JP2011047655A - Defect recognition method and defect recognition device using ultrasonic wave - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To recognize whether a reflector reflecting an ultrasonic wave has a defect due to a crack or a defect other than a defect due to rust, when a reflected wave is obtained in ultrasonic inspection of a low-pressure steam turbine wheel. <P>SOLUTION: A probe holding tool is rotated around a turbine shaft, while a probe is pressed on a turbine wheel, and the probe is scanned, while a distance from the central axis to the turbine wheel and a yawing angle are kept constant. Thereby, based on a pulse signal emitted from an encoder, an ultrasonic waveform and a probe location are automatically recorded on a storage portion. When the reflected wave is obtained, a cross-correlation processing portion calculates and shows a first recognition result based on a change in a path length of an isolated waveform and a second recognition result based on a change in a path length of a wave group. From the first recognition result and the second recognition result, a defect and rust are distinguished. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an ultrasonic inspection method and an inspection apparatus for inspecting the presence or absence of defects using ultrasonic waves, and in particular, a turbine suitable for defect inspection of an impeller blade implantation portion of a steam turbine used at a relatively low pressure. The present invention relates to a defect identification method and a defect identification apparatus for a wing implantation part.

  An ultrasonic inspection apparatus is a typical example of an inspection apparatus that inspects defects existing inside a structure in a nondestructive manner, and is used for defect inspection of finished products.

  For example, in a turbine power plant, during operation, a large stress acts on the blade implantation portion around the turbine wheel, and this stress becomes particularly significant at the hook portion in the blade implantation portion on the low-pressure turbine side. It is necessary to evaluate the soundness of this part.

  On the other hand, since shortening the periodic inspection period is strongly required from the viewpoint of improving the plant operating rate, the soundness evaluation of this blade implantation part is an ultrasonic that does not require removal of the moving blade from the turbine wheel during inspection Inspection is often adopted.

  Here, FIG. 12A is a cross-sectional view including a moving blade showing an outline of a scanning mechanism portion in an example of an ultrasonic inspection apparatus for a blade implantation portion of a general steam turbine wheel, and FIG. It is the front view shown except the wing | blade. In these drawings, 1 is a turbine wheel, 2 is a turbine shaft, 3b is a probe holder, 9 is a probe, and 30 is a moving blade, and a broken line 10 indicates a path of ultrasonic waves at this time.

  In this ultrasonic inspection apparatus, one or two probes 9 are attached to the probe holder 3 b and then pressed against the turbine wheel 1, and the center axis O of the turbine shaft 2 to the probe 9 are pressed. The entire probe holder 3b is moved along the circumference of the turbine shaft 2 while keeping the distance Z and the swing angle θ of the probe 9 constant. Scan the entire area of the implant.

  The probe 9 serves as both an ultrasonic oscillator and an ultrasonic detector, and pulses of the ultrasonic wave 10 are emitted from the probe 9 at a predetermined time interval. Each time a pulse is emitted, the probe 9 is predetermined. If a reflected wave is not detected within the time gate, it is determined that the wing implant is healthy, and if a reflected wave appears, it is determined that there may be a defect such as a crack in the wing implant.

  As conventional techniques of such an ultrasonic inspection method, for example, Patent Document 1 and Patent Document 2 can be cited. In these methods, when a reflected wave appears in a blade implantation portion of a turbine wheel, the turbine wheel The rotor blades are once extracted from and visually inspected to determine whether the reflection of ultrasonic waves is due to defects such as cracks or other than defects such as rust and corrosion marks. If the ultrasonic reflection at this time is due to a real defect, a more detailed inspection is performed by magnetic particle inspection, etc., but if it is something other than a real defect such as rust or corrosion mark, In many cases, the system is operated as it is until the next periodic inspection, and a more detailed inspection is performed at the next periodic inspection.

  Therefore, in the ultrasonic inspection of the turbine wheel blade-implanted portion described in Patent Document 1, Patent Document 2, etc., when a reflected wave is obtained from the rust generated in the inspected portion, the reflector is defective or rusted. In order to identify these, it is necessary to extract the moving blades, and it takes time for the inspection.

  Therefore, for example, in Patent Document 3, Patent Document 4, and Patent Document 5, even when a reflected wave appears in a blade-implanted portion of a turbine wheel, a reflector (a portion that reflects ultrasonic waves) is not extracted. ) Is a defect such as a crack, or a method for determining whether it is a rust or corrosion mark that does not need to be regarded as a defect.

