JPH1151912A - Ultrasonic testing method and ultrasonic testing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic testing method, by which a distribution of a material change progressing from the back face side of a specimen in the specimen thickness direction can be estimated from the front face side of the specimen, and a testing device thereof. SOLUTION: A transmission side axis X for an ultrasonic wave incident from a transmission element 21 via a front face 101 of a specimen 100 and a reception side central axis Y for a reception element 22 receiving a backward scattering wave, which is generated in the specimen 100 because of the incident ultrasonic wave, are crossed mutually, and the transmission element 21 and the reception element 22 are arranged. Reception units 22c, 22d in the reception element 22 are positioned on the outside of the axis Z for a mirror reflection wave of an ultrasonic wave from the front face 101, and the influence of the mirror reflection wave is eliminated from the reception wave. According to a characteristic quantity of the backward scattering wave in each reception time, each depth part condition on a back face 102 side of the specimen 100 is estimated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic test method and an ultrasonic test apparatus, and more particularly, to a situation where it is difficult to perform a test from the surface side, such as carburization or deterioration of material on the inner surface side of a steel pipe or a pressure vessel. The present invention relates to an ultrasonic test method and a test apparatus suitable for a computer.

[0002]

2. Description of the Related Art For example, in an ethylene unit for naphtha pyrolysis, the inner surface of a riser pipe corresponding to the outlet of a cracking furnace is easily deteriorated by carburization, and requires periodic replacement. For this type of riser, a steel pipe of high nickel and high chromium is used from the viewpoint of improving heat resistance. With the martensitic transformation caused by carburization, the inner surface of the steel pipe becomes magnetic.
Therefore, conventionally, a magnet was brought into contact with the outer surface of the riser, and the degree of carburization was evaluated based on the degree of adsorption. However, it was difficult to estimate the thickness of the carburized layer only by evaluating the degree of magnet attraction from the outer surface of the thick steel pipe.

[0003] On the other hand, the inventors have also studied a point of estimating the carburized thickness by measuring the speed of sound using ultrasonic waves. However, when no clear ultrasonic reflection is obtained at the interface between the carburized layer and the sound layer, and the front and back surfaces are rough, the ultrasonic absorption is large,
It was difficult to measure sound speed accurately.

Further, in estimating the degree of deterioration at each coordinate position along the surface of a test specimen, Japanese Patent Laid-Open No.
As described in JP-A-301624, a technique using a backscattered wave is known. However, according to the publication, the entire backscattered wave at each of the coordinate positions of the test body is evaluated, and it is impossible to estimate the deterioration distribution of the test body in the depth direction.

[0005]

SUMMARY OF THE INVENTION In view of such a conventional situation, the present invention provides a method of evaluating the distribution of a change in material progressing from the back side of a specimen in the thickness direction of the specimen from the front side of the specimen. It is an object of the present invention to provide a possible ultrasonic test method and a test apparatus used for the method.

[0006]

In order to achieve the above object, an ultrasonic testing method according to the present invention is characterized in that a transmitting-side central axis of an ultrasonic wave incident from a transmitter through a surface of a test object and a transmitting-side central axis thereof. The transmitter and the receiver are arranged by intersecting the center axis of the receiver for receiving the backscattered wave generated in the test object from the surface side due to the ultrasonic wave, and receiving the receiver. Position is located outside the central axis of the specular reflected wave of the ultrasonic wave caused by the front surface, and the state of each depth portion on the back surface side of the test specimen is evaluated by the characteristic amount of the backscattered wave at each reception time. Is to do.

According to this feature, the backscattered wave can be more remarkably received from an oblique direction by disposing the transmitter and the receiver so that the central axis of the transmitting side and the central axis of the receiving side intersect with each other. . Further, by removing the receiver of the receiver from the center axis of the specular reflected wave on the surface of the test object, there is no inconvenience such as the signal received by the specular reflected wave being saturated, and the minute backscattered wave is reduced. Can be received with noise. As the “receiving unit”, for example, an “acoustic lens” of a receiver or a “wedge” to be brought into contact with a test object is used. The “feature amount of the backscattered wave” in the present invention includes not only the intensity of the received signal but also the integral value, the first moment, and the like of a specific portion in each time gate. Then, if the backscattered wave can be received with low noise and relatively high intensity, the components of the respective feature amounts are also included in a large amount, and the evaluation of the test object becomes more accurate. The feature of the present invention is different from oblique flaw detection in which a flaw or a bottom echo is captured in that a backscattered wave is captured.

