SU1712093A1 - Method of welding with three-phase arc - Google Patents

Abstract

The invention relates to arc welding, in particular to three-phase welding, and can be used to join parts of large thicknesses in various areas of engineering. The purpose of the invention is to improve the quality of welded joints of aluminum alloys of large thickness by improving the stability of penetration along the seam perimeter. In the three-phase arc welding method with a non-consumable electrode with filler wire feeding, the electrodes are mounted in the plane of the joint to be welded. The process is performed with a reverse sequence of alternating phases, and the values of the current and current coefficients in the electrodes are selected 1.5-1.7 and 1.1-1.5, respectively. On the edges to be welded, slit grooves are made with a width determined from the expression B = (d + 0.05H) mm. where d is the diameter of the filler wire; H is the thickness of the edges being welded, with a bluntness of 0.4 times the thickness of the edges being welded N. Welding is carried out in the mode of a submerged arc with the electrode being deepened by 0.1-0.2 times the thickness of the edges being welded. The filler wire is fed into the weld pool in the arc-burning process between the front electrode and the bottom of the weld pool. 2 il., 1 tab.

Description

The invention relates to arc welding, in particular to three-phase welding, and can be used to join parts of greater thickness in various areas of mechanical engineering.

The known method of argon-arc welding with tungsten electrode in the mode of submerged arc. The method is applied with a thickness of the edges being welded 4-8 mm. With an increase in the thickness of the joint, the application of submerged arc welding technology is difficult. Increase welding

a current of up to 600-650 A leads to a strong boiling of the weld pool and the wandering of the arc over its area.

A three-phase arc welding method is known, in which the penetration of large thicknesses (over 10 mm) is performed by a non-consumable tungsten electrode with filler wire feed, power sources are used that provide the maximum current ratio of 1.6 to 1.7 (current ratio to average current value in the electrodes) and the value of the coefficient of currents in the electrodes 1.3-1.4 (the ratio of the current in the first electrode to the current in the second electrode). Here, the process is carried out with a reverse phase rotation sequence, and the electrodes are installed in the interface plane.

The disadvantage of this method is the low quality of the compounds of aluminum alloys of large thickness (from 14-16 mm) due to the low stability of the process and strong splashing. There is no stable | 0 | shaping around the seam perimeter.

The purpose of the invention is to improve the quality of high thickness aluminum alloy compounds by improving the penetration stability along the seam perimeter.

This is achieved by the fact that in the method of welding with a three-phase arc with a non-melting electrode with filler wire, in which two electrodes are set in the plane of the welded joint, the process is performed with the reverse phase sequence, and the values of current coefficients in the product and current in the electrodes are chosen from 1 , 5 to 1.7 and 1.1 to 1.5, respectively, on the edges to be welded, a slit groove with width B d + 0.05H is made, where d is the diameter of the electrode wire; H is the thickness of the edges being welded and a bluntness equal to 0.4 of the thickness of the edges being welded, welding is carried out by a submerged arc with the electrode being 0, 2 thicknesses of the edges being welded, and the filler wire is fed into the weld pool between the front electrode and the Bottom of the bath.

Fig. 1 shows a three-phase arc burning scheme for welding with a filler metal with non-consumable immersed electrodes exceeding one above the other and in the reverse sequence of phase alternation; figure 2 - section aa in figure 1 (preparation of welded edges for three-phase welding).

The method consists in preparing a slotted and-shaped groove 1 of the edges to be welded, width B, determined from the expression B (d + 0.05 N) mm, d - Diameter of the filler wire, mm; H is the thickness of the edges to be welded, and by blunting 2 of the thickness 0.4 of the thickness H of the edges being welded to improve penetration and stabilize the melting. The arcs are excited between two inclined non-consumable electrodes 3 and 4, located in the plane of the joint, and the surface of the product 5. The arcs are immersed below the surface of the welded parts. Dip arcs are achieved by gradually lowering tungsten electrodes between

weld edges to a depth of / 0.10, 2 from the thickness of the edges H, feeding the filler wire 6 into the welding bath 7 during arc burning between the first electrode 3 located in front and the bottom of the welding bath 7, welding with the reverse sequence of phase alternation in the mode, providing current coefficients in the product and the current in the electrodes from 1.5 to 1.7 and from 1.1 to 1.5, respectively.

The excess of the first electrode over the second by 2 mm was used to improve the conditions of filing the filler wire. The departure of the first electrode from the nozzle was set equal to 20 mm, the distance between the electrodes was 5-6 mm.

Molten metal pressure arcs pushed out on the sides of the weld pool and as the welding torch progressed, it was transferred back to form a weld. Welding of metal of thickness H 20–30 mm was performed in a single pass on the lining. For a thickness of 20 mm, a stable melt of 6–9 mm wide was formed with a height of 1.5 mm. For a thickness of 30 mm, a seam reinforcement of up to 1-1.5 mm was formed with a width of 18-25 mm. The filler wire was fed to the edge cutting in front of the weld pool. The optimal wire diameter is 3 mm. Before welding, the wire and the edges to be welded were cleaned of oxide captivity by etching and mechanically (scraping) ..

