JP2008008709A - Ultrasonic flaw detection method and ultrasonic flaw detection system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic flaw detection method for accurately and easily performing the ultrasonic flaw detection of an inspection target having a coating film formed thereto. <P>SOLUTION: In the case where the ultrasonic flaw detection of the inspection target, which is constituted by forming the coating film on the surface of a base material, is performed, the echo height from the boundary surface of the coating film and the base material is measured by a vertical flaw detection method (S101), flaw detection sensitivity for the flaw detection due to an oblique angle flaw detection method is corrected on the basis of the measured echo height (S102 and S103) and the flaw detection of the inspection target due to the oblique angle flaw detection method is subsequently performed using the corrected flaw detection sensitivity (S104). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ultrasonic flaw detection method for flaw detection of a subject, and more particularly to an ultrasonic flaw detection method for flaw detection of a subject with a coating film formed on the surface, and an ultrasonic apparatus for performing the method.

  When ultrasonic flaw detection is performed on an object with a coating film formed on the surface, the ultrasonic wave is attenuated in the coating film, resulting in oversight of the scratch or underestimation or overestimation of the scratch. There was a problem such as. In order to avoid this problem, it is conceivable to carry out flaw detection after removing the coating film, and then paint the surface again. However, this has the problem of increasing the cost.

  In order to cope with such a problem, the following has been proposed as an ultrasonic flaw detection method for flaw detection without removing the coating film.

  First, (1) for each type of coating film, the relationship between the thickness of the coating film and the amount of attenuation of ultrasonic waves in the coating film is examined in advance, and (2) before flaw detection or flaw detection is performed. In this case, the thickness of the coating film of the actual specimen is measured. (3) Based on the results of (1) and (2) above, estimation of ultrasonic attenuation and flaw detection sensitivity (depending on the purpose of flaw detection) And a method of correcting the sensitivity of the ultrasonic flaw detector adjusted appropriately) (see, for example, Patent Documents 1 and 2). As in this method, by previously grasping the relationship between the thickness of the coating film and the attenuation amount of the ultrasonic wave in the coating film, it is possible to detect the subject without removing the coating film.

Second, in order to avoid attenuation of ultrasonic waves by the coating film, there is a method of performing flaw detection by directly injecting ultrasonic waves to the substrate by piercing the coating film with a needle-type probe. It has been proposed (see, for example, Patent Document 3). According to this method, the influence of the coating film can be eliminated, so that more accurate flaw detection can be performed.
JP-A-1-253651 JP 2003-139747 A Japanese Patent Laid-Open No. 10-10094

  By the way, in the case of the first ultrasonic flaw detection method described above, it is premised that the coating film and the boundary surface between the coating film and the substrate have the same acoustic characteristics at any part. However, in reality, the acoustic characteristics of the coating film vary depending on the site due to the effects of secular change, and the boundary between the coating film and the substrate due to surface treatment such as blasting and the effect of the primer. The acoustic characteristics of the surface may vary depending on the part. For this reason, the ultrasonic attenuation amount in the coating film, which has been examined in advance, and the actual ultrasonic attenuation amount are different, or the ultrasonic wave passing amount at the interface between the coating film and the substrate is different. Will be. As a result, according to the first ultrasonic flaw detection method, it is difficult to appropriately correct the flaw detection sensitivity, and underestimation or overestimation of the flaw may occur.

  Further, according to the second ultrasonic flaw detection method described above, since the coating film is damaged by piercing the coating film with a needle-type probe, it is necessary to repair the coating after completion of the flaw detection. There is a problem that occurs. Furthermore, in the case of a needle-type probe, since the size of the vibrator becomes very small, the ultrasonic wave spreads, and as a result, there is a problem that it is difficult to accurately evaluate the size of the scratch.

  The present invention has been made in view of such circumstances, and an object of the present invention is to perform ultrasonic flaw detection of a subject having a coating film formed on the surface thereof accurately without damaging the coating film. An object of the present invention is to provide a flaw detection method and an ultrasonic flaw detection apparatus for carrying out the method.

