Method of automatic argon arc welding of steel pipes by non-melting electrode

FIELD: technological processes.

SUBSTANCE: invention concerns electric arc welding, particularly method of automatic argon arc welding of overlapping joints of steel pipes by non-melting electrode. The method involves preliminary pipe edge preparation and welding by tilted electrode with pipes rotating against electrode to form weld seam. Axial rotation speed of welded pipes is 0.1-0.8 rpm. Electrode is tilted in two planes: by 50-70 degrees against the article axis and by 60-85 degrees against weld seam plane.

EFFECT: improved quality of weld seams in overlapping joints of steel pipes, reduced hopping during rotation of long-length welded article, reduced cost of welded product.

3 cl, 3 dwg, 1 tbl

 

The invention relates to the field of electric arc welding materials non-consumable electrode, and in particular to methods of automatic argon-arc welding of lap joints of steel pipes with non-consumable electrode.

Now to get lap-joints bushings with stainless steel pipe in the production of the upper part of the technological channel of a nuclear reactor BSR-K5 manual argon-arc welding, which has a low level of productivity and quality of the weld, as well as the higher level of residual welding stresses in the product compared to automatic welding.

The known method argon-arc welding of fillet welds lap joints of the consumable electrode, in which the welding of the lead electrode is inclined at an angle of 55 to 60 degrees to the horizontal surface (Wpedzich. Metallurgical and technological fundamentals of arc welding. M, Motor Cycle". 1962, s-285).

This method does not provide the high-quality fillet welds in lap joints of steel pipes due to the formation of cracks and pores, and also because of the considerable excess of the statutory requirements of the magnitude of the runout during rotation product after welding. In addition, the known method has comparatively high cost of welded products due to the highly what about the energy consumption in continuous combustion powerful arc and increased rejection of welded products with low quality of the weld and the increased amount of runout during rotation product after welding.

The closest analogue to the claimed technical solution is known a method of automatic argon-arc welding with non-consumable electrode corner seam lap-joints of steel pipes, including the preliminary preparation of the edges of pipes and welding sloped electrode during rotation of the welded tube relative to the electrode and the given parameters with the formation of the weld (Uphyrkina and other "Installation and welding of pipelines from corrosion-resistant steels in nuclear industry". M: Atomizdat, 1966, p.35, 36-37, 44, 104).

The known method does not provide the quality corner welds in lap-connection of steel pipes due to the formation of pores and other defects, and also because it exceeded the statutory requirements of the magnitude of the runout during rotation of long welded products with corner seams. Therefore, this method offers a relatively high cost of welded products, caused by the increased rejection of products with low quality corner welds and increased amount of runout during rotation of long welded products with corner seams.

The objective of the invention is to improve the quality svarny the welds in lap-connection of steel pipes, the decrease in run-out in rotation long welded products and the cost of welded products.

The technical result is achieved in that in the method of automatic argon-arc welding of steel pipes with non-consumable electrode corner seam lap-joints of steel pipes, including the preliminary preparation of the edges of pipes and welding sloped electrode during rotation of the welded tube relative to the electrode with the formation of the weld, the axial rotation of the welded pipes are a speed of 0.1-0.8 rpm, and the slope of the electrode is carried out in two planes: on the angle of 50-70 degrees relative to the axis of the product and on the corner of 60-85 degrees relative to the plane of the weld.

In the particular case of execution when multiple connection of pipes welded seams, the point of beginning (end) welding each of two adjacent joints have diametrically opposed.

Welding can be performed with a stepper axial rotation of welded pipes by current pulses with alternating cycles of the pulse-pause with the step of providing closure of the heating zone of the previous pulse heating zone of the subsequent pulse.

Known stepper axial rotation of the pipes being welded during the welding process, welding sloped electrode, and maintenance of the welding process in a continuous mode (patent RU №2262424, 2005, Wpedzich. Metallurgichesky the e and technological fundamentals of arc welding. M, motor cycle", 1962, s-285).

However, only the combination of all known and new significant features of the proposed method of automatic argon-arc welding of steel pipes with non-consumable electrode allows to solve the challenge in a significant increase in the quality corner welds in lap joints of steel pipes, reducing the magnitude of the runout during rotation lengthy product after welding and the cost of welded products.

Speed step of the axial rotation of the welded pipe of 0.1-0.8 rpm and maintenance of the welding electrode with tilt in two planes: on the angle of 50-70 degrees relative to the axis of the product and on the corner of 60-85 degrees relative to the plane of the weld enable you to get, as it has been found experimentally that the optimum conditions of thermal effects of the welding arc and crystallization of the metal of the weld pool, which ensures reduction of the heat-affected zone and the warping of the products in General, elimination of defects in the weld, which, consequently, allows to significantly improve the quality of the seams, to reduce the amount of run-out in rotation long welded products, and this in turn reduces the rejection rate of the products and reduces the cost of manufacture.