To increase the penetration depth with the minimum width of the weld, welding was performed with the electrodes placed in

junction plane, coefficient CT - | vy1el

took the maximum 1.5-1.7, and the coefficient Ke is greater than one and 1.1-1.5. For

Stable transfer of the filler metal to the weld pool; the process was performed with an inverse sequence of phase alternation, when the individual arcs burn counterclockwise in the sequence 5-4, 4-3, 3-5. At the moment of arc burning 3-5 pulsed feed moved the filler wire at a speed of 20-35 m / h under the arc. The filing time of the additive is equal to the arc burning time 3-5. If this condition is violated, no complete melting of the additive is observed. The depth of the second electrode relative to the surface being welded must correspond to 0.1-0.2 thickness of the edges to be welded N. At A 0.1N, lacks of penetration are formed, and at D 0.2N - burn-through of the edges being welded. With a width of pa: edges edging B equal to the diameter of the filler

wire d, quality welding is impossible due to the impossibility of filing the filler wire in the slotted groove.

When the width of the groove edges is less than d + 0,051-1, the first electrode closes along the welding process with the metal being welded and the tungsten inclusions are formed in the weld metal. Uneven formation of pro-melt is also observed.

When the width of the groove edges B is larger (d + 0.05 N), the welds are formed with an understatement that cannot be eliminated due to an increase in the feed speed of the filler wire. ;

The size of the blunting of edges 0.4 of the thickness of the edges to be welded is selected; conditions of guaranteed penetration with the formation of the root bead. If the blunting of the edges is less than 0.4N, the formation of cracks at the points of transition of the base metal and the weld root is possible.

If the height of the protrude is exceeded and not more than 0.4N, the weld edges may not be melted in the root part of the weld and oxide captivity may occur.

Examples Perform lyargon-arc welding of a three-phase submerged arc along a slit-like edge of the cylinder edges with a diameter of 500 mm of the alloy AMgb with a thickness of the edges being welded of 20 and 30 mm. Welded with AMGB filler wire with a diameter of 3 mm longitudinal seams and cylinders between themselves. ..

Welding mode at H 30 mm

1e1 540-560 A

1e2 360-420 A

1зд. 730-780 A

VcB. 6.5-7.2 m / h

d3i 10 mm

d32 8 mm

Q 30 l / min

, 5-1,7

Ke 1.3-1.5

The location of the electrodes is in the plane of the junction, the sequence of alternating phases is reversed.

The departure of the first electrode 20 mm.

Welding mode at. H 20

1e1 460-500 A

1e2 340-400 A

1зд. 650-700 A

VcB. 10-12M / il

The remaining parameters are similar to mode I

CT 1.5-1.7

Ke 1.1-1.5

Immersion depth of the first electrode

2 mm for a thickness of 20 mm and 6 mm for a thickness of 30 mm, i.e. ranged from 0.1 to 2H.

The welding was carried out on an ARK2 machine with the help of the AGTP-1 head with a two-electrode torch having an oval-shaped nozzle. A current source ITD 600/1000 was used as a power source. The results of the experiment are presented in the table.

Received high-quality penetration around the perimeter of the seam. The deviation of the seam perimeter at a length of 1 m was no more than 10 mm. The strength of welded joints is 0.8 from the lower strength of the base metal (31 kgf / mm), i.e. 24.8 kgf / mm. The destructive pressure of the welded cylinder 400 MPa with a dogustable 385 MPa.

The invention provides an improvement in the quality of manufacture of critical structures by eliminating tampering, understating and increasing the stability of penetration around the perimeter of the seam by 10-15%.

thirty

Claims (1)

Invention Formula The method of three-phase arc welding with a non-consumable electrode with filler wire feeding, in which two electrodes set in the plane of the welded joint, the process is performed with the reverse sequence of phase alternation, and the values of the current current coefficients in the product and the current in the electrodes are chosen from 1.5 to 1.7 and from 1.1 up to 1.5, respectively, characterized in that, in order to improve the quality of aluminum alloys of large thickness by improving the stability of penetration along the seam perimeter, on the edges to be welded Slit widths are made in width B d + 0,051-1, where d is the diameter of the electrode wire: H is the thickness of the edges to be welded and a dullness equal to 0.4 of the thickness of the edges to be welded, I conduct welding immersed arc with the deepening of the electrode by the amount of 0.1-0.2 thickness of the edges being welded, and the filler wire is fed into the welding, bath between the front electrode and the bottom of the bath. 71712093 The effect of the welding conditions and conditions of the three-phase well on the quality of connections 20.0 , 3.0 2.0 No defects, uniform seam formation 2 1 (Rig.y.