JP2016090272A - Ultrasonic flaw detection method and ultrasonic flaw detection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic flaw detection method and an ultrasonic flaw detection apparatus capable of measuring the property of a fault with high accuracy using a low-frequency ultrasonic wave even when a sample is a high attenuation material.SOLUTION: An ultrasonic beam is scanned to an interior of a test piece 20, echo heights of received waveforms related to a plurality of test holes h1 to h16 disposed side by side in the depth direction within the test piece are measured so as to create a threshold evaluation line Sa for determining whether or not a fault is present. Excitation timing of a plurality of oscillators 12a of a phased array probe 12 is deviated in a plane orthogonal to a weld line L along a weld zone W, and an ultrasonic beam B is sector-scanned so as to move a convergent point P. A received waveform of a reflection wave reflected by an interior of the weld zone W and returning is acquired for every scan angle, and a fault F is detected using the threshold evaluation line Sa for the echo height of each received waveform. When it is determined that the fault F is present within the weld zone W, a property of the fault F is detected using a fault height determination threshold Sb for the echo height of the received wave of the fault F.SELECTED DRAWING: Figure 4

Description

  The present invention determines whether or not there is a defect in a subject (including a portion to be examined), and uses ultrasonic waves to evaluate the properties including the height of the subject in the depth (thickness) direction. The present invention relates to a flaw detection inspection method and an ultrasonic flaw detection inspection apparatus.

As one of the nondestructive inspections, a flaw detection inspection using ultrasonic waves has been conventionally performed. There is a phased array method using a phased array probe having a plurality of transducers as one of the ultrasonic flaw detection tests.
In this phased array method, a phased array probe is set on the subject, and the excitation timing of a plurality of transducers in the phased array probe is shifted, so that the surface orthogonal to the measurement line set on the subject is obtained. The ultrasonic beam is scanned in a sector, for example, and a reflected wave reflected by a defect such as a flaw existing in the subject is received by a plurality of transducers, and the presence or absence of a defect in the subject is imaged. This is an inspection method to be evaluated. Such inspection methods are widely used for inspection of welds in structures such as boilers and nuclear power plants (see, for example, Patent Document 1).

JP 2007-309771 A

  By the way, in the above-described phased array method, when the subject to be examined is a high-attenuation material for ultrasonic waves, it is necessary to set the frequency of the ultrasonic wave incident on the subject to be low in order to reduce the influence of noise. There is.

However, if the frequency of the ultrasonic wave incident on the subject is set low, it will be difficult to attenuate within the subject which is a high attenuation material, but the time resolution of the reflected wave from the defect inherent in the subject will be reduced, and the defect will be It becomes difficult to grasp the end of the.
Here, in the case where the test part is a welded part in a pressure vessel, for example, in determining the possibility that a defect inherent in the welded part will expand, a defect in the depth direction among the properties of the defect Although it is particularly required to recognize the height, as described above, if it is difficult to grasp the edge of the defect, it is naturally difficult to recognize the defect height in the depth direction of the defect, It has been a conventional problem to solve this problem.

  The present invention has been made by paying attention to the above-described problems, and can perform a flaw detection inspection using low-frequency ultrasonic waves. Even if the subject is an ultrasonic high-attenuator, Provided are an ultrasonic flaw detection inspection method and an ultrasonic flaw inspection apparatus capable of accurately measuring properties including a defect height in a depth direction when a defect is present in a subject as well as the presence or absence of the defect. The purpose is that.

In order to achieve the above object, according to a first aspect of the present invention, a defect property (defect shape) in a subject (including a test portion) using a phased array probe having a plurality of transducers is provided. , Defect height, defect length), a test body made of the same material as the subject is prepared, and each excitation of the plurality of vibrators in the phased array probe is prepared. The ultrasonic beam is scanned inside the specimen by shifting the timing, and the echo height of each received waveform related to the plurality of test holes arranged in the depth direction inside the specimen obtained by the scanning is measured. The threshold evaluation line creation step for creating a threshold evaluation line for determining the presence / absence of defects and scanning the ultrasonic beam inside the subject by shifting the excitation timing of the plurality of transducers in the phased array probe Let the A defect is detected using a defect presence / absence determination threshold set by a first threshold evaluation line based on the threshold evaluation line created in the threshold evaluation line creation step with respect to an echo height of a received waveform obtained by inspection. A defect detection step, and a defect property detection step of detecting the property of the defect using a defect height determination threshold with respect to an echo height of the received waveform of the defect detected in the defect detection step. It is said.
In this case, both a linear type and a matrix type can be used as the phased array probe, but it is desirable to use a matrix type phased array probe.

