RU2492983C1 - Welding compound - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention may be used for welding structure operated at negative temperatures. Welding compound contains components in the following ratio in wt %: dusty wastes of lime production - 33.9-44.5, dusty wastes of ferrosilicum production - 20.5-31.1, dusty wastes of aluminium production - 22-27, liquid glass 8-13.

EFFECT: higher mechanical strength of weld joint, decreased gas content, removal of hydrogen, higher stability of arc and quality of weld joint.

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Description

The invention relates to welding, specifically to submerged arc welding, in particular to fluxes intended for use in welding products operating at low temperatures.

Known, selected as a prototype [1], a fused flux for electric arc welding of cold-resistant steels, containing silicon dioxide, calcium oxide, magnesium oxide, calcium fluoride, aluminum oxide, manganese oxide, iron oxide, which has a basicity of 1.5-2.0 and additionally contains potassium oxide and sodium in the following ratio of components, wt.%: silicon dioxide SiO ₂ - 21-27, calcium oxide CaO - 11-17, magnesium oxide MgO - 21-25, calcium fluoride CaF ₂ - 14-20, aluminum oxide Al ₂ O ₃ - 10-14, manganese oxide MnO - 4-7, (potassium + sodium) oxides Na ₂ O + K ₂ O - 2-5, iron oxide Fe ₂ O ₃ - 1-3.

Significant disadvantages of this flux for welding are:

- the absence of carbon-containing components, allowing oxygen removal in the form of gaseous CO and CO ₂ compounds that do not pollute the weld with oxide non-metallic inclusions and, as a result, increase the mechanical properties of the welded structure.

- reduced mechanical properties of the weld due to the high level of gas content in the weld due to the lack of protective carbon dioxide;

- increased contamination by non-metallic inclusions in connection with reduced refining properties of the resulting slag due to the high basicity and increased melting temperature of the latter;

- high cost in connection with the use of expensive natural materials and costs associated with crushing and grinding;

- insufficiently stable burning of the arc due to the insufficient number of elements facilitating the excitation and stabilizing the burning of the arc (in particular sodium and potassium);

- a low degree of hydrogen removal associated with the use of only calcium fluoride as a fluorine-containing component that releases active fluorine during dissociation, which, in turn, forms a gaseous compound HF, removes hydrogen.

Known [2], a flux for welding carbon and low alloy steels containing silicon dioxide, manganese oxide, calcium oxide, magnesium oxide, aluminum oxide, potassium oxide, sodium oxide, iron oxide, calcium fluoride, which additionally contains manganese oxides in the following ratio of components , wt.%: silicon dioxide 35-45, manganese (II) oxide 25-40, calcium oxide 8-18, magnesium oxide 1-8, aluminum oxide 1-8, calcium fluoride 2-8, the sum of potassium and sodium oxides 0 , 5-3.0, iron (III) oxide 0.5-2.5, the sum of manganese (III and IV) oxides 0.2-4.0, while the sum of iron (III) oxides and m manganese (III and IV) should be 1-5 wt.% and with values of this amount up to 2.5 wt.% the content of manganese (IV) oxide should be at least 50% of the total amount of manganese oxides (III and IV), and the basicity flux should correspond to the following ratio: B = (N _CaO +0.6 N _MgO ++ 0.5 N _CaF2 +0.5 N _MnO ) / (N _SiO2 +0.5 N _Al2O3 ) = 0.76-0.95 where N is the mole fraction of the compound.

Significant disadvantages of this flux for welding are:

- high oxidation (content of manganese and iron oxides) and the absence of carbon-containing components in the flux do not allow the removal of oxygen in the form of gaseous compounds CO and CO ₂ , which in turn leads to contamination of the weld with oxide non-metallic inclusions and a decrease in the mechanical properties of the welded structure;

- high cost due to the use of expensive natural materials;

- insufficiently stable burning of the arc due to the insufficient number of elements that facilitate the excitation and stabilize the burning of the arc (in particular sodium and potassium);

- a low degree of hydrogen removal associated with the use of only calcium fluoride as a fluorine-containing component that releases active fluorine during dissociation, which in turn forms a gaseous compound HF, removes hydrogen.