It is preferable that the focal point of the receiver is located outside the surface. By shifting the focus out of the surface of the specimen, the receiving area on the surface of the specimen by the receiver is enlarged,
The detectable range in the depth direction of the test body is expanded.

Further, it is preferable that the characteristic quantity is a reception intensity of the backscattered wave by the receiver, and that either one of the central axis on the transmitting side and the central axis on the receiving side be substantially orthogonal to the surface. . According to the experiments of the inventors, for example, it has been confirmed that the intensity of the backscattered wave is reduced in a layer in which carburization has progressed in a high alloy steel, and by measuring the reception intensity of the backscattered wave by the receiver, the carburized layer is measured. It became clear that the distribution in the depth direction can be estimated.
Further, by making one of the transmission-side central axis and the reception-side central axis substantially perpendicular to the surface, even if the test piece has a curved shape, the position of the test piece in the three-dimensional space can be determined. It becomes easy to specify.

On the other hand, the ultrasonic testing apparatus according to the present invention used in the above method is characterized by a transmitter for ultrasonic waves, a receiver for receiving backscattered waves generated in a test object due to the ultrasonic waves, And a feature value display unit for displaying a feature value of the backscattered wave at each reception time, and the transmitter and the receiver are arranged by intersecting a transmission center axis and a reception center axis of the transmitter. Is to do.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, referring to the attached drawings,
An embodiment of the present invention will be described. As shown in FIG. 1, the ultrasonic test apparatus 1 according to the present invention includes a sensor head 20 and a feature amount display unit 60. The feature amount display means 60 further includes a drive unit 30, a personal computer 40, and a monitor 50.

The sensor head 20 includes a transmitter 21 driven by a pulsar 31 and a receiver 22 for receiving backscattered waves. These transmitter 21 and receiver 22
Are fixed to each other at a certain angle, and scan the surface of the test object three-dimensionally by driving a scanning motor 23 including three stepping motors.

The drive unit 30 includes a pulsar 31 for driving the transmitter 21, a receiver 32 for receiving the backscattered wave received by the receiver 22, and an A / D converter 33 for digitally converting the signal. It has. Further, the motor driver 34 controls the driving amount of the scanning motor 23 stepwise.

The personal computer 40 realizes specific functions indicated by reference numerals 42 to 46 by incorporating software and an interface into a general-purpose product. Further, the trigger 42 is provided with an operating means 41 such as a keyboard or a mouse.
To drive the pulsar 31 to cause the transmitter 21 to transmit an ultrasonic pulse to the test object.

The backscattered wave received via the receiver 22, the receiver 32 and the A / D converter 33 and converted into a digital signal is stored in a memory 43 such as a RAM or a hard disk. The timer 44 sets the time gates G in FIG. 3A in cooperation with the trigger 42, and samples a signal for each time gate G. Processing means 45
Displays the received signal on the monitor 50 as a graph as shown in FIG. Further, the processing means 45 obtains a frequency spectrum from the signal sampled for each time gate G using the FFT means and the like in cooperation with the timer 44, and obtains and displays various characteristic amounts described later.

The motor controller 46 sets a spatial trajectory for scanning the transmitter 21 and the receiver 22 based on an input from the operating means 41, and drives the scanning motor 23 according to the trajectory. Further, the processing means 45
In cooperation with the motor controller 46, the memory 43, and the timer 44, it is also possible to express the above-mentioned feature amount in color tone by C-scan display at each coordinate position along the surface of the test object.

FIG. 2 is a diagram showing the relationship between the transmitter 21 and the receiver 22 and the test object 100. In the present embodiment, the water immersion method is used, and the test body 100, the transmitter 21 and the receiver 22 are immersed in the water W. As the test body 100 in the present embodiment, a riser tube for naphtha decomposition made of high nickel / high chromium steel is used. The surface 101 of the specimen 100 transmits a pulse from the transmitter 21 and
2, a carburized layer 103 exists on the outer surface of the tube corresponding to the receiving side and on the side of the back surface 102 which is the inner surface of the tube. FIG. 1 schematically shows a part of a cross section of a test body 100 which is a rising pipe, which is orthogonal to the pipe axis direction.

The transmitter 21 and the receiver 22 transmit ultrasonic pulses generated from the vibrators 21b and 22b supported on the bases 21a and 22a through the acoustic lenses 21c and 22c, respectively. It is structured to converge to the focal point Fy. This transmitter 21 and receiver 2
As No. 2, a thin-film vibrator using polyvinylidene fluoride is attached to a concave curved surface, and a transmission-side focal point Fx and a reception-side focal point Fx are attached.
It may be configured to form y.