  The inventors should correct the flaw detection sensitivity in order to perform an accurate evaluation without damaging the coating film when performing ultrasonic flaw detection on the specimen having the coating film formed on the surface. We studied earnestly.

  FIG. 1 is a conceptual diagram showing the concept of echo in ultrasonic flaw detection. In FIG. 1, a subject 10 is a structure in which a coating film 12 is formed on the surface of a substrate 11. In the following, as shown in FIG. 1, the echo from the surface of the coating film 12 is a surface echo, the echo from the boundary surface between the coating film 12 and the base material 11 is an interface echo, and the echo from the bottom surface of the base material 11. Are referred to as bottom echoes, respectively.

  FIG. 2 is a graph showing the relationship between the bottom echo height and the coating thickness before the flaw detection sensitivity is corrected. This graph used a phased array probe having 16 transducers to detect a specimen (hereinafter referred to as a specimen with a coating film) having a coating film formed on the surface by a vertical flaw detection method. The test results are shown. In this test, ultrasonic waves having a frequency of 10 MHz are used.

  In FIG. 2, the ratio of the bottom surface echo height between the case of the subject having no coating film formed on the surface and the case of the subject with the coating film is plotted as a bottom surface echo height with a black triangle. Yes.

  As the coating thickness increases, the amount of ultrasonic attenuation in the coating also increases. Therefore, as shown in FIG. 2, the bottom echo height decreases as the coating thickness increases.

  In the first conventional ultrasonic flaw detection method described above, the relationship between the coating film thickness and the bottom echo height as shown in FIG. 2 is investigated in advance, and then the actual coating thickness of the subject is measured. Then, the attenuation amount of the ultrasonic wave is estimated from the thickness of the coating film and the relationship between the coating film thickness and the bottom surface echo height investigated in advance. Then, the flaw detection sensitivity is corrected based on the attenuation amount of the ultrasonic wave. FIG. 3 is a graph showing the relationship between the coating film thickness and the bottom surface echo height when the flaw detection sensitivity is corrected as described above.

  As shown in FIG. 3, the bottom echo height varies greatly depending on the coating thickness. Here, the standard deviation of the bottom echo height is about 1.37 dB, and the difference between the maximum value and the minimum value is about 6 dB. Thus, when a large variation occurs in the bottom surface echo height, a problem of underestimating or overestimating the scratch is caused.

  In this way, when the attenuation amount of the ultrasonic wave is estimated using the bottom surface echo height, an error is likely to occur.

  In addition, when the bottom echo height is used, there are the following problems. In other words, in order to accurately measure the attenuation of ultrasonic waves in the coating film, it is necessary to measure the bottom echo height at the flaw detection site, but the bottom surface of the subject has a welded part, etc. In many cases, it is difficult to measure the bottom echo height. Therefore, it can be difficult to accurately measure the attenuation of ultrasonic waves in the coating film.

  As described above, the present inventors have difficulty in measuring the attenuation of ultrasonic waves in the coating film according to the method using the bottom surface echo height, and as a result, the flaw detection sensitivity cannot be properly corrected. Thought. And since the interface between the coating film and the substrate is often a flat surface, the interface echo height measurement is different from the bottom surface echo height where the probe can be installed. Then, attention was paid to the fact that it can be performed easily and accurately. As shown in FIG. 4, since the interface echo height and the bottom surface echo height are in a substantially one-to-one relationship, the flaw detection sensitivity in consideration of attenuation of ultrasonic waves in the coating film is obtained by using the interface echo height. We thought that it was possible to correct appropriately.

  Based on these findings, the present inventors have made the invention shown below.

