JPH07253413A - Internal defect ultrasonic flaw detecting method for joint connected with different type material - Google Patents

Abstract

PURPOSE:To provide a method for ultrasonic detection of an internal flaw of a join connected with a different type material which can identify not only presence or absence of the flaw but also a size. CONSTITUTION:The method for ultrasonic-detecting an internal flaw of a joint connected with a different type material comprises the steps of holding an incident probe 40 and a receiving probe 50 in predetermined attitudes at a predetermined interval between both the probes, detecting a flaw while moving the probes in a perpendicular direction to a connecting surface 30, comparing a strength of a received transmitted wave with a strength of a strength deciding pattern S formed based on a passed wave strength P measured by a joint having no flaw at the connecting surface and detecting a size of a defect based on the interval of the probe positions in which the strength of the measured transmitted wave becomes the strength or less of the pattern.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic deep damage method for dissimilar joints, which is suitable for detecting the quality of joints of dissimilar material pipe joints to be piped in chemical plants, nuclear power plants, etc. Regarding

[0002]

2. Description of the Related Art An ultrasonic deep-scratch method is used to inspect the quality of joints for pipes and the presence or absence of internal defects. In the case of joints in which members made of different materials are joined together,
At the bonding interface, even if there is no defect, a part of the ultrasonic wave is reflected because the material characteristics (acoustic impedance) are different, and the obliquely incident ultrasonic wave is partially refracted and transmitted.

Therefore, in a crack having a sharp tip such as a poor joint, a fatigue crack or a corrosion crack, it is difficult to detect the scattered wave from the crack tip and the scattered wave from a good joint surface separately.

Further, in the method using the reflected wave from the inner surface of the pipe, it is possible to detect the presence or absence of a crack opened on the inner surface of the pipe, but it is impossible to detect the size of the crack because the tip of the crack cannot be detected. Is.

Then, as a method of ultrasonic deep scratches on a dissimilar joint capable of detecting the size of a crack, a method by the reflection method disclosed in JP-A-3-6185 has been proposed.

However, in the case of using the method disclosed in the above-mentioned Japanese Patent Laid-Open No. 3-6185, in order to obtain a reflection surface, one of the pipe joints must be manufactured in a flange type and the other in a cone type. There is a constraint that it must be.

A transmission method is compared with the reflection method. FIG. 12 is a diagram showing an example of ultrasonic deep scratches by the transmission method. In the figure, 10 is a pipe material, 20 is a pipe material made of a material different from the pipe material 10, and 30
Is a joining surface of the two pipe materials, 40 is an incident ultrasonic deep probe, 50 is a receiving ultrasonic deep probe, and both deep probe 40, 50 move in the direction of the solid line arrow in the figure.

The ultrasonic waves incident on the surface of the pipe member 10 from the ultrasonic deep probe 40 are reflected by the inner peripheral surface of the pipe member 10, and the reflected waves are transmitted through the pipe member and received by the ultrasonic deep probe 50. The intensity of the transmitted wave transmitted through the sound portion of the joint surface 30 and the defect portion R
Since there is a difference in the intensity of the transmitted wave that has passed through, the defect portion A can be detected from this difference.

[0009]

However, as described above, ultrasonic waves are refracted at the joint surface of different materials due to the difference in material characteristics (acoustic impedance). Therefore, 'the distance between the receiving position x _B with respect to the incident position x _B' reception position x _A for the incident position x _A interval differs between. When a focus type deep probe is used, the reception position x _A '
And a distance L _A , L _B from the surface of the pipe material at the receiving position x _B 'has a difference.

Although these positions can be calculated theoretically, it is not practical because the position control of the deep probe becomes complicated.

The present invention has been made to solve the above-mentioned problems, and is obtained by ultrasonically scanning the joint surface while holding the incident and receiving deep contactors at a specific interval and in a specific posture. By processing the transmitted wave intensity data,
An object of the present invention is to provide a method for deep flaw ultrasonic damage of a joint in which dissimilar materials are joined, in which not only the presence / absence of internal defects in the dissimilar joint but also the size thereof can be known.