The transmitting side central axis X and the receiving side central axis Y in FIG.
Is the transmission and reception of ultrasonic waves at each transmitter 21 and receiver 22.
Axes indicating the receiving direction, the acoustic lenses 21c and 22c
, The transmission-side focal point Fx and the reception-side focal point Fy are located on the transmission-side central axis X and the reception-side central axis Y, respectively. The transmitter 21, the receiver 22, and the test object 100 are arranged so that the transmitting-side central axis X and the receiving-side central axis Y obliquely intersect. Further, in the present embodiment, the transmitter 21 is arranged so that the transmission-side central axis X is substantially perpendicular to the surface 101, and scanning is performed along the surface of the test object by the scanning motor 23. In this specification, "substantially perpendicular to the surface"
When the surface of the test piece is a curved surface, it means that the surface is substantially perpendicular to the microelements on the surface or the tangent (tangent surface) thereof.

Incidentally, the transmission-side central axis X does not refract through the transmission-side intersection P1, which is the intersection with the surface 101. Further, the transmission-side central axis X also corresponds to the central axis Z of the specular reflected wave based on the surface 101. Therefore, there is almost no possibility that the specular reflected wave directly enters the receiver 22 and causes disturbance to the received wave. . On the other hand, since the sound velocity is different between the water W and the test body 100, the receiving-side central axis Y and the receiving-side internal axis Y1 are separated by a receiving-side intersection P4 which is an intersection with the surface 101 as shown in FIG. It is refracted to the side external axis Y2.

When the receiver 22 receives the backscattered wave that is incident upon the specimen 100 from the transmitter 21 and is generated, it is desirable to receive the backscattered wave with a certain extent in the thickness direction of the specimen 100. Therefore, in the present embodiment, the reception-side focal point Fy is shifted along the direction of the reception-side central axis Y to a side farther from the test object 100 than the reception-side intersection P4, which is the intersection of the reception-side central axis Y and the surface 101. By displacing the receiver 22 so as to be positioned, the reception area A of the receiver 22 on the surface 101 is enlarged. Of course, the receiving-side focal point Fy may be shifted along the receiving-side central axis Y to a side that enters the interior of the specimen 100 more deeply than the surface 101. Further, in the present embodiment, the transmitting side center axis X
The transmission-side intersection P1 which is the intersection of the transmission-side focal point Fx with the transmission-side focal point Fx.
And the transmission-side focal point Fx may be slightly shifted along the direction of the transmission-side central axis X.

Incidentally, a main intersection P2, which is an intersection of the transmission-side central axis X and the reception-side central axis Y (reception-side internal axis Y1), is a bottom intersection P3, which is an intersection of the transmission-side central axis X and the back surface 102.
In the case where the distance is equal to, about half of the reception area A cannot effectively capture backscattered waves generated from a portion along the transmission-side central axis X. Therefore, the main intersection P2 is positioned closer to the transmitter 21 than the bottom intersection P3, thereby preventing the reception area A from being wasted.

FIG. 3A shows a case where the thickness of the carburized layer 103 is large, FIG. 3B shows a case where the thickness of the carburized layer 103 is small, and FIG. It is a graph which shows a waveform. When the reception intensity is regarded as a feature amount, it is considered that a time zone where the reception intensity is low corresponds to the carburized portion, and the bottom surface echo S2 is caused by the carburized layer 103. It can be converted as the carburized thickness D1 with respect to the central axis X direction. The carburized thickness D1 of (a) obtained by conversion in this way is the same as that of (b).
It was confirmed that the carburized thickness was larger than the carburized thickness D2 of the test piece, and the measured carburized thickness was almost the same as the actual measured value of the carburized thickness by observing the cross section of the test body. Note that the receiving-side central axis Y is disposed obliquely with respect to the transmitting-side central axis X, and that the acoustic lens 21c, which is the receiving unit of the receiver, is located outside the central axis Z of the specular reflected wave. Therefore, the influence of the specular reflected wave is removed from the received waveform, and the saturation of the backscattered wave is prevented. When the transmission-side central axis X is substantially perpendicular to the surface 101, the central axis Z of the specular reflected wave substantially coincides with the transmitting-side central axis X. This embodiment is excellent in that the degree of freedom in arranging the receiving-side central axis Y or the receiver 22 in order to eliminate the influence of is high.