  The ultrasonic flaw detection method of the present invention is an ultrasonic flaw detection method for a subject in which a coating film is formed on the surface of a base material, and an echo height from the interface between the coating film and the base material is determined by a vertical flaw detection method. And the flaw detection sensitivity for flaw detection by the oblique flaw detection method is corrected based on the measured echo height, and flaw detection of the subject by the flaw detection method is performed using the corrected flaw detection sensitivity. Execute.

  Thus, by correcting the flaw detection sensitivity based on the echo height from the boundary surface between the coating film of the subject and the base material, the coating film can be formed accurately and easily without removing the coating film. It is possible to perform a flaw detection on a subject.

  In the ultrasonic flaw detection method according to the above invention, it is desirable that the flaw detection of the subject by the oblique flaw detection method is performed using a point focusing oblique probe.

  In the ultrasonic flaw detection method according to the invention, the flaw detection of the subject by the oblique angle flaw detection method may be performed using a phased array probe.

  The ultrasonic flaw detector of the present invention is an ultrasonic flaw detector that performs flaw detection on a subject having a coating film formed on the surface of a substrate.In the ultrasonic flaw detector, a vertical flaw detector, an oblique flaw detector, Based on the ultrasonic wave received by the probe for vertical flaw detection, measuring means for measuring the echo height from the interface between the coating film and the substrate, and the echo height measured by the measuring means And a correction means for correcting the flaw detection sensitivity for flaw detection by the oblique flaw detection method, and using the flaw detection sensitivity corrected by the correction means, the ultrasonic wave received by the oblique flaw detection probe is used. Based on this, the test is performed on the subject.

  In the ultrasonic flaw detection apparatus according to the present invention, it is preferable that the vertical flaw detection probe and the oblique flaw detection probe are accommodated in one case.

  Further, the ultrasonic flaw detector of the present invention is a phased array probe in which a plurality of transducers are arranged in an ultrasonic flaw detector that performs flaw detection on a subject having a coating film formed on the surface of a substrate. The ultrasonic waves radiated from some transducers of the phased array probe are incident in a direction perpendicular to the flaw detection surface of the subject, and the ultrasonic waves radiated from other transducers are perpendicular to the flaw detection surface. When receiving an acoustic wedge for incidence in a direction other than the ultrasonic wave radiated from the part of the vibrator, based on the received ultrasonic wave, from the boundary surface between the coating film and the base material Measuring means for measuring the echo height of the laser and correction means for correcting the flaw detection sensitivity for flaw detection by the oblique flaw detection method based on the echo height measured by the measurement means, and the other vibrator Received ultrasound emitted from If, on the basis of the ultrasonic wave the received, using the flaw detection sensitivity which is corrected by said correction means, wherein being configured to perform a flaw detection of the object.

  According to the ultrasonic flaw detection method of the present invention and the ultrasonic flaw detection apparatus for performing the method, accurate flaw detection can be performed without damaging the coating film.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 5 is a block diagram showing the configuration of the ultrasonic flaw detector according to Embodiment 1 of the present invention. As shown in FIG. 5, the ultrasonic flaw detector 1 transmits and receives ultrasonic waves to and from the vertical flaw detection probe 2 for vertical flaw detection and the oblique flaw detection probe 3 for oblique flaw detection. 4, an A / D converter 6, an arithmetic processing device 7 that executes predetermined processing, and an output device 8 that includes a display or the like.

  The vertical flaw detection probe 2 and the oblique flaw detection probe 3 are point-focusing oblique flaw probes, and a focal position is set near the bottom surface of the subject 10 including the coating film 12.

  The vertical flaw detection probe 2 and the oblique flaw detection probe 3 are arranged on the surface of the subject 10 in which the coating film 12 is formed on the surface of the substrate 11, that is, on the surface of the coating film 12. The vertical flaw detection probe 2 and the oblique flaw detection probe 3 are connected to a transmitter / receiver 4, and the transmitter / receiver 4 is connected to the vertical flaw detection probe 2 and the oblique flaw detection probe. Ultrasonic waves are transmitted and received through the touch 3.

