SU1310143A1 - Method of argon-arc welding of butt joints - Google Patents

Abstract

This invention relates to welding production technology and can be used when welding butt joints with an increased gap between the edges. The aim of the invention is to improve the quality of welded joints due to the elimination of burn-throughs, the probability of which, with an increased clearance, the junction is very high. According to the method, a seam is made in two passes. The first pass to form a weld with a weld width of 0.25 to 0.5 of the required weld width at the filler wire feed rate set at Lormule v, (l, 25-l, 6) a8v ../ dt, where PA is the speed filler wire feed, mm / s; a - the size of the gap in the joint, mm; S is the thickness of the material being welded, mm; V is the welding speed mm / s; d is the diameter of the filler wire, mm, and incomplete penetration of the edges. The second pass is carried out without filing the filler wire with full penetration of the edges and a predetermined reinforcement of the weld. The use of the method allows to significantly improve the quality of welded joints, especially thin-sheet structures. 2 Il. "With: s about :)

Description

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The invention relates to mechanical engineering and can be used in the manufacture of welded structures from sheet materials.

The aim of the invention is to improve the quality of welded joints with an increase in the gap in the joint.

FIG. shows a weld with a gap after the first pass, a cross section; in fig. 2 - the same, after the second pass.

The welding of butt joints of thin-sheet structures with an expanded gap is carried out in two passes. The first pass is performed with an additive with incomplete penetration of the edges by a narrowed seam. Under these conditions, the welding mode should ensure the melting of the edges being welded in width by 0.25-0.5 from the required weld width, as well as incomplete penetration in thickness (Fig. 1) When applying a weld with a width greater than 0.5 from the desired width reduction of the mechanical properties of the welded joint, in particular, the tensile strength for materials of the alloy type 1420. For the VNS-2 type steels, there is an adverse re-precipitation of carbides in the heat-affected zone. The precipitation of carbides reduces the corrosion resistance of welded joints and their strength characteristics.

When a seam width of 0.25 of the required with incomplete melting edges is interrupted, the stability of the process is disturbed due to the excessive height of the seam and insufficient heating of the edges. Frequent shorting of the electrode to the seam reinforcement is also observed.

Therefore, the optimal range is the width of the seam with the first pass of 0.25-0.5 from the required one.

The imposition of a second passage reached

The melting of the gain from the first pass and the formation of a seam of a given size are observed (Fig. 2). In this case, the thermal effect of the first pass is absorbed by the heat affected zone of the second pass and the mechanical properties of the welded joint are not impaired.

The amount of additive is determined by the ratio

Vrfn (1.25-1.6)

aS V

Si

dT

ABOUT

S 0

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432

where v is the filing wire feed speed, mm / s; a - the size of the gap in the joint,

mm;

Vj. - welding speed, mm / s; dp is the diameter of the filler wire, mm / s.

The method was tested when welding thin-wall structures made of 1420 alloy and VNS-2 steel with a thickness of 1.5 mm, the gap in the joint was 0.5 mm. AMGB wire with a diameter of 2.0 mm was used as an additive in welding alloy 1420. Welding of parts made of alloy 1420 was carried out in the mode shown in the table.

It should be noted that the weld seam was formed without a burn-through along the entire length.

In the case of welding of VNS-2 steel, the gap in the joint was 0.6 mm. The first pass was made manually with a seam width of 2.5-3.0 and a reinforcement height in the range of 0.5-0.8 mm. The second pass was performed by a scanning arc on the next trace: arc current 70 A; voltage 9.0 V; welding speed of 7.2 m / h; electrode rotation speed of 60 rpm; arc scan radius 1.5 mm. In this case, the welded edges melted without sagging the seam, the width of which was 6.2-6.5 mm.

Using the proposed method allows to significantly improve the quality of welding of thin-walled structures by eliminating burn-throughs in the welds.

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Claims (1)

40 claims Argon arc welding of butt joints with filler wire feeding, mainly with an increased gap, in which welding is carried out in two passes, characterized in that, in order to improve the quality of joints by eliminating the formation of burn-throughs, the first pass is performed with an additive with incomplete penetration of the welded edges and weld weld is formed from 0.25 to 0.5 of the required weld width, the filing wire feed rate is set by the formula v, n (1.25-1.6) d: Vj — filler wire feed rate, mm / s; a - gap size in the joint, mm: S - thickness of the welded g; material, mm; g- with e, with v; о рс с ть с and а а D i-; to mm: d is the diameter of the filler wire, mm, and the second pass is carried out without filing the filler wire with a full extension of the welded edges and a sealed reinforcement of the weld. 3TS3 Compiled by G. Tyutchenkov Editor A. Gulko Tehred V. Kadar Proofreader M. Demchik 1850/11 Circulation 976 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Design, And srcg2