direction and to receive the reflected waves of the ultrasonic waves propagated through the object to be measured W.

[0012] The pulsed ultrasonic waves incident from the upper wall surface Wa side propagate downward in the object to be measured W and are reflected by the lower wall surface (bottom surface) Wb as shown in FIG. 1(B). Then, they propagate upward in the object to be measured W in the figure and reach the upper wall surface Wa. The ultrasonic waves then repeat reflections at the upper wall surface Wa and the lower wall surface Wb, and in the ultrasonic probe 10, reflected waves that are multiply reflected in the object to be measured W are received. And from the information of the reflected waves received by the ultrasonic probe 10, a signal waveform 13 of the reflected waves as shown in FIG. 1(C) is generated.

[0013] In this signal waveform 13, by measuring the time difference T between the first reflected wave B1 and the second reflected wave B2, the propagation time of the ultrasonic waves propagating between a pair of wall surfaces can be obtained. On the other hand, since the dimension L between the wall surfaces separately obtained (see FIG. 1(A)) corresponds to the propagation distance of the ultrasonic waves, based on the time difference T and the dimension L between the wall surfaces, the sound velocity value represented by 2L / T can be calculated. The sound velocity value obtained in this way varies depending on the tendency of the crystal orientation as described above. When the obtained sound velocity value is large, it can be evaluated that the distribution of the <111> plane is large (the distribution of the <100> plane is small) in the measurement direction. Conversely, when the sound velocity value is small, it can be evaluated that the distribution of the <111> plane is small (the distribution of the <100> plane is large) in the measurement direction.

[0014] [[ID=I6]]Next, an example of evaluating the crystal orientation of the billet material will be described. In this example, as shown in Fig. 2(A), the billet material was cut transversely into nine parts and each was cut out as a columnar member with a regular octagon shape (distance between opposite faces: 50 mm), and these were used as the measured objects W (W1 to W9). Then, in each measured object W, the sound velocity values in four directions (0°, 45°, 90°, 135°) shown in Fig. 2(B) were measured. In measuring the sound velocity value, as shown in Fig. 2(C), an ultrasonic probe 10 was arranged on one side of a pair of opposing wall surfaces, the reflected wave when ultrasonic waves were incident was detected, and the sound velocity value was calculated from the measured propagation time and the distance between opposite faces (50 mm in this example). A part of the measurement results obtained in this way is shown in Fig. 3.

[0015] Fig. 3(A) shows the evaluation results for the second measured object W2. According to this figure, it can be seen that the sound velocity values are small in the two directions of 0° and 90°, and large in the two directions of 45° and 135°. That is, there are significant differences in the sound velocity values in the measurement directions, and an orientation of the crystal orientation was recognized. Specifically, in the two directions of 0° and 90° where the sound velocity value is small, the distribution of the <111> plane orientation is small (the distribution of the <100> plane orientation is large), and in the two directions of 45° and 135° where the sound velocity value is large, it can be evaluated that the distribution of the <111> plane orientation is large (the distribution of the <100> plane orientation is small).

[0016] Fig. 3(B) shows the evaluation results for the third measured object W3. According to this figure, although there are slight differences in the sound velocity values in the four measured directions, compared with the second measured object W2, the difference in the sound velocity value is small, and it can be evaluated that there is no orientation in terms of the crystal orientation.

[0017] Furthermore, the crystal orientation of the above-mentioned objects W2 and W3 was also evaluated using the EBSD method. Here, in evaluating the crystal orientation using the EBSD method, a test piece was taken from the center of each object, and the crystal orientation was detected in the center using the EBSD method. The area ratio of the crystal orientation planes for the four directions (0°, 45°, 90°, 135°) for which sound velocity was measured was determined, and the results are shown in Figure 4. Here, the vertical axis of the EBSD crystal orientation evaluation results shown in Figure 4 represents the specified orientation plane ( <111> or <100> This indicates the area ratio of surfaces that are oriented within 10° of the measurement direction (the direction in which the sound velocity was measured).