  The transceiver 4 includes an amplifier 5 for amplifying the received ultrasonic wave with a predetermined amplification factor. This amplification factor corresponds to the flaw detection sensitivity of the ultrasonic flaw detector 1.

  The A / D converter 6 digitizes the electrical signal received from the transceiver 4 and outputs the digital data to the arithmetic processing unit 7.

  The arithmetic processing unit 7 executes processing as described later based on the data received from the A / D converter 6. The processing result is output by the output device 8 constituted by a display or the like.

  Note that the vertical flaw detection probe 2 and the oblique flaw detection probe 3 provided in the ultrasonic flaw detection apparatus of the present invention are not limited to point-focusing oblique flaw probes, but other types of probes. It is possible to use a tentacle. However, when a thin plate having a thickness of 5 mm or less is used as a subject, the normal type probe performs flaw detection in a short-distance sound field where the sound field is unstable. Since there is a possibility that the measurement of the size of the flaw cannot be performed accurately, it is desirable to use a probe capable of setting the focal position near the bottom surface of the subject as described above. Examples of such a probe include a phased array probe and the like in addition to the point focusing type oblique angle probe.

  Next, the operation of the ultrasonic flaw detector 1 of the present invention configured as described above will be described.

  FIG. 6 is a flowchart showing a flow of operations of the ultrasonic flaw detector 1 according to the first embodiment of the present invention.

  First, the ultrasonic flaw detector 1 measures the echo height from the boundary surface between the coating film 12 and the base material 11, that is, the interface echo height by the vertical flaw detection method (S101). Specifically, the transmitter / receiver 4 transmits / receives ultrasonic waves via the vertical flaw detection probe 2 to measure the interface echo height.

  The attenuation amount of ultrasonic waves in the coating film can be estimated from the height of the interface echo thus obtained. However, since the ultrasonic path differs between the vertical flaw detection method and the oblique flaw detection method, the interface echo height measured in step S101, that is, the interface echo height measured by the vertical flaw detection method is used as it is. It is not appropriate to carry out flaw detection by the bevel flaw detection method.

  Therefore, the ultrasonic flaw detector 1 calculates the correction amount of the flaw detection sensitivity based on the interface echo height measured in step S101 in order to obtain the flaw detection sensitivity for the oblique flaw detection method (S102). More specifically, the following processing is executed.

  FIG. 7 is a graph showing the relationship between the coating film thickness and the corner echo height when the oblique flaw detection method is used. In FIG. 7, the ratio of the corner echo height between the case of the specimen having no coating film on the surface and the case of the specimen with the coating film is plotted as a corner echo height with a black circle. Yes. Here, the corner echo refers to an echo from the bottom corner of the subject when ultrasonic waves are transmitted at a predetermined oblique angle.

In step S102, the arithmetic processing unit 7 included in the ultrasonic flaw detector 1 calculates the value of the flaw detection sensitivity correction amount ΔH according to the equation ΔH = −9.15δ−10.03. Here, δ indicates the coating thickness obtained from the measurement result of the interface echo height in the vertical flaw detection method. Specifically, δ = ((H _I −H _S ) /5.61). It is a value obtained by +0.32. Note that H _I represents the interface echo height, and H _S represents the surface echo height.

  When correction is performed according to the correction amount calculated in this way, the following significant effects are obtained.

  FIG. 8A is a graph showing the relationship between the bottom surface echo height and the interface echo height and the coating thickness before the flaw detection sensitivity is corrected, and FIG. 8B is the bottom surface after the flaw detection sensitivity is corrected by the ultrasonic flaw detection method of the present invention. It is a graph which shows the relationship between echo height and coating-film thickness.

  In FIG. 8A, the ratio of the bottom surface echo height between the case of the subject having no coating film formed on the surface and the case of the subject with the coating film is defined as the bottom surface echo height before correction of the flaw detection sensitivity. The triangle is plotted. The ratio between the interface echo height and the surface echo height is plotted as a white circle as the interface echo height.