[0012]

In order to achieve the above object, the present invention provides, in claim 1, an ultrasonic wave from a surface of a joint in which members made of different materials are joined to each other through an ultrasonic wave propagating medium. In the ultrasonic deep scratch that deeply scratches the defective portion of the joint from the intensity of the transmitted wave that has been transmitted through the surface and transmitted through the ultrasonic propagation medium, (a) a deep probe for incidence and a deep probe for reception are provided. Each of them is held in a predetermined posture and both deep contact elements are held at a predetermined interval and moved in a direction perpendicular to the joint surface,
(B) The intensity of the received transmitted wave is compared with the intensity of the determination intensity pattern created based on the intensity of the transmitted wave measured by the standard joint having a sound joint surface, and (c) the intensity of the measured transmitted wave is as described above. The size of the defective portion is detected based on the depth of the probe that is less than or equal to the strength of the determination strength pattern.

According to a second aspect of the present invention, the predetermined posture is a posture obtained based on the sound velocity of both members and the sound velocity of the ultrasonic wave propagating medium,
The predetermined interval is characterized in that it is an interval determined based on the speed of sound of both members, the speed of sound of the ultrasonic wave propagation medium, the focal length of the deep probe, and the joint plate thickness. According to a third aspect of the present invention, the intensity of the intensity determination pattern is 1/2 of the intensity of the transmitted wave measured by the joint having no defect on the joint surface.

According to the present invention, ultrasonic waves are incident from the surface of the joint in which members made of different materials are joined to each other through the ultrasonic wave propagating medium, and then received through the ultrasonic wave propagating medium to deeply scratch the defective portion of the joint. In the ultrasonic deep wound, the first deep contactor for both incidence and reception and the second deep contactor for reception are held in predetermined postures and both deep contactors are held at predetermined intervals,
(A) The first and second deep contactors are moved in parallel with the joint surface, the reflected waves of the ultrasonic waves incident on the first deep contactor are received by the same first deep contactor, and the reflected light is reflected. The presence or absence of a defect is detected from the wave intensity, and (b) when the defect is detected, the first,
The second deep contactor is moved in a direction perpendicular to the joint surface, the transmitted wave of the ultrasonic wave incident on the first deep contactor is received by the second deep contactor, and the defect is determined from the intensity of the transmitted wave. The configuration is such that the depth is detected.

According to a fifth aspect of the present invention, ultrasonic waves are incident from the surface of the joint in which members made of different materials are joined to each other through the ultrasonic wave propagating medium and then received through the ultrasonic wave propagating medium to deepen the defective portion of the joint. An ultrasonic deep wound that is damaged, in which the first deep contactor for both incidence and reception and the second deep contactor for reception are held in predetermined postures, and both deep contactors are held at predetermined intervals.
(A) The first and second deep contactors are moved in parallel with the joint surface, the reflected waves of the ultrasonic waves incident on the first deep contactor are received by the same first deep contactor, and the reflected light is reflected. The presence or absence of a defect is detected from the wave intensity, and (b) when the defect is detected, the depth of the defect from the surface is detected by comparing with the reflected wave measured by the joint having no defect on the joint surface, (c) When the defect depth exceeds a predetermined value, the first and second deep contactors are moved in a direction perpendicular to the joint surface, and the transmitted wave of the ultrasonic wave incident on the first deep contactor is changed to the second depth. The structure is such that the depth of the defect is detected from the intensity of the transmitted wave received by the deep probe.

[0016]

According to the invention described in claims 1 to 3, the defect can be obtained by simply moving the incident deep contact element and the receiving deep contact element in the direction perpendicular to the joint surface without individually controlling the positions. The size of can be specified. Further, the intensity determination pattern is used to compare the measured transmitted wave intensity with the intensity determination pattern, and the comparison result is subjected to data processing to detect the presence and size of a defect.

In the invention according to claim 4, first, the first and second deep contactors of the special arrangement are moved along the joint surface, and the presence or absence of an important defect reaching the surface by the reflection method by the first deep contactor. Is detected, and then the first and second deep contactors of this special arrangement are moved perpendicularly to the joint surface at the position where there is a defect, and the first and second
The length of the defect reaching the inside is detected by the transmission method using a deep probe.

