JP7569280B2 - Ultrasonic flaw detection method and ultrasonic flaw detection device - Google Patents

Description

The present invention relates to an ultrasonic flaw detection method and an ultrasonic flaw detection device.

Patent Document 1 describes a technology for simultaneously obtaining ultrasound images of deep areas and high-resolution ultrasound images of shallow areas in the same ultrasound field of view by alternately arranging ultrasound transducers with different oscillation frequencies. It states that an ultrasound scanner at the tip of an insertion part has many ultrasound transducers arranged linearly in the axial direction, with odd-numbered ultrasound transducers being low-frequency transducers with a low oscillation frequency and even-numbered ultrasound transducers being high-frequency transducers that oscillate at high frequencies, and that an ultrasound observation device is provided with a low-frequency ultrasound signal processing section and a high-frequency ultrasound signal processing section, and that when the low-frequency ultrasound signal processing section is operated, the low-frequency transducer is operated to obtain a low-frequency ultrasound linear image, and when the high-frequency ultrasound signal processing section is operated, the high-frequency transducer is operated to obtain a high-frequency ultrasound linear image.

As an example of a technique for ultrasonically inspecting parts having an uneven surface, Patent Document 2 describes: a. immersing the part in a liquid and providing a fluid coupling of a thickness of several ultrasonic wavelengths between the part having an uneven surface and an ultrasonic probe consisting of an array of many small ultrasonic elements, each having an ultrasonic beam spread; b. scanning the part with an ultrasonic beam while activating each ultrasonic element one by one; c. storing ultrasonic waveforms emitted from each ultrasonic element in the array and reflected by the surface of the part and ultrasonic waveforms reflected by internal reflectors of the part for each activation, sweeping the array of ultrasonic waveform data to measure the surface shape, and calculating signal processing parameters as a function of the position of the ultrasonic probe based on the surface shape; and d. processing the data array using the signal processing parameters to correct for irregularities in the surface of the processed part and calculate the inspection results for the reflectors inside the part.

Japanese Unexamined Patent Publication No. 7-163559 JP 2015-145872 A

Remaining life assessments are used to ensure safety in power plant equipment, and for this, information on the location and size of defects inside the inspected object, mainly inside the pipes, is required. Non-destructive testing is carried out to obtain information on defects inside the inspected object, and ultrasonic testing is one of the methods used. With ultrasonic testing, the size of the defect and the location of the defect from the probe can be measured from the ultrasonic waveform received by the probe.

In recent years, aperture synthesis techniques have been attracting attention. These techniques calculate the path of ultrasound into an object to be inspected from the positional information of the ultrasonic transmitting and receiving elements of an ultrasonic probe, the sound speed of the ultrasound inside the object to be inspected, and information on the received waveform of the ultrasound, and visualize the inside of the object to be inspected. However, depending on the pipe to be inspected, unevenness remains due to excess welds, and it is not possible to make the sensor come into close contact with the pipe, making ultrasonic inspection impossible using conventional methods. Therefore, a method is needed to indirectly bring the sensor into close contact with the object to be inspected.

As a method for indirectly bringing the test object and the sensor into close contact, a flaw detection method using a soft gel as an intervening substance is used in the medical field, for example the technology described in the above-mentioned Patent Document 1. The above-mentioned Patent Document 1 features an array sensor that alternates between ultrasonic elements that irradiate high-frequency and low-frequency ultrasonic waves, but is intended for medical use.

The characteristics of ultrasonic flaw detection in medical applications are that the subject to be inspected is a human body, and that the speed of sound of ultrasonic waves in the human body is equivalent to that of water. When the subject to be inspected is a human body, the skin is soft, so when the array sensor is pressed against the skin, the skin naturally takes on the shape of the array sensor, making it possible to perform flaw detection while the subject to be inspected and the array sensor are in close contact with each other. Even if the skin in areas close to bones does not take on the shape of the array sensor and the array sensor cannot be in close contact with the skin, flaw detection is possible by using a soft intermediate medium such as a gel, which has an ultrasonic sound speed close to that of water, without having to consider the refraction of ultrasonic waves at the adhesive surface between the intermediate medium and the subject to be inspected.