As the coating thickness increases, the attenuation of ultrasonic waves in the coating also increases. Therefore, before correction, as shown in FIG. 8A, the bottom echo height increases as the coating thickness increases. Will be reduced.

  On the other hand, after correcting the flaw detection sensitivity using the interface echo height as described above, the bottom surface echo height is substantially constant even when the coating film thickness is different as shown in FIG. 8B. Here, the standard deviation of the bottom echo height after correction by the ultrasonic flaw detection method of the present invention is about 0.19 dB. As described above with reference to FIG. 3, the bottom echo height after the correction is compared with the standard deviation of the bottom echo height after the correction by the conventional first ultrasonic flaw detection method is about 1.37 dB. It can be seen that the variation in is small. If it is this grade, even if a coating film thickness differs, evaluation of a crack can be performed correctly.

  Next, the ultrasonic flaw detection apparatus 1 sets the flaw detection sensitivity using the flaw detection sensitivity correction amount calculated in step S102 (S103). More specifically, the amplification factor in the amplifier 5 included in the transceiver 4 is set so as to be a value based on the flaw detection sensitivity in which the correction amount calculated by the arithmetic processing device 7 is reflected.

  As described above, in the present embodiment, the ultrasonic flaw detector 1 automatically sets the flaw detection sensitivity (amplification factor setting). For example, the operator may manually set the flaw detection sensitivity. Good.

  Then, the transmitter / receiver 4 provided in the ultrasonic flaw detection apparatus 1 performs flaw detection on the subject by transmitting / receiving ultrasonic waves via the oblique flaw detection probe 3 (S104).

  FIG. 9 is a graph showing the results of flaw detection of a specimen with a coating film by the ultrasonic flaw detection apparatus 1 of the present invention. The results shown in this graph show that the ultrasonic flaw detector 1 flaws a test body provided with an artificial flaw and measures the height of the flaw that is present. As this test body, the thing with a coating-film thickness of 0.8 mm, the thing of 2.2-2.3 mm, and the thing of 2.4-2.6 mm were prepared. As a method for measuring the size of the scratch, a drop method is used which is not easily affected by the echo height.

  As shown in FIG. 9, regardless of the thickness of the coating film, the actual height of the flaw (actual flaw height) and the height of the flaw (flaw indication height) evaluated by the ultrasonic flaw detector 1 are shown. The error is extremely small (standard deviation 0.33 mm). Thus, according to the ultrasonic flaw detector 1 of the present invention, flaw detection can be performed accurately and easily even for a specimen with a coating film.

  As described above, in the ultrasonic flaw detection apparatus 1 of the present invention, a good flaw detection result can be obtained regardless of the flaw height. It is because it can be performed. Hereinafter, this point will be described in comparison with the comparative example.

  As an experiment, three types of test specimens with artificially scratched coatings were prepared, and the ultrasonic test method of the present invention and the above-described conventional first ultrasonic test were performed on the test specimens. The flaw detection was performed by the method, and the relationship between the echo height before and after the flaw detection sensitivity was corrected and the coating thickness was determined. The specimen is provided with scratches having a height of 3 mm, 2 mm, 1 mm, and 0.5 mm.

  FIG. 10A is a graph showing the relationship between the coating thickness before the correction of flaw detection sensitivity and the echo height in the case of the first conventional ultrasonic flaw detection method, and FIG. 10B is the same as the coating after the flaw detection sensitivity is corrected. It is a graph which shows the relationship between a film thickness and echo height.

  FIG. 11A is a graph showing the relationship between the coating thickness before flaw detection sensitivity correction and the interface echo height in the case of the ultrasonic flaw detection method of the present invention, and FIG. 11B is the same after flaw detection sensitivity correction. It is a graph which shows the relationship between coating film thickness and interface echo height.

  Referring to FIGS. 10A and 11A, in any case, the echo height decreases as the coating thickness increases.