FIG. 4 is a comparative example for clarifying the superiority of the present invention, and shows the reception intensity of the reflected wave when the transmitter 21 is also used as the receiver. (A), when the thickness of the carburized layer 103 is large, (b)
Corresponds to the case where the thickness of the carburized layer 103 is small. The level of the surface echo S1 caused by the surface 101 is large, which affects the backscattered wave S3 due to the saturation of the received signal and the like, making the evaluation thereof difficult. In addition, since the level of the bottom surface echo S2 is higher in (a) than in (b), it has been found that the backscattered waves in the carburized layer 103 are small and the ultrasonic wave permeability is improved. This tendency confirms that when the backscattered wave is received from the oblique direction via the receiver 22, the strength is small in the carburized layer 103, while the received strength is larger in the healthy part.

Next, another embodiment of the present invention will be described. In the following embodiments, the same members as those in the first embodiment are denoted by the same reference numerals.

The second embodiment shown in FIG. 5 has basically the same configuration as the first embodiment. However, while the receiver 22 is arranged so that the central axis Y on the receiving side is substantially perpendicular to the surface 101, the transmission is performed such that the central axis X on the transmitting side obliquely intersects a perpendicular V substantially perpendicular to the surface 101 of the test object. Child 2
1 is different. Further, the transmitter 21 and the receiver 22 are arranged such that the opening of the acoustic lens 22c, which is the receiving unit of the receiver 22, is located outside the central axis Z of the specular reflected wave caused by the test object surface 101. . This arrangement prevents the specular reflected wave from directly reaching the receiver 22 and lowering the measurement accuracy. In this embodiment,
The focal point Fy on the receiving side is set to the specimen 100 more than the specimen surface 101.
The receiving area A is enlarged by displacing the receiving area A toward the inside.

The third embodiment shown in FIG.
The arrangement of the receiver 22 and its basic configuration are almost the same as those of the first embodiment. However, this figure schematically shows a part of a cross section along the pipe axis direction of a test body 100 which is a rising pipe. That is, in the present embodiment, the transmitter 21 and the receiver 22 are arranged with respect to the test body 100 such that the central axis X on the transmitting side and the central axis Y on the receiving side fall within the same plane as the tube axis.

The fourth embodiment shown in FIG. 7 differs from the above embodiments in that a direct contact method is used instead of a water immersion method. The transmitter 21 and the receiver 22 are made of an acrylic wedge 21.
Vibrators 21b and 22b are provided on d and 22d, and are brought into contact with the surface 101 of the test piece via a couplant such as water or grease. The test body 100 of the present embodiment is not a tube but a flat steel material. The center axis X on the transmitting side and the center axis Y on the receiving side are defined as a receiving inner axis X1 and a transmitting inner axis Y1 at a boundary between the transmitting intersection P1 and the receiving intersection P4 due to a difference in refractive index between the wedges 21d and 22d and the test piece 100. And receiving side external axis X2
And the transmission side external axis Y2. Transmission side internal axis X1
The arrangement of the wedges and the vibrator is set such that both the internal axis Y1 and the receiving side internal axis Y1 are oblique to the surface 101. Since the transmitter 21 and the receiver 22 have a transmission area Bx and a reception area By having a width as shown in the figure, the main intersection P2 is positioned closer to the front surface 101 than the bottom intersection P3, so that the reception area Can be expanded. In addition,
According to the direct contact method, since the central axis Z of the specular reflected wave caused by the surface 101 is located in the transmitter 21, there is no possibility that the specular reflected wave causes disturbance to the receiver 22.

Lastly, another embodiment of the present invention will be described. In the above embodiment, the “reception strength of the backscattered wave” is captured as the “feature amount of the backscattered wave”. However, a fast Fourier transform device (F
FT device), a frequency spectrum is obtained by the FFT device for each of the time gates G, and a value such as an integral value of the frequency spectrum in a specific frequency range or a first moment of the frequency spectrum is defined as a “backscattered wave characteristic amount”. The evaluation of the specimen may be performed.

The present invention is not necessarily limited to the water immersion method and the direct contact method as described above. For example, you may implement so that an ultrasonic wave may be transmitted / received via a water bag.

In the above embodiment, "estimation evaluation of carburized thickness in high alloy steel" was performed as "evaluation of state at each depth of test specimen", but the present invention is not limited to this. For example, with respect to phenomena such as hydrogen erosion, hydrogen embrittlement, thermal embrittlement, and nitriding, the present invention can also be applied to the case of estimating the distribution state in the thickness direction of a specimen.

