RU2249498C1 - Mineral alloy for coatings of welding electrodes and ceramic fluxes - Google Patents

Abstract

FIELD: manufacture of welding materials for electric arc welding of structures of carbon and low-alloy steels.

SUBSTANCE: mineral alloy contains next relation of ingredients, mass %: alumina, 45.0 -51.0; silica, 13.0 - 17.0; titanium dioxide, 3.0 - 4.0; calcium oxide, 10.0 - 16.0; calcium fluoride, 16.0 - 22.0. Composition of alloy prevents porosity of welded on metal due to lowered chemical activity of surface of alumina grains.

EFFECT: elimination of porosity of welded on metal.

2 cl, 5 dwg, 3 tbl

Description

The invention relates to the field of welding materials, in particular to components containing aluminum oxide, for coating welding electrodes and ceramic fluxes for electric arc welding of structures made of carbon and low alloy steels.

The introduction of aluminum oxide into the coating of welding electrodes and, accordingly, after melting into the slag allows to increase the interval of solidification of the slag when it is cooled and the viscosity in the molten state, which favorably affects the welding and technological properties of the electrodes.

Alumina or corundum, sometimes small amounts of muscovite mica, are usually used as components containing alumina in the main coatings of electrodes, as well as in ceramic flux compositions. In this case, porosity problems in the weld metal inevitably arise. The use of alumina in the composition of the mixture of welding fused fluxes, as a rule, does not lead to the appearance of porosity in the weld metal. Therefore, the state of alumina in which it is introduced into the coatings of the welding electrodes can be significant.

The kyanite ore of the Khizovar deposit, the kyanite concentrate from this ore (Kononov ME Refractories from mineral raw materials of the Karelo-Kola region. - Apatity, IHTREMS KSC RAS, 1994, pp. 86-89) and kyanite concentrate after chemical enrichment are known (Nikolaev A) . I. and other Welding production, No. 5, 2000, p. 36 - 40). Technological samples of kyanite ore (reference No. 378) and kyanite concentrate (reference No. 393), which underwent deep chemical enrichment to remove phosphorus and sulfur, were calcined at 900 ° C for 4 hours to directly test the electrode coatings. residues of reagents and carbon-containing minerals.

The chemical composition of kyanite ore and kyanite concentrates is given in table. 1.

Table 1 Name Content, wt.% SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ TiO ₂ CaO MgO P ₂ O ₅ SO ₃ Kyanite ore 56.50 27.85 6.40 0.86 0.62 0.48 0.18 3.90 Kyanite concentrate 38.88 57.57 0.44 0.16 0.51 0.44 0.15 0.23 Chemical enrichment kyanite concentrate 40.6 56.6 0.64 1.14 0.30 0.05 - 0.05 Chemical enrichment kyanite concentrate, sample No. 393 41.1 55.3 1,50 1,50 0.20 0.18 0.01 0.005 Kyanite ore, sample No. 378 42.10 54.30 not determined

A common disadvantage of kyanite ore and kyanite concentrate is the high content of impurities of phosphorus, sulfur and carbon (about 0.3% graphite). The disadvantage of kyanite concentrate chemical enrichment is its chemical activity in relation to water glass - a binder of electrode coatings. As a result of the interaction with activated glass of activated kyanite grains, hydrated aluminum compounds are formed, the decomposition of which during welding leads to the appearance of porosity in the deposited metal.

Known "Fused flux for surfacing" containing silicon oxide 27.0-34.0%, calcium oxide 24.0-32.0%, calcium fluoride 25.0-33.0%, alumina 27.0-34, 0% when fulfilling the ratio of 0.9 А Al ₂ O ₃ / CaO 1,4 1.4 and 0.9 Ca CaF ₂ / Al ₂ O ₃ 1,2 1.2 (patent No. 21555529, 23 K 35/362, publ. 1998 .

The disadvantages of the analogue is its increased tendency to hydrate during storage, associated with a high content of calcium oxide and fluoride in it, which ultimately contributes to the appearance of porosity in the weld metal; insufficiently high content of Al ₂ O ₃ requires an increase in the proportion of “flux” in the coating, which again leads to an increase in the proportion of calcium oxide and fluoride and to the aforementioned adverse effects.

Closest to the proposed invention in terms of its constituent components is “Fused flux” containing silica -21.0-30.0%, titanium dioxide - 11.0-20.0%, calcium oxide - 11.0-14, 0%, alumina - 22.0-25.0%, the ratio of the sum of basic oxides to acid is not more than 0.4, and the total content of silicon and titanium oxides is not less than 27 wt.% (USSR AS No. 590121, 23 K 35 / 362, publ. 1978).

The disadvantage of the prototype is the low content of alumina, which does not allow its effective use for introducing alumina into the electrode coatings.

When creating the invention, the task was to prevent the porosity of welds (in the weld metal) by reducing the chemical activity of the surface of the grains of aluminum oxide.

This is achieved by the fact that in the mineral alloy for coating welding electrodes and ceramic fluxes based on aluminum oxide, silicon oxide, titanium dioxide, calcium oxide and calcium fluoride, the components are taken in the following ratio, wt.%:

alumina 45.0-51.0

silica 13.0-17.0

titanium dioxide 3.0-7.0

calcium oxide 10.0-16.0

calcium fluoride 16.0-22.0.