  In the second aspect of the present invention, in the defect detection step and the defect property detection step, a scanning angle that changes the propagation direction of the ultrasonic beam to a direction that assumes a propagation direction within a plane that intersects the measurement line set on the subject. The ultrasonic beam is scanned by the control and the focal point control for changing the focal point of the ultrasonic beam to an assumed point, and the reflected wave from the subject is oscillated at each scanning angle of the ultrasonic beam. The received waveform is acquired and displayed by synthesizing and received by a child, the echo height is obtained from the received waveform obtained by the scan, and the defect property detecting step includes the ultrasonic wave acquired in the defect detecting step. The scanning angle of the ultrasonic beam corresponding to the received waveform of the reflected wave on which the echo height exceeding the defect height judgment threshold of the received waveform for each beam scanning angle is displayed and the response from the defect. Based on the distance to the defect obtained by the waves, and constitutes that the step of detecting the height of the defect.

  In the third aspect of the present invention, the defect height determination threshold is set based on the threshold evaluation line created in the threshold evaluation line creation step.

  In the fourth aspect of the present invention, the defect height determination threshold is set based on a drop method.

  According to a fifth aspect of the present invention, in the defect detection step, each time the phased array probe is moved stepwise along the measurement line, the ultrasonic beam in a plane that intersects the measurement line. Is configured to perform three-dimensional scanning.

  According to a sixth aspect of the present invention, there is provided an ultrasonic flaw detection inspection apparatus for detecting a property of a defect inside an object using an ultrasonic wave, comprising a plurality of transducers on a flaw detection surface of the object. A phased array probe configured to oscillate ultrasonic waves from the plurality of transducers and receive reflected waves from within the subject by the plurality of transducers; A pulse transmitter / receiver that oscillates an ultrasonic wave with a timing shifted from each other, scans an ultrasonic beam, and synthesizes reflected waves from within the subject received by the plurality of transducers to obtain a received waveform; and Echo height of each received waveform related to a plurality of test holes arranged in the depth direction inside the test body detected by scanning an ultrasonic beam by the phased array probe for the test body made of the same material as the subject In Then, a defect presence / absence determination threshold value is preset and stored, and a defect is detected using the defect presence / absence determination threshold value with respect to an echo height of a received waveform obtained by scanning with the ultrasonic beam, and the phased array search is performed. A configuration is provided that includes a calculation unit that detects a property of the defect using a defect height determination threshold with respect to an echo height of the received waveform related to the defect acquired by a touch element.

  In the ultrasonic inspection method according to the present invention, the defect property is detected by using the defect height determination threshold for the echo height of the received waveform related to the defect detected by scanning the ultrasonic beam. Therefore, it is possible to perform flaw detection inspection using ultrasonic waves with a low frequency that reduces the resolution of reflected waves from the defect. Therefore, the specimen (test part) is, for example, austenitic stainless steel or Ni Even if it is a base alloy, each welded part of these materials, rubber, concrete, cast steel, ultrasonic high attenuation material such as FRP, not only the presence or absence of defects but also the height of the defects Therefore, the measurement of properties including can be performed with high accuracy.

  According to the ultrasonic inspection method and the ultrasonic inspection device according to the present invention, even when the subject is a high attenuation material, not only the presence of a defect but also the case where the defect is inherent in the subject. An excellent effect is obtained that it is possible to accurately measure the properties including the defect height in the depth direction.

