WO2013114545A1 - Method for ultrasonic flaw detection and ultrasonic flaw-detection device - Google Patents

Abstract

Provided are a method for ultrasonic flaw detection and an ultrasonic flaw-detection device capable of measuring easily and with good precision the height of a defect in a body being inspected. A method for ultrasonic flaw detection for changing the refraction angle (θ) of an ultrasonic wave (U) transmitted to the body (100) being inspected to cause the ultrasonic wave (U) to be incident, and for generating a first image showing, for each refraction angle (θ) and each period of time taken by the ultrasonic wave (U) to propagate to a defect (101) that reflects the ultrasonic wave (U), the strength (h) of the wave reflected from the defect (101). The method for ultrasonic flaw detection comprises: a frequency-calculation step for calculating the reflected-image frequency on the basis of the wave reflected from the defect (101) in the first image; and a defect-height estimation step for estimating the height (h) of the defect (101) on the basis of a calibration curve (552) showing the relationship between the height (h) of the defect (101) and the reflected-image frequency, and also on the basis of the reflected-image frequency calculated in the frequency-calculation step.

Description

Ultrasonic flaw detection method and ultrasonic flaw detection apparatus

The present invention relates to an ultrasonic flaw detection method and an ultrasonic flaw detection apparatus, and more particularly, to an ultrasonic flaw detection method and an ultrasonic flaw detection apparatus capable of measuring the height of a defect in an inspection object.

Accurately measuring the height (size) of defects (eg, scratches, cracks, poor penetration of welds, etc.) in the inspected object improves the accuracy of safety evaluation, life prediction, etc. of the inspected object. Is important above.
Conventionally, as a method of measuring the height of a defect by an ultrasonic flaw detection test, the reflected wave from the edge of the defect is captured, and the height of the defect is obtained from the propagation time at the peak value of the reflected wave and the refraction angle of the ultrasonic wave. An end echo method is known (see, for example, Non-Patent Document 1). One probe method that uses one ultrasonic probe is known as one of the edge echo methods, and it mainly captures the reflected wave (corner echo) from the corner of the defect by oblique inspection. After that, by scanning the probe toward the defect, the end echo can be detected in a shorter propagation time than the corner echo, and the height of the defect is measured by geometric calculation by recognizing it. . However, in a small defect, an end echo hardly appears, and advanced knowledge and skill are required to recognize that it is a reflected wave from the end of the defect.

Patent Document 1 discloses an ultrasonic flaw detector using phased array ultrasonic flaw detection in order to increase the detection rate of echoes from the end. In the ultrasonic flaw detection method using this ultrasonic flaw detector, the transmission probe is placed in front of the transmitter probe by controlling the convergence distance by phased array flaw at the position where the end echo is obtained with the maximum sensitivity. This is a method in which an end echo is received by a reception probe having a fixed angle, and an intersection of a number of straight lines connecting the transmission position and the end echo maximum detection point is obtained as a defect end.

Further, Patent Document 2 discloses an ultrasonic test method and an ultrasonic test apparatus that use a longitudinal wave oblique angle probe to determine the size of a defect from an image using longitudinal waves, transverse waves, mode conversion waves, and creeping waves. It is disclosed.

Japanese Patent Laid-Open No. 11-248690 JP 2006-322900 A

However, in the ultrasonic flaw detection apparatus described in Patent Document 1, the probe structure including the transmission probe and the fixed-angle reception probe is positioned so that the end echo can be obtained with the maximum sensitivity. Therefore, a scanning mechanism for scanning the image is required. For this reason, the configuration of the ultrasonic flaw detector becomes complicated, and defects are sized by a large number of calculations, so that the inspector cannot easily inspect using the ultrasonic flaw detector described in Patent Document 1. It was.

Further, in the ultrasonic test method and ultrasonic test apparatus described in Patent Document 2, the reflected wave from the defect due to each reflection mode is recognized, and the size of the defect is calculated geometrically from the position of the probe. It is necessary to ask for it. For this reason, the inspector is requested to have advanced knowledge and skills regarding ultrasonic flaw detection, and the time required for analysis has been increased.

Therefore, an object of the present invention is to provide an ultrasonic flaw detection method and an ultrasonic flaw detection apparatus that can easily and accurately measure the height of a defect in an inspection object.

