SU1539030A1 - Composition of electrode coating - Google Patents

Abstract

The invention relates to welding, in particular to materials for the cold welding of cast iron. The purpose of the invention is to improve the welding and technological properties and quality of the weld metal. Electrode coating has the following composition, wt.%: Marble 12 - 20

feldspar 6 - 10

cryolite 6 - 10

nickel 40 - 50

aluminum 1 - 3

ferrotitanium 15 - 20

potassium chromate 0.5 - 3

mica 1 - 3

soda 0.5 to 1.5, with marble, feldspar and cryolite being introduced in a ratio of 2: 1: 1. Electrode coating is used in combination with wire Sv-08A. The ratio of marble: feldspar: cryolite, equal to 2: 1: 1, provides good welding and technological properties. Nickel prevents the formation of structurally free carbides during the welding of cast iron, increases the stability of austenite in the weld. Ferrotitanium and aluminum are introduced to deoxidize the nickel alloy formed during the transition of nickel from the coating to the weld metal, potassium chromic acid to increase the stability of the arc

mica - plasticizer of the coating in the manufacture of electrodes. 2 tab.

Description

The invention relates to welding, in particular, to the compositions of electrode coatings used for cold welding of cast iron.

The purpose of the invention is to create an electrode for cold welding of cast iron with improved czarochno-technological properties and increased quality of the weld metal using wire of grade 08A by changing the slag and alloying system of the coating.

The ratio of components - marble, feldspar and cryolite is a slag system of optimal composition.

CaO-Na O-KaO-ALiOs-SiOa-Na-jAlFt,

In the process of cast iron welding, this system forms a slag consisting of the following chemical compounds: Galenite 2CaO AlcCH-SiO Anorite CaO AleOj2Si02 Analcite Na O-AlsOj-ASiO Leucite 4SiO Natrolite Na O-Al-HOs SSiO Habasite CaO-Al Os Melting Point slag system 1380-1 20 ° C. Its main advantage is excellent separation of slag crust at a temperature of up to 700-850 ° C, which is explained by the SP

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The minimum oxidizing ability and the absence of conditions for the formation of an intermediate oxidized layer, as well as the minimum coefficient of thermal expansion equal to 6.1-1СГ6 in the range of 20-9004С.

The increased amount of potassium and sodium oxides in the composition of the above system ensures stable arc burning and good weld formation.

The introduction of marble, feldspar and cryolite in quantities of less than 12, 6 and 6%, respectively, and a decrease in the ratio of marble to feldspar and cryolite less than 2: 1: 1 leads to a deterioration of the welding-technological properties of the electrodes. Slag crust separation is deteriorated, forming

seam reduction, arc burning stability is reduced.

When the content of marble, feldspar and cryolite in quantities of more than 20, 10 and 10% respectively and an increase in the ratio of marble to the content of feldspar and cryolite more than 2: 1: 1 leads to a deterioration of the welding-technological properties of the electrodes due to the large amount of slag formed. leading the welding process, increasing the melting point of the slag and reducing its separability.

Nickel is added to the coating in an amount of 0-50%. Nickel prevents the formation of structurally free carbides during the welding of cast iron. It expands the area of the m-phase, increases the stability of austenite with an increase in its content in the seam.

When the nickel content in the weld metal is more than kQ%, a pure austenitic structure is formed, having a hardness of about 180-197 HB.

When the nickel content in the coating composition is less than 0%, a pure austenitic structure is not obtained, the hardness of the weld metal increases, and the tendency of the weld to crack formation increases.

The introduction of nickel 8 in an amount of more than 50 is not economically feasible, since the cost of the electrodes increases without significantly improving the technological properties of the electrodes.

Ferrotitanium is incorporated into the coating in an amount to

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more complete deoxidation of the nickel alloy resulting from the transition of nickel from the coating to the weld metal.

As is known, nickel alloys are prone to the formation of porosity due to the interaction with the dissolved gases H and CO. Aluminum and titanium are used as the most effective deoxidizing agents for nickel alloys.

When the content of ferrotitanium in the composition of the coating is less than 15, effective deoxidation of the weld metal is not provided, which leads to the formation of porosity of the welds.

With the introduction of ferrotitanium in an amount of more than 20%, no further increase in the density of welds is observed, since pores are not formed and it is not economically feasible to inject large amounts of ferrotitanium.

Potassium chromate is introduced into the coating composition in an amount of 0, with the aim of increasing the stability of arc burning and carbon oxidation due to oxygen released during its dissociation.

With the introduction of potassium chromate in an amount of less than 0.5, the arc burning stability decreases, the weld pool carbon oxidizes insufficiently, which increases the hardness of the weld metal.

With the introduction of potassium chromate in an amount of more than 3, the manufacturability of the manufacture of electrodes is impaired due to the rapid solidification of the coating mass. Soda is one of the coating plasticizers.

Mica is introduced into the coating in an amount as a plasticizer for the coating during the manufacture of electrodes by the method of pressure testing. In addition, mica acts as a slag-forming component, which improves the protection of the weld metal from atmospheric gases.

When the content of mica in the coating is less than 1, the manufacturability of the manufacture of electrodes by the method of molding is deteriorated, scoring and cracks are formed on the coating of the electrodes.

When mica is introduced into the coating composition in an amount of more than k%, the welding-technological properties of the electrodes deteriorate due to the formation of a large amount of slag, which makes it difficult to maintain the welding process.

40

45

50

55

The technology of making electrodes with the specified composition of the coating does not differ from the known one. Welding wire of grade 08A is used as electrode rods.

It was made 5 variants of the electrodes, the data are summarized in table. one

To determine the quality of the float1

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The use of the composition of the electrode coating provides high weld-technological properties and quality of the deposited metal and allows for multi-layer cold electric arc welding of cast iron parts and welding of cast iron defects with high quality

of the welded metal and welding technology of welded joints and the ability of the welded welding electrodes to have the same properties as their usual metal-cutting tools produced multi-layer welding. 20 mm deep and 100 mm long with an opening angle of 70 ° on the plate

Claims (1)

Invention Formula The composition of the electrode coating containing marble, cryolite, feldspar, ferrotitanium, mica, aluminum, characterized in that from sulfur iron brand. 15 Welding was performed with electrodes with a diameter of k mm at a constant current of reverse polarity. The strength of the current was 160-180 A. The results of the welding-technical tests are given in Table 2, which improves the welding-technological properties, the coefficient of properties and the improvement of the quality of slag expansion and the amount of the deposited metal, using welds. 2. In addition to the composition for cold welding of test results of the welding technique, it additionally contains niological properties, a ratio of 25 cells, potassium hromic acid and soda, thermal expansion of slag and marble, feldspar and cryolite of the number of welded defects. the seams are shown in the proportion of 2: 1: 1, when it is assumed that the optimum ratio of the components, wt.%: Tav coating options 2, 3, providing the slag and metal ratio. all welds and the possibility of processing them with a conventional metal-cutting tool. Invention Formula The composition of the electrode coating containing marble, cryolite, feldspar, ferrotitanium, mica, aluminum, characterized in that Forming weld satisfactory Slag separability is good. Low arc stability II Seam shaping and slag separability excellent. Steady arc burning. Machinability with a cutting tool is good. IIIToo IV-V. Seam formation is good. Slag separability deteriorated. Large amount of slag workability is good table 2 7.3 6.2 Not No no 2 slagging