1 is a schematic configuration explanatory diagram of an ultrasonic flaw detection inspection apparatus according to an embodiment of the present invention. It is principle explanatory drawing (a), (b) of the scanning angle control of the ultrasonic beam used with the ultrasonic flaw detection inspection method concerning one Embodiment of this invention. It is principle explanatory drawing (a), (b) of the focusing point control of the ultrasonic beam used with the ultrasonic flaw inspection method concerning one embodiment of the present invention. It is a flowchart which shows one execution point of the ultrasonic flaw detection inspection method which concerns on this invention. Operation explanatory diagram (a) showing a situation in which ultrasonic testing is performed on the specimen by the phased array probe, and the received waveform of the test hole inside the specimen obtained by this ultrasonic testing It is a graph (b) which shows the threshold value evaluation line for defect presence determination produced based on echo height. It is a perspective explanatory view showing the situation where an ultrasonic flaw inspection is carried out on a weld with a phased array probe. Graph (a) showing received waveform of reflected wave from upper part of defect among reflected waves from defect inherent in welded part, graph (b) showing received waveform of reflected wave having amplitude of maximum echo height, and defect It is a graph (c) which shows the reception waveform of the reflected wave from the lower part. It is explanatory drawing which shows the setting point of the defect height determination threshold value which evaluates defect height based on the relationship between the scanning angle of an ultrasonic beam and the echo height in the received waveform from a defect, and the scanning angle of an ultrasonic beam. It is explanatory drawing which shows the other setting point of the defect height determination threshold value which evaluates defect height based on the scanning angle of an ultrasonic beam. FIG. 7 is an explanatory diagram (a) of a scanning image from the direction X in FIG. 6 and an explanatory diagram (b) of a scanning image from the direction Y in FIG.

Hereinafter, an ultrasonic inspection method and an ultrasonic inspection device according to the present invention will be described with reference to the drawings.
1 to 10 show an embodiment of an ultrasonic flaw detection inspection method and an ultrasonic flaw detection inspection apparatus according to the present invention. In this embodiment, a subject (test portion) is a Ni-based material having a high attenuation material. A case where the weld portion is made of an alloy will be described as an example.

  As shown in FIG. 1, this ultrasonic flaw detection apparatus 1 performs oblique angle flaw detection using longitudinal waves that are difficult to attenuate, and is a pulsar receiver having a function of exciting an ultrasonic pulse signal and a receiving function ( A pulse transmitter / receiver) 10, a phased array probe 12 which is an oblique probe, an analog / digital converter (hereinafter referred to as an A / D converter) 14, an arithmetic unit 16, and a monitor 18. The pulsar receiver 10 includes a delay circuit 10a that generates a pulse signal to be applied to each of the vibrators 12a, which will be described later, and a synchronization circuit 10b that synthesizes the reception signals from the vibrators 12 at the desired timing. It is equipped.

  The phased array probe 12 is a matrix array in which a plurality of transducers 12a are arranged in a matrix in the vertical and horizontal directions. At the same time, a reflected wave from inside the weld W is received. At this time, since the welded portion W is made of a highly attenuated Ni-based alloy, an ultrasonic wave having a low frequency, for example, several hundred kHz to several MHz, which is difficult to attenuate inside the welded portion W is used for the oblique flaw detection. It is done.

  The reflected wave received by each transducer 12a of the phased array probe 12 is converted into an electric signal, and the reflected wave converted into the electric signal is input to the pulsar receiver 10 and synthesized. The synthesized analog signal is converted into a digital signal by the A / D converter 14 and subjected to signal processing by the arithmetic unit 16.

  The calculation unit 16 includes a threshold setting circuit 16a, an echo height determination circuit 16b, an image processing circuit 16c, a control circuit 16d, and a memory such as a ROM and a RAM (not shown). In the calculation unit 16, these circuits 16a The determination of the presence / absence of a defect and the evaluation of the defect height, which will be described later, are made by ~ 16d. In addition, although the calculating part 16 also has functions other than determination of the presence or absence of a defect, and evaluation of defect height, description is abbreviate | omitted in this embodiment.

  A monitor 18 is connected to the calculation unit 16 as an output device, displays a visualized image of the received waveform obtained by processing the reflected wave in the calculation unit 16, and the presence or absence of the defect F in the weld W, Defect information such as properties including the position of the defect F and the height of the defect (the length in the depth direction of the weld W) when the defect F is inherent in the weld W is displayed. Although not shown, it goes without saying that the computing unit 16 is provided with an input device such as a keyboard.

  Here, the scanning angle control and the focusing point control by the control circuit 16d of the calculation unit 16 will be described with reference to FIGS. 2 and 3 show a situation in which ultrasonic waves are oscillated vertically from each transducer 12a of the phased array probe 12 for easy understanding.