In order to solve such a problem, the present invention changes the refraction angle of the ultrasonic wave propagated to the object to be inspected, enters the ultrasonic wave, and propagates to the defect that reflects the refraction angle and the ultrasonic wave. An ultrasonic flaw detection method for generating a first image that displays the intensity of a reflected wave from the defect every time, and a frequency for calculating a reflected image power based on the reflected wave from the defect in the first image Defect height for estimating the height of the defect based on the reflection image power calculated by the calculation step and the reflection curve indicating the relationship between the height of the defect and the reflected image power An ultrasonic flaw detection method comprising: an estimation step.

Further, the present invention changes the refraction angle of the ultrasonic wave propagated from the probe to the object to be inspected, enters the ultrasonic wave, and transmits the refraction angle and the propagation time to the defect that reflects the ultrasonic wave, An ultrasonic flaw detector comprising flaw detection image generation means for generating a first image that displays the intensity of a reflected wave from a defect, and calculates a reflected image power based on the reflected wave from the defect in the first image And the height of the defect based on the reflected image power calculated by the reflected image power calculating means and based on the calibration curve indicating the relationship between the height of the defect and the reflected image power. An ultrasonic flaw detector, further comprising: a defect height estimating means for estimating

According to the present invention, it is possible to provide an ultrasonic flaw detection method and an ultrasonic flaw detection apparatus that can easily and accurately measure the height of a defect in an inspection object.

It is a block diagram of the ultrasonic flaw detector according to the present embodiment. It is a flowchart for demonstrating the ultrasonic flaw detection method using the ultrasonic flaw detector which concerns on this embodiment. It is a figure explaining the flaw detection inspection of the artificial defect of a test piece. It is an example of a flaw detection image (B scope) obtained by flaw detection inspection of an artificial defect, (a) is an example with a defect depth of 0.6 mm, and (b) is an example with a defect depth of 1.5 mm. (A) is a schematic diagram showing ultrasonic flaw detection using a longitudinal wave of 70 °, and (b) is an example of a calibration curve generated using the longitudinal wave of 70 °. (A) is a schematic diagram showing ultrasonic flaw detection using creeping waves, and (b) is an example of a calibration curve generated using creeping waves. It is a figure explaining the flaw detection inspection of the defect of a to-be-inspected object. It is an example of a flaw detection image (B scope) obtained by flaw detection inspection. It is a graph which shows the relationship between the actual height of the welding defect measured by cut | disconnecting a to-be-inspected object, and the defect height estimated value estimated by this process. It is an example of A scope. It is a figure explaining the relationship between the reflective echo intensity | strength in the corner echo from the artificial defect of defect height h1, and a pulse width. It is a figure explaining the relationship between the reflective echo intensity | strength in the corner echo from the artificial defect of defect height h2, and a pulse width. It is an example of the graph which shows correlation with echo height and defect height.

Hereinafter, modes for carrying out the present invention (hereinafter referred to as “embodiments”) will be described in detail with reference to the drawings as appropriate. In each figure, common portions are denoted by the same reference numerals, and redundant description is omitted.

≪Ultrasonic flaw detector 1≫
First, the ultrasonic flaw detector 1 according to this embodiment will be described with reference to FIG. FIG. 1 is a configuration diagram of an ultrasonic flaw detector 1 according to the present embodiment.
As shown in FIG. 1, an ultrasonic flaw detector 1 includes an ultrasonic probe 2, an ultrasonic transmitter / receiver 3, an analog / digital converter (hereinafter referred to as “A / D converter”) 4, and A computer 5, an operation input unit 6, and an image display unit 7 are provided.
Then, the ultrasonic flaw detector 1 transmits the ultrasonic wave U from the ultrasonic probe 2 to the inspection object 100 in a state where the ultrasonic probe 2 is installed on the inspection object 100 to be inspected. The reflected wave from the defect 101 of the body 100 is received by the ultrasonic probe 2 so that the inspection object 100 is inspected and the height of the defect 101 of the inspection object 100 in the thickness direction (hereinafter referred to as the thickness of the inspection object 100). , Referred to as “defect height h”).
In FIG. 1, the defect 101 is shown as an example in the thickness direction from the surface of the inspection object 100.

<Ultrasonic probe 2>
The ultrasonic probe 2 transmits an ultrasonic wave U when a transmission waveform (transmission signal) is applied from the ultrasonic transmitter / receiver 3, and receives a reflected wave by the ultrasonic probe 2. The received waveform (received signal) can be output to the ultrasonic transceiver 3.
The ultrasonic probe 2 has a plurality of ultrasonic probes 21. The plurality of ultrasonic probes 21 are arranged one-dimensionally or two-dimensionally to constitute a phased array probe. The ultrasonic probe 21 is composed of, for example, a piezoelectric element and has a function of transmitting and receiving ultrasonic waves. The ultrasonic probe 21 may be composed of a single probe element (piezoelectric element), or is configured as a single probe by connecting a plurality of probe elements (piezoelectric elements) in parallel. Alternatively, the probe element for transmission (piezoelectric element) and the probe element for reception (piezoelectric element) may be connected in parallel to constitute a single probe.

