JP2008164397A - Flaw detection method and flaw detector used therein - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flaw detection method capable of simply detecting the flaw produced in an inspection target part difficult to inspect, such as, a welded part at a high speed in a non-contact state, regardless of the thickness and the material of an inspection target, the shape of the welded part, or the like, and to provide a flaw detector used therein. <P>SOLUTION: Ultrasonic waves are transmitted to the inspection target from a probe, while the ultrasonic waves that propagate through the inspection target are received, to detect the flaw of the inspection target part by the receiving signal. The probe is scanned along the inspection target part in a non-contact state, and the respective receiving signals of a plurality of kinds of the ultrasonic waves propagated through the inspection target are displayed as the image of at least either of a B-scope or a C-scope. The flaw is detected on the basis of the existence of the change part R2 in the image. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a defect detection method and a defect detection apparatus used therefor. More specifically, a defect detection method for transmitting an ultrasonic wave from a probe to an object to be inspected, receiving an ultrasonic wave propagating through the object to be inspected, and detecting a defect in an inspection object part based on the received signal, and a defect detection method used therefor The present invention relates to a defect detection apparatus.

  Conventionally, for example, the methods described in Patent Documents 1 to 3 are known as the defect detection method as described above. In the steel material inspection method described in Patent Document 1, an ultrasonic line sensor is disposed oppositely in the thickness direction of the steel material with the hot-rolled steel material interposed therebetween, and the steel material being conveyed is inspected. However, the ultrasonic line sensor is disposed in water.

  Moreover, in the ultrasonic flaw detector described in Patent Document 2, the probe is arranged in a non-contact manner with respect to the test material. However, the probe holder that holds the probe is filled with water.

  In any document, since ultrasonic waves are propagated through water, it was not possible to inspect a test specimen that cannot use a contact medium such as water depending on the material. In addition, a device for supplying and storing water is required, and the device itself is complicated.

  Moreover, according to the thin plate inspection method described in Patent Document 3, the inspection is performed in a non-contact manner without using a contact medium. However, since the probe is arranged at the thin plate edge portion in order to reduce the area where the flaw cannot be detected, the arrangement position of the probe is limited and applicable test bodies are limited.

  On the other hand, an ultrasonic flaw detection test method as shown in FIG. 13 is known as a defect detection method for welds. In this test method, an ultrasonic wave is incident on the inspection object 100 ′ to receive a reflection signal from the defect, the beam path from which the reflection signal is obtained, the incident angle of the probe 10 ′, and the inspection object 100 ′. The position of the defect in the thickness direction is measured from the thickness of the plate.

  However, an ultrasonic wave must be incident so that the reflected signal from the defect can be directly received, and the probe 10 'due to the influence of the dead zone of the probe 10' and the extra 103a 'of the weld 103'. In some cases, the reflection signal from the defect end cannot be obtained due to the proximity limit. Further, as shown in FIG. 14, in the case of a small defect due to the influence of the near field, a plurality of peak signals can be obtained, so that it is difficult to specify the position.

  In order to avoid these influences, it is possible to perform flaw detection by reflecting one or more times. However, since the incident ultrasonic wave propagates in a wide range in the entire thickness direction of the inspection object 100 ′, as shown in FIG. 15, the position of the obtained reflected signal in the thickness direction is specified and from the defect D ′. It was difficult to distinguish the signal from the signal due to the shape. For this reason, it is difficult to detect flaws in the welded portion 103 ′ of the thin plate, and the lower limit of the applicable plate thickness is defined as 6 mm in the JIS standard.

  As other defect detection methods for welded parts, for example, those described in Patent Documents 4 and 5 are known. In the method for detecting flaws in a welded portion described in Patent Document 4, a transmitting probe and a receiving probe are arranged on both sides of the welded portion, flaw detection is performed by the TOFD method, and specific flaws are extracted from the defects. In addition, the ultrasonic inspection method disclosed in Patent Document 5 performs the TOFD method for detecting the position of the defect from the diffracted wave and the reflection echo method for detecting the position of the defect from the echo of the incident ultrasonic wave to accurately determine the position of the defect. Is measured.

