SU1422138A1 - Method of checking the quality of welded joints - Google Patents

Description

(21) 4213910 / 25-28

(22) 03/23/87

(46) 09/07/88. Bnsh. 33

(71) Institute of Electric Welding named after E.O. Paton

(72) A.R. Donin and V.A. Troitsky

(53) 620.179.16 (088.8)

(56) USSR Copyright Certificate 567128, cl. G 01 N 29/04, 1977.

U.S. Patent 3,965,726, cl. G 01 N 29/04, 1976.

(54) METHOD FOR MONITORING THE QUALITY OF WELDED CONNECTIONS

(57) The invention relates to

non-destructive quality control of welded joints, in particular, to acoustic emission control. The aim of the invention is to improve the reliability of quality control of a welded joint. The method of quality control of welded joints is that the number of AE pulses with an amplitude exceeding the average level of 4-5 times is recorded and measured during welding, cooling and loading, the obtained numbers are compared and the quality of the welded compounds.

 to to

with

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The invention relates to non-destructive quality control of materials and products by measuring acoustic emission parameters (AE) and can be used to control welds of pipes, pressure vessels, welded structures during their manufacture.

The aim of the invention is to increase the reliability of quality control of a welded joint.

In the proposed method, as the parameters of the AE, measure 9t the number of AE pulses with amplitude, which exceeds the average amplitude by no less than four times. Measurement of the number of AE pulses is carried out in the process of heating, cooling to a temperature of 10 ° C, and subsequent loading of the welded joint to the level adopted during the control of the reference joint. They compare the obtained numbers and judge by their ratio about the quality of the welded joint.

If a

 N, 15.3; , it is considered that there are developing defects in the welded joint, if

N. N.jX3; NjCB,

It is considered that the welded joint is of high quality, where NJ, N, N3 is the number of AZ pulses of the chosen amplitude, respectively, in the process of heating, cooling and loading.

The method is carried out by the following

in a way.

The AE converter is installed in the immediate vicinity of the welding zone (at a distance of 30-40 cm so that the temperature at the point of reception of AE signals does not exceed). The sensitivity of the equipment is chosen in such a way that the signal from a simulating shock at a distance of 0.7 from the transducer. m recorded on the recorder pulse with an amplitude not exceeding 0.1 of the scale of the recorder (a simulated blow can be a light tapping of a metal object on the surface of the seam or a ball hit from a certain height, or an ultrasonic pulse introduced into the metal using an ultrasonic radiator).

In the process of welding, the amplitude of the AE signals was recorded (using serial devices AF-11, IAS or Lribor AF-15 during operation

five

)

5 0 5

0

.

,

five

channel version) at the previously selected sensitivity. If the amplitude of the AE signals is large (equal to or greater than the scale of the recorder), the sensitivity is reduced until the average level of the AE signals becomes equal to 0.1-0.2 of the scale of the recorder. After recording the amplitude of AE signals, the number of AE pulses with an amplitude exceeding the average level of AE signals is counted several times (at least 4-5 times).

After the end of welding, the AE converter is installed in the center of the weld at some distance from it so that the temperature at the point of reception does not exceed. . The sensitivity of the equipment is chosen so that the signal from the imitating impact produced at the end of the weld is recorded on the recorder with a pulse of amplitude not exceeding 0.1 of the scale of the recorder. The AE signals (their amplitudes) are recorded until the temperature of the weld is 110 t. Count the number of AE pulses with an amplitude that exceeds the average level of AE signals at least 4–5 times.

Then, the amplitude of the AE signals is recorded in the Load Process of the welded product. As a rule, any type of loading is included in the production cycle of the product, for example, hydrostatic loading during the production of large-diameter pipes.

The required level of loading and its duration are pre-determined. For this, a reference article with a known defect, for example a crack, is tested. The load level at which the crack begins to develop and emit AE signals is considered sufficient to test serial products. To clarify the required level of loading, several reference products with different cracks are tested. At the same time, the sensitivity of the equipment should be such that at a load level slightly lower than selected, the AE signals are insignificant (the amplitude does not exceed 0.1 of the recorder scale). Writing the amplitude of the AE signals at the selected load, count the number of pulses with an amplitude exceeding the average

314

level not less than 4-5 times. They compare the obtained numbers and judge by their ratio about the quality of the welded joint.

Claims (1)

Invention Formula The method of quality control of welded joints, which consists in the fact that in the process of welding and cooling, acoustic emission signals are recorded and, according to their parameters, the quality of the welded joint is judged, which is so that, in order to increase the reliability of control. after cooling, the weld is additionally loaded, and as parameters, the numbers N, Nj, Nj of acoustic emission pulses are measured with an amplitude exceeding the average volume by 4-5 times, respectively, in the processes of welding, cooling the ground to temperature t and loading, and. , if a N 7 Nj. 3; N, 7, 3. define the welded joint as defective, and in case N, .Nj O; N, 3. weld is defined as quality.