RU2579412C2 - Flux for steel mechanised welding and surfacing - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: claimed flux consists of silicon manganese production wastes that contain the following ratio components, wt %: silicon dioxide 25-49, aluminium oxide 4-28, calcium oxide 15-32, calcium fluoride 0.1-15, magnesium oxide 1.7- 9.0, manganese oxide 3-17, iron oxide 0.1-3.5. Impurities used can be sulphur in amount not higher than 0.12 wt % and phosphorus in amount not higher than 0.02 wt %.

EFFECT: lower costs, flux higher strength, stable arc, reduced loss of doping elements.

Description

The invention relates to welding, in particular to mechanized submerged arc welding, in particular to fluxes intended for welding and surfacing of low- and medium-alloy steels.

Known selected as a prototype [1] flux for mechanized welding of steels containing SiO ₂ , Al ₂ O ₃ , CaO, CaF ₂ , MgO, MnO, FeO in the following ratio, mass. %: SiO ₂ = 15-21; A1 ₂ O ₃ = 14.5-18.5; CaO = 13.5-17.5; CaF ₂ = 19-23; MgO = 7-10; MnO = 2-5; FeO = 12-22.

Significant disadvantages of this flux for welding are

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

- increased contamination of the weld and weld metal with non-metallic inclusions in connection with reduced refining properties of the resulting slag due to the high concentration of MgO and increased melting points and flux viscosity;

- high flux oxidation (iron oxide content), leading to a significant oxidation of alloying elements in welded steels, as well as to a decrease in the mechanical properties of welded structures due to contamination of the weld with oxide non-metallic inclusions.

Known [2] fused welding low-silicon flux for welding low- and medium-alloy steels containing silicon oxide, aluminum oxide, calcium oxide, manganese oxide, calcium fluoride, the sum of potassium and sodium oxides, sodium fluoride, iron oxides, phosphorus, characterized in that the flux contains components in the following ratio, mass. %: iron oxides 2-4, silicon oxide 9-12, calcium oxide 18-24, aluminum oxide 36-48, manganese oxide 5-7, magnesium oxide 5-7, calcium fluoride 5-8, the sum of the oxides of potassium and sodium 1 -2.5, sodium fluoride 1.0-2.5, phosphorus 0.007-0.010, while the mass ratio of silicon oxide, calcium and aluminum is 1: 2: 4, and the ratio of phosphorus to the sum of iron oxides is less than 0.004.

Significant disadvantages of this flux for welding are

- high cost in connection with the use of expensive natural materials and the costs associated with the preparation of the mixture for melting and smelting flux in special smelting units;

- high oxidation (iron oxide content), leading to contamination of the weld with oxide non-metallic inclusions and a decrease in the mechanical properties of the welded structure, as well as to significant oxidation of alloying elements in welded steels.

The technical results of the invention are

- reduction in the cost of the welding process due to the disposal of production waste;

- reduction of pollution became non-metallic inclusions;

- reduction of fumes of alloying elements during welding and surfacing;

- improving the mechanical properties of the welded joint.

For this, a flux for mechanized welding of steels is proposed, in which slag of silicomanganese production is used as a component in the following ratio of components, mass. %:

silicon dioxide 25-49,

aluminum oxide 4-28,

calcium oxide 15-32,

calcium fluoride 0.1-1.5,

magnesium oxide 1.7-9.0,

manganese oxide 3-17,

iron oxide 0.1-3.5,

however, as an impurity, the flux may contain sulfur not more than 0.12%, phosphorus not more than 0.02%.

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 content of FeO and MnO was selected based on the provision, on the one hand, of low oxidation of the alloying elements, and, on the other hand, of good fluidity of the slag system.

Concentrations of CaO, SiO ₂ , CaF ₂ , Al ₂ O ₃ , MgO are selected based on the conditions for ensuring good covering properties and optimal refining ability of the resulting slag with respect to non-metallic inclusions. The selected limits provide good slag formation and high refining and covering properties of the forming slag.

The concentration of sulfur and phosphorus in the flux is limited in order to reduce the harmful effect of these elements on the quality of the weld (elimination of cold and hot cracks during welding, as well as a decrease in the values of mechanical properties).

For the manufacture of flux for welding, we used slag from silicomanganese production, melted in ore-thermal furnaces by a carbon thermal method, by a continuous process. The mixture consisted of manganese ore, quartzite and coke. Ferroalloy (silicomanganese) was released together with slag into a ladle. After casting silicomanganese, the slag was drained from the ladle when it was cooled. Depending on the intensity of cooling, a glassy or pumiceous slag was obtained, which is used later in welding. Silicomanganese contained 64.7-71.7% Mn and 14.8-18.2% Si. Slag contained, mass. % .: Sio ₂ = 25-49, Al ₂ O ₃ = 4-28, CaO = 15-32, CaF ₂ = 0.1-1.5, MgO = 1.7-9.8 MnO = 3-17 , FeO = 0.1-3.5, S≤0.20 P≤0.05.

The manufacture of the inventive flux for mechanized welding and surfacing of steels was carried out by crushing, screening and sieving through a sieve (mesh 2 × 2 mm). The inventive flux for welding was used on samples of steel grades 09G2S and 09G2, for surfacing on steels 60G, 35KhGSA, welding and surfacing were carried out using Sv-08GA wire. Welding and surfacing were carried out using plates with a length of at least 500 mm on an ASAW-1250 welding tractor. Samples were cut from the welded plates for mechanical tests (tensile strength - b _V , N / mm ² , yield strength - b _T , N / mm ² , elongation δ,%, impact strength at a temperature of minus 40 ° C KCU ^-40C , J / cm ² ), as well as macro and micro studies.

For comparison, as a prototype for comparison [1] used fused welding flux brand AN-18 with a chemical composition, mass. %: SiO ₂ = 18; Al ₂ O ₃ = 15.5; CaO = 16; CaF ₂ = 21.3; MgO = 9.8; MnO = 5; FeO = 14.

Using the inventive flux for welding in comparison with the prototype allows you to:

1. Reduce the cost of flux 2.6 times.

2. To reduce steel pollution by non-metallic oxide inclusions of an exogenous nature by an average of 0.04 mm.

3. Reduce the fumes of manganese by 1.7% in the weld.

4. To increase the general level of the weld mechanical properties, a yield strength _T B and a tensile strength b at _B 0.5-1.2 N / mm ^2, elongation of 0.7%, toughness at low temperatures by an average of 0, 9 J / cm ² .

List of sources taken into account

1. Pat. USSR 261149 B23K 35/362.

2. Pat. USSR 1685660 B23K 35/362.

Claims (1)

Flux for mechanized welding of steels containing silicon dioxide, alumina, calcium oxide, calcium fluoride, magnesium oxide, manganese oxide and iron oxide, characterized in that it contains the above components in the form of slag from silicomanganese production in the following ratio, wt.%:
silicon dioxide 25-49,
aluminum oxide 4-28,
calcium oxide 15-32,
calcium fluoride 0.1-1.5,
magnesium oxide 1.7-9.8,
manganese oxide 3-17,
iron oxide 0.1-3.5,
while as an impurity, the flux contains sulfur not more than 0.12 wt.% and phosphorus not more than 0.02 wt.%.