RU2416504C2 - Composite welding wire - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention may be used in arc welding and building up of metal parts. Composite coat is applied onto metal rod. Said coat is made up of metal matrix with dispersed phase from activating flux powder distributed uniformly therein. Inner and outer composite coat contains activating flux with different chemical composition. To reduce moisture absorption, inner composite coat comprises activating flux powder that contains hygroscopic components. Composite wire may comprises metal coat applied onto metal rod surface and/or on surface of inner and/or outer composite coat.

EFFECT: increased depth of penetration, better drop transition and reduced moisture absorption.

2 cl, 1 dwg, 3 tbl

Description

The present invention relates mainly to mechanical engineering and can be applied in welding and surfacing of metal parts in a protective gas environment.

Known electrode wire (Paton B.E., Voropai N.M., Buchinsky V.N., Kozlov E.I., Fenev S.V. Copyright certificate of the USSR No. 671960, V23K 35/02 from 01.12.77) , the surface of which is made with microroughnesses, the depressions of which contain an activating flux. The introduction of flux into the troughs of microroughness allows to improve the electrical contact of the wire with the current-carrying mouthpiece of the welding torch during mechanized welding. However, the formation of microroughness requires mechanical or chemical treatment, which increases the complexity of manufacturing wire. The activating flux is distributed unevenly over the surface of the wire, which can lead to unstable flux entry into the arc burning zone.

Known welding electrode wire (Paton B.E., Voropay N.M., Nikiforov B.A. et al. Welding electrode wire. B23K 35/06, 35/10. USSR author's certificate No. 1696231 of 09/09/1987, Bull No. 45 dated 12/07/1991). This wire consists of a metal rod with an internal channel, the cavity of which is filled with slag-forming and alloying components, and a metal coating is applied to the external and internal surface of the rod. The specified wire improves the drop transfer of electrode metal, however, it does not have an activating flux in its composition and is not able to increase the penetration depth of the metal. In addition, the manufacture of wire is characterized by increased complexity, which increases the cost of the wire.

Known activated welding wire for welding and surfacing (Parshin S.G., Parshin S.S. Activated welding wire. IPC ⁷ V23K 35/365, V23K 35/04. RF Patent No. 2294272 of November 11, 2005 Bull. No. 6 from 02.27.2007), which is taken as a prototype. The specified wire consists of a metal rod and a composite coating with an activating flux deposited on the rod. The coating consists of a metal matrix with a dispersed phase uniformly distributed in it from an activating flux powder. Activated wire allows you to increase the depth of penetration of the metal and improve the drip transfer of electrode metal into the weld pool. However, the composite coating is made of flux powder with a particle size of 10-100 μm, which increases the porosity of the composite coating and leads to moisture absorption by the hygroscopic flux components. This affects the quality of welding and contributes to the formation of gas pores.

 The technical result of the invention is to increase the depth of penetration of the metal and improve the drip transition of the metal by applying composite coatings to the surface of the wire.

 The essence of the invention lies in the fact that an activating flux is placed on the welding wire. Unlike the prototype, two composite coatings are placed on the welding wire - internal and external, which consist of a metal matrix and a dispersed phase - an activating flux. In this case, the hygroscopic components of the activating flux, for example from chloride or bromide salts, are placed in the inner composite coating, and fluoride salts are placed in the outer composite coating, which is applied to the surface of the inner composite coating.

As the metal matrix, metal is used, for example, copper Cu, molybdenum Mo, titanium Ti, aluminum Al, nickel Ni, chromium Cr, and an activating flux powder consisting of oxides and salts is used as the dispersed phase. Before applying composite coatings, a metal coating may be applied to the wire, as well as to the surface of the composite coatings. This coating improves the adhesive ability of composite coatings and reduces the transient electrical resistance between the coatings and the wire.

This combination of known and new features allows to increase the depth of penetration of the metal, improve the drip transition and reduce moisture absorption of the hygroscopic components of the flux. This becomes possible because composite coatings contain an activating flux, which counteracts the arc and reduces the interfacial tension of the metal. The dispersion of the activating flux is evenly distributed in the volume of the metal matrix, therefore, composite coatings have high electrical conductivity and thermal conductivity [see Sayfullin R.S. Physicochemistry of inorganic polymeric and composite materials. M .: Chemistry, 1990, 239 pp.]. This makes it possible to ensure reliable electrical contact with the current supply nozzle of the torch during prolonged flow of the welding current. To reduce moisture absorption, the hygroscopic dispersed phase is placed in the inner composite coating, which is adjacent to the metal rod, and the non-hygroscopic dispersed phase is placed in the outer composite coating, which is in contact with the atmosphere.

The invention is illustrated in the drawing, which shows a view of a wire with metal and composite coatings. The proposed wire consists of a metal rod 1, on which the inner and outer composite coatings 2, 3 are located, consisting of a metal matrix 4 with hygroscopic particles of the activating flux 5 uniformly distributed over the matrix and non-hygroscopic particles of the activating flux 6. Before applying the composite coating to the surface of the welding the wire may be coated with an internal metal coating 7. After applying the composite coating, an external coating may be applied to its surface. 9 PTFE coating and / or intermediate metal coating 8.

The purpose of the invention is achieved in that composite coatings consisting of a mixture of a metal (metal matrix) and an activating flux (dispersed phase) are applied to the surface of the welding wire. Composite coatings ensure good electrical contact of the wire with the torch’s current mouthpiece and effective influence on the arc of the activating components of the coatings that counter the arc and increase its penetrating ability (Simonik A.G., Petiashvili V.I., Ivanov A.A. Effect of contraction of the arc discharge with the introduction of electronegative elements // Welding production, No. 3, 1976, p. 49). When melting the coatings, a slag film is formed, which reduces the interfacial tension of the metal. This reduces the diameter and mass of the droplets, which improves the drip transition of the electrode metal into the weld pool.