As shown in FIG. 2A, when the delay circuit 10a of the pulsar receiver 10 controls the excitation timing of the transducers 12a adjacent to each other of the phased array probe 12 to be delayed by Δt ₁ from the left side to the right side in the figure. As shown in FIG. 2B, the propagation direction T ₁ of the ultrasonic beam B is inclined with respect to the flaw detection surface 2 a of the base material 2. Control for delaying the excitation timing of the adjacent transducer 12a by Δt ₁ and changing the propagation direction T ₁ of the ultrasonic beam B to the assumed direction (desired direction) is scanning angle control, so-called steering control. At this time, if the delay time is changed stepwise from Δt ₁ to Δtn, that is, if the propagation direction of the ultrasonic beam B is changed stepwise from T ₁ to Tn in the assumed direction, sector scanning is performed. It will be.

  On the other hand, as shown in FIG. 3 (a), the delay circuit 10a of the pulsar receiver 10 causes the excitation timing of the transducers 12a adjacent to each other of the phased array probe 12 to be delayed earlier in the center at both ends of the figure. 3B, as shown in FIG. 3B, the phase of the ultrasonic wave from each transducer 12a is aligned at the focal point P, that is, the ultrasonic beam B is focused at the focal point P where the ultrasonic energy is concentrated. To do. The control for focusing the ultrasonic beam B at a (desired) focusing point P is focusing point control, so-called focusing control, and the distance to the focusing point P can be set by arbitrarily setting the excitation timing of the vibrator 12a. By changing the assumed focusing point P to the left and right as shown by the arrows, sector scanning can be performed.

The set value of the delay time for changing the propagation direction of the ultrasonic beam B to an assumed direction (desired direction) or changing the assumed distance to the focal point P is called a focal law. In the embodiment, the focal law is set to scan the ultrasonic beam B based on the above-described scanning angle control and focusing point control.
That is, the focal low sets the delay timing of the pulse signal in the delay circuit 10a of the pulsar receiver 10 and the synchronization timing of the reception signal in the synchronization circuit 10b.

  Next, the point of implementation of the ultrasonic flaw detection method according to one embodiment of the present invention using the ultrasonic flaw detection apparatus 1 described above will be described. In addition, the process of each step other than step S2 in the flowchart which shows the process of the ultrasonic flaw inspection of FIG. 4 is performed by each circuit 16a-16d of the calculating part 16. FIG.

  Here, when performing an ultrasonic flaw inspection with the phased array probe 12, the focal point of the ultrasonic beam B inside the welded portion W as a subject with the phased array probe 12 stopped at an arbitrary position. Since P is moved in the depth (thickness) direction, the focusability changes depending on the shape of the phased array probe 12 and the depth of the focus point P in the depth direction.

  Specifically, when the ultrasonic beam B is sector-scanned and the focusing point P is moved to a shallow position inside the weld W, the ultrasonic beam B needs to be shaken at a large angle with respect to the vertical direction. Therefore, the echo height measured by lowering the focusing property is lowered. On the other hand, when the ultrasonic beam B is sector-scanned and the focusing point P is moved to a deep position inside the welded portion W, the ultrasonic wave is used. The echo height is still lowered due to the spread and attenuation.

  As described above, when the phased array probe 12 is stopped at an arbitrary position and the ultrasonic beam B is scanned inside the welded portion W, the echo height depends on the depth of the focal point P in the depth direction. Since it is necessary to grasp the change, as shown in FIG. 4, in step S1, the test is made of the same material as that of the welded portion W that is the subject and has a known size and shape as a defect at a predetermined position. An ultrasonic flaw detection inspection is performed on the specimen 20 provided with holes (circular holes of about φ3 mm in this embodiment) h1 to h16.

  That is, as shown in FIG. 5A, the phased array probe 12 is set on the flaw detection surface 20a of the test body 20 to start the oblique flaw detection, and the ultrasonic beam B (the beam in FIG. A sector scan is performed at a predetermined angle step.

  Within the sector scanning range of the ultrasonic beam B, each reflection reflected and returned by the test holes h1 to h16 arranged at equal intervals in the depth direction inside the test body 20 (5 mm intervals in the illustrated example). Received waveforms are acquired by receiving and synthesizing the waves by the plurality of transducers 12a.

