JPH05288722A - Method for ultrasonic examination of sheet defect - Google Patents

Abstract

PURPOSE:To obtain a method for ultrasonic examination which detects precisely a sheet defect such as a crack or a lack of penetration occurring in the direction of the thickness of a welded part of a welded structure such as an offshore structure or a land structure. CONSTITUTION:Two angle probes made up of a longitudinal wave angle probe 4a for transmission and an angle probe 4b for reception are disposed on one side of a welding line 2a on the surface of an object 1 of inspection so that they are not located on the same line as the direction vertical to the welding line 2a. A longitudinal wave 5 transmitted from the longitudinal wave angle probe 4a strikes on a sheet defect 3 in the thickness direction and then strikes on the rear 1b of the object 1, and a wave 5a converted in a mode from the longitudinal wave 5 into a lateral wave on this rear is received by the angle probe 4b, and thereby the sheet defect 3 is detected precisely.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to ultrasonic waves for accurately detecting surface defects such as cracks and poor penetration that occur in the thickness direction of welded portions of welded structures such as marine structures and land structures. Regarding flaw detection method.

[0002]

2. Description of the Related Art Conventionally, a single probe method as shown in FIG. 9 may be used to detect a planar defect such as a vertical crack that occurs in the thickness direction. In FIG. 9, 1 is an inspection object, 1a is a flaw detection surface, 2 is a welded portion, 2a is a welding line, 3 is a defect, and 4 is an oblique probe. However, the received sound pressure of the ultrasonic wave in the one-probe method is the largest when the ultrasonic wave is incident from the direction perpendicular to the defect surface, so that in the case of a planar defect generated in the thickness direction, Has a drawback in that the received sound pressure cannot be high because it is difficult to inject ultrasonic waves perpendicularly to the defect surface. In addition, the same mode parts in the following drawings will be described using the same reference numerals.

As a method other than the one-probe method described above, there is a method in which transmission and reception are divided as in the invention of Japanese Patent Laid-Open No. 54-140586. However, in the vertical probe, welding is performed due to excess welded portions. There is a drawback that it is difficult to detect vertical cracks in metal.

Therefore, the tandem flaw detection method shown in FIG. 10 is often used as a method of dividing the transmission and reception using the bevel probe, and the transmission probe and the reception probe are orthogonal to the welding line. The flaws are detected by arranging them on the same line in the same direction.

However, in this tandem flaw detection method,
As shown in FIG. 11, in a thin test piece, two probes interfere with each other, so that the transmitting / receiving position can be approached only a certain distance, and thus the conventional tandem flaw detection can be performed on the inspection object. There was a drawback that the wall thickness was limited.

Furthermore, when it is desired to set the transmitting and receiving probe arrangements to the opposite positions, there is a drawback that the setting cannot be done only by scanning the probe forward and backward, and the front and rear arrangements cannot be easily reversed. ..

Further, coarse columnar crystals of austenite structure are generated, such as austenitic stainless steel welds or welds in which the base metal is 9% Ni steel and the weld contains about 70% Ni. In such a material, a longitudinal wave is used because the attenuation of ultrasonic waves in the material is large.
In this case, the conventional tandem flaw detection method using the transverse wave 5a is not effective because the attenuation of ultrasonic waves in the material is large.
Longitudinal wave 5 transmitted from the surface of the inspection object as shown in 2
After hitting the defect, a method of receiving the mode-converted wave from the longitudinal wave 5 to the transverse wave 5a on the back surface is conceivable. In this case, however, it is necessary to dispose the probe closer than the tandem flaw detection. However, there is a drawback that the inspectable range 7 is limited.

On the other hand, the two-transducer bevel probe has a structure in which transmission and reception are divided into left and right, and a flaw detection method using this probe is a defect echo directly reflected from a defect. Only the observation method is implemented, and it is not applied to a method such as tandem flaw detection in which the propagation path of the ultrasonic wave from the transmission to the defect and the propagation path of the ultrasonic wave from the defect to the reception unit are different. Therefore, even if we consider applying the two-transducer probe to a method such as tandem flaw detection in which the outward path and the return path to the defect are different, the placement of the oscillators in the transmitter and the receiver will improve the reception efficiency of the defective echo. It is probable that there were some drawbacks such as not placing them.

Alternatively, as shown in JP-A-02-63441 and JP-A-02-63442, a three-dimensional transducer is used to form a single vibrating element group in a three-dimensional manner. Although there is a device for the purpose of obtaining information, this type of array-type probe requires a large number of transducers, and when the target defect size is small, 1
It is not possible to increase the size of each transducer and transmit a sufficient sound pressure level with a material that has a large attenuation in the material of ultrasonic waves, or the degree of freedom of placement of the transducer is low, or advanced signal processing of collected data However, there is a drawback in that it becomes a high-cost device and cannot be widely applied to welded parts.

