UA127289C2 - METHOD OF SOLDERING WITH A TAPE ELECTRODE - Google Patents

Abstract

The invention belongs to welding production and can be used in the manufacture and restoration of parts and equipment by electric arc welding of corrosion-resistant and wear-resistant coatings with a strip electrode. The method of welding with a strip electrode includes feeding an additional non-current-conducting additive tape into the welding bath, with its lag from the tape electrode along the length of the welding bath and the volume rate of additive supply below the volume rate of supply of the tape electrode. The dimensions of the filler tape are determined from the expression of the dependence of the specific intensity of melting of the filler tape with the melt, due to which the intense heat flow in the center of the welding bath is reduced and the necessary distribution of heat over its area and depth is ensured. This allows you to control the distribution of heat input in the deposited layer, to form a more uniform line of fusion of the deposited metal with the main one, to reduce the likelihood of slag inclusions and influxes in the zones of slow movement of liquid metal, and also to reduce residual stresses in the seam zone.

Description

The invention belongs to welding production, namely to the application of corrosion-resistant and wear-resistant coatings on structures made of low-carbon and low-alloy steels by the method of surfacing with a strip electrode under flux.

It is known that during surfacing under a layer of flux, the use of fluxes with high electrical conductivity ensures arc-free (electroslag) melting of the base and electrode metal, which leads to an increase in surfacing productivity up to 40-45 kg/h. and a decrease in the share of the base metal in the deposited material to 5-10,905 (see article

Peculiarities and some technological characteristics of slag-grossla coating with one slag strip // Automatic welding. - 1999. - Mo 3. - P. 16-21). The disadvantage of the known is the uneven penetration of the base metal with a depression in the middle of the width of the bath, which is characteristic of the method of wide-layer surfacing with strip electrodes. In addition, in this surfacing process, a long welding bath covered with molten slag is formed. Therefore, in some cases, the use of the electroslag surfacing method is limited due to the high heat input into the base metal, its overheating, and increased tendency to the formation of hot cracks. There is a known method of electroslag surfacing with a strip electrode, which provides a corrosion-resistant composition of the metal in the first layer due to a small share of the base metal (see the article "Electroslag surfacing with a tape under a ceramic flux of a homogeneous single-layer anti-corrosion coating of the inner surface of pipes with a diameter of 850 and 990 mm for gas stations" / Welding production. - 2019. - Mo. 11. - P. 29-37).

The known disadvantage is the large volume of the slag and metal bath, which sharply increases the heating of my product, which is welded. Due to overheating of the product, the continuous surfacing process requires the use of a double or triple step, which complicates the technology.

In addition, the probability of formation of defects in the overlapping area of the seams increases, requiring high accuracy of the installation of the floating head when filling the gaps.

The closest in terms of its technical essence and the results achieved is the method of electroslag surfacing with a strip electrode, in which an additive in the form of several non-current-conducting flux cored wires is fed into the welding bath with a lag along the length of the bath. This provides an increase to 18-20 m/h. speed of deposition of the layer

From a thickness of 4.5--5.5 mm with a value of the share of the base metal no more than 5 95. The volume rate of the additive supply is usually 0.3--0.5 of the volume rate of the electrode supply.

In order to increase this ratio, preheating of the filler wire using an additional current source is used. To change the composition of the deposited metal, while keeping the composition of the strip electrode constant, the composition of the filler wire is changed (MO 2016203286А1

IPC V2ZK 25/00, V2ZK 35/02).

The disadvantage of the known is the need to use an additional current source, which is associated with the preliminary heating of the filler wires. This circumstance increases the complexity of technology and equipment for surfacing when using a large number of electrodes that are fed into the welding bath at the same time. In addition, it is necessary to use magnetic control of the weld pool melt in order to reduce the inhomogeneity of the composition of the deposited metal, since the known method has limited opportunities for controlling heat input.

The invention is based on the task of improving the method of surfacing with a strip electrode, in which, due to the control of heat input along the width and area of the welding bath, conditions are created to increase the productivity of surfacing, the formation is improved, and the height of the deposited layer is stabilized.

To solve the problem in the method of welding with a strip electrode, which includes its supply to the welding bath and a non-current-conducting additive, with the lag of the additive from the strip electrode along the length of the welding bath and the volume rate of the additive supply below the volume rate of the supply of the strip electrode, according to the invention , the additive is used in the form of a tape, while the proportion of the volumetric rate of supply of the additive tape to the volumetric rate of supply of the tape electrode is

In k, -- -(0.08-- 0.32) in, , and the dimensions of the filler tape are determined from the expression:

FI1

M dps) -K,--- aV";

M ps). . at. o where is the specific melting intensity of the filler tape with the bath melt, W/mm3;

K. . Mr. . . . . is the empirical coefficient of the melting intensity of the filler tape, which is in . Kk, - 0.02--0Lo range is ; ф - indicator of the ratio of the surface area of the unit length of the filler tape to the area of its cross section;

M - voltage on the arc, B;

I - surfacing current strength, A; a - the distance between the tape electrode and the filler tape, mm;

B - width of the strip electrode, mm; 5. 5 - thickness of the tape electrode, mm;

У, - M provided that Ус) У(СЕ),

M dv): - . where is the specific melting intensity of the strip electrode, W/mm3.