  The echo height of each received waveform of the test holes h1 to h16 obtained by sector scanning of the ultrasonic beam B is measured, and as shown in the graph of FIG. 5B, a threshold evaluation line Sa for determining the presence or absence of defects. (Threshold evaluation line creation step). In the graph of FIG. 5B, the horizontal axis is the depth (mm), and the vertical axis is the echo height (%).

  At this time, as described above, the echo heights of the reception waveforms of the test holes h1 to h5 at the shallow position of the test body 20 and the echo heights of the reception waveforms of the test holes h13 to h16 at the deep position of the test body 20 are used. The height is lower than the echo height of each received waveform in the test holes h6 to h12 in the center of the test body 20 in the depth direction, and therefore the threshold evaluation line Sa has a mountain shape.

  Then, by using the first threshold evaluation line (threshold evaluation line Sa in this embodiment) based on the mountain-shaped threshold evaluation line Sa, a defect presence / absence determination threshold corresponding to the depth inside the welded portion W is set. be able to. Note that the first threshold evaluation line is a line set to some percent of the echo height level of the threshold evaluation line Sa, and the threshold evaluation line Sa itself is the first threshold evaluation line as in this embodiment. It may become.

  In this way, after the mountain-shaped threshold evaluation line Sa is created, in step S2, an ultrasonic flaw inspection is performed on the welded portion W that is the subject. That is, as shown in FIG. 6, the phased array probe 12 is set on the flaw detection surface 2 a in the base material 2 near the welded portion W. At this time, a contact medium such as glycerin paste or machine oil (not shown) is applied to the flaw detection surface 2a to avoid the formation of an air layer between the phased array probe 12 and the flaw detection surface 2a.

In this state, oblique flaw detection is started, and in a plane orthogonal to the weld line (measurement line) L along the weld W, the transducers 12a adjacent to each other of the phased array probe 12 according to a preset focal law. In order to move the focusing point P in the depth (thickness) direction of the weld W, the ultrasonic beam B (shown by the beam center line BL in FIG. 6) is shifted by 3 at a predetermined angle step. Sectorally scans in dimension.
This three-dimensional sector scan of the ultrasonic beam B is performed every time the phased array probe 12 is moved along the weld line L at regular intervals.

  Then, for each angle step (scanning angle) within the sector scanning range of the ultrasonic beam B, the reflected wave reflected and returned in the welded portion W is received and synthesized by the plurality of transducers 12a, and the received waveform is synthesized. Get each.

  When there is an echo height exceeding the threshold evaluation line Sa (defect presence / absence determination threshold according to the depth inside the welded portion W) in the received waveform of the reflected wave acquired by sector scanning of the ultrasonic beam B, In step S3, it is determined that there is a defect F within the scanning range. On the other hand, if there is no echo height exceeding the threshold evaluation line Sa in the received waveform of the reflected wave, the ultrasonic flaw inspection at this point is terminated. Then, the phased array probe 12 is moved along the weld line L to the next point (defect detection step).

  If it is determined in step S3 that there is a defect F within the scanning range, the echo height having an amplitude exceeding the defect presence / absence determination threshold is measured from the received waveform for each angle step in step S4.

  Here, FIGS. 7A to 7C are all received waveforms of reflected waves from the defect F detected within the scanning range of the ultrasonic beam B, and are the upper part of the defect F shown in FIG. The received waveform, the received waveform at the center of the defect F, and the received waveform at the lower part of the defect F are shown, the vertical axis shows the echo height (amplitude;%), and the horizontal axis shows the time (μs). . In step S5, when the echo heights Eu, Ep, Ed respectively measured with the received waveforms shown in FIGS. 7A to 7C exceed the defect height determination threshold Sb as shown in FIG. Then, the scanning range corresponding to each received waveform in which the echo heights Eu, Ep, Ed are shown (the range sandwiched between the alternate long and short dashed lines in FIG. 8) is obtained.

At this time, the defect height determination threshold Sb is set based on the threshold evaluation line Sa created in the threshold evaluation line creation step, and in this embodiment, the echo height of the threshold evaluation line Sa shown in FIG. It is set based on the second threshold evaluation line Sc (= Sa / 2) with the level halved.
Note that the defect height determination threshold Sb may be set based on a drop method in which some value of the maximum echo height Ep of the amplitude in the received waveform is the defect height determination threshold Sb. For example, FIG. As shown in FIG. 5, the value may be set based on a 6 dB drop method in which a value that is 1/2 of the maximum echo height Ep is used as the defect height determination threshold value Sb.