The desired technical results of the invention are:

- improving the mechanical properties of the weld due to the reduction of steel contamination by non-metallic inclusions,

- reduction of gas content due to the creation of additional gas protection as a result of carbon oxidation;

- removal of hydrogen due to binding to insoluble compounds with fluorine;

- reducing the cost of the welding process through the use of industrial waste.

- increasing the stability of arc burning and the quality of the weld

To do this, we propose a welding flux containing silicon dioxide, manganese oxide, calcium oxide, magnesium oxide, aluminum oxide, potassium oxide, sodium oxide, iron oxide, calcium fluoride, in which dusty waste is used as materials based on silicon dioxide and manganese oxide ferrosilicon production; as materials based on calcium oxide, magnesium oxide use pulverized waste from the production of lime; as materials based on aluminum oxide, potassium oxide, sodium oxide, iron oxide and calcium fluoride, dusty waste from aluminum production is used, and potassium-sodium liquid glass is used as a binder material containing potassium oxide, sodium oxide, while dusty production waste lime, gas cleaning dust with a CaO content of at least 85 wt.% was used; dust of gas cleaning from a ferroalloy production with a SiO ₂ content of not less than it is 98 wt.%, and dust of electrostatic precipitators having the following chemical composition, wt.%: Al ₂ O ₃ = 21-46.23; F ⁺ = 18-27; Na ₂ O = 8-15; K ₂ O = 0.4-6%, CaO = 0.7-2.3; SiO ₂ = 0.5-2.48; Fe ₂ O ₃ = 2.1-3.27; C _total = 12.5-30.2, MnO = 0.07-0.9, MgO = 0.06-0.9, S = 0.09-0.59, P = 0.1-0.18 ;

in the following ratio of components, wt.%:

Dusty lime waste 33.9-44.5 Ferrosilicon dusty waste 20.5-31.1 Dusty aluminum waste 22-27 Liquid glass 8-13

The claimed limits are selected empirically based on the quality of the welds obtained during welding, the stability of the welding process and the required mechanical properties.

The introduction of pulverized waste lime production into the flux composition allows to provide refining (from non-metallic inclusions) due to the required amount of calcium and magnesium oxides and to create covering properties of the resulting welding slag.

The introduction of ferrosilicon dusty waste into the flux composition provides the required flux basicity and viscosity obtained during welding of the slag system. The oxides of iron and manganese contained in the dusty waste of the production of ferrosilicon increase the gas permeability of the slag layer, and therefore their limitation is necessary.

The introduction of aluminum electrostatic precipitators into the flux of dust allows:

- to carry out intensive carbon bales due to the formation of CO and CO ₂ formed during the interaction of carbon fluoride CF _x (1≥x> 0) with oxygen dissolved in steel, while due to the fact that carbon is in a bound state, carburization of steel is practically not occurs;

- carry out the removal of hydrogen due to a complex of fluorine-containing compounds (such as Na ₂ SiF ₆ , NaF, KF, CF _x (1≥x> 0), AlF ₃ , Na ₃ AlF ₆ ) decomposing at welding process temperatures with the release of F, which the turn interacts with hydrogen dissolved in steel to form a gaseous HF compound;

- increase the stability of arc burning due to elements that facilitate ionization in the arc column - potassium and sodium.

The introduction of liquid glass is due, on the one hand, to use it as a binder of the inventive flux, and, on the other hand, as a material that increases, due to the contained potassium and sodium, the stability of arc burning.

For the manufacture of flux for welding, they were used as: pulverized waste from lime production — gas treatment dust of lime production with a CaO content of at least 85%;

dusty waste from the production of ferrosilicon - dust gas treatment of ferroalloy production during the melting of ferrosilicon with a SiO ₂ content _of not less than 98%;

pulverized waste from aluminum production - dust from electrostatic precipitators of aluminum production with the following chemical composition, wt.%: Al ₂ O ₃ = 21-46,23; F ⁺ = 18-27; Na ₂ O = 8-15; K ₂ O = 0.4-6%, CaO = 0.7-2.3; SiO ₂ = 0.5-2.48; Fe ₂ O ₃ = 2.1-3.27; C _total = 12.5-30.2, MnO = 0.07-0.9, MgO = 0.06-0.9, S = 0.09-0.59, P = 0.1-0.18 ;

liquid glass - potassium-sodium liquid glass with a density at 15-25 ° C - 1.30-1.55 g / cm ³ and a silicate module [SiO ₂ : (K ₂ O + Na ₂ O) · 1,0323] - 2.6-3.0.