According to the fifth aspect of the invention, the detection of the defect length by the transmission method using the first and second deep contact elements is not suitable for a short defect reaching the surface, but the reflection by the first deep contact element is not suitable. Focusing on the fact that it is possible to specify the length of a short defect reaching the surface by the method, and when a predetermined value that can be detected by this reflection method is exceeded, the length of the defect reaching the inside by the transmission method using the first and second deep contact elements By detecting, short defects from the surface to long defects can be detected.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIG. First, the case of defect length detection by the transmission method will be described, and then the case of defect length detection by the combination of the transmission method and the reflection method will be described.

In FIG. 1, 10 is a pipe material and 20 is a pipe material 1.
A pipe material made of a material different from 0, 30 is a joint interface of both pipe materials, 30R is a defective portion formed at the joint interface, 40 is an incident ultrasonic deep probe, and 50 is a receiving ultrasonic deep probe. The deep contactors 40, 50 are driven in the direction of the solid line arrow by a driving mechanism (not shown) while maintaining the posture described later. Reference numeral 60 denotes an ultrasonic wave propagating medium (water in this example).
And the pipe materials 10 and 20 are filled.

In the figure, θ ₄₀ is the ultrasonic probe for incidence 40
L ₄₀ is the distance between the entrance ultrasonic deep probe 40 and the surface of the pipe material 10 (distance in the radial direction of the pipe material), θ ₅₀ is the attitude (tilt angle) of the reception ultrasonic deep probe 50, L ₅₀ is the distance (distance in the radial direction of the pipe material) between the receiving ultrasonic probe and the surface of the pipe material 10. Further, W ₄₀ is the initial axial distance between the bonding interface 30 and the ultrasonic deep probe 40 for incidence, and W ₅₀ is the bonding interface 30.
And an initial axial distance between the ultrasonic wave deep probe 50 for reception.

These numerical values L ₄₀ , θ ₄₀ , W ₄₀ and L ₅₀ , θ
₅₀ and W ₅₀ are values obtained by the following equations (1) to (3).

[0023]  W₄₀= D + L₄₀・ Sin θ₄₀, W₅₀= D + L₅₀・ Sin
θ₅₀ ... (3) where C_W; Speed of sound of water C_S40; Transverse wave sound velocity C of pipe 10_S50The transverse wave sound velocity L of the pipe member 20; the focal length of the deep contactors 40, 50 in the medium d; the thickness of the joint.
While moving, the intensity Q of the transmitted wave received by the deep probe 50
A determination pattern in which the intensity Q is measured and set in advance (see FIG.
To the intensity dB)._SCompare with.

This strength judgment pattern S shows the strength pattern (indicated by P) of the transmitted wave measured at a sound joint in which the joint interface 30 is perfectly sound. Is lower by a predetermined intensity (6d in this example)
B) The intensity pattern S of intensity is set as the intensity determination pattern. This 6 dB is half the value of the intensity pattern P.

If the bonding interface 30 has a defective portion, the transmitted wave intensity Q decreases as shown in FIG. 3 while passing through the defective portion.

As shown in FIG. 2, the defective portion 30 is formed on the joint surface 30.
When there is R, the transmitted wave intensity Q is when the deep probe 40 is between the positions X _40-1 and X _40-2 (when the deep probe 50 is at the position X _50-1 ,
When it is between X _50-2 ), the strength is lower than the strength of the strength determination pattern S, and when the deep contact element 40 is between positions X _40-3 and X _40-4 (deep contact element 50 is at position X _{50). -3} , X _50-4 )), the strength is lower than the strength of the strength determination pattern S.

From this fact, the defective portion 30R is formed on the joint surface 30.
You can see that there is.

In this embodiment, when the transmitted wave intensity Q is lower than the intensity of the judgment pattern S, the deep probe positions X _40-1 , X _40-1 , X
_50-1 , X _40-2 , X _50-2 and the depth of the contact point X _40-3 , X _50-3 , X _40-4 when the strength of the judgment pattern S becomes greater than that of the judgment pattern S after passing through the defect portion 30R. , X _50-4 and X _{50-1 to} X
_50-2 (X _{40-1 to} X _40-2 ), X _{50-3 to} X _50-3 (X _{40-3 to} X
_40-3 ), [half-width shown in FIG. 5; 20 log (1/2) =
-6.02] is obtained and 1 / of the sum of the half widths 1 and 2 is calculated.
2 is estimated to be the length of the defective portion 30R in the pipe thickness direction.