In step S6, the scanning angle θ ₂ corresponding to the echo height Ed of the ultrasonic beam B (BL) and the defect F are detected as shown in the scanning image from the direction X in FIG. The depth direction position (vt ₂ · cos θ ₂ ) of the lower portion of the defect F is calculated from the distance vt ₂ to the lower portion of the defect F obtained by the reflected wave.
Further, the position in the depth direction of the upper part of the defect F is determined by the scanning angle θ ₁ corresponding to the echo height Eu of the ultrasonic beam B (BL) and the distance vt ₁ to the upper part of the defect F obtained by the reflected wave from the defect F. (Vt ₁ · cos θ ₁ ) is calculated.
The defect height Fh is displayed by subtracting the upper depth direction position (vt ₁ · cos θ ₁ ) from the lower depth position (vt ₂ · cos θ ₂ ) of the defect F.

  When the three-dimensional sector scanning of the ultrasonic beam B is carried out at regular intervals along the welding line L, the entire defect F can be grasped, and FIG. 6B in FIG. In the scanned image from the direction Y, a highly accurate defect length Fl obtained by integrating the results of three-dimensional sector scanning performed on each cross section intersecting with the weld line L is displayed (defect property detection step). ).

  As described above, in the ultrasonic flaw detection inspection method and the ultrasonic flaw detection inspection apparatus 1 according to the present embodiment, the focal point P of the ultrasonic beam B is moved in the depth (thickness) direction inside the welded portion W. In advance, the threshold evaluation line Sa for determining the presence / absence of a defect is prepared in order to grasp that the focusing property changes depending on the shape of the phased array probe 12 and the depth of the focusing point P in the depth direction. Then, the defect presence / absence determination threshold value can be set according to the depth inside the welded portion W, and as a result, the presence / absence of the defect F can be accurately determined.

  In addition, when the defect F is inherent in the welded portion W, the threshold value that is the depth information of the welded portion W with respect to the echo height of the received waveform related to the defect F obtained by scanning the ultrasonic beam B The property of the defect is detected by using the defect height determination threshold value Sb set based on the evaluation line Sa.

  That is, a flaw detection inspection using an ultrasonic wave with a low frequency that reduces the resolution of the reflected wave from the defect F can be performed. As a result, as in this embodiment, the weld 2 is a Ni-based material that is a high attenuation material. Even if it is made of an alloy, not only the determination of the presence or absence of the defect F but also the measurement of properties including the defect height Fh can be performed with high accuracy.

  In the ultrasonic flaw detection method according to this embodiment, the excitation timing of the transducers 12a adjacent to each other of the phased array probe 12 is shifted and moved in the depth (thickness) direction assuming the focal point P. Since the ultrasonic beam B is sector-scanned at a predetermined angle step in order to perform the detection, that is, the focal point P where the ultrasonic energy is concentrated is scanned in the assumed direction. As a result, the properties including the defect height Fh can be measured with higher accuracy.

  Furthermore, in the ultrasonic inspection method according to the present embodiment, every time the phased array probe 12 is moved along the weld line L at a predetermined interval, the ultrasonic inspection is performed in a plane perpendicular to the weld line L. Since the scanning of the sound beam B is performed three-dimensionally, the property of the defect F can be measured with higher accuracy.

  Furthermore, in the ultrasonic inspection method according to the present embodiment, when the defect height determination threshold value Sb is set based on, for example, the 6 dB drop method, the property of the defect F can be measured in a short time. It will be.

  In the above embodiment, in the flowchart shown in FIG. 4, when it is determined in step S3 that there is a defect F in the welded portion W, the echo height is measured from the received waveform for each angle step in step S4. However, when it is determined in step S3 that there is a defect F in the welded portion W, the range in which the defect F is present may be scanned again (zone focus).