Note that the ultrasonic flaw detector 1 according to the present embodiment uses a phased array to appropriately vary the timing for exciting each ultrasonic probe 21 of the ultrasonic probe 2 with a transmission waveform (transmission signal). In the following description, it is assumed that the refraction angle θ of the ultrasonic wave U propagating through the inspected object 100 can be continuously changed (for example, the refraction angle θ = 0 ° to 85 °). It is not limited to.
For example, by changing the angle of each ultrasonic probe of the ultrasonic probe 2 physically and continuously changing the incident angle of the ultrasonic wave U, the ultrasonic wave U propagating through the object 100 is measured. A configuration using a variable angle probe (not shown) that can continuously vary the refraction angle θ of the lens may be used.

<Ultrasonic transceiver 3>
The ultrasonic transmitter / receiver 3 transmits to each ultrasonic probe 21 in order to transmit the ultrasonic wave U from the ultrasonic probe 2 based on a flaw detection start command from the computer 5 (central control unit 50 described later). A waveform (transmission signal) is applied. In addition, the reception waveform (reception signal) of the reflected wave received by each ultrasonic probe 21 is amplified and output to the A / D converter 4.

Therefore, the ultrasonic transmitter / receiver 3 includes a transmitter / receiver controller 31, a signal generator 32, a transmission side amplifier 33, and a reception side amplifier 34.
The transmitter / receiver control unit 31, the signal generator 32, and the transmission-side amplifier 33 send transmission waveforms (transmission signals) to the corresponding ultrasonic probes 21 of the ultrasonic probe 2 in order to generate the ultrasonic waves U. It is a mechanism for applying. The reception-side amplifier 34 is a mechanism for amplifying the reception waveform (reception signal) received from each ultrasonic probe 21 and outputting it to the A / D converter 4.

The transceiver control unit 31 causes the signal generator 32 to generate an excitation signal based on a flaw detection start command from the computer 5 (a central control unit 50 described later). The excitation signal generated by the signal generator 32 is amplified by the transmission side amplifier 33 and is output to each ultrasonic probe 21 of the ultrasonic probe 2 as a transmission waveform (transmission signal).

Here, the transceiver control unit 31 controls the timing at which the signal generator 32 generates the excitation signal and the timing at which the ultrasound probe 21 is excited, so that the ultrasound probe probe 2 The refraction angle θ of the ultrasonic wave U that enters the inspection object 100 and propagates through the inspection object 100 can be controlled.

Also, the reception waveform (reception signal) of the reflected wave received by each ultrasonic probe 21 is amplified by the reception side amplifier 34 and output to the A / D converter 4.

<A/D converter 4>
The A / D converter 4 converts the analog signal (received waveform, received signal) amplified by the receiving-side amplifier 34 of the ultrasonic transceiver 3 into a digital signal (digital waveform), and the computer 5 (flaw detection image to be described later) It has a function of outputting to the generation unit 51). As the A / D converter 4, for example, a commercially available external A / D converter or a board-type A / D converter built in a computer can be used.

<Computer 5>
The computer 5 stores a central control unit 50, a flaw detection image generation unit 51, a reflected image power calculation unit 52, a calibration curve generation unit 53, a defect height estimation unit 54, and at least a flaw detection image 551 and a calibration curve 552. Storage unit 55.
The computer 5 includes, for example, a ROM (Read Only Memory) (not shown) in which an initial boot program is stored when the power is turned on, a RAM (Random Access Memory) (not shown) used as a working memory. In addition, an HDD (Hard Disc Drive) (not shown) that stores an OS (Operations System), various application programs, and the like and functions as the storage unit 55, a CPU (Central Processing Unit) (not shown) as an arithmetic processing unit Etc., and a CPU (not shown) executes various application programs, whereby a central control unit 50, a flaw detection image generation unit 51, a reflected image frequency calculation unit 52, a calibration curve generation unit 53, a defect height estimation unit 54 functions.