Next, the test conducted by the present inventor will be described.

(1) Test 1 Specimen: Defective part of a joint specimen consisting of SUS304L pipe 10 and Ti-5Ta pipe 20; depths of 0.5 mm and 1.0 mm from the inner surface of the pipe to the joint interface. 1.5 mm,
Artificial defects of 2.0 mm and 2.0 mm were made. Fatigue cracks propagated from the inner surface of the pipe by repeated axial load.

As the speed of sound, the speed of sound of water (Cw) is 1480 m / sec. The speed of sound of the pipe material of SUS304L (Cs ₁ ); 3260 m /
sec Ti-5Ta sound velocity of pipe material (Cs ₂ ); 3010 m / s
ec Joint thickness: 5 mm Focal length: 25 mm is given and substituted into the above formulas (1) to (3), L ₄₀ = 9.42 mm θ ₄₀ = 18.7 ° W ₄₀ = 8.02 mm L ₅₀ = 10. 62 mm θ ₅₀ = 20.3 ° W ₅₀ = 8.68 mm was obtained.

Table 1 shows the test results of the practice of the present invention.
The depth of the fatigue crack was determined by cutting the cross section.

[0033]

[Table 1]

As is clear from Table 1, the half-width is 1/2
The value of is very close to the size (length or depth) of the defect.

(2) Test 2 Table 2 shows that as shown in FIG.
The case where there is 0IN is shown.

[0036]

[Table 2]

As is clear from Table 2, the half-value width of 1
The value of / 2 is very close to the size (length or depth) of the defect.

(3) Test 3 Table 3 is a table showing an example of the result of the test conducted to detect the defect length of the internal defect of the joint having no insert material.

As the test piece, at the time of joining the joint used in Test 1, a release material was inserted into the joint surface, and inside the joint interface,
A circular artificial defect having a diameter of 1.0 mm and 2.0 mm was formed. The other conditions are the same as those in Test 1.

Table 3 shows the results of judgment on the central cross section of the circular artificial defect.

[0041]

[Table 3]

As is apparent from Table 3, the present invention is
The size of the internal defect of the joint can also be known.

By the way, if the internal defects of the joint are to be thoroughly inspected for the entire joint surface by the above-mentioned method, the joint surface is gradually moved along the joint surface while reciprocating in the direction perpendicular to the joint surface. , The distance to move the deep probe becomes long, and the time required for detection becomes long. By the way, the most important defect is a defect that reaches the surface, and this defect is easily detected, and the length from the surface of the defect is specified by moving the defect in the direction perpendicular to the bonding surface at the position of the defect. Is effective.

Based on such knowledge, the deep probe 40 in FIG. 1 is used for both incidence and reception, and a structure capable of detecting a defect by the reflection method by itself is constructed. A specific example thereof is shown in FIG. 7, in which the positional relationship between the first deep probe 140 and the second deep probe 150 is the same as in FIG. 1, and the first and second deep probe 140,
The selection of the posture and interval of 150 is similar to that described in FIG. However, it is different in that the first deep contactor 140 is used for both incidence and reception and is capable of detecting a defect reaching the surface by a reflection method. That is, the first deep contactor 14
When 0 is switched for incidence and the second deep probe 150 is switched for reception (first mode), the transmission method flaw detection in FIG. 1 is possible, and the first deep probe 140 is switched for incidence and reception. Second
When the deep probe 150 is switched off (second mode), the reflection method flaw detection by the first deep probe 140 becomes possible.