In any of the patent documents, since the signal is directly obtained from the defect and the position of the defect is specified by analyzing the signal, the above-described problem is not solved. In addition, the defect position must be accurately scanned with reference to the weld line, and a scanning device must be provided along the weld line, depending on the position and shape of the weld. In some cases, a scanning device cannot be installed, and flaw detection cannot be performed.
JP 2006-82135 A JP 2000-46812 A JP 2002-310997 A JP 2003-215114 A JP 2001-13114 A

  In view of such a conventional situation, the present invention provides a high-speed non-contact defect that is difficult to inspect a welded part or the like, regardless of the thickness, material, or shape of the welded part. It is another object of the present invention to provide a defect detection method capable of simple detection and a defect detection apparatus used therefor.

  In order to achieve the above object, the defect detection method according to the present invention is characterized in that an ultrasonic wave is transmitted from a probe to an object to be inspected, and an ultrasonic wave propagated through the object to be inspected is received by the received signal. In the method for detecting a defect in an inspection object, the probe is scanned in a non-contact manner along the surface of the inspection object, and each reception signal of a plurality of types of ultrasonic waves propagated through the inspection object is detected by a B scope or At least one of the C scopes is displayed as an image, and the defect is detected by the presence of a changed portion in the image.

  According to the above feature, the defect is not directly detected based on the value of the reflection signal from only the inspection target part or the feature amount, but the difference between the defect and the healthy part is changed by the B scope image or the C scope image. Therefore, it is possible to easily detect the presence / absence of a defect in a part that is difficult to detect. Further, since scanning is performed in a non-contact manner, no contact medium is required, and the presence or absence of defects can be detected at high speed. The inspection object may be a flat plate. Moreover, the said test object part may contain the welding part. Even such an object to be inspected pays attention to the changed portion, so it is possible to reliably detect the presence or absence of a defect.

  Further, the change unit may be specified by comparing with at least one image of a B scope or a C scope in a healthy inspected object generated in advance. An amplitude of the received signal in a specific width in the plate thickness direction may be extracted, the defect may be detected based on the amplitude, and at least a size of the defect in the plate thickness direction may be estimated.

  The probe may be composed of a transmission probe and a reception probe. In this case, the transmission probe and the reception probe may be arranged opposite to the inspection target part on both sides, and the transmission probe and the reception probe are arranged on the inspection target part. However, it may be arranged on one side. The probe may be a transmission / reception probe that transmits and receives ultrasonic waves.

  It is preferable that the inspected object has a plate thickness different from the inspection target portion, and transmits ultrasonic waves from the probe located on the thin side of the inspection target portion. Moreover, the said to-be-inspected object may be comprised from the metal material, and the said to-be-inspected object may be a high temperature state.

  In order to achieve the above object, the defect detection apparatus used in the defect detection method according to the present invention is characterized in that the probe is scanned in a non-contact manner along the surface of the object to be inspected, and is transmitted through the object to be inspected. Each of the received signals of the ultrasonic waves is displayed as an image of at least one of the B scope and the C scope, and the defect is detected due to the presence of a change portion in the image.

  According to the feature of the defect detection method and the defect detection apparatus used therefor according to the present invention, regardless of the material of the object to be inspected or the shape of the inspection target part such as a welded part, for example, a thin plate that is difficult to inspect is thin. Even for the object to be inspected, it has become possible to detect a defect in the inspection object portion at high speed and in a simple manner without contact.

  Other objects, configurations, and effects of the present invention will become apparent from the following embodiments of the present invention.

Next, a first embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the defect detection apparatus 1 according to the present invention uses a pair of transmission probe 11 and reception probe 12 as a probe 10. The transmission probe 11 causes an ultrasonic wave to be incident on the inspected object 100, and the incident ultrasonic wave is received by the reception probe 12. The transmission probe 11 and the reception probe 12 are disposed opposite to the welded portion 103 on both sides. The position detector 20 works with the probe 10 to detect the spatial position of the probe 10. The transmission / reception device 30 connected to the probe 10 and the position detector 20 includes a CPU 31, a transmission unit 32, a reception unit 33, a position detection unit 34, a display unit 35, and a signal processing unit 36. In addition, as a to-be-inspected object 100, what has the welding part 103 which faced and welded the flat steel materials 101 and 102 is used. In the present embodiment, the welded portion 103 is an inspection target portion, and the welded portion 103 is formed with a surplus portion 103 a that protrudes from the surface 100 a of the inspection object 100.

  The transmission unit 32 generates a transmission signal and inputs it to the transmission probe 11, and inputs a plurality of types of ultrasonic waves received by the reception probe 12 as echoes in the device under test 100 to the reception unit 33, and the signal processing unit 36. The CPU 31 performs arithmetic processing. Further, the position data of the probe 10 is obtained by inputting a signal from the position detector 20 to the position detector 34 and performing arithmetic processing by the signal processor 36 and the CPU 31.