However, in industrial inspection, it is necessary to inspect materials such as metals, where the speed of ultrasonic waves is much faster than that of water. Naturally, since the inspection object is made of metal, it will not deform to fit the shape of the array sensor, and an intermediate layer through which the ultrasonic waves propagate (hereinafter referred to as intermediate catalytic layer) is required to bring the array sensor into close contact with the inspection object.

However, because the speed of ultrasound in the material used as the intermediate catalytic medium is different from that in metal, refraction of ultrasound occurs at the bonding surface between the intermediate catalytic medium and the specimen. Imaging methods that do not take into account the refraction of ultrasound will result in errors in the defect location and dimensions, making it unrealistic to directly apply medical ultrasonic flaw detection technology to industry.

For these reasons, when performing ultrasonic inspections on curved industrial objects, it is considered effective to use a wedge that indirectly brings the sensor into close contact with the surface of the object, extract the coordinates of the surface shape, and calculate the propagation path of the ultrasonic waves into the interior of the object.

The aforementioned Patent Document 2 is characterized by providing an intermediate layer between the ultrasonic array sensor and the surface of the object to be inspected, extracting the surface coordinates of the object to be inspected from the received ultrasonic waveform, and determining the propagation path of the ultrasonic waves into the inside of the object to be inspected, thereby enabling ultrasonic flaw detection that takes unevenness into account.

However, the ultrasonic frequency band suitable for extracting the shape of the surface of the test object using an intermediate layer is different from the frequency band suitable for detecting flaws inside the test object.

Therefore, even if high frequencies suitable for extracting the shape of the surface of the object to be inspected are applied to the above technology, the accuracy of surface shape extraction is improved. However, there is a problem in that ultrasonic waves are scattered and attenuated inside the object to be inspected, which can cause defect signals to be overlooked due to a decrease in the strength of the reflected signal from inside the object to be inspected.

In addition, when using low frequencies suitable for detecting flaws inside the test object, the accuracy of extracting the shape of the test object's surface is low, so the propagation path of the ultrasonic waves into the test object cannot be correctly determined, resulting in a problem of reduced accuracy in detecting flaws inside the test object.

The above method is based on the premise of using a fluid coupling such as water as an intermediate layer, which requires that the space between the sensor and the test object be constantly filled with fluid. However, as it requires a method for supplying and draining large amounts of water, this method cannot be used in some test environments.

The objective of the present invention is to provide an ultrasonic inspection method and ultrasonic inspection device that can more easily achieve both extraction of surface shape and inspection of the interior of an object to be inspected, something that was previously difficult to achieve.

The present invention includes a number of means for solving the above problems, and an example thereof includes the steps of: arranging, on an object to be inspected, an ultrasonic probe having two or more types of ultrasonic elements with different vibration frequencies and a wedge that brings the object to indirect contact with the ultrasonic probe; controlling the transmission and reception of ultrasonic waves from the ultrasonic elements of the ultrasonic probe; determining the boundary between the wedge and the object to be inspected based on the received waveform of ultrasonic waves at the ultrasonic element having the higher vibration frequency among the two or more types of ultrasonic elements of the arranged ultrasonic probe; and imaging the inside of the object to be inspected based on the received waveform of ultrasonic waves at the ultrasonic element having the lower vibration frequency among the arranged ultrasonic probes.

According to the present invention, it is easier than ever to simultaneously extract the surface shape and detect flaws inside the test object. Problems, configurations, and effects other than those described above will become clear from the description of the embodiments below.

1 is a diagram showing an overview of an ultrasonic flaw detection apparatus according to an embodiment of the present invention; FIG. FIG. 2 is a schematic diagram of waveform recording by a high-frequency element in the ultrasonic flaw detection device according to the embodiment. 1 is a schematic diagram showing the coordinates of a surface of an object to be inspected being extracted from a waveform received by a high-frequency element in an ultrasonic flaw detection device according to an embodiment of the present invention. 1 is a schematic diagram showing refraction of ultrasonic waves into an object to be inspected when ultrasonic waves are irradiated by a low-frequency element in an ultrasonic flaw inspection device according to an embodiment, and reception of the ultrasonic waves by the low-frequency element. FIG. 2 is a diagram showing an inspection flow of an ultrasonic flaw detection method according to an embodiment.