  The methods of Patent Document 3 and Patent Document 4 receive the waveform of the reflected wave received and recorded within a predetermined time gate when the ultrasonic probe is at a certain position, and the same within the time gate at other positions. A correlation coefficient is calculated by cross-correlating the recorded reflected wave waveform, and if the correlation coefficient is larger than a predetermined threshold value, it is determined that the wing implantation part is defective, If it is smaller than the threshold, it is determined that the defect is other than a defect.

  On the other hand, in the method of Patent Document 5, when an instruction reflected wave having a tail at the rear of the beam path is not confirmed, it is determined that the reflected wave is caused by rust or pitting corrosion. Also, referring to the B scope obtained from the ultrasonic probe at the position where the rotor wheel is sandwiched, whether the peak position of the indicated reflected wave indicating a crack defect is on the band-like reflected wave indicating the first hook portion By judging whether or not, it is judged whether or not the size of the crack defect penetrates the first hook.

JP-A-1-161145 JP-A-7-244024 Japanese Patent Laid-Open No. 10-267902 JP 2002-310999 A JP 2002-148243 A

  Among the above prior arts, the methods of Patent Document 3 and Patent Document 4 are suitable methods for identifying small cracks (cracks that do not pass through the hook) and rust, whereas large cracks and rust are rather distinguished. There was a problem that accuracy was inferior. On the other hand, the method of Patent Document 5 is a method suitable for identifying large cracks and rust, but it is difficult to identify small cracks (cracks that do not penetrate the hook) and rust, and touches on the automation of evaluation. It is not done.

  An object of the present invention is to provide a defect identification method and an identification apparatus using ultrasonic waves that can automatically identify rust and a defect regardless of the size of the defect.

  In order to achieve the above object, the present invention is characterized in that an ultrasonic wave is incident on a turbine blade implantation portion using a probe, and the rust in the turbine blade implantation portion is based on the reflected wave received in the gate for a predetermined time. In the defect identification method using the ultrasonic wave for identifying the defect and the defect, the first feature amount is calculated along the inclination of the isolated waveform on the B-scope of the reflected wave and the wave group moves along the inclination. The second feature value is calculated, and the rust and the defect in the turbine blade implantation part are identified by a combination of the first feature value and the second feature value.

  Also, rust and defects are identified when either the first feature value exceeds a predetermined threshold value or the second feature value exceeds a predetermined threshold value. It is characterized by that.

  The first feature value and the second feature value are subjected to a predetermined weight calculation process to identify rust and a defect.

  Further, a correlation coefficient is used as the first feature amount. As the correlation coefficient, the length of the portion of the correlation coefficient graph of the reflected waves with the probe moving distance as a variable exceeding a predetermined correlation coefficient threshold value can be used.

  In addition, an amplitude is used as the second feature amount. As the amplitude, the length of the portion of the reflected wave relative amplitude graph with the probe moving distance as a variable exceeding a predetermined relative amplitude threshold can be used.

  Further, in the defect identification device for identifying the rust and the defect in the turbine blade implantation part based on the reflected wave received in the gate for a predetermined time by using the probe to enter the turbine blade implantation part, When the ultrasonic probe is moved, a first feature amount is calculated along a slope at which the isolated waveform of the reflected wave moves on the B scope, and a first feature amount is calculated along the slope at which the wave group of the reflected wave moves. A cross-correlation processing unit that calculates a second feature value and identifies rust and a defect from both the first feature value and the second feature value, and a display unit that displays a result identified by the cross-correlation process unit It is characterized by having.

  According to the present invention, when the ultrasonic probe is moved, the first feature amount is calculated along the inclination of the isolated waveform moving, and the second feature amount is calculated along the inclination of the wave group movement. In the ultrasonic inspection of the turbine blade implantation portion by a relatively simple probe scanning method by identifying rust and defects from both the first feature amount and the second feature amount, the moving blade It is possible to automatically identify whether the ultrasonic reflector is a defect or something other than a defect while performing an ultrasonic inspection without extracting the defect, thereby reducing the number of inspection processes. The period can be shortened.