  In the above embodiment, the ultrasonic flaw detection inspection method and the ultrasonic flaw detection inspection apparatus according to the present invention are used to detect defects in the welded portion 2 made of a Ni-based alloy that is a high attenuation material. You may use for the defect detection of large structures, such as elastic bodies, such as rubber | gum, and a plant.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Ultrasonic flaw detector 2a Flaw detection surface 10 Pulsar receiver (pulse transmitter / receiver)
12 Phased Array Probe 12a Transducer 16 Calculation Unit 20 Specimen 20a Test Surface B Ultrasonic Beam Ed, Ep, Eu Echo Height F Defect Fh Defect Height Fl Defect Length h1 to h16 Test Hole L Weld Line (Measurement line)
P Focus point Sa Threshold evaluation line for determining the presence or absence of defects (first threshold evaluation line)
Sb Defect height determination threshold Sc Second threshold evaluation line W in which the echo height level of the threshold evaluation line Sa is halved Welded portion (subject)

Claims (6)

An ultrasonic flaw detection method for detecting the nature of a defect inside a subject using a phased array probe having a plurality of transducers,
A test body made of the same material as the subject is prepared, and an ultrasonic beam is scanned inside the test body by shifting each excitation timing of the plurality of transducers in the phased array probe. A threshold evaluation line creating step for creating a threshold evaluation line for determining the presence / absence of a defect by measuring the echo height of each received waveform related to a plurality of test holes arranged in the depth direction inside the obtained test body,
By shifting the excitation timing of the plurality of transducers in the phased array probe, an ultrasonic beam is scanned inside the subject, and the threshold evaluation is performed on the echo height of the received waveform obtained by the scanning. A defect detection step of detecting a defect using a defect presence / absence determination threshold set by a first threshold evaluation line based on the threshold evaluation line created in the line creation step;
A defect property detection step of detecting the property of the defect using a defect height determination threshold with respect to an echo height of the received waveform of the defect detected in the defect detection step;
Ultrasonic flaw detection method including: In the defect detection step and the defect property detection step, scanning angle control for changing the propagation direction of the ultrasonic beam to a direction that assumes a direction intersecting a measurement line set on the subject and a focal point of the ultrasonic beam The ultrasonic beam is scanned by focusing point control to change the point to an assumed point, and the reflected waves from within the subject are received and synthesized by the plurality of transducers for each scanning angle of the ultrasonic beam. Obtain and display the received waveform, obtain the echo height from the received waveform obtained by the scan,
In the defect property detection step, the received waveform of the reflected wave in which an echo height exceeding the defect height determination threshold is displayed among the received waveforms for each scanning angle of the ultrasonic beam acquired in the defect detection step. 2. The ultrasonic inspection according to claim 1, wherein the defect detection step is a step of detecting a height of the defect based on a scanning angle of the ultrasonic beam corresponding to the distance and a distance to the defect obtained by a reflected wave from the defect. Method.   The ultrasonic flaw detection inspection method according to claim 1, wherein the defect height determination threshold is set based on the threshold evaluation line created in the threshold evaluation line creation step.   The ultrasonic flaw detection inspection method according to claim 1, wherein the defect height determination threshold is set based on a drop method.   In the defect detection step, each time the phased array probe is moved stepwise along the measurement line, the ultrasonic beam is scanned three-dimensionally in a plane intersecting the measurement line. Item 5. The ultrasonic flaw detection inspection method according to any one of Items 2 to 4. An ultrasonic flaw detection apparatus that detects the nature of defects inside a subject using ultrasonic waves,
Provided with a plurality of transducers and set on the flaw detection surface of the subject, oscillate ultrasonic waves from the plurality of transducers, and receive reflected waves from within the subject by the plurality of transducers A phased array probe,
The plurality of vibrators oscillate ultrasonic waves with their respective excitation timings shifted from each other, scan the ultrasonic beam, and synthesize a reflected wave from within the subject received by the plurality of vibrators to receive a waveform. A pulse transceiver to obtain,
Echo height of each received waveform related to a plurality of test holes arranged in the depth direction inside the test body detected by scanning an ultrasonic beam by the phased array probe with respect to the test body made of the same material as the subject A defect presence / absence determination threshold value is set and stored in advance, and a defect is detected using the defect presence / absence determination threshold value with respect to an echo height of a received waveform obtained by scanning the ultrasonic beam, and the phased An ultrasonic flaw detection inspection apparatus comprising: a calculation unit that detects a property of the defect using a defect height determination threshold with respect to an echo height of the received waveform related to the defect acquired by the array probe.

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