CORED WIRE FOR OUT-OF-FURNACE TREATMENT OF METALLURGICAL MELTS

Abstract

A wire for out-of-furnace treatment of metallurgical melts comprises a metallic sheath which encloses a core comprising at least one element selected from the group consisting of Ca, Ba, Sr, Mg, Si and Al, wherein at least one layer of a composite coating is applied to an inner and/or outer surface of said sheath, which coating consists of a lacquer paint material and contains high-melting ultrafine particles selected from compounds of metal carbides and/or nitrides and/or carbonitrides and/or silicides and/or borides. The composite coating comprises a protector material, for which ferroalloys and/or flux agents are used. The metals contained in the high-melting compounds are titanium and/or tungsten and/or silicon and/or magnesium and/or niobium and/or vanadium. Said coating is applied evenly onto the surface of the sheath.

Claims

1. A cored wire intended for out-of-furnace treatment of metallurgical melts has a steel sheath that encases a filler material containing at least one element chosen from among the group of Ca, Ba, Sr, Mg, Si, Al, in addition, at least one layer of composite coating is applied onto the inner and/or outer surface of the sheath, that is in fact a paintwork material containing ultrafine particles selected from compounds of metal carbides and/or metal nitrides, and/or metal carbonitrides, and/or metal silicides, and/or metal borides.

2. The cored wire according to claim 1 wherein the paintwork material is polymer-based and/or alcohol-based.

3. The cored wire according to claim 1 wherein the composite coating contains a protective material represented by ferroalloys and/or fluxes.

4. The cored wire according to claim 1 where in the metals contained in the compounds are represented by titanium, and/or tungsten, and/or silicon, and/or magnesium, and/or niobium, and/or vanadium.

5. The cored wire according to claim 1 wherein layers of the composite coating are applied onto the surfaces of the sheath uniformly.

6. The cored wire according to claim 1 wherein the filler material additionally contains at least one component chosen from among the group of CaC.sub.2, Na.sub.2CO.sub.3, CaCO.sub.3, SrCO.sub.3, CaO, MgO.

Description

EXAMPLE 1

[0038] In an electric arc furnace, steel 20GFL was melted. It had the following base components in terms of their percentages by weight:

[0039] Ca—0.16-0.25,

[0040] Si—0.20-0.50,

[0041] Mn—0.90-1.40.

[0042] V—0.06-0.12,

[0043] P up to 0.05,

[0044] S up to 0.05,

[0045] Fe being the balance;

[0046] the melt was tapped into two 10-t ladles.

[0047] In ladle #1, for the purpose of refining and modifying the molten metal, a cored wire was used 14 mm in diameter with its metal sheath (jacket) being 0.40 mm thick. It had the following components in terms of their percentages by weight: Si—43-51, Ca—18-22, Ba—10-15, Sr—10-15, its core ratio being 0.55. The inner surface of the metal sheath (jacket) had a paintwork-based coating applied to it. It had a modifying ultra-dispersed element, TiC.sub.0.4N.sub.0.6 (titanium carbonitride) with its particles being less than 5 mμ, in size making up 20% of the total and a slag-forming mixture, CaO+CaF.sub.2 (calcium oxide+calcium fluoride) with its particles being less than 100 μm making up 80% of the total. The coat applied is 150-200 μm thick. The amount of the coat applied ensures that one meter of the cored wire contain at least 10 g of titanium carbonitride. A total of 5 kg of cored wire was consumed per one ton of molten metal.

[0048] In ladle #2, for the purpose of modifying the molten metal, a cored wire containing silicon calcium (SiCa40) was used.

[0049] As the properties of the melt modified with the cored wire having the alleged composition and those of the melt modified with the cored wire containing silicon calcium (SiCa40) were compared, the following results were obtained.

[0050] Use of the cored wire having the alleged composition made it possible to reduce the size of the grain by 24%, increase the microhardness by 7.4% and improve KCV impact toughness at −60° C. of the modified melt by 49%. It also became possible to reduce the content of non-metallic inclusions.

[0051] Use of the cored wire having the above composition made it possible to improve the strength, ductility and impact toughness of the modified melt.

EXAMPLE 2

[0052] In an electric arc furnace, steel 20GFL was melted. It had the following base components in terms of their percentages by weight:

[0053] Ca 0.16-0.25,

[0054] Si 0.20-0.50.

[0055] Mn 0.90-1.40.

[0056] V 0.06-0.12,

[0057] P up to 0.05,

[0058] S up to 0.05,

[0059] Fe being the balance,

[0060] the melt was tapped into two 10-t ladles.