  Then, the position detector 20 is attached to the probe 10, and the inspection object surface 100a is continuously scanned without contact with the inspection object surface 100a along the welding line L direction of the welded part 103 on the inspection object 100. Then, the B scope image and / or the C scope image is generated from the position signal of the probe 10 sent from the position detector 20 and the plural kinds of ultrasonic signals received by the probe 10 and displayed. Displayed on the unit 35. The scanning of the probe 10 is not necessarily performed so as to be parallel to the welding line L of the welded portion 103, and may be performed in the direction of the welding line L. That is, instead of measuring the exact position of the defect from the reflection signal of the defect, it is sufficient to detect at least the presence or absence of a defect based on the presence or absence of a change portion appearing in a B-scope image and / or a C-scope image described later.

  Here, changes in the defect position and the ultrasonic beam path will be described with reference to FIGS. The ultrasonic wave incident from the transmission probe 11 propagates in the inspection object 100 with a spread. For example, as shown in FIG. 2A, when the defect D1 exists on the surface 100a side of the inspection object 100, the ultrasonic wave W1 propagating in the vicinity of the surface 100a among the incident ultrasonic waves is greatly attenuated by the defect D1. Then, most of the propagation is interrupted, and the reception probe 12 hardly receives the ultrasonic wave W1, and a B-scope image as shown in FIGS.

  FIG. 3 is a B-scope image of the object to be inspected in FIG. 2A in which the thickness of the object to be inspected 100 exceeds 6 mm. FIG. 5 is a diagram of the object to be inspected in which the object 100 has a thickness of 1.8 mm. Is the case. Usually, the B-scope image of the healthy part is displayed as indicated by reference numeral R1 in FIG. However, since the ultrasonic wave W1 propagating in the vicinity of the surface 100a is greatly attenuated by the defect D1 and most of the propagation is blocked, the ultrasonic beam path changes. Therefore, the defective portion is displayed as a changed portion partitioned by a pair of stepped portions dp in a part of the B scope image as indicated by reference numeral R2 in FIG. Similarly, in the case of the thin plate inspection object shown in FIG. 5, a change portion R <b> 2 partitioned by a pair of stepped portions dp is displayed in a part of the B scope image due to a change in the beam path. The deformed portion R2 is a unique signal change that appears due to a change in the beam path length due to the defect D1. Therefore, the presence / absence of a defect in the inspection object 100 can be detected based on the presence / absence of the change portion R2.

  As shown in FIG. 2B, when the defect D exists on the back surface 100b side of the inspection object 100, the ultrasonic wave W3 reflected by the back surface 100b in the vicinity of the defect D2 among the incident ultrasonic waves is the defect D2. The reception probe 12 hardly receives the ultrasonic wave W3 and generates a B-scope image as shown in FIGS.

  FIG. 4 is a B-scope image of the object to be inspected in FIG. 2B where the thickness of the object to be inspected exceeds 6 mm, and FIG. 6 is the case of the object to be inspected having a thickness of 1.8 mm. . The ultrasonic wave W3 reflected from the back surface 100b in the vicinity of the defect D2 is greatly attenuated by the defect D2 and most of the propagation is blocked. Therefore, the ultrasonic beam path changes, and the change in the beam path causes the B scope image as shown in FIG. A change portion R2 occurs in a part of. Similarly, in the case of the thin plate inspected object shown in FIG. 6, a change portion R2 is generated in a part of the B scope image due to the change in the beam path length. This deformed portion R2 is a unique signal change that appears due to a change in the beam path length due to the defect D2, and even if the defect is located on the back side of the object to be inspected, the presence or absence of the defect in the object to be inspected depends on the presence or absence of this changed part Can be detected.

