Self-shielded flux-cored welding wire and preparation method thereof

Abstract

The present invention provides a self-shielded flux-cored welding wire and a preparation method thereof, and specifically relates to the field of welding materials. The self-shielded flux-cored welding wire of the present invention comprises a steel strip and a flux core filled in the steel strip, and the flux core comprises the following components and the weight proportions of each component are respectively: 25-40 parts of barium fluoride, 5-10 parts of fluorite, 1-3 parts of rare earth fluoride, 1-3 parts of potassium fluoride, 1.5-3.5 parts of barium carbonate, 3-8 parts of marble, 1.5-2.5 parts of graphite, 20-30 parts of aluminum-magnesium alloy, 10-20 parts of aluminum powder, 2-4 parts of aluminum-iron, 1-3 parts of silicon-calcium alloy, and the balance is iron powder. The deposited metal of the self-shielded flux-cored welding wire of the present invention has good mechanical properties, tensile strength and yield strength, and reduces carbon emissions and manganese content in smoke.

Description

Technical Field

[0001] The invention relates to the field of welding materials, and in particular to a self-shielded flux-cored welding wire and a preparation method thereof. Background Art

[0002] Low carbon emission, environmental protection and occupational health and safety have always been topics that the welding industry attaches great importance to. When welding wire, in order to ensure the welding quality, carbon dioxide gas is generally used to protect the weld, so the "carbon emission" problem caused by this cannot be ignored. According to relevant data, the carbon emissions per kilogram of welding materials during welding are: 212.96g / kg for 100% CO2 protected flux-cored welding wire and 459.80g / kg for 100% CO2 protected solid welding wire. In addition, in order to ensure that the deposited metal has good mechanical properties, a certain proportion of manganese is often added to the welding wire, resulting in a high concentration of manganese oxide in the welding fume. After long-term inhalation by welding workers, occupational diseases such as "manganese poisoning" will occur, which seriously endangers the physical and mental health of welders. Therefore, the study of a low-manganese type welding material that does not require gas protection has become an indispensable part of the future development of welding materials. Summary of the invention

[0003] In view of the above shortcomings of the prior art, the present invention provides a self-shielded flux-cored welding wire and a preparation method thereof to improve the problems of excessive carbon emission and excessive manganese content in smoke.

[0004] To achieve the above-mentioned purpose and other related purposes, the present invention provides a self-shielded flux-cored welding wire, comprising a steel strip and a flux core filled in the steel strip, wherein the flux core comprises the following components, based on 100 parts by weight of the flux core, and the weight proportions of the components are respectively: 25-40 parts of barium fluoride, 5-10 parts of fluorite, 1-3 parts of rare earth fluoride, 1-3 parts of potassium fluoride, 1.5-3.5 parts of barium carbonate, 3-8 parts of marble, 1.5-2.5 parts of graphite, 20-30 parts of aluminum-magnesium alloy, 10-20 parts of aluminum powder, 2-4 parts of aluminum-iron, 1-3 parts of silicon-calcium alloy, and the balance is iron powder.

[0005] In one example of the present invention, the calcium fluoride content in the fluorite is ≥98wt%; the carbon content in the graphite is ≥95wt%; the calcium carbonate content in the marble is ≥98wt%; the aluminum content in the aluminum-magnesium alloy is 47-53wt%, and the magnesium content is 47-53wt%; the calcium content in the silicon-calcium alloy is ≥28wt%, and the silicon content is 55-65wt%.

[0006] In one example of the present invention, the content of rare earth oxide in the rare earth fluoride is ≥83wt%, and the content of fluorine is ≥26wt%; the content of cerium dioxide in the rare earth oxide is ≥45wt%.

[0007] In one example of the present invention, the purity of the aluminum powder is ≥97wt%; the purity of the barium fluoride is ≥98wt%; the purity of the barium carbonate is ≥98wt%; the purity of the potassium fluoride is ≥94wt%; the purity of the aluminum-magnesium alloy is ≥96wt%, the aluminum content is 47-53wt%, and the magnesium content is ≥47wt%.

[0008] In one example of the present invention, the steel strip is a cold-rolled low-carbon steel strip, in which the carbon content is ≤0.04wt%, the manganese content is ≤0.25wt%, the silicon content is ≤0.05wt%, the sulfur content is ≤0.02wt%, the phosphorus content is ≤0.02wt%, and the remainder is iron and some unavoidable impurities.

[0009] In one example of the present invention, the weight of the flux core is 8% to 14% of the total weight of the self-shielded flux-cored welding wire.

[0010] In an example of the present invention, the diameter of the self-shielded flux-cored welding wire is 0.6 mm to 1.6 mm.

[0011] In an example of the present invention, the self-shielded flux-cored welding wire adopts direct current positive connection during welding.