It is explanatory drawing which shows one Embodiment of the ultrasonic inspection apparatus by this invention. It is explanatory drawing of the B scope which an ultrasonic inspection apparatus displays when moving the probe in one Embodiment of this invention. It is explanatory drawing of the isolated waveform reflected wave by a crack (small). It is explanatory drawing of the wave group reflected wave by a crack (large). It is a flowchart which shows the method of identifying the crack and rust in one Embodiment of this invention. It is a top view explaining the position coordinate of a probe and the intersection coordinate of the straight line of the direction which a probe faces. It is a perspective view explaining the position coordinate of a probe, and the intersection coordinate of the straight line of the direction which a probe faces. It is explanatory drawing which shows the mode of the ultrasonic reflection from a crack and rust at the time of applying an ultrasonic inspection to a turbine wheel blade implantation part. It is the wave form diagram which showed the recording waveform in the case of the defect by a crack, and the waveform of a correlation process result. It is the wave form diagram which showed the recording waveform in the case of the defect by rust, and the waveform of a correlation process result. It is explanatory drawing of the display screen in embodiment of this invention. It is explanatory drawing of the state which rust generate | occur | produced in the top part of the wing implantation part of the test body. It is explanatory drawing of the state which the crack (small) generate | occur | produced in the 1st step hook of the wing implantation part of a test body. It is explanatory drawing of the state which the crack (large) generate | occur | produced in the 1st step hook of the wing implantation part of a test body. It is explanatory drawing of the process result of the data of rust by the 1st identification in embodiment of this invention. It is explanatory drawing of the data processing result of a crack (small) by the 1st identification in embodiment of this invention. It is explanatory drawing of the data processing result of a crack (large) by the 1st identification in embodiment of this invention. It is explanatory drawing of the data processing result of rust by the 2nd identification in embodiment of this invention. It is explanatory drawing of the data processing result of a crack (small) by the 2nd identification in embodiment of this invention. It is explanatory drawing of the data processing result of a crack (large) by the 2nd identification in embodiment of this invention. It is sectional drawing which shows the outline | summary of the ultrasonic inspection of the turbine wheel blade implantation part by a prior art. It is a front view which shows the outline | summary of the ultrasonic inspection of the turbine wheel wing implantation part by a prior art.

Hereinafter, an ultrasonic inspection method and an ultrasonic inspection apparatus according to the present invention will be described in detail with reference to illustrated embodiments.
[Basic configuration]
FIG. 1 shows an embodiment of the present invention, and in the same manner as in the prior art described above, after the probe 9 is attached to the probe holder 3b, it is pressed against the turbine wheel 1 and applied to the probe holder 3b. The wheels 4a and 4b that are provided are configured to perform an inspection by traveling and moving on the outer periphery of the turbine shaft 2. At this time, a pulse voltage 11a is applied from the flaw detector 12 to the probe 9, and the ultrasonic wave 10 is incident on the blade implantation portion of the turbine wheel 1, and the reflected wave is received by the probe 9 and the ultrasonic wave is received. A signal 11b is obtained and amplified by the flaw detector 12.

  Therefore, the probe 9 can be scanned while keeping the distance from the central axis of the turbine wheel 1 and the swing angle by simply moving the entire probe holder 3a around the turbine shaft 2. As a result, once the probe holder 3a is attached, the entire circumference of the blade implantation portion of the turbine wheel 1 can be inspected with a relatively simple operation.

  An encoder 5 is installed on the probe holder 3a, and a pulse signal 6 is transmitted every time the probe 9 moves along the outer peripheral surface of the turbine shaft 2 by a certain distance. Therefore, immediately after receiving the pulse signal 6, the A / D converter 15 A / D converts the ultrasonic signal 14 synchronized with the trigger signal 13 of the flaw detector 12. At this time, the time Ts from when the trigger signal 13 is received until the conversion is started and the time width Tw of the conversion are set in advance, and the time gate from this time Ts to (Ts + Tw) is a time gate.

  The position reading unit 7 resets the position signal 8 to 0 at the start of the ultrasonic examination, and thereafter increments the position signal 8 by 1 every time the pulse signal 6 is received. The numerical value and the integrated value of the pulse signal 6 are made equal. Then, the position signal 8 read by the position reading unit 7 and the digital signal 16 converted by the A / D conversion unit 15 are transferred to the storage unit 17 and automatically stored. By adopting such a configuration, it is possible to automatically record the ultrasonic waveform and the probe position following the movement operation of the probe holder 3a.

  The reflected wave presence / absence determining unit 18 extracts the maximum amplitude of the digital signal 16 having the time width Tw and compares it with a threshold value. If the maximum amplitude is larger than the threshold value, it is determined that there is a reflected wave. judge. The determination result 19 is transferred to the storage unit 17 and stored in association with the position signal 8 and the digital signal 16.