The ultrasonic inspection method and ultrasonic inspection device according to the embodiment of the present invention will be described with reference to Figs. 1 to 5. Note that in the drawings used in this specification, identical or corresponding components are designated by the same or similar reference numerals, and repeated explanations of these components may be omitted.

First, the overall configuration of the ultrasonic flaw detection device and the details of each component will be described. Figure 1 is a diagram showing the overall configuration of the ultrasonic flaw detection device of this embodiment.

In FIG. 1, the ultrasonic flaw detection device 100 of this embodiment is suitable for inspecting an object 106 having a curved surface, and includes an ultrasonic array probe 101, a wedge 102, a transmission/reception control device 104, and a calculation device 105.

The ultrasonic array probe 101 has multiple ultrasonic elements and is capable of emitting and receiving ultrasonic waves from the ultrasonic elements.

The ultrasonic array probe 101 of this embodiment has frequency characteristics that enable strong transmission and reception due to resonance characteristics, and is composed of at least two or more types of low-frequency elements 107 and high-frequency elements 108 that have different vibration frequency characteristics.

In this example, the ultrasonic array probe 101 has an equal number of ultrasonic elements capable of transmitting and receiving two types of frequencies: low-frequency elements 107 capable of emitting low-frequency ultrasonic waves suitable for detecting flaws inside the object 106, and high-frequency elements 108 capable of emitting high-frequency ultrasonic waves suitable for extracting surface shapes. The low-frequency elements 107 are preferably 2 to 5 MHz, and the high-frequency elements 108 are preferably 10 MHz or higher, but are not limited to these ranges. Furthermore, the numbers do not need to be the same, and one may be more than the other.

Although the case where there are two different frequencies has been described, there can be three or more. When there are three or more, one or more elements on the low frequency side, including the element with the lowest frequency, are classified as low frequency elements capable of emitting low frequency ultrasound suitable for detecting flaws inside the inspected object, and one or more elements on the high frequency side, including the element with the highest frequency, are classified as high frequency elements capable of emitting high frequency ultrasound suitable for extracting surface shape.

When the center of the ultrasonic array probe 101 is taken as the origin O, the positions of the low-frequency elements 107 and high-frequency elements 108 in the ultrasonic array probe 101 are known, and the low-frequency elements 107 and high-frequency elements 108 are arranged at equal intervals with each other sandwiched between them. In addition, the low-frequency elements 107 and high-frequency elements 108 are arranged alternately as shown in FIG. 1 to prevent the occurrence of areas where the resolution is reduced when each element receives ultrasonic waves. Here, in FIG. 1, the horizontal direction relative to the sensor is defined as the X coordinate, and the depth direction relative to the sensor is defined as the Z coordinate.

The wedge 102 has a shape that allows it to be placed on top of the inspection object 106, and has a moving surface that extends along the movement direction of the ultrasonic array probe 101. The wedge 102 is configured so that the ultrasonic array probe 101 can move while being in close contact with it, and indirectly contacts the inspection object 106 and the ultrasonic array probe 101. Preferably, the wedge 102 is a straight member that extends linearly in the movement direction of the ultrasonic array probe 101. Note that the wedge 102 is not limited to a straight member, and may be an arcuate member that extends in an arc in the movement direction.

This wedge 102 is preferably made of a solid material such as acrylic, but is not particularly limited and may be made of a fluid or gel depending on the test conditions.

The wedge 102 has a groove 103 on the surface that comes into contact with the test object 106 to accommodate the irregularities present on the surface of the test object 106, and the space between the groove 103 and the test object 106 is filled with a liquid contact medium 103A.

The shape and position of the groove 103 are known, and the refraction of ultrasound passing through the groove 103 can be calculated using the calculation device 105.

The contact medium 103A placed in the groove 103 is preferably a contact medium for ultrasonic measurement, such as Sonicoat manufactured by Taiyo Nippon Sanso Gas & Welding Co., Ltd., but any liquid or gel-like substance that transmits even ultrasonic waves can also be used.

The transmission/reception control device 104 is a device that controls the transmission and reception of ultrasound from the low-frequency elements 107 and high-frequency elements 108 of the ultrasonic array probe 101.

This calculation device 105 is, for example, a computer (PC), and has a processing unit 105a equivalent to a CPU, a recording unit 105b consisting of a HDD or SSD, and a display unit 105c consisting of a display.