[0018] As shown in Figure 4(A), in the crystal orientation evaluation method of this embodiment, the second object to be measured W2, in which crystal orientation was observed, is also found to have the same orientation in the EBSD method. That is, in the two directions of 0° and 90°, <111> The distribution of azimuthal planes is small ( <100> The distribution of azimuthal planes is large, and in the two directions of 45° and 135°, <111> The distribution of azimuthal planes is small ( <100> It can be observed that the distribution of azimuthal planes is large.

[0019] Furthermore, as shown in Figure 4(B), in the crystal orientation evaluation method of this embodiment, for the third object to be measured W3 in which no crystal orientation was observed, the EBSD method can also be evaluated as having no crystal orientation in the four measured directions. Thus, a correlation was observed between the evaluation results obtained by the crystal orientation evaluation method of this embodiment and the evaluation results obtained by the EBSD method, indicating that the crystal orientation evaluation method of this embodiment can also accurately evaluate the trend of crystal orientation.

[0020] As described above, the crystal orientation evaluation method of this embodiment does not require the sample to be placed in a chamber and measured under a vacuum environment, as is the case with the conventionally known EBSD method. It also allows for the easy evaluation of the crystal orientation tendency over a wide range of dimensions, even for large samples, without cutting them. This crystal orientation evaluation method of this embodiment is particularly suitable for applications where it is necessary to roughly understand the presence or absence of orientation in the crystal orientation at each measurement point, such as in the evaluation of the billet material described above.

[0021] Next, we will describe the crystal orientation evaluation apparatus used in the crystal orientation evaluation method of this embodiment. The crystal orientation evaluation device 1 shown in Figure 5 is a device for evaluating a round rod-shaped object W to be measured, and comprises an ultrasonic probe 10, dimension measuring means 15, 15B, and a signal calculation unit 20, and further includes a roller 30 that rotatably supports the object W to be measured.

[0022] The ultrasonic probe 10 has a transducer and emits ultrasonic waves toward the object to be measured W based on a drive signal supplied from the ultrasonic transmitting / receiving unit 11, and also receives reflected waves from the bottom surface of the object to be measured W and converts them into electrical signals.

[0023] The ultrasonic transmitting and receiving unit 11, to which the ultrasonic probe 10 is connected, creates a drive signal for the ultrasonic probe 10 to output ultrasonic waves and transmits it to the ultrasonic probe 10, and also receives the reflected wave signal from the ultrasonic probe 10, amplifies the electrical signal and outputs it to the signal processing unit 12.

[0024] The signal processing unit 12 generates a signal waveform 13 for the reflected wave (see, for example, Figure 1(C)) based on the electrical signal output from the ultrasonic transmitting / receiving unit 11, and outputs it to the signal calculation unit 20.

[0025] The dimension measuring means 15 and 15B use two laser displacement sensors to sandwich the object W to be measured from above and below and measure its thickness. The dimension measuring means 15 and 15B are positioned adjacent to the ultrasonic probe 10 and measure the distance L between the walls, outputting the measured value to the signal calculation unit 20. The distance L between the walls measured here corresponds to the propagation distance of the ultrasonic waves emitted from the ultrasonic probe 10 within the object W to be measured. Note that the dimension measuring means is not limited to the laser displacement sensors described above, and any means capable of measuring the distance L between the walls can be used as appropriate.

[0026] The signal calculation unit 20 sets a predetermined threshold for the signal waveform 13 output from the signal processing unit 12, and identifies the portion of the signal waveform 13 with a strong peak intensity exceeding the threshold as the reflected signal from the bottom surface. It then extracts the time difference T between the first reflected wave B1 and the second reflected wave B2 as the propagation time of the ultrasonic waves propagating between the pair of walls. Using this time difference T and the dimensional information L obtained from the dimensional measuring means 15, 15B, it calculates the sound velocity value C expressed as 2L / T.

[0027] The signal calculation unit 20 is connected to an output unit 21 and a storage unit 22. The obtained signal waveform 13 and the calculated sound velocity value C are output to the output unit 21, and these signal waveforms 13 and sound velocity values ​​C are stored in the storage unit 22 along with information about the measurement location. These signal calculation unit 20, output unit 21, and storage unit 22 can be configured, for example, by a computer. If the dimension L between the walls is known, the dimension measuring means 15, 15B can be omitted by pre-storing the dimension L in the storage unit 22.