An object of the present invention is to provide an ultrasonic flaw detection method for accurately detecting a surface defect such as a crack or a penetration defect which occurs in the thickness direction of a welded portion.

[0011]

An ultrasonic flaw detection method according to the present invention is a tandem flaw detection method or an inspection object as a method for detecting a planar defect in a thickness direction such as a vertical crack that occurs substantially parallel to a welding line direction. After the longitudinal wave transmitted from the longitudinal wave bevel probe placed on the surface of the object hits the defect and hits the back surface, the wave on the back side that has undergone mode conversion from longitudinal wave to transverse wave is detected by the bevel probe on the receiving side. 2 In the probe method, transmission 1
The transducers of the transmitter and the receiver are high from the defect so that the two bevel transducers consisting of one receiver and one receiver are not on the same line on one side of the weld line in the direction perpendicular to the weld line. This is a method of detecting the planar defects generated in the wall thickness direction by arranging and holding them individually or by an integrated frame so as to obtain reception efficiency, or by scanning.

[0012]

According to the present invention, after the longitudinal wave transmitted from the surface of the object to be inspected hits the defect, the method of receiving the mode-converted wave from the longitudinal wave to the transverse wave on the back surface or the tandem flaw detection method, the transmission 1 In order to dispose two beveled probes each consisting of one and one receiving unit on one side of the welding line so as not to be on the same line with respect to the direction perpendicular to the welding line, this is a conventional technique.
1 and 12 as compared with the case where the individual probes are arranged front and back.
As is clear from the comparison of the inspectable range of, the inspectable range can be wide.

Particularly, in the case of a thin test piece, when two probes are arranged in front and back on the same line perpendicular to the welding line,
Since the two probes interfere with each other, the transmission / reception position can be approached only a certain distance. However, by arranging the two probes in the left / right direction instead of the front / back direction, the range of possible inspections can be expanded. You can

Further, when the two probes are arranged in front and rear on the same line, it is impossible to easily set the transmitting and receiving probe arrangements to opposite positions, but the two probes are the same. When the probe is arranged so as to be displaced from the line, the front-rear relationship with respect to the weld line can be easily reversed by scanning the probe in the weld line direction.

When it is desired to scan two probes at the same time, the two probe arrangements can be fixed to an integral frame in accordance with the target defect to facilitate scanning.

Further, since they are not arranged front and back on the same line, one or both of the probes can be freely scanned in order to obtain a high received sound pressure from the defect to improve the defect detection capability. Is possible.

Further, since the bevel probe is used,
As compared with the vertical flaw detection method in which flaws are detected from above the weld metal surplus, a high received sound pressure can be obtained without being affected by the surface transmission loss due to the surplus shape.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIGS. 1 (a) and 1 (b), the welded portion 2 of the inspection object 1 has a planar defect 3 in the thickness direction such as a vertical crack that occurs substantially parallel to the welding line 2a direction. There is. A longitudinal wave bevel probe 4a is provided on the surface 1a of the inspection object 1, and a bevel probe 4a is arranged at a position deviated from the same line.
In the flaw detection method of the present invention, the longitudinal wave 5 transmitted from the longitudinal wave bevel probe 4a hits the back surface 1b after hitting the defect 3, and the back surface 1b is mode-converted from the longitudinal wave 5 to the transverse wave 5. This is a two-probe method in which the transverse wave 5a is detected by the oblique-angle probe 4b on the receiving side. That is, 2 consisting of 1 transmission and 1 reception
An ultrasonic flaw detection method for arranging individual bevel probes on one side of the welding line 2a so as not to be collinear with the direction perpendicular to the welding line 2a and detecting planar defects generated in the thickness direction. Is.

In the limit of the back surface side of the inspectable range 7, the two probes do not interfere with each other as compared with the case where the probes are arranged on the same line at right angles to the welding line 2a. Can be taken (see comparison between FIG. 1 and FIG. 12). That is, as shown in FIG. 1 (b), even if the longitudinal wave bevel probe 4a reaches the toe position A of the welding bead, the longitudinal wave 5 is also reflected at the back surface 1b at the welding bead stop position. Even if it comes to the position B which comes to the end, since the two probes are not on the same line, the receiving probe is put in a predetermined position independently of the transmitting probe, and this is converted into a transverse wave mode. This is because the received waves can be received. As a result, it becomes possible to accurately detect the planar defect. In addition, as the transducer size at this time, a rectangular transducer size that is long in the up-down direction and short in the left-right direction is adopted, and the directivity in the thickness direction of ultrasonic waves is sharp and the directivity in the left-right direction is made dull. It is also possible to set the directivity.