The first and second deep contactors 140 and 150 in FIG. 7 are switched to the above-described second mode and rotated along the joint surface 30 of the pipe material 10 as shown by an arrow α (circumferential direction of the pipe material). Then, the defect 30R reaching the surface can be detected.
The state is shown in FIG. It is assumed that there is no defect in the range of angle α1 → α2, there is a defect in the range of angle α2 → α3 → α4, and there is no defect in the range of angle α4 → α5. In the range where there is no defect, the intensity of the reflected wave received by the first deep probe 140 is substantially constant and does not change as shown by S in FIG. In the range where there is a defect, the intensity of the reflected wave received by the first deep probe 140 is as shown in FIG.
The protruding portion Q is detected like 0, and the existence of a defect reaching the surface can be specified by the existence of the protruding portion Q. Then, the position where the protrusion F is detected (angle α2 → α3 → α4 in FIG. 8) is detected.
Range), the first and second deep contactors 140, 150 are switched to the above-mentioned first mode, and as shown in FIG. 2, the first and second deep contactors 140, When the 150 is moved back and forth several times as necessary, the length from the surface of the defect 30R in FIG. 8 can be specified.

As described above, when the reflection method using one deep contact element and the transmission method using two deep contact elements are switched and used, first, the reflection method using one deep contact element along the joint surface ( Long flaws that cannot be identified by the reflection method by performing flaw detection in the circumferential direction and switching to the penetration method with two deep probes at the position where the flaw is detected, and by flaw detection perpendicular to the joint surface (axial direction when it is a pipe material). Can be specified by the transmission method. In this case, the movement of the deep probe is a combination of the movement along the joint surface and the movement perpendicular to the partial joint surface, which shortens the distance that the deep probe must move and is required for flaw detection. The time can be shortened.

By the way, the presence or absence of a defect can be detected by the change in the intensity of the reflected wave in FIG. 10, but the length from the surface of the defect cannot be specified. Although this length is determined by the transmission method, it has been found that the transmission method also has drawbacks. The transmission method is suitable for detecting the defect length in the thickness direction, but in the case of a short defect reaching the surface, it is difficult to specify the length. On the contrary, it was found that short defects reaching the surface can be detected by the above-mentioned reflection method.

In order to specify the defect length by the reflection method, a sample having the same shape is used, and the average intensity S of the reflected wave in the sound portion is used.
Is measured, and the ratio of the reflected wave intensity Q of the measured object to the average intensity S is calculated. Then, as shown in FIG. 11, when the defect depth D is shorter than the surface portion, D = a · Q / S + b
It can be seen that there is a measurable range in which the defect depth D can be detected by the linear expression.

That is, when the first deep contactor 140 is used for incidence / reception and a defect is detected in the reflected wave, it is compared with the average intensity of the reflected wave measured in the joint having no defect on the joint surface, and a predetermined measurement can be performed. The defect depth (length from the surface) within the range can be specified. However, if it exceeds the predetermined measurable range,
It becomes impossible to specify the defect depth by the reflection method (because of the sharp rise as shown in FIG. 11).

Therefore, when the defect detected by the reflection method exceeds a predetermined length, the first and second deep contactors 140, 150 of FIG.
Is switched to the first mode and brought into the state shown in FIG. Then, in the vicinity of the defect, as shown in FIG. 2, the first and second deep contactors 140, 15
The defect depth is specified by moving 0 in the direction perpendicular to the joint surface. As described above, when the defect depth is short, the defect position and the defect length are specified by the second mode reflection method, and when the defect depth is long, the defect length and the defect length are specified by the first mode transmission method. It is possible to detect the presence or absence of defects and their length in a short time.

Next, the present inventor has made the first and second deep contactors 14
A test in which 0 and 150 are used as the second mode reflection method to detect defects will be described.

(3) Test 3 Specimen: Specimen using a joint composed of SUS304L pipe 10 and Ti-5Ta pipe 20 Defective part of the test specimen;
Semicircular artificial defect portions of mm, 1.0 mm, 1.5 mm, and 2.0 mm were made. Ultrasonic wave incident side tube material: SUS304L (because of smaller acoustic impedance than Ti-5Ta)

As the speed of sound, the speed of sound of water (Cw) is 1480 m / sec. The speed of sound of the pipe material of SUS304L (Cs ₁ ); 3260 m /
sec Ti-5Ta sound velocity of pipe material (Cs ₂ ); 3010 m / s
ec Joint thickness: 5 mm Focal length: 25 mm was given and substituted into the above formulas (1) to (2) to obtain L ₄₀ = 9.42 mm θ ₄₀ = 18.7 ° W ₄₀ = 8.02 mm.

