SU884920A1 - Flux for welding copper - Google Patents

Description

(54) copper welding flux

The invention relates to the field of welding, in particular, flux intended for welding copper in a protective gas environment. A flux known for welding copper and copper alloys, containing the following components, wt.% Xl j: Silicon oxide 32 36 Aluminum oxide 8-12 Manganese Oxide8-12 Manganese Dioxide 0.2-1-1 Magnesium Oxide 15-18 Calcium Oxide 0, Calcium Fluoride Remaining The disadvantage of this flux is that it does not provide the mechanical properties of a welded joint of equal strength to the base metal. This flux is used for submerged arc welding of copper. The closest to the proposed composition is a flux containing the following components, wt.% Borax anhydrous 94-96 Magnesium metal4-6 This flux is used in welding with filler metal of the same composition as the base material. The mechanical properties of the welded joint using known flux amounted to tensile strength and -13-16 kgf / mm, an elongation of 18-2%. The low level of strength of the welded joint is due to the nature of the microstructure of the heat-affected zone containing coarse grains with a diameter of 2 mm, which leads to a rapid destruction of the welded joint during rolling. The purpose of the invention is to increase the strength of the welded joint by modifying the structure while maintaining the flatness at high levels. To achieve this goal, a copper welding flux has been developed that contains anhydrous borax and metallic magnesium, which additionally contains

titanium sponge and crystalline in the following ratio of components, B "es.%:

Magnesium Metallic5-9

Crystalline silicon1-3

Titanium sponge 10-13Bura is waterless. Others

Magnesium metal reduces the melting point and increases the chemical activity of the flux.

Magnesium content less than 5% impairs deoxidation of the weld pool, and above 9% lead to its fading when the flux is melted.

The optimum magnesium content is 8%.

 Silicon crystal is introduced into the flux in order to impart increased mechanical strength and improve the deoxidation of the weld pool.

If the silicon content in the flux is less than 1%, the strength of the welded joint is less than 20 kgf / mm and it observes the formation of pores in the weld, which indicates poor deoxidation.

A content of more than 3% leads to the formation of a welded joint with reduced ductility (see table). The optimum silicon content is 1.5%.

To obtain a fine-grained structure and, consequently, an increase in mechanical strength, sponge titanium is introduced into the flux. Sponge titanium reacts more fully with the weld metal, rather than metallic tzatan.

With the introduction of less than 10% of titanium flux, a coarse-grained weld metal structure is observed.

In the manufacture of a flux with a content of 13% by 13%, you have removed that the total gas is transferred to the melt, and remains in the form of corules. Consequently, the titanium flux contained should not exceed 13%.

Manufacturing technology is as follows.

First, boric slag is alloyed, consisting of 91-95% anhydrous borax and 5-9% magnesium metal B graphite crucible without air access at 1000 ° C. The resulting melt is poured into a stainless steel mold and cooled to room temperature.

Then the components are weighed in the amount, wt.%: Silicon 1-3 and titanium g-ubaty 10-13, boric slag, fall asleep in a graphite crucible and mix well.

The crucible is tightly closed with a graphite grip, in which there is a hole for the thermocouple.

After installing the thermocouple, the hole in the lid is covered with a refractory mass consisting of magnesite powder and liquid glass.

The crucible with the prepared mixture is heated at a high-frequency installation to

145 ° C and incubated for 10 minutes.

The resulting melt is poured into a stainless cTai-ffi water-cooled mold, since the melt interacts with carbon steel i.

After the bone gap, the glassy alloy is crushed in ball mills. The milled mass is sieved through a sieve with 1600 holes per cm.

This flux is introduced into the deoxidized weld pool through a copper lining with a milled 7 N-IM width and 0.5 mm depth. The lining provides the flux with argon or other gas inert to copper. The flux of the proposed composition has a melting point below the melting point of the metal being welded on.

The flux can also be applied to the edges to be welded in the form of a paste, obtained by mixing flux with alcohol in a 1: 3 ratio.

The paste is applied with a brush in a uniform layer 10 mm wide on either side of the joint. After evaporation of the alcohol, the flux is firmly held on the edges to be welded.

With the introduction of flux into the weld pool, wandering of the base of the arc column decreases, the concentration of the arc power increases, and the depth of penetration increases.

For quality and quality characteristics of the strength and plasticity of the welded joints were melted

several compositions of the present flux. These characteristics were compared in terms of the upper, middle, and lower profiles of the factors of a ra elements.

The microstructure of the welded joint B of the heat-affected zone using the proposed and known flux is shown in the photograph, while the grain size of the okrollochny zone is 0, O9 mm. The optimal composition, wt.%: Bura anhydrous 80

Magnesium metal7

Silicon Crystal 1.5 Titanium Sponge11.5

Burabazvodny

Magnesium metal (famous flux)

Magnesium metal

Crystalline silicon

Titanium sponge (metal)

Bura anhydrous

Magnesium metal

Crystalline silicon

Titanium sponge (metal) /

Bura.bezvodna

Magnesium, metallic

Crystalline silicon

Titanium sponge (metal)

Bura anhydrous

84

The tensile strength was 21 kgf / mm, and the relative elongation was 18%. The weld has a satisfactory corrosion resistance.

Claims (2)

1. USSR author's certificate number 538869, cl. 23 K 35/362, 1975. 2.Malstrem A.M. Electric arc welding of copper. M.-L. Mashgiz, 1954, p. 25 (prototype).