JPS59153167A - Method of testing welding section of multilayer joining structure by ultrasonic wave - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to ultrasonic defect testing techniques, and more particularly to a method for ultrasonically testing welds in multilayer bonded structures, such as lap joints in structures such as pressure vessel cans.

The single-echo technique uses a transceiver probe to detect defects by a decrease in the intensity of the wall echo (tk), transmitting ultrasonic energy through the lap joint to be tested from the face of the bottom plate (weld The ultrasonic testing method is known (Kiev).

'l'ekhnika publishers, A
, K., Gurvich, N., Lipidemia 1ov
Author: [Jltrazvukovoi control
5varnykh 5hvov-Ultrasonic test of welded parts-
(See page 347).

With such a method, it is possible to detect cracks, insufficient melting of the weld root, single foreign objects or collections thereof. Laterally extending defects caused by insufficient melting are
This is detected by placing the transmitting probe and receiving glove on the same side of the test specimen and observing the overall decrease in the intensity of the back wall echo.

In order to fully transmit the ultrasonic vibrations throughout the weld metal, the lateral legs must move the entire globe perpendicular to the weld along equal paths.

As is clear from the above description, such a method is complex and therefore not reliable enough.

A simple method has been proposed for testing welds with shear waves by placing two probes with equal beam angles on both sides of the entire tested weld so as to fully transmit the ultrasonic vibrations (Krautkramer GmbH, Sch-W).
eil/rXaht-Pr'ufanlageTyP
5NUP-Q VA-8O5-381).

However, this method cannot test welds, such as multilayer bonded structures, where the bath contact depth exceeds the thickness of the plate layers. Lap joints bath welded by the two-arc method (using CO2 arc and submerged arc processes) are formed by welding two weld layers, referred to as the bottom layer and the top layer. The lower layer has a full penetration depth extending over two plates, but the upper layer's penetration depth does not extend beyond one plate, and the upper layer is wider than the lower layer, so the lower layer Overlap.

Because the metal sheets are loosely rolled, large gaps (δ>1.511121) may be present between the sheets, which are not weld defects but reflect ultrasonic vibrations. Dad, while welding the upper layer, slag may flow into the gap between the sheets.

A large gap between the sheets may lead to an excessive number of defects and ultimately cause unreliability of the testing process due to the presence of gaps in the test area.

The present invention provides a method for testing all welds of a multilayer bonded structure using ultrasonic waves, and provides a method that can completely improve the reliability of testing welds that vary in shape.

According to the present invention, ultrasonic vibrations are generated on both sides of the welded part in test l1li+2, and echoes from the defective part are received,
In a method of ultrasonically testing a weld of a multilayer bonded structure in which it is determined by these echoes whether the m-junction is defective, a shear wave is generated on one side of the bath weld, while the weld A method is provided which is characterized in that it generates a Lamb wave on the other side.

By combining all of these types of ultrasonic waves, ultrasonic energy can be transmitted throughout the weld simultaneously.

This is because we know that generating only shear waves in the weld area cannot detect defects along the weld throughout the weld, and the ultrasonic vibrating beam that generates the shear waves has a dead zone along its path. 〃λ et al.

When carrying out the entire method of the present invention, shear ultrasonic waves are generated at a distance from the weld that is substantially twice the distance between the position where the Lamb waves are generated and the weld, and the shear ultrasonic waves are It receives all the signals sent through the weld during the nozzle, compares this signal with a reference signal, and measures the distance between the transducer and the weld based on the comparison result.
It is preferable.

In this way, interference between the channels of the ultrasound system and the parameters of the test process and dead zones is eliminated, thereby increasing the reliability within lx.

The method of the present invention for ultrasonically testing the entire weld of a multilayer bonded structure will become clear from the following description in conjunction with the accompanying drawings. Two ultrasonic probes are installed at the beginning of the weld for all test samples, and the distance between these probes and the weld is L2 = 2.
Maintain at L1. These gloves are then moved along the weld at a constant speed. At this time, the beam angle is, for example, α
1-49° glove.

11, ultrasonic vibrations are generated intermittently in the welded portion consisting of the overlapping metal sheets and two layers, the upper layer 13 and the lower layer 14. When a substantial gap between the sheets enters the path of the glove, a corresponding signal 8 is generated. In order to ensure that defects in the sheetra winding process do not affect the test results, the test zone is
is set to 2/3 of the width of the bath contact area. In this case, the globe 11 generates Lamb waves in the metal sheet so that the ultrasonic vibrations are fully transmitted to the entire welded part.

In order to test parts of the weld that cannot be tested by the glove 11, for example, weld L2 = 1201111
A shear wave is generated and used by another globe 12 placed at a distance of . The beam angle of this probe 12, that is, the angle at which the vibration wave enters the metal, is α2 near 4°.
, which is close to the second critical value. This serves as a test for only the upper layer of the weld.

In this case, in order to further improve the reliability of the test of the weld, the test zones 4 and 6 are made to be KM relative to each other.

In order to fully monitor the bond between the glove and the test sample, signals 7 and 9 representing such bond are discriminated. These signals are useful for monitoring the accuracy of the weld scan. If these signals 7 and 9 move away from the discrimination zones 5 and 1o, i.e. if a change occurs after comparison with the reference signal, then the accuracy of scanning over the weld by the acoustic device including the glove is reduced; In other words, the distance relationship between both probes and the bath contact portion has changed.

Once the test operation is complete, the probe is returned to the starting position and is ready for the next test cycle.