In FIG. 2, in the above-mentioned transmitting and receiving probes 4a and 4b, the probe having a structure in which the transmitting part and the receiving part are fixed to the integral frame 6 is used to generate in the thickness direction. 3 shows an ultrasonic flaw detection method for detecting a surface-shaped defect.

In the probe arrangement described above, FIG. 3 shows the sound from the defect 3 with the transmitting and receiving probe 4a and the receiving probe 4b both transmitting and receiving ultrasonic waves toward the defect 3. An ultrasonic flaw detection method is shown in which the angle of incidence of ultrasonic waves on the welding line 2a and the distance to the welding line 2a are adjusted so as to obtain a high pressure, and the planar defects 3 generated in the thickness direction are detected. ..

In the probe arrangement described above, in FIG. 4, the probe on the receiving side 4a and the transmitting side 4b, or either one of them is used as a welding line in order to obtain a high received sound pressure from a defect. An ultrasonic flaw detection method is shown in which scanning is performed in the orthogonal direction X or the ultrasonic wave incident direction Y to detect the planar defects 3 generated in the thickness direction.

In FIG. 5, in the tandem flaw detection method, which is a method of detecting a planar defect 3 such as a weld crack generated in the thickness direction, two beveled probes each including one transmitter and one receiver. 4a and 4b are arranged on one side of the welding line 2a so as not to be collinear with the direction perpendicular to the welding line, and the incident angle of the ultrasonic wave to the welding line 2a and the distance to the welding line are set to predetermined values. , An ultrasonic flaw detection method for detecting a planar defect 3 generated in the thickness direction is shown.

In FIG. 6, in the transmitting and receiving probes 4a and 4b described above, a probe having a structure in which the transmitting portion and the receiving portion are fixed to the integral frame 6 is used to generate in the thickness direction. The ultrasonic flaw detection method for detecting the planar defect 3 is shown.

In FIG. 7, in the probe arrangement described above, both the transmitting and receiving directions of ultrasonic waves of the transmitting probe 4a and the receiving probe 4b are directed to the defect 3, and the sound pressure from the defect is set. In order to obtain a high defect rate, an ultrasonic flaw detection method for detecting the planar defect 3 generated in the wall thickness direction by adjusting the incident angle of the ultrasonic wave to the welding line 2a and the distance to the welding line is shown.

In FIG. 8, in the probe arrangement described above, the receiving side 4a is arranged so that a high sound pressure from a defect can be obtained.
And an ultrasonic flaw detection method for detecting a planar defect 3 generated in the wall thickness direction by scanning the probe on the transmitting side 4b or on either side in the direction X orthogonal to the welding line 2a or in the ultrasonic wave incident direction Y. Shows. Obviously, the aspects of the present invention are not limited to the above-mentioned aspects.

[0027]

According to the present invention, after the longitudinal wave transmitted from the surface of the inspection object hits the defect, the method of receiving the mode-converted wave from the longitudinal wave to the transverse wave on the back surface, or the tandem flaw detection method, In order to arrange two bevel transducers, one transmitting and one receiving, on one side of the welding line so as not to be on the same line with respect to the direction perpendicular to the welding line, it is necessary to use two of the conventional techniques. As can be seen from the comparison of the inspectable range in FIG. 1 and FIG.
The inspectable range can be widened in the thickness direction. In particular, in the case of a thin inspection body, when two probes are arranged in front and back on the same line perpendicular to the welding line, the two probes interfere with each other, so that the transmission / reception position is kept at a constant distance. However, by arranging the two probes in the left-right direction instead of the front-back direction, the practicable inspection range can be expanded.

Further, when the two probes are arranged in front and rear on the same line, it is impossible to easily set the transmitting and receiving probe arrangements to opposite positions, but the two probes are the same. When the probe is arranged so as to be displaced from the line, the front-rear relationship with respect to the weld line can be easily reversed by scanning the probe in the weld line direction.

Further, since they are not arranged front and back on the same line, one or both of the probes can be freely scanned in order to obtain a high received sound pressure from the defect, thereby improving the defect detection capability. Is possible.

Furthermore, since the bevel probe is used, compared to the vertical flaw detection method in which flaws are detected on the weld metal overfill, the received sound is not affected by the surface transmission loss due to the overfill shape, and the received sound is high. The pressure is obtained.

[Brief description of drawings]

1A and 1B are a plan view and a sectional view of a first embodiment according to the present invention.

2A and 2B are a plan view and a sectional view of a second embodiment according to the present invention.

3 (a) and 3 (b) are a plan view and a sectional view of a third embodiment according to the present invention.