First, when flaw detection was performed by the reflection method in the second mode, a portion where the reflection intensity Q was higher than the average reflection intensity S was detected. From the angular range Δα where the reflection intensity is high, the width of the defect at each position (innermost surface of the tube) Wn
Was measured and compared with the defect width measured from the cut surface of the interface after the measurement. The results are shown in Table 4.

[0055]

[Table 4]

As is clear from Table 4, the interface defect on the inner surface of the tube can be simply measured by measuring the reflected wave while driving the deep contact element for both incident / reception (transmission / reception) of the second mode in the tube circumferential direction. It was confirmed that it can be measured.

Further, with respect to the above-mentioned defective portion, Table 5 shows the results obtained by switching the mode to the first mode, and determining the defect depth by the incident deep probe, the deep probe for reception and the transmission method.

[0058]

[Table 5]

As is clear from Table 5, the defect depth can be accurately measured by performing flaw detection in the first mode on the defect portion and applying the half-width ½.

(4) Test 4 As shown in FIG. 6, the same results as in Test 1 can be obtained when the insert material 301N is present at the joint interface. Also,
It was confirmed in advance that the following equation relating to the defect depth D was established in this experimental example from the verification curve shown in FIG. 11 using other jointed pipe joints. D = 0.87 × (Q / S) +0.65 Table 6 shows the measured defect depth and the artificial defect depth (measured after cross-section cutting) obtained by using this formula.

[0061]

[Table 6]

As is clear from Table 6, the defect depth can be measured by ultrasonic flaw detection by the reflection method within the predetermined measurable range shown in FIG.

[0063]

As described above, the invention according to claims 1 to 3 uses the intensity determination pattern, compares the measured transmitted wave intensity with the intensity determination pattern, and processes the comparison result to process the defective portion. Although the presence and the size are detected, a value extremely close to the size of the actual defect portion can be obtained. Moreover, since the attitude and the interval of the deep probe for incidence are moved while maintaining the specific attitude and interval, the drive system of the deep probe has the advantage of being a simple and practical drive system.

The invention according to claim 4 is as described above.
The first and second deep contactors are provided so as to be switchable between the reflection method and the transmission method, the first and second deep contactors are moved along the bonding surface, and the position of the defect is specified by the reflection method. Then, the first and second deep contactors are moved perpendicularly to the joint surface, the size of the defect is specified by the transmission method, and the movement of the first and second deep contactors is minimized to accurately detect the defect in a short time. Can be detected.

The invention according to claim 4 is as described above.
In view of the fact that the size of surface defects can be specified by the reflection method, the size of small defects on the surface is detected by the reflection method, the size of large defects from the surface to the inside is detected by the transmission method, and short defects from the surface are detected. There is an advantage that a wide range of defects ranging from to long defects can be accurately detected.

[Brief description of drawings]

FIG. 1 is a diagram showing postures and intervals of deep contactors used for implementing the present invention.

FIG. 2 is a diagram showing incident waves and transmitted waves of ultrasonic waves for explaining the present invention.

FIG. 3 is a diagram showing a determination method according to the present invention.

FIG. 4 is a diagram showing an example of a strength determination pattern in the present invention.

FIG. 5 is a diagram for explaining a method for obtaining the size of a defective portion.

FIG. 6 is a diagram showing postures and intervals of a joint and a deep contactor when an insert material is present on a joint surface.

FIG. 7 is a diagram showing postures and intervals of deep contactors used in another embodiment of the present invention.

FIG. 8 is a diagram showing an incident wave / reflected wave of an ultrasonic wave in another invention.

FIG. 9 is a graph showing another reflection intensity without defects in the present invention.

FIG. 10 is a graph showing another reflection intensity with defects in the present invention.

FIG. 11 is a graph for calculating a defect depth D according to another embodiment of the present invention.

FIG. 12 is a diagram for explaining ultrasonic deep scratches by a conventional transmission method.