The central controller 50 controls the entire ultrasonic flaw detector 1.
The flaw detection image generation unit 51 adjusts the offset time and adds the digital signals (digital waveforms) of the ultrasonic probes 21 output from the A / D converter 4 and adds them to the A scope (also called A-scan). .) Is generated. Here, the A scope is a waveform indicating the relationship between the amplitude (reflection echo intensity) of the received ultrasonic signal and the propagation time to the reflection source.
Further, the flaw detection image generation unit 51 generates a B scope (also referred to as a B-scan) from the A scope generated for each refraction angle θ of the ultrasonic wave U. Here, the B scope is a two-dimensional image displayed by A scope information with respect to the propagation direction (refractive angle θ) of the ultrasonic beam, and a sectional image obtained by sector scanning on the yz plane.
The A scope and the B scope generated by the flaw detection image generation unit 51 are stored in the storage unit 55 as a flaw detection image 551.

The reflection image power calculation unit 52 calculates the reflection image power D from the flaw detection image 551 (B scope). The reflected image power D will be described later.

The calibration curve generation unit 53 has a function of generating a calibration curve 552 indicating the correlation between the reflected image power D and the defect height h. In the ultrasonic flaw detector 1 in which the calibration curve 552 is input in advance in the storage unit 55, the calibration curve generation unit 53 may not be provided.

The defect height estimation unit 54 has a function of estimating the defect height h based on the reflected image power D and the calibration curve 552.

The storage unit 55 has a function of storing the flaw detection image 551 (A scope, B scope) generated by the flaw detection image generation unit 51 and the calibration curve 552 generated by the calibration curve generation unit 53. Note that the calibration curve 552 may be input in advance.

<Operation input unit 6, image display unit 7>
The computer 5 (central control unit 50) is connected to an operation input unit 6 such as a keyboard and a mouse, and an inspector (operator) can receive an instruction by operating the operation input unit 6. Yes.
The computer 5 (central control unit 50) is connected to the image display unit 7 and is estimated by the flaw detection image 551 (A scope, B scope) generated by the flaw detection image generation unit 51 and the defect height estimation unit 54. The defect height h and the like can be displayed on the image display unit 7.
Note that the computer 5, the operation input unit 6, and the image display unit 7 may be an integrally formed laptop computer, tablet terminal, PDA (Personal Digital Assistant) or the like.

≪Ultrasonic flaw detection method using ultrasonic flaw detection equipment≫
Next, an ultrasonic flaw detection method (defect height estimation method) using the ultrasonic flaw detection apparatus 1 of the present embodiment will be described with reference to FIG. FIG. 2 is a flowchart for explaining an ultrasonic flaw detection method using the ultrasonic flaw detection apparatus 1 according to the present embodiment.
In the following description, the defect 101 (see FIG. 7) due to insufficient penetration of the first layer of the Y groove portion, which is a welding defect, will be described as an example of the defect 101 of the object 100 to be inspected.

Here, prior to the description of the flowchart shown in FIG. 2, the premise of the ultrasonic flaw detection method using the ultrasonic flaw detection apparatus 1 according to the present embodiment will be described with reference to FIG.
FIG. 3 is a diagram for explaining flaw detection inspection of the artificial defect 201 of the test piece 200.
First, a defect (defect 101) due to insufficient melting of the first layer is simulated on a test piece 200 having the same material and thickness as the object 100 to be inspected for flaw detection, and a slit (artificial defect 201) is formed by electric discharge machining. . In the following description, the test piece 200 was carbon steel having a plate thickness of 12 mm.
Further, the defect height h of the artificial defect 201 formed on the test piece 200 is measured in advance and is known. Alternatively, after the flaw detection inspection of the artificial defect 201 (step S101 in FIG. 2 described later), the test piece 200 may be cut and the defect height h of the artificial defect 201 may be measured. The test piece 200 includes a plurality of artificial defects 201 having different defect heights h.
The inspector installs the ultrasonic probe 2 of the ultrasonic flaw detector 1 on the test piece 200 and causes the ultrasonic flaw detector 1 (central control unit 50) to execute the processing shown in FIG.

In step S <b> 101, the central control unit 50 transmits a flaw detection start command to the transmitter / receiver control unit 31 of the ultrasonic transmitter / receiver 3 to perform an ultrasonic flaw inspection of the artificial defect 201 of the test piece 200.
As shown in FIG. 3, the sector scan (for example, the refraction angle θ = 0 ° to 85 °) is performed by continuously changing the refraction angle θ (see FIG. 1) to the test piece 200 by phased array ultrasonic flaw detection. Perform an ultrasonic flaw inspection. In the case of phased array ultrasonic flaw detection, a refraction angle is obtained by using a longitudinal wave 70 ° (longitudinal wave having a refraction angle θ = 70 °) that can generate a longitudinal wave, a transverse wave, a mode conversion wave, and a creeping wave. A sector scan image can be obtained at θ = 0 ° to 85 °, and an image from the artificial defect 201 in a plurality of modes can be obtained.