4A and 4B are a plan view and a sectional view of a fourth embodiment according to the present invention.

5 (a) and 5 (b) are a plan view and a sectional view of a fifth embodiment according to the present invention.

6A and 6B are a plan view and a sectional view of a sixth embodiment according to the present invention.

7 (a) and (b) are a plan view and a sectional view of a seventh embodiment according to the present invention.

8A and 8B are a plan view and a sectional view of an eighth embodiment according to the present invention.

FIG. 9 is an explanatory diagram of a conventional single probe method.

FIG. 10 is an explanatory diagram of a conventional tandem flaw detection method.

FIG. 11 is an explanatory diagram showing that the front and rear probes interfere with each other when the conventional tandem flaw detection method is arranged in the front and rear, and thus flaw detection cannot be performed.

12 (a) and 12 (b) are explanatory views of a flaw detection method using two probes using longitudinal waves, and an explanation that the inspection area is limited because the probes are arranged in front and behind. It is a figure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Object to be inspected 1a ... Detection surface 2 ... Welding part 2a ... Welding line 3 ... Defect 4 ... Bevel probe 4a ... Bevel probe for transmission 4b ... Bevel probe for reception 5 ... Longitudinal wave ( Ultrasonic wave 5a ... transverse wave (ultrasonic wave) 6 ... integral frame 7 ... inspectable area

Front page continued (72) Hideyuki Hirasawa, Inventor Hideyuki Hirasawa, 3-1-1 Higashikawasaki-cho, Chuo-ku, Kobe-shi, Hyogo Kawasaki Heavy Industries, Ltd.Kobe factory (72) Takehito Yamakawa 8 Niijima, Harima-cho, Kako-gun, Hyogo (72) Inventor Yutaka Senda 8th Niijima, Harima-cho, Kako-gun, Hyogo Prefecture Kawasaki Heavy Industries, Ltd. Harima-factory

Claims (8)

[Claims] 1. On the surface of an object to be inspected, two oblique-angle probes consisting of one transmitting longitudinal wave probe and one receiving probe are provided on one side of the welding line and perpendicular to the welding line. The longitudinal wave transmitted from the longitudinal wave bevel probe hits the surface defect in the thickness direction after hitting the planar defect in the thickness direction, and is arranged so as not to be on the same line with respect to the direction. By receiving the wave mode-converted from the wave to the transverse wave by the bevel probe,
An ultrasonic flaw detection method for a planar defect, which comprises detecting the defect. 2. The planar defect generated in the thickness direction is detected by using a probe having a structure in which a transmitting and receiving probe is fixed to an integral frame. Ultrasonic flaw detection method for surface defects. 3. An angle of incidence of ultrasonic waves on a welding line so that both the transmitting and receiving directions of ultrasonic waves of a transmitting probe and a receiving probe are directed to a defect so that a high sound pressure can be obtained from the defect. The ultrasonic flaw detection method for a planar defect according to claim 1, wherein the planar defect generated in the thickness direction is detected by adjusting the distance to the welding line. 4. The probe on the receiving side and / or the transmitting side is scanned in a direction perpendicular to the welding line or in an ultrasonic wave incident direction so that a high received sound pressure from the defect can be obtained.
The ultrasonic flaw detection method for a planar defect according to claim 1, wherein a planar defect generated in the thickness direction is detected. 5. In the tandem flaw detection method, which is a method for detecting planar defects such as weld cracks that occur in the thickness direction, two bevel probes, one transmitting and one receiving, are used for welding lines. Arranged on one side so as not to be collinear with the direction perpendicular to the welding line, set the incident angle of the ultrasonic wave to the welding line and the distance to the welding line to a predetermined value, and the surface condition generated in the thickness direction Ultrasonic flaw detection method for planar defects, which is characterized in that 6. A probe for transmission and reception, wherein a probe having a structure in which a transmitter and a receiver are fixed to an integral frame is used.
The ultrasonic flaw detection method for a planar defect according to claim 5, wherein a planar defect generated in the thickness direction is detected. 7. The angle of incidence of ultrasonic waves on the welding line so that both the transmitting and receiving directions of ultrasonic waves of the transmitting probe and the receiving probe are directed to the defect so that a high sound pressure can be obtained from the defect. The ultrasonic flaw detection method for a planar defect according to claim 5, wherein the planar defect generated in the thickness direction is detected by adjusting the distance to the welding line. 8. In order to obtain a high sound pressure from the defect,
6. The planar defect generated in the thickness direction is detected by scanning the probe on the receiving side and / or the transmitting side in a direction perpendicular to the welding line or in the ultrasonic wave incident direction. An ultrasonic flaw detection method for the surface defect described.