  Next, referring to FIG. 10B and FIG. 11B, in the case of the ultrasonic flaw detection method of the present invention, the echo height is substantially the same as long as the flaw is the same even if the coating thickness is different. In the conventional case, it can be seen that the echo height varies even with the same flaw height.

  FIG. 12 shows the degree of variation in echo height as a sensitivity correction error. FIG. 12 is a graph showing the relationship between the sensitivity correction error and the flaw height in the case of the ultrasonic flaw detection method of the present invention and the conventional first ultrasonic flaw detection method. Here, the sensitivity correction error refers to the maximum and minimum values of the flaw echo height when the flaw height after correction is the same.

  As shown in FIG. 12, in the case of the present invention, the value of the sensitivity correction error is small regardless of the flaw height. On the other hand, in the case of the conventional method, the value of the flaw height is small. The value of the sensitivity correction error is larger than that according to the invention.

  From the above, in the case of the ultrasonic flaw detection method according to the present invention, even if the coating thickness is different, the echo height can be corrected to be substantially the same if the scratch height is the same. Thus, in the conventional case, it can be seen that the sensitivity correction error is large and appropriate correction is not performed.

(Embodiment 2)
The ultrasonic flaw detection apparatus according to Embodiment 1 includes two probes, a vertical flaw detection probe and an oblique flaw detection probe. On the other hand, the ultrasonic flaw detection apparatus according to Embodiment 2 implements the ultrasonic flaw detection method of the present invention using one probe.

  FIG. 13 is a front view showing a configuration of a probe provided in the ultrasonic flaw detector according to Embodiment 2 of the present invention.

  In FIG. 13, reference numeral 21 denotes a phased array probe in which a plurality of transducers are arranged in the horizontal direction on the drawing. The phased array probe 21 is provided on an acoustic wedge 22. .

  The acoustic wedge 22 is formed with a hole 23 penetrating in the vertical direction. The hole 23 is filled with a medium (for example, water) having a sound speed different from that of the acoustic wedge 22.

  As shown in FIG. 13, the hole 23 has a rectangular shape in which the upper side in contact with the phased array probe 21 and the lower side in contact with the flaw detection surface of the subject 10 are provided in the horizontal direction with respect to the flaw detection surface of the subject 10. The portion 23a and the lower side are similarly provided in the horizontal direction, whereas the upper side 24 is provided in contact with the phased array probe 21 and inclined at a predetermined angle with respect to the flaw detection surface of the subject 10. Part 23b.

  Since other configurations and operations of the ultrasonic flaw detector according to Embodiment 2 are the same as those in Embodiment 1, illustration and description thereof are omitted.

  As indicated by the wavy arrow in FIG. 13, the ultrasonic wave radiated from the phased array probe 21 into the acoustic wedge 22 and the hole 23 is incident on the flaw detection surface of the subject 10. Among these, the ultrasonic wave radiated from a part of the transducer of the phased array probe 21 through the portion indicated by 23a is incident on the flaw detection surface of the subject 10 perpendicularly, whereas the phased array probe 21 is phased. The ultrasonic waves radiated from the other transducers of the array probe 21 through the portion indicated by 23b are refracted at the upper side 24 and are incident at a predetermined angle with respect to the flaw detection surface of the subject 10. To do.

  As described above, by using the acoustic wedge 22 in which the hole 23 is formed, a single probe can be used for flaw detection at two or more refraction angles. In the case of a phased array probe, since the incident angle of ultrasonic waves can be controlled electronically, vertical flaw detection and oblique flaw detection can be performed with one probe. Since there is a limit to the spread, it is difficult to perform flaw detection at two refraction angles (for example, vertical and oblique angles of 45 degrees, oblique angles of 45 degrees and 70 degrees, etc.) at the same time. According to the present embodiment, it is possible to simultaneously perform flaw detection at two refraction angles that are so different.