The manufacturing technology of the proposed wire can be performed in a manner known in the industry [see Sayfullin R.S. Composite electrochemical coatings and materials. M .: Chemistry, 1972, 168 pp.]. The cleaned welding wire is immersed in an electrolytic bath, which contains finely divided activating flux powder in the electrolyte in the desired concentration. Depending on the composition of the flux and the metal matrix, sulfate, salt, cyanide or phosphate electrolytes are used for coating. The welding wire is connected to the negative pole of the power source. Under the action of polarizing forces, particles of an activating flux and simultaneously positive ions of a metal recovered from an electrolyte are deposited on the surface of the welding wire. For uniform distribution of flux particles in the volume of the electrolyte, the bath is purged with argon. As a result, a composite coating with a thickness of 0.25-100 μm is formed on the wire, with an activating flux evenly distributed throughout the volume. For applying metal coatings, an electrolyte without an activating flux is used. After coating, the wire is dried and wound into coils for use in mechanized or automatic welding.

As an example of the application of the proposed wire, we can cite composite wire surfacing on a pipe with a diameter of 273 mm and a thickness of 10 mm made of carbon steel. Sv-08G2S welding wire with a diameter of 1.6 mm was successively placed in electrolytic baths containing a solution of a copper-containing electrolyte with an activating flux from hygroscopic KCl chloride and from non-hygroscopic fluorides CaF ₂ , BaF ₂ , SrF ₂ , NaF. With a total exposure of the wire for 10 minutes at a current density of 2 A / dm ² , two composite coatings with a total thickness of 20 μm, consisting of a copper matrix and an activating flux, were applied to the wire surface. In this case, two types of composite wire were manufactured: with coatings (Cu + KCl) + (Cu + CaF ₂ -BaF ₂ -SrF ₂ ) and with coatings (Cu + KCl) + (Cu + NaF).

The obtained composite welding wires were tested during automatic surfacing of low carbon steel plates in an argon and carbon dioxide environment. The average penetration depth H _{pr was} determined by transverse macro sections after etching in nitric acid. When welding in carbon dioxide at a wire feed speed of 5 m / min, the penetration depth of steel increased by 18.2-26%. In argon medium at a wire feed speed of 5 m / min, the penetration depth of steel increased by 36.7-47.6%, see Table 1.

Table 1 The average penetration depth during surfacing with composite wire Sv-08G2S with a diameter of 1.6 mm The name of the wire N _CR , mm at a welding speed, cm / min in argon medium N _CR , mm at a welding speed, cm / min in a carbon dioxide medium thirty 40 fifty thirty 40 fifty Ordinary flux-free wire 3 2,8 2,4 3.2 3 2.7 Flux-cored wire (Cu + KCl) + (Cu + CaF ₂ -BaF ₂ -SrF ₂ ) 4.1 3.9 3.4 3.9 3.6 3.2

Drop transition studies were carried out using a PCI 8000S Motion Scope video camera with a Lens-18-108 lens with a shooting frequency of 2000 frames per second when surfacing on a pipe with a diameter of 273 mm and a wall thickness of 10 mm. When welding in carbon dioxide with a reverse polarity, the frequency of droplet formation increased to 2.66 times, and the diameter of the droplets decreased to 1.4 times. When welding in argon at a reverse polarity, the droplet formation frequency increased to 1.64 times, and the droplet diameter decreased to 1.75 times. The duration of short circuits and the pause time between short circuits also decreased, see Tables 2, 3.

table 2 Characteristics of a droplet transition during surfacing with a composite wire in a carbon dioxide medium. Wire feed speed 5.0 m / min The name of the wire Drop rate, pieces / s Diameter of drops, mm Short circuit duration, s Pause time between short circuits, s Ordinary flux-free wire 6-8 3.2-4.5 0.007-0.015 0.08-0.12 (Cu + KCl) + (Cu + CaF ₂ -BaF ₂ -SrF ₂ ) 12-14 3.6-4.5 0.006-0.01 0.07-0.09 (Cu + KCl) + (Cu + NaF) 14-16 3.2-3.5 0.006-0.01 0.06-0.09

Table 3 Characteristics of the droplet transition during composite surfacing in argon. 5.2 m / min wire feed speed The name of the wire Drop rate, pieces / s Diameter of drops, mm Short circuit duration, s Pause time between short circuits, s Ordinary flux-free wire 28-30 2.5-3.5 0.0045-0.0055 0.018-0.03 (Cu + KCl) + (Cu + CaF ₂ -BaF ₂ -SrF ₂ ) 38-42 2.5-2.7 0.0045-0.0055 0.015-0.022 (Cu + KCl) + (Cu + NaF). 38-46 2-2,2 0.004-0.0075 0.009-0.015

Thus, the proposed composite wire provides a technical effect, which is expressed in increasing the depth of penetration of the metal and improving the drip transition of the electrode metal, can be made and applied using methods known in the art, therefore, it has industrial applicability.

Claims (2)

1. Composite welding wire for welding and surfacing, containing a metal rod and a composite coating deposited on it, made of a metal matrix with a dispersed phase uniformly distributed in it from activating flux powder, characterized in that the composite coating consists of internal and external composite coatings, differing in the chemical composition of the activating flux, and the internal composite coating includes an activating flux powder containing hygroscopic com onenty. 2. The composite wire according to claim 1, characterized in that it contains a metal coating deposited on the surface of the metal rod and / or on the surface of the inner and / or outer composite coating.

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