When it is determined that the wave is reflected twice in succession, the correlation signal 23 is calculated by calculating the digital signals 21 and 22 of the reflected waveform in the cross-correlation processing unit 22. The reflector identifying unit 26 automatically identifies whether the reflector is a defect or something other than a defect based on the calculated correlation coefficient, and displays the identification result 25 on the display unit 24.
[Probe position and ultrasonic waveform]
Here, the relationship between the probe position and the ultrasonic waveform will be described with reference to FIGS. 2, 3A, and 3B. FIG. 2 is an explanatory diagram of a B scope that is displayed by the ultrasonic inspection apparatus when the probe is moved and that develops the time change of the reflected wave in a plane as a sectional view in the depth direction. The horizontal axis in FIG. 2 is the moving distance on the outermost circumference of the wheel at the position where the ultrasonic wave is incident by the probe scanning, and the vertical axis is the path distance, that is, the distance to the ultrasonic reflector.

  A typical B scope in the case where there is rust on the entire surface of the wheel and there is one small crack (a crack that does not penetrate the hook) and one large crack (a crack that penetrates the hook) is schematically shown.

  A characteristic of the reflected wave of a small crack is that the path of the isolated reflected wave changes almost linearly with respect to the moving distance on the outermost circumference of the wheel at the position where the ultrasonic wave is incident. As shown in the explanatory diagram of the reflected wave depending on the size of the crack in FIG. 3A, as the probe position changes from (1) → (2) → (3), the linear distance to the crack changes, This is due to a phenomenon in which the amplitude changes while the waveforms are similar to a1, a2, and a3.

On the other hand, the characteristic of the reflected wave with a large crack is that the path of the isolated reflected wave changes almost linearly with respect to the moving distance on the outermost circumference of the wheel at the position where the ultrasonic wave is incident. A plurality of multiple reflected waves such as b1 and c1 are generated at the same time and change as a wave group. The wave group has a feature that it shows a steeper change than the isolated reflected wave and the amplitude of the isolated reflected waves of a, b, and c is switched, so that the similarity is low. 4, it is difficult to identify such a large crack.
[Principle identification principle]
In the embodiment of the present invention, firstly, after recording the ultrasonic waves from the entire circumference of the turbine wheel blade implantation part, the principle of identifying whether the reflector is defective or rust is described with reference to FIGS. 4 to 7B. explain.

  FIG. 4 is a flowchart showing a method for identifying cracks and rust. First, the inclination of movement of the isolated waveform and the movement of the wave group are calculated from the geometric shape of the turbine wheel blade implantation part and the arrangement of the probes (waveform inclination: step S101).

  FIG. 5A shows a plan view for explaining the intersection coordinates of the position coordinates of the probe when the probe is moved and the straight line in the direction of the probe, and FIG. 5B shows a perspective view. In FIG. 5B, it is assumed that the ultrasonic wave refracted from the probe position A2 proceeds in the direction of the point C2 on the outermost periphery of the wheel. Ultrasound spreads due to the influence of directivity, but since the amplitude on the sound axis is the largest, if there is a defect in the position of point C2, the maximum reflected wave amplitude is shown when the probe position is point A2. become. At this time, the path is a linear distance between the points A2 and C2. When the probe position is at point A1, the path is a linear distance between point A1 and point C2. Therefore, the path change of the isolated waveform can be obtained by this geometrical relationship.

  On the other hand, the change in the path length of the wave group is caused by the multiple reflection of the ultrasonic wave at the hook position, and it is clear from the comparison with the experimental data that the path length substantially matches the linear distance between the points A1 and F12. It was. The point F12 is a point moved downward by the hook depth from the point E12. The point E12 is a straight line obtained by projecting the sound axis when the probe is at the point A1 onto the xy plane, the point O, and the point G2. It is given by the intersection of straight lines connecting with. By obtaining the above relationship numerically, it is possible to calculate the inclination of the isolated waveform and the inclination of the wave group in step S101.

  Next, in the B scope of FIG. 2, a first feature amount representing the similarity of the waveform along the inclination of the isolated waveform is calculated (first identification: step S102). When the probe holder 3b is scanned once with respect to the turbine wheel 1, the storage unit 17 records the position signal 8, the digital signal 16, and the determination result 19 of the presence or absence of a reflected wave for the entire circumference. Here, the probe positions that have been determined to have continuous reflected waves are grouped together, and the waveform recorded at the probe position with the maximum amplitude within the group is used as the reference waveform. Cross-correlation with the waveform recorded at the probe position.