(Embodiment 3)
As in the case of the first embodiment, the ultrasonic flaw detection apparatus according to the third embodiment includes two probes, a vertical flaw detection probe and an oblique flaw detection probe. However, in the case of the first embodiment, the two probes are provided independently, whereas in the third embodiment, the two probes are accommodated in one case.

  FIG. 14 is a front view showing a configuration of a probe provided in the ultrasonic flaw detector according to Embodiment 3 of the present invention.

  In FIG. 14, 31 indicates a probe for vertical flaw detection, and 32 indicates a probe for oblique flaw detection. The vertical flaw detection probe 31 and the oblique flaw detection probe 32 are accommodated in an acoustic wedge 33 that also serves as a case of these probes.

  Since other configurations and operations of the ultrasonic flaw detector according to Embodiment 3 are the same as those in Embodiment 1, illustration and description thereof are omitted.

  As indicated by the broken-line arrows in FIG. 14, the ultrasonic wave radiated from the vertical flaw detection probe 31 into the acoustic wedge 33 is incident perpendicularly to the flaw detection surface of the subject 10, and the oblique flaw detection probe. The ultrasonic wave radiated from the child 32 into the acoustic wedge 33 is incident with a predetermined angle with respect to the flaw detection surface of the subject 10. In this way, the ultrasonic wave radiated from the vertical flaw detection probe 31 and the ultrasonic wave radiated from the oblique flaw detection probe 32 are incident on the same position on the flaw detection surface of the subject 10. Adjusted.

  As described above, two probes for vertical flaw detection and oblique flaw detection are accommodated in one case, and the incident angle of the ultrasonic wave radiated from these probes can be adjusted by the acoustic wedge 33. As a result, ultrasonic waves from both probes can be incident on the same position on the flaw detection surface of the subject 10.

  When both probes are made independent as in the case of the first embodiment, the ultrasonic waves from these probes are caused to enter the same position on the flaw detection surface of the subject 10. Interference will occur. For this reason, in the case of the first embodiment, the ultrasonic waves from both probes are incident on the flaw detection surface of the subject 10 as close as possible to the extent that interference does not occur. However, in order to perform a highly accurate flaw detection using the ultrasonic flaw detection method of the present invention, in either case of vertical flaw detection or oblique flaw detection, ultrasonic waves radiated from the probe are applied to the subject. It is desirable that the light is incident on the same position on the flaw detection surface. In this respect, it can be said that the ultrasonic flaw detector according to Embodiment 3 is a desirable configuration.

  The ultrasonic flaw detection method and the ultrasonic flaw detection apparatus according to the present invention can accurately perform flaw detection on a subject on which a coating film has been formed without removing the coating film, so that a coating film may be formed. This is useful when performing ultrasonic testing of many structures.