The computing device 105 has a function of recording the waveforms received by each element of the echoes reflected from the surface of the test object 106 and the echoes reflected inside the test object 106 by performing flaw detection using the ultrasonic array probe 101, and visualizing the inside of the wedge 102 and the inside of the test object 106 by taking into account the refraction of the ultrasonic propagation path due to the surface of the test object 106 using the sound speed inside the wedge 102 and the sound speed inside the test object 106.

In particular, the processor 105a of the computing device 105 visualizes the boundary between the wedge 102 and the object to be inspected 106 based on the received waveform of the ultrasonic waves at the high-frequency element 108 with the higher vibration frequency input via the transmission/reception control device 104. Preferably, the surface shape of the object to be inspected 106 is identified by extracting the coordinates of the surface of the object to be inspected 106 using the transmitted/received waveform at the high-frequency element 108 capable of transmitting and receiving the higher frequency of at least two types of frequency components, and the sound speed inside the wedge 102.

Figure 2 shows a simulation of waveform recording using an element of an ultrasonic array sensor that can transmit and receive high-frequency waves.

In FIG. 2, ultrasonic waves emitted from the high-frequency elements 108 are reflected by the surface of the test object 106 and are recorded by all of the high-frequency elements 108 arranged in the ultrasonic array probe 101. By repeating the above recording process in which ultrasonic waves are emitted from all of the high-frequency elements 108 in sequence, and are received by all of the high-frequency elements 108 in sequence and the waveforms are recorded, a matrix of waveform information is recorded.

The recorded waveform information is visualized, preferably by aperture synthesis, using the sound speed inside the wedge 102 and the sound speed of the contact medium 103A to obtain an echo from the surface of the test object 106, which is a strong reflection source.

Figure 3 shows the coordinate information when the received waveform recorded by the high-frequency element in Figure 2 was visualized at the speed of sound inside the wedge and the surface shape was extracted.

Using the recorded waveform of the reflected wave from the surface of the test object 106 by the high-frequency element in FIG. 2 and the sound speed inside the wedge 102, an image of the reflected echo from the surface of the test object 106 is obtained using the calculation device 105, preferably by aperture synthesis processing.

Coordinate information is recorded from the reflected echo from the surface of the test object 106, with the center of the sensor set as the origin O. This process makes it possible to extract coordinate information 109 of the surface of the test object 106, with the center of the ultrasonic array probe 101 set as the origin O. Compared to the low frequencies used in conventional methods, this extracts coordinate information of the surface shape at high frequencies with short wavelengths, making it possible to extract surface coordinates with high resolution.

The processing unit 105a of the computing device 105 also images the inside of the inspection object 106 based on the received waveform of the ultrasonic wave at the low-frequency element 107, which has a lower vibration frequency. Preferably, the previously identified surface shape of the inspection object 106 and the sound speed inside the inspection object 106 are used to calculate the refraction angle when the ultrasonic wave enters the inside of the inspection object 106 from the wedge, and then the propagation path of the ultrasonic wave from the low-frequency element 107 to the calculation point is obtained, and the inside of the inspection object 106 is imaged using the obtained propagation path of the ultrasonic wave.

Figure 4 shows the refraction of ultrasound into the test object 106 when ultrasound is irradiated by a low-frequency element, and its reception by the low-frequency element.

To calculate the refraction angle when an ultrasonic wave passes through the boundary between different media, the shape of the boundary and the speed of sound of the ultrasonic wave in each material are required.

As shown in FIG. 4, coordinate information 109 of the surface of the test object 106 is known from the steps in FIG. 2 and FIG. 33. In addition, by using the sound speed of the ultrasonic waves inside the wedge 102, the sound speed of the contact medium 103A, and the sound speed of the ultrasonic waves inside the test object 106, the refraction of the ultrasonic waves on the surface of the test object 106 can be calculated.

Therefore, it is possible to calculate the propagation path 112 of the ultrasonic wave, which involves refraction, passing through the inside of the test object 106 from the low-frequency element 110 to the low-frequency element 111, and by using the above-mentioned propagation path 112 of the ultrasonic wave and the calculation device 105, preferably by aperture synthesis processing, a flaw detection image of the inside of the test object 106 with higher accuracy than conventional methods can be obtained.