  FIG. 6 schematically shows a situation in which a reflected wave from a defect such as a crack is obtained by the probe 9 and a reflected wave from something other than a defect such as rust and corrosion marks is obtained. Is. In the case of the crack 27, since the position of the ultrasonic reflector is clear at one place, a relatively simple waveform is obtained as shown in FIGS. 3A and 3B. In this case, even if the position of the probe 9 is changed from the point A1 to the point A2, only the path length (ultrasonic path) is changed, the received waveform is not greatly changed, and the waveform is well preserved. I understand that.

  When the time width of the gate is Tw, the waveform recorded at point A1 is X (t), and the waveform recorded at point A2 is Y (t), X (t) and Y (t) are shifted by time τ. The correlation value R (τ) is expressed by the following equation (1), where the maximum value of the correlation value R (τ) when the time τ is moved and changed from −Tw to Tw is defined as a correlation coefficient. Call.

  This correlation coefficient is an index indicating the related depth of the two waveforms, and takes a large value as shown in FIG. 7A when the reflector is defective. On the other hand, since the rust 28 does not show clear reflectors in a lump and a plurality of small reflectors are distributed in a complicated manner on the surface of the top of the turbine wheel, as shown in FIG. The waveform is superimposed. In this case, if the position of the probe 9 is changed from the point B1 to the point B2, the intensity ratio of the reflected waves from the plurality of reflectors changes, so that the received waveform also changes and the waveform is not saved. Therefore, the correlation coefficient calculated from the waveform recorded at point B1 and the waveform recorded at point B2 takes a small value as shown in FIG. 7B.

  Ultimately, using the reflected wave with the maximum amplitude of the reflected wave group with an amplitude exceeding a certain threshold as a reference, the correlation coefficient between the reference waveform and several waveforms before and after is obtained, and the ultrasonic wave enters. The relationship between the moving distance of the position of the wheel on the outermost circumference of the wheel and the correlation coefficient is graphed, and the length of the distance where the correlation coefficient exceeds the predetermined threshold obtained experimentally is indicated by the reflection source from which the waveform is obtained. It is used as an index for determining whether or not it is a defect.

  Next, in the B scope of FIG. 2, a second feature amount representing the size of the reflection source along the inclination of the wave group to move is calculated (second identification: step S103). The gate b is moved along the change in the path length of the wave group calculated in step S101, and the maximum amplitude is searched. Note that the width of the gate b is specified in advance by the user or stored in the storage unit 17 as a constant. Next, the relationship between the movement distance on the outermost circumference of the wheel at the position where the ultrasonic wave enters by probe scanning and the maximum amplitude is graphed, and the length of the distance exceeding a certain threshold is used as an index.

Finally, rust and cracks are identified from both the first identification and the second identification (overall identification: step S104). This is obtained by applying a weight to the value of the first feature value obtained by the first identification and the value of the second feature value obtained by the second identification. Alternatively, in the case of identifying a defect by the first identification or identifying the defect by the second identification, an arithmetic expression is set such that the defect is identified by the comprehensive identification. Finally, the inspector can determine the identification result on the display screen of the ultrasonic inspection apparatus as shown in the example of FIG.
[Examples of identification results]
Finally, the effects of the embodiment of the present invention will be described with reference to FIGS. 9A to 11C, taking rust, defect (small), and defect (large) processing results as examples.

  FIG. 9A is an explanatory diagram of the state of the test body in a state where rust is generated at the top of the wing implantation part, and FIG. 9B is a test body in which a crack (small) is generated in the first stage hook of the wing implantation part. FIG. 9C is an explanatory diagram of a state of the test body in a state where a crack (large) is generated in the first stage hook of the wing implantation portion.

  FIG. 10A shows the result of performing the first identification process described above on the rust of the test specimen. FIG. 10A shows that the distance over which the correlation coefficient exceeds the experimentally obtained threshold of 0.6 is shorter than the crack (small) in FIG. On the other hand, the crack (large) in FIG. 10C has a shorter correlation distance than the rust in FIG. 10A and is difficult to distinguish from rust.

  FIG. 11A shows the result of performing the above-described second identification process on the rust of the test specimen. In the rust of FIG. 11A, the distance exceeding the experimentally obtained threshold value of 0.25 is zero, but the crack (small) in FIG. 11B is also as short as 10 mm or less, and it is difficult to distinguish from rust. On the other hand, the crack (large) in FIG. 11C indicates a relatively long distance. Therefore, according to the comprehensive identification combining the advantages of the first identification and the second identification, it becomes possible to automatically identify rust and defects regardless of the size of the defects.

