RU2226144C1 - Activating material for welding and surfacing - Google Patents

Abstract

FIELD: welding and surfacing of metallic parts. SUBSTANCE: activating material is in the form of core coated with envelope. The last is made of mixture of polymer and activating flux at next relation of ingredients, mass. %: activating flux, 5 - 80; polymer, 20 - 95. Core may be made of metallic wire or metallic band or from metal powder. Polymer is selected of group containing polytetrafluoroethylene, polyamide, polyimide. Density of surfaced metal is increased due to degassing welding bath and due to reducing oxides. EFFECT: enhanced quality of welded joints. 3 cl, 1 ex

Description

The invention relates primarily to mechanical engineering and can be applied, for example, for welding and surfacing of metal parts.

Known activating flux for electric arc welding (RF Patent No. 2164849 dated 04/10/2001, MKI 7V23K35 / 362) of the following composition: lithium hexafluoroaluminate 17 ... 25%, titanium dioxide 17 ... 25%, silicon dioxide 35. ..40%, calcium chloride 20 ... 30%. This activating flux in the form of a solution of flux powder in ethanol is applied to the surface of abutting edges. This welding method is adopted as a prototype. After the evaporation of alcohol, welding is carried out on a flux layer, which allows to increase the penetrating ability of the arc. However, the composition of the flux includes hygroscopic salts, which contributes to the occurrence of defects in the form of gas pores. To remove moisture, it is necessary to calcine the flux before welding, which increases the complexity of welding operations.

A known method of welding with an open arc (Author's certificate No. 1692783, MKI V23K 9/14 of 11.23.91), in which calcium oxide is introduced into the arc together with polyethylene or fluoroplastic. This method allows to increase the toughness and ductility of the weld due to the removal of nitrogen, hydrogen and oxygen from the weld pool. However, the known method is developed for welding and surfacing with bare electrode wire and does not allow to increase the penetrating ability of the arc. In addition, the powder components, when introduced into the arc, are scattered by the protective gas flow, which reduces the efficiency of the method.

The technical result of the invention is to increase the depth of penetration of the metal and improve the quality of welded joints by using an activating material consisting of a core coated with a polymer shell.

The essence of the invention lies in the fact that in the zone of arc burning during electric arc welding or surfacing, an activating material is supplied, which includes an activating flux. Unlike the prototype, an activating flux is introduced into the arc burning zone together with a polymer, for example polytetrafluoroethylene, polyamide, polyimide. Activating fluxes are composed of halide salts, which are highly hygroscopic. The use of flux together with the polymer eliminates the saturation of hygroscopic components with water vapor and eliminates the dispersion of flux powder from the welding zone.

The activating material consists of a core, which can be made of metal wire or metal tape or metal powder. The metal core is covered with a shell consisting of a mixture of a polymer with an activating flux, in the following ratio of components, wt.%: Activating flux 5 ... 80; polymer 20 ... 95. When the content of the activating flux in the shell is less than 5%, the activating material reduces the penetrating ability of the arc. When the content of the activating flux in the cladding is more than 80%, the strength of the cladding and the adhesion of the cladding to the core are reduced, resulting in increased flux dispersion.

An activating material consisting of a metal core coated with a shell of a polymer mixture with an activating flux additionally serves as an additive to fill the grooves of the welded edges. The use of this material for surfacing parts contributes to an increase in the density of the deposited metal due to the degassing of the weld pool and the reduction of oxides.

When heated, the flux contained in the shell of the proposed material melts and reacts with the molten metal, forming gaseous halides such as FeF ₂ , SiF ₄ , TiF ₄ , AlF ₃ and others. Vapors act on the arc discharge and reduce the conductive diameter of the arc column, which increases the penetrating arc ability. When the polymer is heated, dispersed carbon, fluorine and fluorocarbons are formed: CF, CF ₂ , CF ₃ , CF ₄ . (see Handbook of plastics. / Ed. by Kataev V.M., Popov V.A., Sazhin B.I.-M.: Chemistry, 1975, v.2, 568 p.). Fluorine and carbon fluorides also increase the penetration ability of the arc. Carbon particles are distributed over the surface of the weld pool and at high temperature they reduce oxides, with the formation of volatile compounds CO, CO ₂ . A large number of halides in the arc burning zone reduces the hydrogen content in the weld pool metal due to the formation of volatile compounds HF, HCl, HBr. Slag formed during flux melting reduces the surface tension of the molten metal and refines it.

The manufacturing technology of the activating material with a metal core is as follows. An activating flux powder with a fraction size of less than 50 μm is mixed with a finely divided polymer powder, for example tetrafluoroethylene, polyamide, polyimide. The resulting mixture of flux and polymer powders is dissolved in ethanol, and the metal core is repeatedly coated with the resulting suspension. Then the coating is heated to the polymer melting temperature, as a result of which a strong gas-tight shell with a thickness of 0.05 ... 1 mm is formed on the core surface.

An example of the use of activating material is the welding of plates with a thickness of 6 mm from a titanium alloy OT4. Fine powder activating flux composition CaF ₂ - 30%; MgF ₂ - 20%; LiF - 35%; CaCl ₂ - 15% was calcined and mixed with fluoroplast-4D powder having a particle size of 0.4 μm in the ratio, wt.% Of the mixture: flux powder 40%; polymer powder 60%. The resulting mixture was dissolved in ethanol and repeatedly applied to the surface of a VT-1 titanium wire with a diameter of 2 mm with sintering of each layer at a temperature of 270 ° C, resulting in a shell with a thickness of 120 μm. The welded plates were joined without cutting the edges in the lower position. The arc was ignited from a tungsten electrode with a diameter of 4 mm with a current strength of 240 A of direct polarity. Then, an activating material consisting of a titanium core coated with a mixture of a polymer and an activating flux was introduced into the arc burning zone. The shell of the material melted in front of the arc along with the titanium core and decomposed with the release of a pair of halides, increasing the melting ability of the arc. When moving the arc at a speed of 3.3 mm / s, a complete penetration of the welded plates was obtained, with the formation of a facing roller. The depth of metal penetration in this mode increased by 2.5 times, compared with welding without activating material. Ultrasonic testing on a flaw detector UD2-12 showed the absence of defects in the resulting welded joints.

Thus, the present invention provides a technical effect and can be applied using methods known in the art, therefore, it has industrial applicability.

Claims (3)

1. Activating material for welding and surfacing, including an activating flux, characterized in that the activating material is made in the form of a core coated with a shell, while the shell consists of a mixture of polymer with an activating flux in the following ratio of components, wt.%: Activating flux 5-80 Polymer 20-95 2. The activating material according to claim 1, characterized in that the core consists of a metal wire, or a metal tape, or a metal powder. 3. The activating material according to claim 1, characterized in that it contains a polymer selected from the group: polytetrafluoroethylene, polyamide, polyimide.