In addition, the claimed technical solution has an optional feature, namely:

the content of aluminum oxide, silicon oxide, titanium dioxide and calcium oxide in the mineral alloy and the mixture for its smelting can be in the following ratio:

Al ₂ O ₃ / CaO = 2.8-5.1; SiO ₂ / CaO = 0.8-1.7; TiO ₂ / CaO = 0.15-0.7.

The main distinguishing features of the proposed mineral alloy are its phase characteristics, determined by the ratios of the components, which are given in table. 2 as well as:

- the ratio of CaO / SiO ₂ + TiO ₂ in the mineral alloy is in the range of 0.42-1.0, while in the prototype it should be no more than 0.4;

- the total content of silicon and titanium oxides in the mineral alloy is a maximum of 24.0%, while in the prototype it should be at least 27.0%.

table 2 Component ratio In the present invention In prototype Al ₂ O ₃ / CaO 2.8-5.1 1.6-2.3 SiO ₂ / CaO 0.8-1.7 1.9-2.7 TiO ₂ / CaO 0.15-0.7 0.8-1.8

The invention is illustrated by phase equilibrium diagrams shown in figures 1-5.

In figure 1, 2 shows the significant differences in the mineralogical compositions of the analogue (patent No. 2155529) - the main mineral compound is gelenite (2CaO · Al ₂ O ₃ · SiO ₂ ), the prototype is the main mineral compound is anorthite (CaO · Al ₂ O ₃ · 2SiO ₂ ) and mineral - alloy are the main mineral compounds;

figure 3 - the formation in a mineral alloy of calcium aluminates;

figure 4 - location of the composition region of the mineral alloy in the crystallization field of rankinite and close to it part of the crystallization field of pseudowollastonite;

figure 5 - the location of the tested compositions of the mineral alloy of industrial samples 1, 2 and laboratory samples 3-7.

When developing and before using a mineral alloy in coatings of welding electrodes and ceramic fluxes, tests of its various composition were carried out by welding the rollers automatically under a layer of a mineral alloy prepared for use as intended.

Evaluation of the results was carried out according to the appearance of the weld bead and slag crust, as well as the ease of separation of the slag crust from the surface of the weld bead. The evaluation of the test results is given in table. 3.

Table 3 Conditional marking Content, wt.% Ratio Assessment of test results Al ₂ O ₃ SiO ₂ CaO TiO ₂ CaF ₂ Al ₂ O ₃ / CaO SiO ₂ / CaO TiO ₂ / CaO 1 industrial sample 46.6 13.6 14.7 5.2 18.8 3.2 0.9 0.4 ex. 2 industrial samples 45.9 15,2 15.3 6.0 18.0 3.0 1,0 0.4 ex. 3 labs 50,0 13.0 12.0 6.0 19.0 4.2 1,1 0.5 ex. 4 labs 45.0 11.0 14.0 8.0 22.0 3.2 0.78 0.6 sat. 5 lab. 48.0 11.0 20,0 6.0 15.0 2,4 0.55 0.3 unsatisfied. 6 lab. 49.5 18.0 10.5 2.0 20,0 4.7 1.7 0.2 sat. 7 lab. 50,0 10.0 18.0 2.0 20,0 2.78 0.6 0.1 unsatisfied.

Industrial samples 1, 2 and laboratory sample 3 showed good welding and technological properties: smooth formation of the deposited bead, a dense and even slag crust, which, when cooled, is independently separated from the surface of the deposited bead. The figurative points of these samples on the diagram of CaO-SiO ₂ -TiO ₂ (figure 5) are located in the claimed field of the compositions of the mineral alloy.

The welding and technological properties of laboratory samples 4 and 6 were worse: when removed, the slag crust partially crushed and remained in the places where the rollers joined the base metal. Laboratory samples 5 and 7 showed unsatisfactory test results of welding and technological properties, expressed in the uneven formation of the weld bead and slag crust.

Industrial samples 1 and 2 were used in the mixture formulations for the manufacture of experimental welding electrodes, ceramic, in particular, agglomerated fluxes, during welding of which porosity was not observed both in the metal and in the slag crust.

As can be seen from the above test results of these samples, the proposed mineral alloy allows you to completely eliminate the porosity in the weld beads and the signs of its possible appearance - pores in the slag crust, as well as to ensure good formation of the weld bead when welding in various positions (lower, horizontal, vertical: upwards).

Claims (2)

1. A mineral alloy for coating welding electrodes and ceramic fluxes, containing aluminum oxide, silicon oxide, titanium dioxide, calcium oxide and calcium fluoride, characterized in that the components of the mineral alloy are taken in the following ratio, wt.%: Alumina 45.0-51.0 Silica 13.0-17.0 Titanium dioxide 3.0-7.0 Calcium oxide 10.0-16.0 Calcium Fluoride 16.0-22.0 2. The mineral alloy for coating welding electrodes and ceramic fluxes according to claim 1, characterized in that the content of aluminum oxide, silicon oxide, titanium dioxide and calcium oxide in the mineral alloy should be in the following ratio: Al ₂ O ₃ / CaO = 2.8-5.1; SiO ₂ / CaO = 0.8-1.7; TiO ₂ / CaO = 0.15-0.7.

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