[Explanation of Codes] 10, 20 Tubular Material 30 Joining Surface 30IN Insert Material 40 Injecting Deep Touch Element 50 Receiving Deep Touch Element 60 Ultrasonic Propagation Medium 140 First Deep Contact Element (Injection / Receiving) 150 Second Deep Contact Element (Receive)

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[Procedure amendment]

[Submission date] April 4, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Title of invention

[Correction method] Change

[Correction content]

Internal defects of the joint formed by joining dissimilar materials [Title of Invention] Ultrasonic methods

Claims (5)

[Claims] 1. An ultrasonic wave is incident from a surface of a joint in which members made of different kinds of materials are joined to each other through an ultrasonic wave propagation medium, a transmitted wave transmitted through the joint surface is received through the ultrasonic wave propagation medium, and is transmitted therethrough. In the ultrasonic wave deep damage to the defective part of the joint due to the wave intensity, (a) the deep probe for incidence and the deep probe for reception are each in a predetermined posture, and both deep probes are spaced at a predetermined distance. Strength judgment pattern created based on the intensity of the transmitted wave measured by a joint having no defect on the joint surface. (C) The size of the defective portion is detected based on the distance between the deep contact positions where the intensity of the measured transmitted wave is equal to or less than the intensity of the intensity determination pattern. Internal flaw ultrasonic deep scratching method for joints joined together. 2. The predetermined posture is a posture obtained based on the sound velocity of both members and the sound velocity of the ultrasonic propagation medium, and the predetermined intervals are the sound velocity of both members, the sound velocity of the ultrasonic propagation medium, and the deep contact. The method of claim 1, wherein the distance is determined based on the focal length and the joint plate thickness of the joint. 3. The internal defect of the joint in which dissimilar materials are joined according to claim 1, wherein the strength of the strength judgment pattern is 1/2 of the transmitted wave intensity measured in the joint having no defect in the joint surface. Ultrasonic deep trauma method. 4. An ultrasonic wave which injects an ultrasonic wave from the surface of a joint in which members made of different materials are joined to each other through an ultrasonic wave propagation medium and then receives the ultrasonic wave through the ultrasonic wave propagation medium to deeply scratch a defective portion of the joint. Sonic deep scars, in which the first deep contactor for both incidence and reception and the second deep contactor for reception are kept in predetermined postures and both deep contactors are held at predetermined intervals, and (a) the above 1. The first and second deep contactors are moved in parallel with the joint surface, the reflected waves of the ultrasonic waves incident on the first deep contactor are received by the same first deep contactor, and the intensity of the reflected wave causes a defect. (B) When a defect is detected, the first and second deep contactors are moved in a direction perpendicular to the joint surface to transmit the ultrasonic waves incident on the first deep contactor. A wave is received by the second deep probe and the magnitude of the defect depth is detected from the intensity of the transmitted wave. Internal defects ultrasonic Fukakizu method of the joint formed by joining wood. 5. An ultrasonic wave which injects an ultrasonic wave from the surface of a joint in which members made of different materials are joined to each other through an ultrasonic wave propagation medium and then receives the ultrasonic wave through the ultrasonic wave propagation medium to deeply scratch a defective portion of the joint. Sonic deep scars, in which the first deep contactor for both incidence and reception and the second deep contactor for reception are kept in predetermined postures and both deep contactors are held at predetermined intervals, and (a) the above 1. The first and second deep contactors are moved in parallel with the joint surface, the reflected waves of the ultrasonic waves incident on the first deep contactor are received by the same first deep contactor, and the intensity of the reflected wave causes a defect. And (b) when a defect is detected, the defect depth from the surface is detected by comparing with the reflected wave measured at the joint where the joint surface has no defect. When the value exceeds a predetermined value, the first and second deep contactors are moved in a direction perpendicular to the joint surface, and the first deep contactor is inserted. The internal depth of ultrasonic wave of a joint in which dissimilar materials are joined is characterized in that the transmitted wave of the ultrasonic wave is received by the second deep probe and the magnitude of the defect depth is detected from the intensity of the transmitted wave. How to scratch.