DESCRIPTION OF SYMBOLS 1 ... Turbine wheel, 2 ... Turbine shaft, 5 ... Encoder, 6 ... Pulse signal, 7 ... Position reading part, 8 ... Position signal, 9 ... Probe, 10 ... Ultrasound (path | route), 11a ... Pulse signal, 11b DESCRIPTION OF SYMBOLS ... Ultrasonic signal, 12 ... Flaw detector, 13 ... Trigger signal, 14 ... Ultrasonic signal, 15 ... A / D converter, 16 ... Digital signal, 17 ... Memory | storage part, 18 ... Cross correlation process condition setting part, 19 ... Cross correlation processing interval, 20, 21 ... digital signal, 22 ... cross correlation processing unit, 23 ... correlation coefficient, 24 ... reflector identification unit, 25 ... reflector identification condition, 26 ... identification result, 27 ... display unit, 28 ... cracks, 29 ... rust, 30 ... moving blades

Claims (12)

Defect identification using ultrasonic waves, in which ultrasonic waves are incident on the turbine blade implant using a probe and the rust and defects are identified in the turbine blade implant based on the reflected wave received in the gate for a predetermined time In the method
A first feature amount is calculated along a slope of movement of the isolated waveform on the B scope of the reflected wave, a second feature amount is calculated along a slope of movement of the wave group, and the first feature amount is calculated. A defect identification method using ultrasonic waves, wherein rust and defects are identified in the turbine blade implantation portion by a combination of the second feature amount and the second feature amount.   2. The defect identification method using ultrasonic waves according to claim 1, wherein the first feature amount exceeds a predetermined threshold value and the second feature amount exceeds a predetermined threshold value. A defect identification method using ultrasonic waves, characterized by identifying rust and defects in any of the cases.   The defect identification method using ultrasonic waves according to claim 1, wherein a predetermined weight calculation process is performed on the first feature amount and the second feature amount to identify rust and a defect. A defect identification method using characteristic ultrasonic waves.   The defect identification method using ultrasonic waves according to claim 1, wherein a correlation coefficient is used as the first feature quantity.   In the defect identification method using ultrasonic waves according to claim 4, a correlation coefficient graph of reflected waves having a probe moving distance as a variable as a correlation coefficient of the first feature amount is a predetermined coefficient. A defect identification method using ultrasonic waves, characterized by using a length of a portion exceeding a correlation coefficient threshold value.   4. The defect identification method using ultrasonic waves according to claim 1, wherein an amplitude is used as the second feature amount.   The defect identification method using ultrasonic waves according to claim 6, wherein the amplitude of the second feature amount is a predetermined relative amplitude of a relative amplitude graph of a reflected wave having a probe moving distance as a variable. A defect identification method using ultrasonic waves, characterized by using a length of a portion exceeding a threshold value.   Defect identification using ultrasonic waves, in which ultrasonic waves are incident on the turbine blade implant using a probe and the rust and defects are identified in the turbine blade implant based on the reflected wave received in the gate for a predetermined time In the apparatus, when the ultrasonic probe is moved, the first feature amount is calculated along the inclination that the isolated waveform of the reflected wave moves on the B scope, and the inclination of the wave group of the reflected wave moves is calculated. A second feature amount is calculated along with the cross-correlation processing unit for identifying rust and a defect from both the first feature amount and the second feature amount, and the result identified by the cross-correlation processing unit is displayed. A defect identification device using ultrasonic waves, characterized by having a display unit.   9. The defect identification apparatus using ultrasonic waves according to claim 8, wherein a correlation coefficient is used as the first feature quantity.   The defect identification apparatus using ultrasonic waves according to claim 9, wherein a correlation coefficient graph of reflected waves having a probe moving distance as a variable is a predetermined correlation coefficient of the first feature quantity. A defect identification apparatus using ultrasonic waves, characterized by using a length of a portion exceeding a correlation coefficient threshold value.   9. The defect identification apparatus using ultrasonic waves according to claim 8, wherein an amplitude is used as the second feature amount.   12. The defect identification apparatus using ultrasonic waves according to claim 11, wherein a predetermined relative amplitude of a relative amplitude graph of a reflected wave having a probe moving distance as a variable is used as the amplitude of the second feature amount. A defect identification apparatus using ultrasonic waves, characterized by using a length of a portion exceeding a threshold value.

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