  When the defect D exists, various phenomena of the ultrasonic waves are overlapped by the change of the beam path length and the change of the signal intensity as described above, and a B scope image as shown in FIGS. 3 to 6 is generated. In the B scope image, a change portion R2 that is partitioned by a pair of stepped portions dp is generated in a part of the image due to a signal change caused by the presence of the defect D. Therefore, it is possible to confirm the presence or absence of a defect by directly detecting the reflection signal from the defect and not detecting the defect and paying attention to the presence or absence of the change portion R2 that appears due to a specific signal change of the ultrasonic wave due to the defect. Therefore, even if the thickness of the object to be inspected is a thin plate of 6 mm or less, the defect can be reliably detected regardless of whether the position of the defect D is on the front surface 100a side or the back surface 100b side of the inspected object 100. In addition, even if the defect is inside the inspection object 100, the ultrasonic beam path changes, so the presence or absence of the defect can be detected. In the above description, the surface to be inspected and the back surface are expressed. However, in the case of a tubular object to be inspected such as a pipe, it is expressed by replacing the outer surface and the inner surface.

Next, the defect detection procedure for the welded portion will be described.
First, a pair of probes 10 including a transmission probe 11 and a reception probe 12 to which a position detector 20 is attached are placed in the direction of the weld line L of the welded portion 103 of the test object 100 with respect to the test object surface 100a. Non-contact continuous scanning without a contact medium. Then, the reception probe 12 receives a plurality of ultrasonic waves propagating through the inspected object 100, creates a B scope image of the received signals via the signal processing unit 36 and the CPU 31, and displays them on the display unit 35. To do. In this B scope image, the horizontal axis is the scanning distance in the welding line L direction, which is the scanning direction of the probe 10, and the vertical axis is the depth in the plate thickness direction.

  For example, in a test object having a plate thickness of 1.8 mm, as shown in FIG. 2A, when a defect D1 is located on the test object surface 100a side, a B-scope image as shown in FIG. 5 is displayed. Displayed on the unit 35. In this B-scope image, the received signal at the healthy portion is displayed almost uniformly in a strip shape parallel to the horizontal axis. On the other hand, as described above, since a part of the incident ultrasonic wave is blocked from propagating by the defect D1, the beam path is changed, and the changing portion is partitioned by the pair of stepped portions dp in part with respect to the flat portion of the healthy portion. R2 is formed. The presence / absence of the defect D1 is detected by confirming the presence / absence of the change portion R2.

  In addition, as shown in FIG. 2B, when the defect D2 is located on the inspected object back surface 100b side, a B scope image as shown in FIG. 6 is displayed. Even in this case, since the propagation of a part of the incident ultrasonic wave is interrupted by the defect D2, the beam path changes, the change part R2 is formed, and the presence or absence of the defect D2 is confirmed by confirming the presence or absence of the change part R2. To detect.

Next, a second embodiment of the present invention will be described. In the following embodiments, the same reference numerals are given to the same members as those in the first embodiment.
In the above embodiment, the defect is detected based on the presence or absence of the change portion R2 in the B scope image that appears due to the change in the ultrasonic beam path. In the present embodiment, the presence / absence of a defect and the size of the defect in the thickness direction are estimated from the change in the amplitude of the received signal at each scanning position.

  When the defect D exists in the propagation path, the ultrasonic wave incident on the inspection object 100 is attenuated by the defect D, and the amplitude of the reception signal received by the reception probe 12 corresponds to the defect area of the defect D. And get smaller. FIG. 7 shows the relationship between the amplitude of the received signal and the scanning position of the probe.

  In the figure, reference numerals Qa1 to Qa4 indicate amplitude signals of received signals at specific scanning positions in the sound portion, and reference numerals Qb1 and Qb2 indicate amplitude signals of received signals at defects. In these amplitude signals, when comparing the maximum values of the amplitudes of both amplitudes within a given time width t, the signals Qa1 to Q4 have substantially the same amplitudes Pa in the healthy part. On the other hand, the signals Qb1 and 2 at the defective portion have amplitudes that change according to the size of the defect because the ultrasonic waves are attenuated according to the defect area, and have both amplitudes Pb that are smaller than both amplitudes Pa at the healthy portion.

  A curve Q represents a curve obtained by plotting the two amplitude values for each scanning position and connecting the points. As this curve Q shows, both amplitudes of the signal Qb2 at other defective portions are smaller than both amplitudes Pb in the signal Qb1, and it can be seen that the ultrasonic wave is attenuated more greatly at the scanning position of the signal Qb2. . That is, the presence / absence of a defect and its size can be estimated by paying attention to the change in the amplitude of the received signal.

  Here, the defect detection procedure will be described. The probe 10 is scanned in the direction of the weld line L of the welded portion 103, and the maximum value of both amplitude values of the received signal within an arbitrary time width t for each scanning position from the received signal received by the CPU 31 and the signal processing unit 36. The signal processing for calculating is performed. The amplitude values are plotted on a graph having the scanning direction as the horizontal axis for each scanning position and displayed as a curve Q on the display 35. The presence / absence of a defect and the size of the defect are estimated from this curve Q.