[0028] Multiple rollers 30 are provided, and the upper part of each roller contacts the downward outer surface of the object to be measured W, supporting the round bar-shaped object to be evaluated W. These rollers 30 are rotatable about a roller shaft 30a that extends parallel to the axial direction of the object to be measured W. At least some of the multiple rollers 30 are drive rollers connected to a drive motor 32 controlled by a drive control unit 33, and based on the rotation of these drive rollers, the object to be measured W is rotatable about its central axis, as shown by the arrows in Figure 5(A). In other words, these rollers 30, drive motor 32, and drive control unit 33 constitute a relative movement mechanism that allows at least one of the ultrasonic probe 10 or the object to be measured W to be movable, thereby changing the position of the measurement point.

[0029] According to the crystal orientation evaluation device 1 of this embodiment, which is configured in this way, it is possible to measure the sound velocity of ultrasonic waves propagating within a cylindrical object W while rotating the object W, and to evaluate the tendency of the crystal orientation in the radial direction passing through the axial center of the object W.

[0030] While the crystal orientation evaluation device 1 described above was for evaluating a round rod-shaped object W, when evaluating a flat plate-shaped object W, as shown in Figure 6, the ultrasonic probe 10 is positioned opposite the wall surface Wa of the object W, and at least one of the ultrasonic probe 10 or the object W is configured to be movable. This allows the measurement point to be moved along the trajectory indicated by arrow F in the figure, and the sound velocity of the ultrasonic waves propagating inside the object W can be measured. This makes it possible to evaluate the tendency of the crystal orientation over a wide area of ​​the object W.

[0031] Although embodiments of the present invention have been described in detail above, this is merely an example. For example, as a method for introducing ultrasound to the object to be measured, in addition to the contact method used in the above embodiments, in which the ultrasonic probe is brought into contact with the surface of the object to be measured via a contact medium, it is also possible to employ an immersion method in which the object to be measured and the ultrasonic probe are immersed in water. Furthermore, although the above embodiment was an example in which the propagation time of ultrasonic waves was measured by detecting the reflected waves of ultrasonic waves, it is also possible to place ultrasonic probes on one wall surface and the other wall surface, respectively, and measure the propagation time of ultrasonic waves by detecting the transmitted waves of ultrasonic waves. In short, the present invention can be configured in various modified forms without departing from its spirit. [Explanation of Symbols]

[0032] 1. Crystal orientation evaluation device 10 Ultrasonic probe 15,15B Dimensional measuring means 30 Rollers (relative movement mechanism) 32. Drive motor (relative movement mechanism) 33 Drive control unit (relative movement mechanism) B1,B2 reflected wave C Speed ​​of sound L Wall-to-wall dimension (propagation distance) T Time difference (propagation time) W Measured object Wa, Wb wall surface

Claims

1. A wall-to-wall dimension acquisition step in which the distance between opposing wall surfaces of an object to be measured, made of a metal material, is obtained as the ultrasonic propagation distance, A propagation time measurement step involves injecting ultrasonic waves into the body to be measured from an ultrasonic probe positioned opposite the wall surface, detecting the reflected or transmitted waves of the ultrasonic waves, and measuring the propagation time of the ultrasonic waves between the pair of wall surfaces. A sound velocity calculation step, which calculates the sound velocity value from the wall-to-wall dimension of the object to be measured and the propagation time, The process involves performing these steps at multiple measurement locations on the object to be measured, A crystal orientation evaluation method that evaluates the tendency of the crystal orientation in the object to be measured based on the sound velocity values ​​at each measurement point.

2. A crystal orientation evaluation apparatus used in the crystal orientation evaluation method described in claim 1, A support portion for the object to be measured, The ultrasonic probe is positioned opposite the wall surface of the supported object to be measured, A relative movement mechanism is provided that allows the ultrasonic probe or at least one of the object to be measured to be movable, and the position of the measurement point to be changed. A crystal orientation evaluation device equipped with the following features.

3. The crystal orientation evaluation apparatus according to claim 2, further comprising a dimension measuring means arranged adjacent to the ultrasonic probe and capable of measuring the dimension between wall surfaces at the measurement location of the object to be measured.

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