The manufacture of the inventive flux for welding was carried out by mixing the inventive components. The resulting mixture was stirred for 25-35 minutes until a homogeneous mass. Next, the resulting mixture was dried at a temperature of 150-300 ° C for 20-30 minutes, after which grinding was performed. Next, sifting was carried out through a sieve (cell 3 × 3 mm). Larger granules were poisoned by grinding. The inventive flux for welding was used on samples of steel grade 09G2S, welding was carried out with wire Sv-08GA.

The effect of changes in the chemical composition of components with boundary, foreign and claimed limits of the inventive flux for welding on the mechanical properties of the weld (tensile strength - σ _B , N / mm ² , yield strength - σ _T , N / mm ² , elongation δ,%, toughness at minus 40 ° C KCU ^-40C, J / cm ^2, and hydrogen content [H], ^cm3 / 100g metal is given in the table. it should be noted that the manufacture of the flux with foreign outside failed to obtain full flux : when using liquid glass in the ratio 7.5 part of the dust fraction is in the unbound state waterglass (column 9), and at a ratio of 13.5 waterglass part not absorbed weight of pulverulent components and complicates the manufacturing process of the flux due to the high adhesion (column 1).

Using the inventive mixture in comparison with the base (prototype) allows you to:

1. To increase the toughness of the weld due to the reduction of contamination of steel by non-metallic inclusions.

2. Reduce the hydrogen content by the introduction of fluorine-containing components and create an extra gas protection (no more than 1 cm ³ / 100g metal.

3. To reduce the cost of the welding process due to the use of production waste.

4. To improve the formation of the weld during welding by stabilizing the burning of the arc.

List of sources taken into account during the examination:

1. Pat. RF 2313434 B23K 35/362

2. Pat. USSR 1759229 B23K 35/362

Table The influence of the ratio of the ingredients of the flux for welding on the mechanical properties of welds Ingredients The content in the flux, wt.% Option one 2 3 four 5 6 7 8 9 Dusty lime waste 33.5 39,4 34.9 33.9 36.74 40.29 42.96 44.5 45 Ferrosilicon dusty waste 31.5 25.6 30.1 31.1 28.26 24.71 22.04 20.5 twenty Dusty aluminum waste 21.5 22 23 25 24 26 24 27 27.5 Liquid glass 13.5 13 12 10 eleven 9 eleven 8 7.5 σ _B , N / mm ² 500 510 515 508 518 522 510 σ _T , N / mm ² 350 362 360 370 357 362 358 δ,% 21 21 21 21 22 22 21 KCU ^-40C , J / cm ² 122 134 118 128 122 125 123 [N], cm3 / 100 g meth 0.8 0.7 0.7 0.5 0.4 0.5 0.4

Claims (1)

Welding flux containing silicon dioxide, manganese oxide, calcium oxide, magnesium oxide, aluminum oxide, potassium oxide, sodium oxide, iron oxide, calcium fluoride, characterized in that dusty waste products are used as materials based on silicon dioxide and manganese oxide ferrosilicon, as a material based on calcium oxide, magnesium oxide, dusty waste from lime production was used, as materials based on aluminum oxide, potassium oxide, sodium oxide, iron oxide and calcium fluoride anes pulverulent waste of aluminum production, as well as a binder comprising potassium oxide and sodium oxide, used potassium-sodium water glass in the following ratio, wt.%:
Dusty lime waste 33.9-44.5 Ferrosilicon dusty waste 20.5-31.1 Dusty aluminum waste 22-27 Liquid glass 8-13,
in this case, gas cleaning dust with a CaO content of at least 85 wt.% was used as dusty waste of lime production, gas cleaning dust of ferroalloy production with a SiO2 content _of not less than 98 wt.% was used as dusty waste of production of lime, and aluminum dust was used as dusty waste used dust of electrostatic precipitators having the following chemical composition, wt.%: Al ₂ O ₃ = 21-46,23; F ⁺ = 18-27; Na ₂ O = 8-15; K ₂ O = 0.4-6; CaO = 0.7-2.3; SiO ₂ = 0.5-2.48; Fe ₂ O ₃ = 2.1-3.27; C _total = 12.5-30.2; MnO = 0.07-0.9; MgO = 0.06-0.9; S = 0.09-0.59; P = 0.1-0.18.