Then, the flaw detection image generation unit 51 generates a flaw detection image 551 (B scope). FIG. 4 is an example of a flaw detection image (B scope) obtained by flaw detection inspection of the artificial defect 201, (a) is an example of a defect depth h = 0.6 mm, and (b) is a defect depth h. = 1.5 mm. In addition, the display of the reflected image from a defect (artificial defect 201) is improving the discriminability by displaying the reflection echo intensity color tone. However, in the example of FIG. 4, for the sake of space, the whiteness is shown as the reflected echo intensity is high, and the black color is shown as the reflected echo intensity is low.

In step S102, the central control unit 50 displays the flaw detection image 551 (B scope) (see FIGS. 4A and 4B) generated by the flaw detection image generation unit 51 on the image display unit 7, and B The inspector is made to select the reflection image 202 (see FIGS. 4A and 4B) corresponding to the reflection echo of the artificial defect 201 from the scope.

In step S <b> 103, the reflected image power calculation unit 52 calculates the reflected image power D of the reflected image 202 corresponding to the reflected echo of the artificial defect 201.
Here, the reflected image power D is an image power (pixel count, pixel image, whose reflected echo intensity exceeds a preset reflected echo intensity in the reflected image 202 corresponding to the reflected echo of the artificial defect 201 on the B scope. Area value).
In the example of FIG. 4A, the reflected image power D = 303 with respect to the defect depth h = 0.6 mm. In the example of FIG. 4B, the reflected image power D = 468 with respect to the defect depth h = 1.5 mm.
Then, the reflected image power calculation unit 52 records the defect depth h and the reflected image power D in the storage unit 55 in association with each other.

In step S104, the central control unit 50 determines whether or not the flaw detection inspection for all the artificial defects 201 has been completed.
If the flaw detection inspection has not been completed for all the artificial defects 201 (No in S104), the process of the central control unit 50 proceeds to Step S105. In step S105, the central control unit 50 displays, for example, a screen for instructing the movement of the ultrasonic probe 2 on the image display unit 7, and displays the ultrasonic probe of the ultrasonic flaw detector 1 to the inspector. The probe 2 is moved (reinstalled) to the flaw detection position of the next artificial defect 201. Then, returning to step S101, the ultrasonic inspection of the next artificial defect 201 is performed.
On the other hand, when the flaw detection inspection for all the artificial defects 201 is completed (S104: Yes), the process of the central control unit 50 proceeds to step S106.

In step S <b> 106, the calibration curve generation unit 53 generates an approximate expression that approximates the relationship between the plurality of defect depths h recorded in the storage unit 55 and the reflected image power D.
In step S107, the calibration curve generating unit 53 performs a regression analysis of the resultant approximate expression, to calculate the correlation coefficient R ² value.

In step S108, the calibration curve generating unit 53, a correlation coefficient R ² value of the approximate expression is equal to or less than 0.8. Note that if the correlation coefficient R ² value is 0.8 or more, it is generally said that there is a high possibility that an approximate expression is established.
When the correlation coefficient R ² value is not 0.8 or more (S108, No), the process of the calibration curve generation unit 53 returns to Step S106 and generates the approximate expression again. Alternatively, as indicated by an arrow indicated by a broken line in FIG. 2, the process may return to step S <b> 101 and redo from the ultrasonic inspection of the artificial defect 201.
When the correlation coefficient R ² value is 0.8 or more (S108 / Yes), the calibration curve generation unit 53 stores the approximate expression as the calibration curve 552 in the storage unit 55, and the processing of the central control unit 50 is performed as follows. The process proceeds to step S109.

Here, an example of a calibration curve 552 showing the relationship between the defect height h of the artificial defect 201 and the reflected image power D obtained by the processing from step S106 to step S108 is shown. FIG. 5 is an example of a calibration curve 552 generated using a longitudinal wave of 70 °. As another example, FIG. 6 is an example of a calibration curve 552 generated using a creeping wave.
In the example of the calibration curve 552 generated using the longitudinal wave 70 ° shown in FIG. 5, the approximate expression is D = −50 h ² +379.2 h + 48.08, and the correlation coefficient R ² value is 0.955. In the example of the calibration curve 552 generated using the creeping wave shown in FIG. 6, the approximate expression is D = −1.0903h ² + 67.722h + 40.249, and the correlation coefficient R ² value is 0.9788. . In any case, high correlation was obtained.