After "visualization" has been performed in the computing device 105, the image can be displayed in real time on the display unit 105c, or alternatively or additionally, the image can be recorded in the recording unit 105b for later review.

The computation device 105 can use aperture synthesis to image the inside of the test object 106, but other ultrasound imaging techniques such as phased array techniques can also be used.

Returning to FIG. 1, the inspection object 106 is the material to be inspected for ultrasonic flaws, such as a pipe, and may be flat or have a locally curved surface. There are no particular restrictions on the material, but it is preferably a metal.

Next, the ultrasonic flaw detection method according to this embodiment will be described with reference to FIG. 5. FIG. 5 is an overall flow diagram of the flaw detection method according to this embodiment of the present invention.

As shown in FIG. 5, imaging of the inside of the inspection object 106 using the ultrasonic flaw detection method according to this embodiment consists of various steps (processes).

First, of the two frequencies that the ultrasonic probe can oscillate, ultrasonic waves of the higher frequency are transmitted and received (step S1). This step S1 corresponds to the process of placing the ultrasonic array probe 101 and the wedge 102 on the test object 106, and the process of controlling the transmission and reception of ultrasonic waves from the ultrasonic array probe 101.

In step S1, first, one of the high-frequency elements 108 emits ultrasonic waves (step S1-1), and all of the high-frequency elements 108 receive the ultrasonic waves (step S1-2). After that, it is determined whether ultrasonic waves have been emitted by all of the high-frequency elements 108 (step S1-3). If it is determined that ultrasonic waves have been emitted, the process proceeds to step S2, whereas if it is determined that ultrasonic waves have not been emitted, the process returns to step S1-1, and ultrasonic waves are emitted by all of the high-frequency elements 108.

Next, using the high-frequency ultrasonic waveform received in step S1, the coordinates of the surface of the test object 106 are extracted with the center of the ultrasonic array probe 101 as the origin (step S2). This step S2 corresponds to the process of determining the boundary between the wedge 102 and the test object 106 based on the received ultrasonic waveform at the high-frequency element 108 with the higher vibration frequency.

In step S2, the inside of the wedge is first imaged, preferably by aperture synthesis, using the high-frequency ultrasonic waveform received and recorded by the high-frequency element 108 in the previous step S1-2 and the sound speed inside the wedge 102 (step S2-1).

Then, the shape of the surface of the object 106 to be inspected is extracted from the image of the inside of the wedge 102, and the surface coordinates of the object 106 to be inspected are extracted when the center of the ultrasonic array probe 101 is set as the origin (step S2-2).

When using an array sensor capable of oscillating only low-frequency components, it was necessary to extract the shape of the surface of the above-mentioned inspection object 106 using a low-frequency ultrasonic waveform. Since a low-frequency ultrasonic waveform has a long wavelength and low resolution, it was impossible to detect minute irregularities on the surface of the inspection object 106. As a result, the refraction of ultrasonic waves into the interior of the inspection object 106 could not be calculated correctly, which caused errors in the defect position and defect dimensions.

However, by using high-frequency ultrasonic waves to extract the surface shape of the above-mentioned inspection object 106, it is possible to extract the surface shape of the above-mentioned inspection object with higher accuracy, which improves the accuracy of calculating the propagation path of ultrasonic waves into the interior of the above-mentioned inspection object 106 and reduces errors in the defect position and defect dimensions.

Next, of the two frequencies that the ultrasonic element can oscillate, ultrasonic waves of the lower frequency are transmitted and received (step S3). This step S3 also corresponds to a process of controlling the transmission and reception of ultrasonic waves from the ultrasonic array probe 101.

In step S3, first, one of the low-frequency elements 107 emits ultrasonic waves (step S3-1), and all of the low-frequency elements 107 receive the ultrasonic waves (step S3-2). After that, it is determined whether ultrasonic waves have been emitted by all of the low-frequency elements 107 (step S3-3). If it is determined that ultrasonic waves have been emitted, the process proceeds to step S4, whereas if it is determined that ultrasonic waves have not been emitted, the process returns to step S3-1, and ultrasonic waves are emitted by all of the low-frequency elements 107.

Next, the inside of the test object 106 is imaged using the low-frequency ultrasonic waves (step S4). This step S4 corresponds to the process of imaging the inside of the test object 106 based on the waveform of the ultrasonic waves received by the low-frequency element 107.