  This embodiment can also be implemented together with the first embodiment. For example, the curve Q may be superimposed and displayed in combination with the above-described B scope image. Further, it may be performed independently of the first embodiment, and for example, the curve Q may be displayed on a graph having an amplitude on the vertical axis as shown in FIG. In this embodiment, both the peak amplitude and the peak amplitude of the amplitude signal are used, but a swing amplitude may be used.

  Here, the probe 10 constituted by a pair of the transmission probe 11 and the reception probe 12 is scanned in a non-contact manner without interposing a contact medium with respect to the inspected object surface 100a with respect to the inspected object. An example will be described. As shown in FIG. 8, the inspected object 100 is a plate-shaped steel material, and a rectangular extravagant portion 103a is formed in the approximate center of the inspected object 100, and a plurality of simulated defects D3 having a length of 10 mm are created therein. did. The simulated defect D3 has a different depth. The simulated defect D3a has a depth of 0.5 mm, the simulated defect D3b has a depth of 1.0 mm, the simulated defect D3c has a depth of 1.5 mm, and the simulated defect D3d has a depth of 2. 0.0 mm. Even in such an object to be inspected, it can be confirmed that each of the defects D3a to D3 is clearly detected including the defects D3a and b formed inside the surplus portion 103a, and the defects can be detected. It turned out to be.

  Therefore, it is not necessary to use a contact medium such as water, and it is possible to inspect even a material or an inspection location where a contact medium such as a composite material or a machine part cannot be applied. In addition, since scanning is performed without contact, inspection can be performed at high speed. Furthermore, it is possible to inspect for the presence or absence of defects even in a high-temperature inspected object that is difficult to be inspected by contacting the probe due to a high temperature such as immediately after welding or hot rolling.

  In addition, FIG. 9 shows the relationship between the amplitude of the received signal and the scanning position of the probe in the above-described non-contact scanning with the inspection object. Similar to the second embodiment, in non-contact scanning, it is confirmed that the ultrasonic wave is attenuated and the amplitude changes according to the size of each of the simulated defects D3a to D3. The presence and size of D can be estimated.

  Finally, reference is made to the possibilities of other embodiments of the invention. The following embodiments can be implemented in combination as appropriate.

  In the above embodiment, the displayed image is a B scope image. However, the C scope image may be used without being limited to the B scope image. In such a case, the probe is scanned in a two-dimensional manner without contact with the object to be inspected. Further, both of these images may be displayed together, or one of them may be displayed.

  In each of the above embodiments, the probe 10 is composed of a pair of transmission probe 11 and reception probe 12. However, unlike the above embodiments, one transmitting / receiving probe 10 capable of transmitting / receiving may be used as the probe 10. Moreover, in the said embodiment, although the to-be-inspected object 100 used the to-be-inspected object 100 which faced and welded plate-shaped 1st, 2nd members 101 and 102, not only a plate shape but a tubular to-be-inspected object is used. It is also possible.

  The shape of the welded portion 103 or surplus portion 103a to be inspected is not limited to the shape as in each of the above embodiments, and may be, for example, a complicated shape as shown in FIG. It is possible to apply to the defect detection of the welding part 103 or the surplus part 103a. In each of the embodiments described above, the inspection target portion is the welded portion 103 having the surplus portion 103a. However, the inspection target portion is not limited to the welded portion 103, and covers, for example, machine parts having protrusions, processing, forged parts, and the like. A defect can be detected in the same manner as an inspection object. Furthermore, in each said embodiment, although steel materials were used as the to-be-inspected object 100, it is not restricted to steel materials, The to-be-inspected object which consists of various metal materials may be sufficient. As described above, the defect can be detected as being present inside the protruding portion protruding from the surface of the object to be inspected, such as the extra portion 103a of the welded portion 103.

  The mode of welding and the shape of the inspection site in the inspection object are not limited to the butt welding in the above embodiment. For example, as shown in FIG. 11 (a), a fillet welded portion 113 of an object to be inspected 110 which is welded by overlapping a part of the first and second members 111 and 112 of a flat steel material may be used as an inspection target portion. . Further, as shown in FIG. 5B, a fillet welded portion 123 in which the first and second members 121 and 122 are butted in a T shape may be used.