Before starting step S109, the inspector installs the ultrasonic probe 2 of the ultrasonic flaw detector 1 on the inspection object 100 as shown in FIG.

Returning to FIG. 2, in step S <b> 109, the central control unit 50 transmits a flaw detection start command to the transmitter / receiver control unit 31 of the ultrasonic transmitter / receiver 3, and executes an ultrasonic flaw inspection of the defect 101 of the inspection object 100. . Then, the flaw detection image generation unit 51 generates a flaw detection image 551 (B scope). Note that the flaw detection inspection in step 109 and the flaw detection inspection in step S101 are the same except that the inspection target is changed from the artificial defect 201 of the test piece 200 to the defect 101 of the inspection object 100, and thus description thereof is omitted. To do.
An example of the flaw detection image (B scope) obtained by the flaw detection inspection of the defect 101 in step S109 is shown in FIG.

In step S110, the central control unit 50 displays the flaw detection image 551 (B scope) (see FIG. 8) generated by the flaw detection image generation unit 51 on the image display unit 7, and the defect 101 is inspected from the B scope to the inspector. The reflected image 102 (see FIG. 8) corresponding to the reflected echo is selected.

In step S <b> 111, the reflected image power calculation unit 52 calculates the reflected image power D of the reflected image 102 corresponding to the reflected echo of the defect 101.
Here, the reflected image power D is an image power (in which the reflected echo intensity exceeds a predetermined reflected echo intensity set in advance in the reflected image 102 corresponding to the reflected echo of the defect 101 on the B scope shown in FIG. 8 ( Number of pixels, area value).
In the example of FIG. 8, the reflected image power D was 344.

In step S112, the defect height estimation unit 54 determines the defect height of the defect 101 from the reflection image power D calculated in step S111 and the calibration curve 552 (an approximate expression generated by the processing from step S101 to step S108). Estimate h.
In the example of FIG. 8, the defect height h of the defect 101 is 1.0 mm.

In step S113, the central control unit 50 determines whether or not the flaw detection inspection has been completed at all flaw detection positions.
If the flaw detection inspection has not been completed for all flaw detection positions (No in S113), the process of the central control unit 50 proceeds to Step S114. In step S114, the central control unit 50 displays, for example, a screen for instructing the movement of the ultrasonic probe 2 on the image display unit 7, and the ultrasonic probe of the ultrasonic flaw detector 1 is displayed to the inspector. The probe 2 is moved (reinstalled) to the next flaw detection position of the inspection object 100. Then, returning to step S109, the ultrasonic flaw detection inspection at the next flaw detection position is performed.
On the other hand, when the flaw detection inspection at all flaw detection positions is completed (Yes at S113), the process of the central control unit 50 is ended.

Here, in FIG. 9, the actual height (horizontal axis) of the weld defect (defect 101) measured by cutting the inspection object 100 and the estimated value of the defect height h estimated by the process shown in FIG. The vertical axis). As a result of the regression analysis, the actual height (horizontal axis) and the estimated value (vertical axis) of the defect 101 can be approximated by a straight line, and the correlation coefficient R ² value is 0.9606, and a high correlation is obtained.
Thus, the defect height h of the defect 101 can be simply calculated from the reflection image power D calculated from the flaw detection image 551 (B scope) obtained by the ultrasonic flaw detection inspection and the calibration curve 552 obtained in advance. It can be measured (estimated) with high accuracy.

≪Action ・ Effect≫
The operation and effect of the ultrasonic flaw detection method using the ultrasonic flaw detection apparatus S according to the present embodiment will be described in comparison with the ultrasonic flaw detection method using the conventional ultrasonic flaw detection apparatus.

According to the ultrasonic flaw detector S according to the present embodiment, when the defect height h of one defect 101 is estimated, the ultrasonic probe is scanned by a scanning mechanism like the ultrasonic flaw detector described in Patent Document 1. Can be estimated along with the surface of the object to be inspected (in the left-right direction in FIG. 1). For this reason, since the scanning mechanism like the ultrasonic flaw detector described in Patent Document 1 is not required, the configuration of the ultrasonic flaw detector becomes simple, and the ultrasonic probe 2 to the object 100 is inspected. It becomes easy to attach and remove.

In addition, since the ultrasonic flaw detector S according to the present embodiment can estimate the defect height h of the defect 101 from the reflected image power D and the calibration curve 552 obtained in advance, complicated calculation is unnecessary. Compared with the ultrasonic flaw detector described in Patent Document 1, the defect height h of the defect 101 can be estimated in a short time. Further, unlike the ultrasonic test method and ultrasonic test apparatus described in Patent Document 2, the defect height h of the defect 101 can be simply and accurately without requiring the inspector to have advanced knowledge and skill regarding ultrasonic flaw detection. Can be measured (estimated).