In step S4, first, the refraction of the ultrasound on the surface of the inspection object 106 is calculated using the surface shape of the inspection object 106 extracted in step S2, the sound speed of the ultrasound inside the wedge 102, and the sound speed of the low-frequency ultrasound inside the inspection object 106, and the propagation path of the ultrasound from the low-frequency element of the ultrasound probe to the inside of the inspection object 106 is determined (step S4-1).

Then, the inside of the test object 106 is imaged, preferably by aperture synthesis, using the above-mentioned ultrasonic propagation path and the ultrasonic waveform at the low-frequency element 107 (step S4-2).

When using an array sensor capable of oscillating only high-frequency components, it was necessary to use a high-frequency ultrasonic waveform to detect flaws inside the above-mentioned inspection object 106. High-frequency ultrasonic waveforms have a short wavelength and are easily affected by scattering and attenuation inside the inspection object 106, and the strength of the reflected waveform from inside the inspection object 106 is weak, which causes defect signals to be overlooked.

However, by using a low-frequency ultrasonic waveform to detect flaws inside the inspection object 106, the strength of the reflected waveform from inside the inspection object 106 is increased, making it possible to improve the visibility of defect signals.

Next, we will summarize the effects of this embodiment.

The ultrasonic flaw detection method of the present embodiment described above includes the steps of arranging an ultrasonic array probe 101 having two or more types of low-frequency elements 107 and high-frequency elements 108 with different vibration frequencies and a wedge 102 that indirectly brings the ultrasonic array probe 101 into contact with the ultrasonic array probe 106 on the object to be inspected 106; controlling the transmission and reception of ultrasonic waves from the low-frequency elements 107 and high-frequency elements 108 of the ultrasonic array probe 101; determining the boundary between the wedge 102 and the object to be inspected 106 based on the received waveform of ultrasonic waves at the high-frequency element 108 with the higher vibration frequency among the two or more types of low-frequency elements 107 and high-frequency elements 108 of the arranged ultrasonic array probe 101; and imaging the inside of the object to be inspected 106 based on the received waveform of ultrasonic waves at the low-frequency element 107 with the lower vibration frequency among the arranged ultrasonic array probe 101.

In this way, by acquiring information on the inspection object 106 at high frequencies, it is possible to extract with higher accuracy than with conventional methods. Furthermore, by improving the accuracy of extracting the surface shape, the accuracy of calculating the refraction path of the ultrasonic waves entering the interior of the inspection object 106 from the wedge 102 is improved, and therefore the accuracy of detecting the defect position and defect dimensions inside the inspection object 106 is also improved. In particular, the accuracy of extracting the curved surface portion of the inspection object 106 can be improved.

This provides an inspection method and inspection device that can achieve both highly accurate surface extraction of the inspection object 106, which was not possible with conventional methods, and improved visibility of defect signals by increasing the strength of the reflected signal from inside the inspection object 106. This increases the reliability of remaining life assessment of plant equipment, etc. using ultrasonic flaw detection, making it possible to improve the operating rate of the equipment.

In addition, in the process of determining the boundary between the wedge 102 and the test object 106, the coordinates of the surface of the test object 106 are extracted using the transmitted and received waveform of the ultrasonic waves from the high-frequency element 108 on the side with the higher vibration frequency and the sound speed inside the wedge 102, so imaging and subsequent imaging of the inside of the test object 106 can be performed with higher accuracy.

Furthermore, in the process of imaging the inside of the test object 106, the refraction angle when the ultrasonic wave enters the inside of the test object 106 from the wedge 102 is calculated using information on the boundary between the wedge 102 and the test object 106 obtained in the process of determining the boundary between the wedge 102 and the test object 106, the sound speed inside the wedge 102, and the sound speed inside the test object 106. The propagation path of the ultrasonic wave from the low-frequency element 107 and the high-frequency element 108 to the calculation point is determined, and the propagation path is used for imaging, thereby obtaining a clearer image of the inside.

In addition, in the process of imaging the inside of the test object 106, a clear image can be obtained by imaging the inside of the test object 106 using aperture synthesis.