A significant reduction in the number of rejected expensive products, welded by the present method,for improving the quality corner weld lap joints of steel pipes and decrease the amount of run-out in rotation long items after welding can significantly reduce the cost of welded products.

The process of welding so that the start point (end) welding each of two adjacent joints was located diametrically opposite allows you strengthen a positive effect on reducing warpage of the product, and hence the magnitude of run-out in rotation long weldment after welding, which leads to additional improve the quality of the product.

The process of welding mode stepper axis of rotation of the welded pipes with the formation of a weld overlay on the welded surface of the current pulses with alternating cycles of the pulse-pause with the step of providing closure of the heating zone of the previous pulse heating zone of the subsequent pulse, allows for greater technical result due to the additional electricity savings in the welding process and improve the quality of the weld.

The proposed method is illustrated with drawings and photographs presented in figures 1-3.

Figure 1 shows the position of the electrode during welding of the sample in two dimensions: relative to the axis of the product and the plane of the weld.

Figure 2 shows the macrostructure of the corner weld seams of welded pipes of different dimensions after welding:

a) in the step-pulse mode;

b) in a continuous mode.

Figure 3 shows the microstructure of a fillet weld, the area the cat is who influence and parent metal of welded pipe after welding:

a) in the step-pulse mode;

b) in a continuous mode.

To validate the proposed technical solution was carried out the following work:

- made sleeve 1 (Fig 1) diameter 115×10 mm length 50 mm with cutting ends for welding of steel 08KH18N10T (TU 143-197-78);

the inside sleeve was inserted pipe 2 (Fig 1) with a diameter of 95×5 mm length 80 mm of steel 08KH18N10T (TU 143-197-78);

- mark the designated welding the sleeve to the pipe and made potholders sleeve to the pipe by welding from both sides;

- made welding samples for installing TT 180.

Example 1

According to the claimed technical solution welding fillet welds lap-joints of samples of steel pipes was carried out by argon-arc welding with a consumable electrode in a continuous mode with the following parameters:

- ignition of the arc for 2-5 seconds before the start of rotation of the sample;

- current arc 165±10 A;

the flow rate of argon 15±5 l/min;

- voltage arc 11±1;

the overlap seam 10-25 mm

In the welding process varied the following parameters:

the speed of rotation of the sample is 0.1; 0.8 rpm;

the angle of inclination of the electrode relative to the axis of the product α (1): 50; 70 degrees;

the angle of inclination of the electrode relative to the plane of the weld β (1): 60; 85 degrees;

- the start (end) point of welding two adjacent joints: match the or diametrically opposite.

Example 2

According to the claimed technical solution welding fillet welds lap-joints of samples of steel pipes was carried out by argon-arc welding with a consumable electrode in the step-pulse mode with the following parameters:

- ignition of the arc for 2-5 seconds before the start of rotation of the sample;

- power arc current pulse 170±10 A;

- current arc in the interval 30±10 A;

the pulse duration of 0.8±0.2 sec;

- the duration of a pause 0,65±0.2 sec;

the flow rate of argon 15±5 l/min;

- voltage arc 11±1;

the overlap seam 10-25 mm

In the welding process varied the following parameters:

the speed of rotation of the sample: 0,05; 0,1; 0,35; 0,8; 1 rpm;

the angle of inclination of the electrode relative to the axis of the product a (1): 50; 70 degrees;

the angle of inclination of the electrode relative to the plane of the weld b (1): 60; 85 degrees;

- the start (end) point of welding two adjacent joints: match, or diametrically opposite.

Example 3

On the closest analogue welding fillet welds lap-joints of pipe samples was carried out by argon-arc welding with a consumable electrode in a continuous mode with the following parameters:

- ignition of the arc for 2-5 seconds before the start of rotation of the sample;

- the angle of the electrode relative to the vertical to the pipe axis 80±5 C;

with the speed of rotation of the sample of 1.2 rpm;

- current arc 130±10 A;

- the start (end) point of welding two adjacent seams match.

For comparison welded samples of pipes of different sizes 70×6,0 and a diameter of 60×5.5 mm steel HN and HN.

For each option were made on three samples. All samples were subjected to external inspection, dye penetrant of welds and measuring the magnitude of the runout during rotation of the sample. Each weld cut one template for metallographic studies. Determined the relative price per meter 1 of the weld. All studies were performed by standard techniques. The results are given in the table and figure 2-3.