Here, the relationship between the reflected echo intensity from the artificial defect 201 (defect 101) and the defect height h will be described.
FIG. 10 shows an example of the A scope measured in step S101 (see FIG. 2). The horizontal axis indicates the propagation time to the reflection source, and the vertical axis indicates the reflected echo intensity.
The reflection echo 203 from the artificial defect 201 (defect 101) has a larger pulse width W as the reflection echo intensity H increases. In FIG. 10, the pulse width W is the width in the propagation time axis direction at the predetermined reflection echo intensity used in advance when calculating the reflected image power D (see steps S103 and S111). The width of a base part, a half value width, etc. may be sufficient.

11 and 12 are diagrams for explaining the relationship between the reflected echo intensity and the pulse width in the corner echo from the artificial defect 201 (slit). FIG. 11A is a schematic diagram showing ultrasonic flaw detection at the defect height h1, and FIG. 11B is a schematic diagram showing the reflected echo intensity H1 and the pulse width W1 in the corner echo at the defect height h1. FIG. 12A is a schematic diagram showing ultrasonic flaw detection at a defect height h2 (h2> h1), and FIG. 12B is a reflected echo intensity H2 and pulse width of a corner echo at a defect height h2. It is a schematic diagram which shows W2.
As shown in FIGS. 11 and 12, when the defect height of the artificial defect 201 (slit) is h1 <h2, the reflected echo intensity is H1 <H2. The pulse width is W1 <W2.

Conventionally, a method for estimating the defect heights h1 and h2 from the reflected echo intensities H1 and H2 using the correlation between the reflected echo intensity (peak height) and the defect height h is known (for example, (Refer nonpatent literature 1, P127).
However, it is known that when the defect height h of the artificial defect 201 (slit) is increased, the reflected echo intensity (reflected echo height) is saturated. An example is shown in FIG. In FIG. 13, when the refraction angle θ is 45 °, the frequency is 5 MHz, and the vibrator dimensions are 10 mm × 10 mm, the horizontal axis represents the width, diameter, or depth of the flaw (corresponding to the defect height h). .), And the vertical axis represents the relative echo height (corresponding to the reflected echo intensity H).
As shown in FIG. 13, when the defect height h is estimated from the reflected echo intensity H, when the defect height h increases, the reflected echo intensity H is saturated and the defect height h can be accurately estimated. There wasn't.

On the other hand, according to the ultrasonic flaw detection method by the ultrasonic flaw detection apparatus 1 according to the present embodiment, the defect height h is estimated from the reflected image power D. Here, the width in the propagation time direction of the ultrasonic wave at the reflected image power D is the pulse width W of the reflected echo 203.
Thus, by estimating the defect height h from the reflected image power D, as shown in FIG. 5B and FIG. 6B, it is possible to accurately estimate even in a region where the defect height h is higher. Can do.

≪Modification≫
The ultrasonic flaw detector 1 according to the present embodiment is not limited to the configuration of the above embodiment, and various modifications can be made without departing from the spirit of the invention.

In the ultrasonic flaw detector 1 according to the present embodiment, the reflected image power D is a reflection among the reflected images 102 (202) corresponding to the reflected echoes of the defect 101 (reflection defect 201) on the B scope (flaw detection image 551). Although the description has been given assuming that the image intensity (the number of pixels and the area value) exceeds the predetermined reflection echo intensity set in advance, the present invention is not limited to this. For example, the reflected image power D may be a volume value obtained by integrating the reflected echo intensity in each pixel.

Further, in the ultrasonic flaw detector 1 according to the present embodiment, before the ultrasonic flaw inspection (see steps S109 to S114 shown in FIG. 2) is performed on the defect 101 of the object 100, the artificial defect 201 of the test piece 200 is checked. Although it has been described that the ultrasonic inspection is performed to generate the calibration curve 552 (see steps S101 to S108 shown in FIG. 2), the present invention is not limited to this.
In advance, a calibration curve 552 for each material and thickness of the object 100 to be inspected for ultrasonic flaw detection is stored in the storage unit 55 as a database, and before the ultrasonic flaw inspection for the object 100 to be inspected, The material and plate thickness of the body 100 may be input to read the corresponding calibration curve 552 from the database.