Furthermore, the ultrasonic array probe 101 has two or more types of low-frequency elements 107 and high-frequency elements 108, of which the high-frequency elements 108 have a higher vibration frequency, arranged at equal intervals, and the ultrasonic array probe 101 has two or more types of low-frequency elements 107 and high-frequency elements 108, of which the low-frequency elements 107 have a lower vibration frequency, arranged at equal intervals, thereby preventing unevenness in resolution and enabling clearer images to be obtained.

＜Other＞
The present invention is not limited to the above-described embodiment, and various modifications and applications are possible. The above-described embodiment has been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to having all of the configurations described.

100... ultrasonic flaw detector 101... ultrasonic array probe (ultrasonic probe)
102: wedge 103: groove 103A: contact medium 104: transmission/reception control device (transmission/reception device)
105: Calculation device 105a: Processing unit 105b: Recording unit 105c: Display unit 106: Test object 107: Low-frequency element (ultrasonic element) capable of emitting low-frequency ultrasonic waves
108...High-frequency element (ultrasonic element) capable of emitting high-frequency ultrasonic waves
109: Surface coordinate information 110: Low-frequency element that oscillates low-frequency ultrasonic waves 111: Low-frequency element that receives low-frequency ultrasonic waves 112: Ultrasonic wave propagation path passing through the inside

Claims (8)

a step of disposing an ultrasonic probe having two or more types of ultrasonic elements with different vibration frequencies and a wedge for indirectly contacting the ultrasonic probe with the object to be inspected on the object to be inspected;
controlling transmission and reception of ultrasonic waves from the ultrasonic elements of the ultrasonic probe;
determining a boundary between the wedge and the object to be inspected based on a received waveform of an ultrasonic wave at an ultrasonic element having a higher vibration frequency among two or more types of ultrasonic elements of the arranged ultrasonic probe;
and imaging the inside of the object to be inspected based on a waveform of ultrasonic waves received by the ultrasonic element having a lower vibration frequency among the arranged ultrasonic probes. The ultrasonic inspection method according to claim 1,
an ultrasonic flaw detection method, characterized in that in the process of determining the boundary between the wedge and the object to be inspected, the coordinates of the surface of the object to be inspected are extracted using the transmitted and received waveform of the ultrasonic wave at the ultrasonic element on the side with the higher vibration frequency and the sound speed inside the wedge. The ultrasonic inspection method according to claim 1,
The ultrasonic flaw detection method is characterized in that, in the process of visualizing the inside of the inspection object, the boundary determined in the process of determining the boundary between the wedge and the inspection object, the sound speed inside the wedge, and the sound speed inside the inspection object are used to calculate the refraction angle when ultrasonic waves enter the inspection object from the wedge into the inside of the inspection object, the propagation path of ultrasonic waves from the ultrasonic element to a calculation point are determined, and the inside of the inspection object is visualized using the propagation path. The ultrasonic inspection method according to claim 1,
The ultrasonic flaw detection method according to claim 1, wherein in the step of imaging the inside of the object to be inspected, the inside of the object to be inspected is imaged by an aperture synthesis method. An ultrasonic probe having two or more types of ultrasonic elements with different vibration frequencies;
a wedge that is installed on an upper portion of the test object and brings the test object into indirect contact with the ultrasonic probe;
a transmitting/receiving device that controls transmission and reception of ultrasonic waves from the ultrasonic elements of the ultrasonic probe;
an ultrasonic flaw detection device comprising: a calculation device that visualizes the boundary between the wedge and the object to be inspected based on the received waveform of ultrasonic waves at the ultrasonic element having the higher vibration frequency among the two or more types of ultrasonic elements, and visualizes the inside of the object to be inspected based on the received waveform of ultrasonic waves at the ultrasonic element having the lower vibration frequency. The ultrasonic flaw detector according to claim 5,
The ultrasonic probe is characterized in that the ultrasonic elements having higher vibration frequencies among the two or more types of ultrasonic elements are arranged at equal intervals. The ultrasonic flaw detector according to claim 5,
The ultrasonic probe is characterized in that the ultrasonic elements having lower vibration frequencies among the two or more types of ultrasonic elements are arranged at equal intervals. The ultrasonic flaw detector according to claim 5,
The ultrasonic flaw detection device, wherein the arithmetic unit images the inside of the object to be inspected by using an aperture synthesis method.

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