In addition, the method provides for profiling along the width of the filler tape in such a way that the total value of the removal of the edges b" is no more than 35 95 of its total width. At b»»35 95, there are possible violations of the formation of the extreme areas of the deposited roller.

Since the center of the bath is significantly overheated, the depth of penetration increases mainly in the center of the seam, in the zone of active flow of liquid metal. This leads to an uneven formation of the fusion line, an increase in the probability of the formation of slag inclusions and influxes in the zones of slow movement of liquid metal. In this case, the height of the reinforcement along the length of the seam becomes uneven, thickenings and depressions appear on the surface of the welded roller. In order to eliminate these shortcomings, it is advisable to control the process of melting by varying the size and volume speed of the filler strip electrode, due to which the intensity of the heat flow in the center of the bath is reduced and the necessary distribution of heat over the area and depth of the bath is ensured. . . Kk. - M, M residual stresses in the deposited metal. When the value of the proportion of filler metal " k / e in the range of 0.08-0.32 provides optimal heat input into the welding bath. In this case, as shown by calculation and experimental data, the proportion of thermal energy that can be spent on melting the filler strip is 2-10 95 from the corresponding value for the strip electrode. When " is more than 0.32, the formation of the roller deteriorates. . . Kk -0.08. . . possible violations of the stability of the melting process. If " ;» noticeable changes in the process

There is no surfacing.

The essence of the invention is explained by the diagram shown in fig. 1. The method is carried out as follows. Ribbon electrode 1, on which the welding arc is formed, provides heat investment in the base metal and the main part of the transfer of the electrode metal in . In . welding bath 3, supplied with a volumetric rate is. Lagging behind the electrode with respect to the surfacing speed vector 5, filler tape 2 with bulk is fed. In o. . . I speed ". The hinged assembly 4, which is located in front of the rear flux hopper 6, allows you to change the angle of inclination of the filler belt B relative to the normal to the deposition velocity vector and additionally control the hydrodynamic state in the welding bath. The additional degree of mobility of the hinged assembly allows you to redistribute the flow of molten metal along width of the bath and makes it possible to compensate for adverse phenomena associated with the influence of the current supply and magnetic "blowing", eliminating such defects as undercuts, uneven formation of the roller, inflows.

The efficiency of heat investment in the welding bath depends on the size ratio. . and. In the strip electrode and filler tape, which is primarily determined by the value C), which characterizes the intensity of heating and melting of the thinner filler tape by the melt of the slag and metal bath. This value depends on the ratio Ф of the surface area per unit length of the filler tape to the cross-sectional area of the tape (with a decrease in the thickness of the filler tape from 1.0 to 0.2 mm, the value of Ф increases from 2 to approximately 10).

Additional opportunities to reduce the probability of defects are provided by the use of filler tape, which reduces heat input into the metal and slag bath, reduces their size and fluidity. Since highly alloyed stainless steels are sensitive to increased heat input during surfacing, which can be accompanied by the appearance of defects in the deposited layer, the proposed method is advisable to use for applying an anti-corrosion layer. In addition, increasing the productivity of melting makes it possible to increase the deposition rate or the height of the deposited layer while maintaining the deposition rate. When applying an anti-corrosion layer, it allows to reduce the number of necessary passes.

An example of a specific application of the strip electrode surfacing method. To apply a corrosion-resistant layer on the pipe grid blank, the method of electric arc welding with a strip electrode was used. The workpiece from structural steel 09G2S was made in the form of a cylindrical forging with a diameter of 900 mm and a height of 150 mm.

A cold-rolled electrode tape was used as the material of the tape electrode (CE).

ЛН-02 x 25Н22АГАМ2 (TU IЭ3-406) with a cross-section of 60 mmx0.5 mm, as filler tape (PS) - a tape of the same material with a cross-section of 24 mmx0.2 mm. The parameters of the surfacing mode (current strength Й, arc voltage ОО, surfacing speed 5, average layer height Pi, and the number of surfacing layers Mi) are given in Table 1. In addition, a profiled filler tape with 2 mm bevelled edges on each side was used ( рх-17 Us) as shown in fig. 2.