Before performing ultrasonic defect testing of multilayer structures, it is necessary to align the test zone and sensing zone. Ultrasonic probes 11 and 12 are L1=60+m+ and L
2=12011111 on the sample 16. In order to confirm the gate signal 6 which defines the test zone of channel no. It will be done. The echoes reflected from this reflective surface define the starting point of the test zone 6. The edge of the gate signal is defined relative to the vertical hole or test reflector 15 for adjusting the sensitivity of the test.

The same sample is used when determining the gate signal 4't for determining the control zone of channel No. 2.

Awn diameter 14 manufactured by winding a metal strip
The entire method of the present invention was used to test a longitudinally welded lap joint of a multilayer iron having a length of 20 mm and a length of 1,620,111 mm. The wall of the iron was 16.8 ml thick and consisted of four layers, each layer having a thickness of 4.1-. The four 7F tubes were assembled to form a gas pipe with a length of 11.6FFL, and were designed to have an operating pressure of 75 atmospheres.

α1=49°, fl=1, 8MHz, α2=74
°, f2 =2. ) Two ultrasonic waves with characteristics mz,
A test speed of 20 m/a was achieved using a rope. These probes moved along the entire weld. The frequency of the transmitted pulse was 1000 Hz, and the echo from the defect and the signal representing the coupling between the probe and the sample were discriminated as shown in FIG. 1Th” of the test on the entire welded part
To increase reliability, L”1 = 60 on both sides of # junction
m.

Two probes were placed at a distance of L2 = 12011" (ratio of 1: 2) so that both Lamb waves and shear ultrasound could be generated. The first probe of these two probes (α1 = 4 '9'') is tested up to 2/3'k of the upper layer closest to the probe and the entire lower layer to a depth greater than the thickness of one sheet, and the other glove (α-7
4°), the entire upper layer of the weld was tested.

To scan the weld along a predetermined path, a signal representing all probe-to-probe connections is compared with a reference signal 1-
1. That is, the change in the relationship between the distances from both probes to the weld as the test progresses was determined by the deviation of the reference signal from the discrimination area. When the present invention is implemented, it is possible to reduce excessive failure judgments due to large gaps between sheets, and to use waves of 21 fif per layer in the welded part. The reliability of ultrasonic testing for defects in lap joints of multilayer pipes is improved because the test is performed to detect micro defects, large defects, and stacked defects in various orientations.

In the above method, interference between the channels of the ultrasound system and the test parameters is eliminated by placing the probes at a distance in a substantially 1:2 relationship. Therefore, the reliability of the test is improved. The problem is that the signals 7 and 9 representing the coupling may move to such an extent that the test sheets 74 or 6 are judged as bad. Furthermore, it is possible that some parts of the welded joint are not tested by the shear wave (globe 12) and thus some defects are not detected. Therefore, the distance relationship described above ensures the maximum signal-to-noise ratio for each channel and takes into account the noise that occurs in the gaps between the sheets.

The above description is for a weld width of 276.

This is because the weld is constructed such that the center of the lower layer is even separated from the center line of the upper layer (FIGS. 1 and 2). Therefore, in order to reduce the possibility of repeated failure judgments due to large gaps between sheets, the probe 11 does not scan the test zone in the lateral direction, but rather scans the test zone temporally. The case is fully opened so that all of the ultrasonic energy is transmitted by Lamb waves in one bath to the 276 welding sections in the vicinity of the probe. When only shear waves are generated in the weld zone, a dead zone commonly occurs along the propagation path of this ultrasonic beam, making it impossible to detect all defects in the entire weld along the entire length of the weld. . For this reason, it is preferable to test 2/6 of the width of the entire lower layer and upper layer using Lamb waves, but for the remaining 1/11, it is sufficient to use shear waves.

Depending on the composition of the metal to be tested, the thickness of the metal layer, and the operating characteristics of the ultrasonic defect detector used, a maximum ratio of 1:2 may be achieved without any loss in signal-to-noise ratio and test reliability. and may be varied to a certain extent towards the minimum ratio.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a welded joint of a multilayer bonded structure tested by the method of the present invention, and FIG. 2 is a cross-sectional view of a welded joint of a multilayer bonded structure similar to that shown in FIG. This is a ward that will fully explain where it is used. 4.6...Test zone 5,1o...Discrimination zone 1
1.12...Glove 16...Upper layer 14...Lower layer 15...Vertical hole 1 E2 Petrovsky Soviet Union, Kiev-Ulitsa, Trudvik Reserve-Off 56 Vy Cavy 4 0 Inventor Vladimir Aleksandrovich TroikkiSoviet UnionKiev Ulitsa Sapernoye Pol26EiKevy600 Inventor Vladimir Teimovyevich
Bobrov Soviet Union Kishinev-Ulitsa, Belskogo 34-1 Kev 117 0 Inventor Mikhail Iosifovytsch Meisenberg Soviet Union Kishinev-Ulitsa Munchestskaya 116 Kev 42

Claims (1)

[Claims] (1) Welding of multilayer bonded structures in which ultrasonic vibrations are generated on both sides of the weld to be tested, receive echoes from the defective part, and judge whether the weld is defective by these echoes. A method of testing a welded part using ultrasonic waves, which method is characterized in that a shear wave is generated on one side of the welded part, and a lamb wave sound is generated on the other side of the welded part. Q) The shearing ultrasonic wave is generated at a distance from the weld that is substantially twice the distance between the Lamb wave tube generation location and the weld, and is transmitted through the weld during a predetermined time interval. Claim O(1): receiving a signal, comparing it with a reference signal, and determining the total distance between the transducer and the weld by the result of the comparison.
The method described in section.