50 -"-
Table

Comparative data the proposed method and the closest analogue
no experienceOption technical solutionsMaterial steel pipeThe dimensions of the welded samples, mmThe welding parametersThe results of the tests
Welding modeThe speed of rotation of the sample, rpmThe angle of the electrode relative degrees The location of the start (end) point of welding two adjacent jointsThe presence of defects in the weld seamThe magnitude of the runout during rotation of the specimen after welding, mmThe relative cost of manufacturing the POG. meter weld, % Rel.
SleevePipe
The axis of the productThe plane of the weld
12345678910111213
1the inventive method08KH18N10T⊘115×10⊘95×5continuous0,15060diametrically oppositelyno0,1289,2
2-"-08KH18N10T⊘115×10⊘95×5-"-0,87085-"-no0,1490,4
3-"-08KH18N10T⊘115×10⊘95×5the step-pulse0,160-"-no0,1088,4
4-"-08KH18N10T⊘115×10⊘95×5-"-0,87085-"-no0,1589,3
5-"-08KH18N10T⊘115×10⊘95×5-"-0,15060matchno0,3098,4
6-"-08KH18N10T⊘115×10⊘95×5-"-0,87085-"-no0,3699,6
7-"-HN⊘115×10⊘95×5-"-0,15060diametrically oppositelyno0,1188,7
8-"-HN⊘115×10⊘95×5-"-0,87085-"-no0,139,5
9-"-HN⊘115×10⊘95×5-"-0,15060-"-no0,12at 88.1
10-"-HN⊘115×10⊘95×5-"-0,87085-"-no0, 1389,3
11-"-08KH18N10T⊘90×10⊘70×6-"-0,15060-"-no0,1088,7
12-"-08KH18N10T⊘90×10⊘70×6-"-0,87085-"-no0,12to 89.9
13-"-08KH18N10T⊘80×10⊘60×5,5-"-0,15060-"-no0,1188,2
14-"-08KH18N10T⊘80×10⊘60×5,50,87085-"-no0,1488,9
15The closest analogue08KH18N10T⊘115×10⊘95×5continuous1,280-0,25100

Analysis of the data presented in table and figure 2-3 shows that the claimed method differs from the most similar analogue higher quality corner welds lap-joints of steel pipes (no in weld cracks, pores and other defects), the smaller value of a beating during the rotation of the samples after welding (0.1-0.15 mm in the proposed method and 0.22 mm at the closest analogue) and a lower cost of production 1 per meter of weld (88,4-90,4% relative from the proposed method and 100% at the closest analogue). Metallographic analysis of welded joints of the samples showed that the results of the data generating angular weld lap joints of steel pipes in the process argon-arc welding by the present method are the same for welded pipes of different sizes from different stainless alloys. From figure 2 and 3 shows that when vypolneniyasvoey weld by the present method are more high-quality welds free of defects in the form of long poor penetration, undercutting, incomplete fusion, fistulas, fissures and other defects.

The optimal parameters of the proposed method are the following (experiments No. 1-4, 7-14):

- the velocity of the axial rotation of the welded product is 0.1-0.8 rpm;

- the angle of the electrode relative to the axis of the product - 50-70 degrees;

- the angle of the electrode relative to the plane of the weld 60-85 degrees;

- the location of the start (end) point of welding of each of two adjacent seams are diametrically opposed.

The reduction of welding parameters:

- velocity of the axial rotation of a welded product is less than 0.1 Rev/min;

- the angle of the electrode relative to the plane of the weld is less than 60 degrees;

- the angle of the electrode relative to the axis of the product is less than 50 degrees do not provide the quality corner welds free of defects.

The increase of the welding parameters:

- velocity of the axial rotation of a welded product more than 0.8 rpm;

- the angle of the electrode relative to the plane of the weld is more than 85 degrees;

- the angle of the electrode relative to the axis of the product more than 70 degrees does not provide further improve the quality of welded corner seams, to decrease the amount of run-out in rotation product after welding and increases the cost of manufacture of welded products.

The coincidence of the initial location (the target) point of welding of each of two adjacent joints leads to a significant increase in the magnitude of the runout during rotation product after welding.

The inventive method was tested with a positive result in the production environment JSC CHMP for release of pilot batches of products BSR-CS of steel 08KH18N10T welding installation TT 180.

1. The method of automatic argon-arc welding with non-consumable electrode corner seam lap-joints of steel pipes, including the preliminary preparation of the edges of pipes and welding sloped electrode during rotation of the welded tube relative to the electrode with the formation of the weld, characterized in that the axial rotation of the welded pipes are a speed of 0.1-0.8 rpm, and the slope of the electrode is carried out in two planes: on the corner of 50-70° relative to the axis of the product and on the angle 60-85° relative to the plane of the weld.

2. The method according to claim 1, characterized in that the welding perform a number of welds, at this point beginning (end) welding each of two adjacent joints have diametrically opposed.

3. The method according to claim 1 or 2, characterized in that the welding is performed with a stepper axial rotation of welded pipes by current pulses with alternating cycles of the pulse - pause with the step of providing closure of the heating zone of the previous pulse heating zone of the subsequent pulse.



 

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