[0032]

As described above, according to the features of the ultrasonic test method and the test apparatus according to the present invention, the influence of the reflected wave caused by the surface of the test object is eliminated, and the minute backscattered wave is reduced in noise. As a result, it is possible to accurately estimate and evaluate the distribution of the material change progressing from the back side of the specimen in the thickness direction of the specimen from the front side of the specimen. As a result, the life of pipes, containers, and the like in various plant facilities can be more accurately estimated, which can contribute to maintaining the soundness of the facilities.

It should be noted that the reference numerals described in the claims are merely for convenience of comparison with the drawings, and the present invention is not limited to the configuration of the attached drawings by the description. .

[Brief description of the drawings]

FIG. 1 is a logical block diagram of an ultrasonic test apparatus according to the present invention.

FIG. 2 is a diagram illustrating a relationship between a transmitter and a receiver and a test body in a cross section including a transmission-side central axis and a reception-side central axis.

FIG. 3 is a graph showing a relationship between a received signal intensity of a backscattered wave by a receiver and time in a state where a central axis of a transmitting side and a central axis of a receiving side cross each other, wherein (a) is a case where a carburized layer is thick; , (B) shows the results when the carburized layer is thin, and (c) shows the results when using a sound specimen without the carburized layer.

4A and 4B are results showing a comparative example with respect to the present invention, and show a reception result when the center axis on the transmitting side is orthogonal to the surface of the test sample and this transmitter also serves as a receiver; FIG.
In the case where the carburized layer corresponding to (a) is thick, (b) shows FIG.
It shows the results corresponding to the case where the carburized layer shown in (b) is thin.

FIG. 5 is a diagram corresponding to FIG. 2 in a state where a transmission-side central axis is inclined with respect to a surface of a test object while a central axis of a reception side is substantially orthogonal to the surface of the test object;

FIG. 6 is a diagram corresponding to FIG. 2 in a cross section along the tube axis direction of the test body.

FIG. 7 is a diagram corresponding to FIG. 2 in a case where a direct contact method is used for a flat test piece.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ultrasonic test apparatus 20 Sensor head 21 Transmitter 21a Base 21b Vibrator 21c Acoustic lens 21d Wedge 22 Receiver 22a Base 22b Vibrator 22c Acoustic lens 22d Wedge 23 Scan motor 30 Drive unit 31 Pulser 32 Receiver 33 A / D Converter 34 Motor driver 40 Personal computer 41 Operation means 42 Trigger 43 Memory 44 Timer 45 Processing means 46 Motor controller 50 Monitor 60 Feature display means 100 Specimen 101 Front surface 102 Back surface 103 Carburized layer X Central axis on transmission side X1 Internal axis on transmission side X2 Transmitting external axis Fx Transmitting focal point Y Receiving central axis Y1 Receiving internal axis Y2 Receiving external axis Fy Receiving focal point P1 Transmitting intersection P2 Main intersection P3 Bottom intersection P4 Receiving side Intersection A Reception area S1 Surface echo S2 Bottom echo S3 Backscattered wave D1 Carburization thickness D2 Carburization thickness G Time gate Bx Transmission area By Reception area V Perpendicular.

Claims (4)

[Claims] 1. A transmission-side central axis (X) of an ultrasonic wave incident from a transmitter (21) through a surface (101) of a test object (100), and the test object (100) caused by the ultrasonic wave. The transmitter (21) and the receiver (22) intersect with the center axis (Y) of the receiver (22) that receives the backscattered wave generated in the receiver from the surface (101) side. Place,
The receivers (22c, 22d) of the receiver (22) are positioned outside the central axis (Z) of the specular reflected wave of the ultrasonic wave caused by the surface (101), and the backscattered wave at each reception time. An ultrasonic test method for evaluating the state of each depth portion on the back surface (102) side of the test body (100) by the characteristic amount of (1). 2. The ultrasonic testing method according to claim 1, wherein a focal point (Fy) of the receiver (22) is located outside the surface (101). 3. The characteristic quantity is a reception intensity of a backscattered wave by the receiver (22), and the transmission-side central axis (X)
3. The ultrasonic testing method according to claim 1, wherein one of the receiving-side central axes (Y) is substantially perpendicular to the surface (101). 4. 4. An ultrasonic test apparatus used in the ultrasonic test method according to claim 1, wherein a transmitter (21) of the ultrasonic wave and a test object (21) caused by the ultrasonic wave. 10
Receiver (22) for receiving backscattered waves generated in 0)
And a feature value display means (60) for displaying a feature value of the backscattered wave at each reception time, wherein the transmission-side center axis (X) and the reception-side center axis (Y) are crossed with each other so as to intersect with each other. An ultrasonic test apparatus comprising a transmitter (21) and a receiver (22).