  In these examples, the transmission / reception probes 11 and 12 are preferably arranged at positions P1 to P5, for example. In the inspected object 110, for example, the transmission probe 11 is disposed at P1, and the reception probe 12 is disposed at P2. In the inspected object 120, the transmission probe 11 is arranged at P3, and the reception probe 12 is arranged at P4 and P5, respectively. Further, even if the transmission probe 11 is arranged at P5 and the reception probe 12 is arranged at P3 and P4, respectively, the inspection can be carried out rationally in the same manner.

  The transmission / reception probes 11 and 12 may be arranged at positions P1 'to 5' on the back side of P1 to P5. For example, in the inspected object 110, the reception probe 12 is arranged at P2 ′, the transmission probe 11 is arranged at P1 ′, the reception probe 12 is arranged at P1, and the transmission probes are respectively arranged at P1 ′ and P2 ′. The touch element 11 may be arranged. In addition, in the inspected object 120, in addition to the case where the transmission probe 11 is arranged at P3 and the reception probe 12 is arranged at P4 ′, 5 ′, the transmission probe 11, P3 ′, 4 is arranged at P5 ′. The inspection can be performed even if the touch elements 12 are arranged. That is, the transmission / reception probes 11 and 12 that make a pair can be arranged at arbitrary positions of the object to be inspected that are connected by the welded portion to be inspected. The arrangement of the transmission probe 11 and the reception probe 12 that can be inspected is not limited to the above-described combination, and various modifications can be made.

  In each of the above embodiments, the thickness of the object to be inspected is the same among the members. However, it is possible to detect a defect even if the inspection object is not limited to a member having the same plate thickness but is welded to a member having a different plate thickness. In such a case, it is desirable that the ultrasonic wave be incident on the object to be inspected from the side of the thin member. Thereby, it is possible to prevent a mistake due to a difference in plate thickness from being detected as a defect.

  In each of the above embodiments, the changed part is identified by comparing the changed part with a flat part appearing as a healthy part of the B scope image, and the presence or absence of a defect is confirmed. However, it is also possible to generate a B-scope image in advance in a healthy object and specify the changed portion by comparison with the B-scope image. For example, in the case where the shape of the healthy part to be inspected is complicated, the B scope image may appear as a shape that is difficult to compare rather than a flat shape as the healthy part as in the above embodiment. In such a case, by comparing with a previously generated B-scope image of a healthy object to be inspected, it is possible to identify a change portion that appears due to a signal change due to a defect, and it is possible to detect a defect.

  Further, in each of the above embodiments, as shown in FIG. 12A, the transmission probe 11 and the reception probe 12 are arranged almost symmetrically on both sides with respect to the welded portion 103 as the inspection target portion. However, the arrangement is not limited to the symmetrical arrangement, and the arrangement may be asymmetric with respect to the welded portion 103. When it arrange | positions asymmetrically, the degree to which it receives to the influence of the defect of the to-be-inspected object back surface center of the welding part width | variety in the direction orthogonal to the plate | board thickness direction of the to-be-inspected object 100 can be made small. That is, for example, as shown by reference numerals 11 ′ and 12 ′ in the figure, the probe W is arranged to be biased to one side so that the transmission / reception path of the ultrasonic wave W4 becomes W4 ′, and is specified on the center back surface side of the weld width. A large defect exceeding the height of can be detected. Furthermore, as shown in FIG. 12B, the transmission probe 11 and the reception probe 12 may be positioned on one side with respect to the welded portion 103. Further, as shown in the above embodiment, it is also possible to detect a defect with one transmitting / receiving probe 10 capable of transmitting / receiving as shown in FIG. In each figure, it is also possible to perform inspection by exchanging the positions of the transmission probe 11 and the reception probe 12.

  In the above embodiment, the type of ultrasonic waves to be received may be various ultrasonic waves such as longitudinal waves, transverse waves, and plate waves. Further, the reflected signal is not limited to a single reflection, and may be a plurality of reflected signals. That is, any type of ultrasonic wave is not particularly limited as long as it can detect a change in beam path length due to a defect as described above.

  INDUSTRIAL APPLICABILITY The present invention can be used as a defect detection method for a welded part and a defect detection apparatus for a welded part used therefor. This defect detection method and apparatus can be applied without being limited to the shape of the object to be inspected, such as a flat plate shape and a tubular shape. Furthermore, not only steel materials but also various metal materials such as composite materials and resins are inspected. It can be applied to body defect detection.