It is a conceptual diagram which shows the concept of the echo in ultrasonic flaw detection. It is a graph which shows the relationship between the bottom echo height and coating film thickness before correction | amendment of a flaw detection sensitivity. It is a graph which shows the relationship between the coating-film thickness at the time of correcting flaw detection sensitivity, and a bottom face echo height. It is a graph which shows the relationship between bottom echo height and interface echo height. It is a block diagram which shows the structure of the ultrasonic flaw detector which concerns on Embodiment 1 of this invention. 3 is a flowchart showing a flow of operations of the ultrasonic flaw detector according to the first embodiment of the present invention. It is a graph which shows the relationship between the coating-film thickness in the case of an oblique flaw detection method, and a corner echo height. It is a graph showing the relationship between the bottom surface echo height and the interface echo height and the coating thickness before correction of the flaw detection sensitivity, It is a graph which shows the relationship between the bottom echo height and the coating-film thickness after correction | amendment of the flaw detection sensitivity by the ultrasonic flaw detection method of this invention. It is a graph which shows the result of the flaw detection of the test substance with a coating film by the ultrasonic flaw detector 1 of this invention. It is a graph which shows the relationship between the coating-film thickness before correction | amendment of a flaw detection sensitivity, and echo height in the case of the conventional 1st ultrasonic flaw detection method. It is a graph which shows the relationship between the coating-film thickness after correction | amendment of flaw detection sensitivity, and echo height in the case of the conventional 1st ultrasonic flaw detection method. It is a graph which shows the relationship between the coating-film thickness before correction | amendment of a flaw detection sensitivity, and an interface echo height in the case of the ultrasonic flaw detection method of this invention. It is a graph which shows the relationship between the coating-film thickness after correction | amendment of flaw detection sensitivity, and an interface echo height in the case of the ultrasonic flaw detection method of this invention. It is a graph which shows the relationship between the sensitivity correction error and the flaw height in the case of using the ultrasonic flaw detection method of the present invention and the conventional first ultrasonic flaw detection method. It is a front view which shows the structure of the probe with which the ultrasonic flaw detector which concerns on Embodiment 2 of this invention is provided. It is a front view which shows the structure of the probe with which the ultrasonic flaw detector which concerns on Embodiment 3 of this invention is provided.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ultrasonic flaw detector 2 Probe for vertical flaw detection 3 Probe for oblique flaw detection 4 Transmitter / receiver 5 Amplifier 6 A / D converter 7 Arithmetic processing device 8 Output device 10 Subject 11 Substrate 12 Coating film 21 Probe Child 22 Acoustic wedge 31 Probe for vertical flaw detection 32 Probe for oblique flaw detection 33 Acoustic wedge

Claims (6)

In the ultrasonic flaw detection method for a subject in which a coating film is formed on the surface of a substrate,
By vertical flaw detection, measure the echo height from the interface between the coating film and the substrate,
Based on the measured echo height, the flaw detection sensitivity for flaw detection by the bevel flaw detection method is corrected,
An ultrasonic flaw detection method characterized by performing flaw detection on the subject by an oblique flaw detection method using the corrected flaw detection sensitivity.   The ultrasonic flaw detection method according to claim 1, wherein flaw detection of the subject by the oblique angle flaw detection method is performed using a point-focusing oblique angle probe.   The ultrasonic flaw detection method according to claim 1, wherein flaw detection of the subject by the oblique angle flaw detection method is performed using a phased array probe. In an ultrasonic flaw detection apparatus that performs flaw detection on a subject in which a coating film is formed on the surface of a substrate,
A probe for vertical flaw detection,
A probe for oblique flaw detection,
Based on the ultrasonic wave received by the probe for vertical flaw detection, measuring means for measuring the echo height from the interface between the coating film and the substrate,
Correction means for correcting the flaw detection sensitivity for flaw detection by the oblique flaw detection method based on the echo height measured by the measurement means,
The ultrasonic wave is configured to perform the flaw detection of the subject based on the ultrasonic wave received by the oblique angle flaw detection probe using the flaw detection sensitivity corrected by the correction means. Flaw detection equipment.   The ultrasonic flaw detector according to claim 4, wherein the vertical flaw detector and the oblique flaw detector are housed in one case. In an ultrasonic flaw detection apparatus that performs flaw detection on a subject in which a coating film is formed on the surface of a substrate,
A phased array probe in which a plurality of transducers are arranged;
Ultrasound radiated from some transducers of the phased array probe is incident in a direction perpendicular to the flaw detection surface of the subject, and ultrasonic waves radiated from other transducers are other than perpendicular to the flaw detection surface An acoustic wedge for incidence in the direction of
When receiving ultrasonic waves radiated from the part of the vibrator, based on the received ultrasonic waves, measuring means for measuring the echo height from the interface between the coating film and the substrate,
Correction means for correcting the flaw detection sensitivity for flaw detection by the oblique flaw detection method based on the echo height measured by the measurement means,
When receiving ultrasonic waves radiated from the other transducers, based on the received ultrasonic waves, the flaw detection sensitivity corrected by the correction means is used to perform flaw detection of the subject. An ultrasonic flaw detector characterized by comprising:

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