1 Ultrasonic flaw detector 2 Ultrasonic probe (probe)
3 Ultrasonic Transceiver 4 A / D Converter 5 Computer 6 Operation Input Unit 7 Image Display Unit 21 Ultrasonic Probe (Probe)
Reference Signs List 31 Transmitter / Receiver Control Unit 32 Signal Generator 33 Transmission Side Amplifier 34 Reception Side Amplifier 50 Central Control Unit 51 Flaw Detection Image Generation Unit 52 Reflected Image Frequency Calculation Unit 53 Calibration Curve Generation Unit 54 Defect Height Estimation Unit 55 Storage Unit 100 Inspected Object DESCRIPTION OF SYMBOLS 101 Defect 102 Reflected image 200 Test piece 201 Artificial defect 202 Reflected image 551 Inspection image (image)
552 Calibration curve U Ultrasonic θ Refraction angle h Defect height D Reflected image power H Reflected echo intensity

Claims (10)

1. The ultrasonic wave is incident upon changing the refraction angle of the ultrasonic wave propagated to the object to be inspected, and the intensity of the reflected wave from the defect is displayed for each propagation time to the defect that reflects the refraction angle and the ultrasonic wave. An ultrasonic flaw detection method for generating a first image, comprising:
   A power calculation step of calculating a reflected image power based on a reflected wave from the defect in the first image;
   Based on a calibration curve indicating the relationship between the height of a defect and the reflected image power, and based on the reflected image power calculated by the power calculating step, a defect height estimating step that estimates the height of the defect; An ultrasonic flaw detection method comprising:
2. An artificial defect is formed on a test piece having the same material and plate thickness as the object to be inspected, and the ultrasonic wave is incident upon changing the refraction angle of the ultrasonic wave to be propagated to the test piece. For each propagation time to the artificial defect that reflects sound waves, a second image that displays the intensity of the reflected wave from the artificial defect is generated, and based on the reflected wave from the artificial defect in the second image A calibration curve generating step of calculating a reflection image power and generating the calibration curve based on a relationship between the height of the artificial defect and the reflection image power;
   The ultrasonic flaw detection method according to claim 1, wherein the calibration curve generation step is performed before the frequency calculation step.
3. The reflected image power is
   The ultrasonic flaw detection method according to claim 1, wherein the ultrasonic flaw detection method is based on a size of a region where the intensity of a reflected wave from the defect in the first image is a predetermined threshold value or more.
4. The reflected image power is
   2. The ultrasonic flaw detection method according to claim 1, wherein the method is based on a sum of intensity of reflected waves from the defect in a region where the intensity of the reflected wave from the defect in the first image is a predetermined threshold value or more. .
5. By changing the refraction angle of the ultrasonic wave propagating from the probe to the object to be inspected, the ultrasonic wave is incident, and at each propagation time to the defect that reflects the refraction angle and the ultrasonic wave, the reflected wave from the defect An ultrasonic flaw detector comprising flaw detection image generation means for generating a first image for displaying intensity,
   Reflected image power calculating means for calculating a reflected image power based on a reflected wave from the defect in the first image;
   A defect height estimating means for estimating the height of the defect based on the reflected image power calculated by the reflected image power calculating means based on a calibration curve indicating the relationship between the height of the defect and the reflected image power. And an ultrasonic flaw detector.
6. The calibration curve is
   An artificial defect is formed on a test piece having the same material and plate thickness as the object to be inspected, and the ultrasonic wave is incident upon changing the refraction angle of the ultrasonic wave to be propagated to the test piece. For each propagation time to the artificial defect that reflects sound waves, a second image that displays the intensity of the reflected wave from the artificial defect is generated, and based on the reflected wave from the artificial defect in the second image 6. The ultrasonic flaw detector according to claim 5, wherein a reflected image power is calculated and generated based on a relationship between a height of the artificial defect and the reflected image power.
7. The reflected image power is
   The ultrasonic flaw detection apparatus according to claim 5, wherein the ultrasonic flaw detection apparatus is based on a size of a region where the intensity of the reflected wave from the defect in the first image is equal to or greater than a predetermined threshold.
8. The reflected image power is
   6. The ultrasonic flaw detector according to claim 5, wherein the ultrasonic flaw detection apparatus is based on a sum of intensity of reflected waves from the defect in a region where the intensity of the reflected wave from the defect in the first image is a predetermined threshold value or more. .
9. The ultrasonic flaw detector according to claim 5, wherein the probe is a phased array type ultrasonic probe.
10. The ultrasonic flaw detector according to claim 5, wherein the probe is a variable-angle ultrasonic probe.

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