It is a block diagram of the defect detection apparatus which concerns on this invention. It is the schematic which shows the change of the beam path length of the ultrasonic wave by a defect, (a) shows the case where a defect is located in the to-be-inspected object surface side, (b) shows the case where a defect is located in the to-be-inspected object back side. It is a B scope image which shows the example of a scanning result in case a defect is located in the thick plate to-be-inspected surface side. It is a B scope image which shows the example of a scanning result in case a defect is located in the thick plate to-be-inspected object back side. It is a B scope image which shows the example of a scanning result in case a defect is located in the thin plate to-be-inspected surface side. It is a B scope image which shows the example of a scanning result in case a defect is located in the thin plate to-be-inspected object back side. It is a graph which shows typically the relation between both amplitude values of a received signal, and a scanning position. It is the schematic which shows other embodiment of this invention, (a) is a front view, (b) is a side view. It is a graph which shows the relationship between both amplitude values in other embodiment of this invention, and a scanning position. It is a figure which shows an example of the other to-be-inspected object applied to this invention. It is a figure which shows an example of the to-be-inspected object applied to this invention. It is a figure which shows the example of arrangement | positioning of the probe of this invention. It is the schematic which shows the ultrasonic testing method of the conventional welding part. It is a scanning graph of a small defect in a near field. It is a figure which shows the waveform example of the signal from the spread of an ultrasonic wave, a defect, etc.

Explanation of symbols

1: defect detection device, 10, 10 ′: probe, 11, 11 ′: transmission probe, 12, 12 ′: reception probe, 20: position detector, 30: transmission / reception device, 31: CPU, 32: Transmission unit, 33: Reception unit, 34: Position detection unit, 35: Display unit, 36: Signal processing unit, 100, 100 ′: Inspected object, 100a: Front surface, 100b: Back surface, 101: First member, 102: 2nd member, 103, 103 ': Welding part (inspection object part), 103a: Overlaying part (protrusion part), D, D1-3, D': Defect, dp: Step part, R1: Healthy part, R2: change part, L: welding line (scanning direction), Pa, b: both amplitudes, Q: curve, Qa1-4, Qb1, 2: amplitude signal, t: time width, W, W1-4, W4 ′: Ultrasound

Claims (13)

A defect detection method for transmitting an ultrasonic wave from a probe to an object to be inspected and receiving an ultrasonic wave propagated through the object to be inspected, and detecting a defect in an inspection object part by the received signal,
The probe is scanned in a non-contact manner along the surface of the inspected object, and each received signal of a plurality of types of ultrasonic waves propagated through the inspected object is displayed as an image of at least one of a B scope or a C scope, A defect detection method, wherein the defect is detected based on the presence of a changed portion in the image. The defect detection method according to claim 1, wherein the object to be inspected is a flat plate. The defect detection method according to claim 1, wherein the inspection target part includes a welded part. The defect detection method according to claim 1, wherein the change unit is specified by comparing with at least one image of a B scope or a C scope in a healthy inspected object generated in advance. The amplitude of the said received signal in the width | variety of a specific plate | board thickness direction is extracted, the said defect is detected with the said amplitude, and the magnitude | size of the said plate | board thickness direction of the said defect is estimated at least. The defect detection method according to any one of the above. The defect detection method according to claim 1, wherein the probe includes a transmission probe and a reception probe. The defect detection method according to claim 6, wherein the transmission probe and the reception probe are arranged to face both sides of the inspection target part. The defect detection method according to claim 6, wherein the transmission probe and the reception probe are arranged on one side with respect to the inspection target part. The defect detection method according to claim 1, wherein the probe is a transmission / reception probe that transmits and receives ultrasonic waves. The board to be inspected is different in thickness from the inspection target part, and transmits ultrasonic waves from a probe located on the thin side of the inspection target part. The defect detection method in any one of. The defect detection method according to claim 1, wherein the object to be inspected is made of a metal material. The defect detection method according to claim 1, wherein the inspection object is in a high temperature state. A defect detection apparatus for use in the defect detection method according to claim 1,
The probe is scanned in a non-contact manner along the surface of the inspected object, and each received signal of a plurality of types of ultrasonic waves propagated through the inspected object is displayed as an image of at least one of a B scope or a C scope, A defect detection apparatus that detects the defect based on the presence of a changing portion in the image.