[0061] In ladle #1, for the purpose of refining and modifying the molten metal, a cored wire was used 14 mm in diameter with its metal sheath (jacket) being 0.40 mm thick. It had the following components in terms of their percentages by weight: Si—43-51, Ca—18-22, Ba—10-15, Sr—10-15, its core ratio being 0.55. The inner surface of the metal sheath (jacket) had a paintwork-based coating applied to it. It had a modifying ultra-dispersed element, 70% TiC+30% VC (70% titanium carbide+30% of vanadium carbide) with its particles being less than 5 mμ in size making up 20% of the total, and ground ferrotitanium (FeTi70) with its particles being less than 100 μm in size making up 30% of the total, and a slag-forming mixture, CaO+CaF.sub.2 (calcium oxide+calcium fluoride) with its particles being less than 100 μm making up 50% of the total. The coat applied was 150-200 μm thick. The amount of the coat applied ensured that one meter of the cored wire contain at least 15 g of titanium carbide and vanadium carbide. A total of 5 kg of cored wire was consumed per one ton of molten metal.

[0062] In ladle #2, for the purpose of modifying the molten metal, a cored wire containing silicon calcium (SiCa40) was used.

[0063] As the properties of the melt modified with the cored wire having the alleged composition and those of the melt modified with the cored wire containing silicon calcium (SiCa40) were compared, the following results were obtained.

[0064] Use of the cored wire having the alleged composition made it possible to reduce the size of the grain by 29%, increase the microhardness by 8.1% and improve KCV impact toughness at −60° C. of the modified melt by 52%. It also became possible to reduce the content of non-metallic inclusions.

EXAMPLE 3

[0065] In an induction furnace, grey iron (SCh25) was melted. It had the following base components in terms of their percentages by weight:

[0066] Ca 3.20-3.40,

[0067] Si 1.40-2.20,

[0068] Mn 0.70-1.00,

[0069] P up to 0.20,

[0070] S up to 0.15,

[0071] Fe being the balance,

[0072] the melt was tapped into two 5-t ladles.

[0073] In ladle #1, for the purpose of refining and modifying the molten metal, a cored wire was used 14 mm in diameter with its metal sheath (jacket) being 0.40 mm thick. It had the following components in terms of their percentages by weight: Si—65-75, Ca—0.80-1.5, Ba—3.5-5.00, Al—1.00-2.00, its core ratio being 0.5. The inner surface of the metal sheath (jacket) had an alcohol-based coating applied to it. It had the following modifying elements: SiC+Si.sub.3N.sub.4 (silicon carbide+silicon nitride) with its particles being less than 5 mu in size making up 20% of the total and ground, finely dispersed ferrosilicon with magnesium and barium with its particles being less than 100 μm making up 80% of the total. The coat applied is 150-200 μm thick. The amount of the coat applied ensured that one meter of the cored wire contain at least 15 g of a mixture of carbides and nitrides. A total of 5 kg of cored wire was consumed per one ton of molten metal.

[0074] In ladle #2, for the purpose of modifying the molten metal, a cored wire containing ferrosilicon (FeSi75) was used.

[0075] As the properties of the melt modified with the cored wire having the alleged composition and those of the melt modified with the cored wire containing ferrosilicon (FeSi75) were compared, the following results were obtained.

[0076] Use of the cored wire having the alleged composition made it possible to increase the yield strength by 10.3% and the tensile strength by 12.1%. It also became possible to improve the wear resistance of the resultant castings.

[0077] The cored wire with the alleged composition may be manufactured as follows. A metal strip between 0.2 and 0.6 mm thick is roll formed into a cylinder-shaped sheath, or jacket, having a trough like configuration. A preliminarily prepared powdered filler material is fed into the sheath (jacket) from a hopper bin and distributed uniformly along its length. A composite coating is applied to the inner and/or outer surface of the sheath (jacket) before or after the roll forming process and before the sheath (jacket) is filled with the filler material. The coating is applied to the inner and/or outer surface of the sheath (jacket) by spraying or by sprinkling or by means of rollers. After the sheath (jacket) is filled with the filler material, the sheath (jacket) is further roll formed to close around the filler material and form a continuous lock seam. The cored wire thus produced is packaged in coils.

[0078] Cored wires are injected into molten metal using injection machines at speeds ranging from 35 to 300 m/min. Consumption of cored wire is calculated based on the rate of consumption of filler material equaling 1.5-7.0 kg per ton of molten metal.

[0079] The present cored wire for out-of-furnace treatment (secondary treatment) metallurgical melts is distinguished by the great reliability in how it functions and ease of manufacture; it can be manufactured using familiar equipment, materials and techniques.

[0080] The terms and word combinations used in this description such as “contains”, “containing”, “in the predominant embodiment”, “predominantly”, “in particular”, “may be” should not be interpreted as excluding the presence of other materials, parts, structural elements, actions.