For surfacing with a direct current of reverse polarity, a molten flux OF-10 (TU 14-1-2328-78) was used, which was fed into the front 5 and rear 6 flux hoppers (Fig. 1). The lag of the filler tape from the tape electrode was 18-20 mm. The value of the indicator of the ratio of the surface area of a unit length of the filler tape to the area of its cross-section, taking into account the specified dimensions, was F-101.

When calculating according to formula (1) for the specified parameters, we obtained the value of specific . . et U dpe) - 36.9 W/mm' of the intensity of melting of the filler tape by the melt of the bath. For these parameters, the value of the empirical coefficient of the melting intensity of the filler tape

Ke-0.08. With those and and M sv) e-0.08. The value of the specific melting intensity of the strip electrode for the specified surfacing parameters is 38.1 W/mm3. Since Mo) 5 Wuxi), the accepted mode parameters can be applied when performing the proposed version of the melting technology.

Table 1

The main parameters of welding with a strip electrode

Offered: SE cross-section 2 |bOhmx0.5mm « PS cross-section 800-860 | 32-34 3.6 5.6 2 24mmx0, 2MM

Z Surfacing according to the basic technology was carried out in 3 layers (Mi-3), and according to the proposed method in 2 layers (M2-2). After surfacing, the geometric dimensions of the surfacing layers were measured. The average height of the PN layer; during surfacing according to the basic version was 4.0 mm, according to the proposed version - 5.8 mm (see Table 1). The total height of the layers after surfacing according to the two options was on average: 12 mm when surfacing according to the basic option (3 layers) and 11.6 mm according to the proposed option (2 layers). Thus, the required total height of the deposited layer when using the proposed method is achieved in a smaller number of passes. Table 1 shows the average values of the height of one layer, which is 1.45 times greater when surfacing according to the proposed option.

It should also be noted that the specific power decreases by almost 20 95 during surfacing with the use of filler tape, which is necessary for melting the electrode metal.

After deposition, a layer-by-layer chemical analysis of the deposited metal was carried out (table 2). The chemical analysis data, which are shown in Table 2, show that when using the proposed version of the welding technology with a strip electrode and filler tape, the dilution of the second deposited layer with the base metal does not exceed 8 95.

Table 2

The chemical composition of the metal of the deposited layers during deposition according to the basic and proposed variants of the technology

Mo Variant of technology | Layer Composition of chemical elements, wt. at 0035 | 3.20 | 0.60 | 22.35 | 18.12 1 | Basic 0.028 23.00 | 21.30 0.025 24.81 | 22.30 2 Proposed 0.029 2247 | 191 0.022 24.90 | 22.30

Taking into account the increase in the height of the deposited layer when using the proposed method, it was possible to reduce their number from 3 C to 2. This was also facilitated by a decrease in the value of the share of the base metal, which gives additional advantages of the proposed method of surfacing due to the saving of highly alloyed austenitic surfacing material.

The consumption of electrode metal is reduced by 10--12 95 compared to the basic version.

Stabilizing the height of the deposited layer allows you to reduce the costs of mechanical processing after deposition and reduce the total height of the deposited layer by reducing the allowance for processing. In addition, improving the quality of the deposited layer ensured a decrease in the energy intensity of the process per kilogram of deposited metal by 12-14 95.

Claims (2)

FORMULA OF THE INVENTION 1. The method of welding with a strip electrode, which includes its supply to the welding bath and a non-current-conducting additive, with the lag of the additive from the strip electrode along the length of the welding bath and the volume rate of the additive supply below the volume rate of the supply of the strip electrode, which differs in that the additive are used in the form of a tape, while the proportion of the volumetric rate of supply of filler wire i "n" from the volumetric rate of supply Ka --- -410,08-032 of the tape electrode is He l and the dimensions of the filler tape FIY Md(ps) - Ke av5- is determined from the expression: 5, M d(ps) o - - -. - with where is the specific melting intensity of the filler tape with the bath melt, W/mm3; Ke is the empirical coefficient of the melting intensity of the filler tape, which is in . "Kk, -0.02--010 in the range, where ф is an indicator of the ratio of the surface area of a unit of filler tape length to its cross-sectional area; M - voltage on the arc, B; - surfacing current strength, A; a - the distance between the tape electrode and the filler tape, mm; B - width of the strip electrode, mm; Z 55 - thickness of strip electrode, mm; M k In the condition that UPs)7 M(se). MADse). . . - W/ with where the specific melting intensity of the strip electrode, W/mm3. 2. The method according to claim 1, which is characterized by the fact that the filler tape is used, profiled in width in such a way that the total value of the removal of the edges is no more than 35 95 of the total width of the tape.