[0012] The present invention also provides a method for preparing a self-shielded flux-cored welding wire, comprising the following steps: uniformly mixing the above-mentioned components to configure a flux core; rolling a steel strip into a U-shaped groove, and filling the uniformly mixed flux core into the U-shaped groove to close it; drawing and reducing the steel strip filled with the flux core to the required specifications to obtain a self-shielded flux-cored welding wire.

[0013] In one example of the present invention, each component is dried before being mixed evenly.

[0014] The self-shielded flux-cored welding wire of the present invention can ensure that the weld has sufficient strength and plasticity by adding a certain proportion of carbon, silicon and rare earth elements to interact with each other. By adding a variety of fluorides and carbonates, the welding wire itself generates a gas-protected molten pool during welding, which has good anti-porosity ability, and no gas protection is required during welding, which greatly reduces carbon emissions. In addition, the fluorine element generated by the decomposition of fluorides combines with the hydrogen element of the molten pool to volatilize hydrogen fluoride gas, so that the weld has ultra-low diffusible hydrogen. Adding a certain amount of fluorite and potassium fluoride can improve slag removal and arc stability, so that the self-shielded flux-cored welding wire of the present invention has a stable arc, easy slag removal, and beautiful shape during welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 The present invention is a flow chart of the preparation of the self-shielded flux-cored welding wire. DETAILED DESCRIPTION

[0017] The following is an explanation of the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the features in the following embodiments and the embodiments can be combined with each other without conflict. It should also be understood that the terms used in the embodiments of the present invention are intended to describe specific embodiments, rather than to limit the scope of protection of the present invention. The test methods for which specific conditions are not specified in the following examples are usually carried out under conventional conditions or according to the conditions recommended by the manufacturers.

[0018] It should be noted that "%" and "wt%" in this specification represent mass percentage, and "part" represents part by weight.

[0019] The self-shielded flux-cored welding wire of the present invention comprises a steel strip and a flux core filled in the steel strip. Taking the weight of the flux core as 100 parts, the flux core comprises the following components and the weight of each component is respectively: 25-40 parts of barium fluoride, 5-10 parts of fluorite, 1-3 parts of rare earth fluoride, 1-3 parts of potassium fluoride, 1.5-3.5 parts of barium carbonate, 3-8 parts of marble, 1.5-2.5 parts of graphite, 20-30 parts of aluminum-magnesium alloy, 10-20 parts of aluminum powder, 2-4 parts of aluminum-iron, 1-3 parts of silicon-calcium alloy, and the balance is iron powder.

[0020] The functions of each component in the drug core are as follows:

[0021] Barium fluoride, fluorite: The purity of barium fluoride is ≥98wt%, and the content of calcium fluoride in fluorite is ≥98wt%; it is mainly used for slag making, gas making and dehydrogenation. The weight proportion of barium fluoride in the core of the present invention is 25 to 40 parts. For example, the weight proportion of barium fluoride can be any value within the range of 25 to 40 parts, such as 25 parts, 35 parts or 40 parts; the weight proportion of fluorite is 5 to 10 parts, for example, the weight proportion of fluorite can be any value within the range of 5 to 10 parts, such as 5 parts, 8 parts or 10 parts.

[0022] Rare earth fluoride: the content of rare earth oxide in the rare earth fluoride is ≥83wt%, and the content of fluorine is ≥26wt%; the content of cerium dioxide in the rare earth oxide is ≥45wt%. Among them, the rare earth element can refine the grains, change the morphology of inclusions, improve the plasticity and toughness of the deposited metal, and the fluorine element can generate gas and dehydrogenate. The weight proportion of the rare earth fluoride in the core of the present invention is 1 to 3 parts, for example, the weight proportion of the rare earth fluoride can be any value within the range of 1 to 3 parts, such as 1 part, 2 parts or 3 parts.

[0023] Potassium fluoride: The potassium element in potassium fluoride is used to stabilize the arc and reduce spatter, and the fluorine element plays the role of gasification and dehydrogenation. The weight proportion of potassium fluoride in the core of the present invention is 1 to 3 parts of potassium, for example, the weight proportion of potassium fluoride can be any value within the range of 1 to 3 parts, such as 1 part, 2 parts or 3 parts.

[0024] Barium carbonate, marble: the purity of barium carbonate is ≥98wt%, the content of calcium carbonate in marble is ≥98wt%, gasifier, enhances the protection effect, and the carbon dioxide generated by the decomposition of barium carbonate and calcium carbonate during welding can keep the molten pool in inert gas protection. The weight proportion of barium carbonate in the flux core of the present invention is 1.5 to 3.5 parts, for example, the weight proportion of barium carbonate can be any value within the range of 1.5 to 3.5 parts, such as 1.5 parts, 2.8 parts or 3.5 parts; the weight proportion of marble is 3 to 8 parts, for example, the weight proportion of marble can be any value within the range of 3 to 8 parts, such as 3 parts, 5 parts or 8 parts.

[0025] Graphite: The carbon content in graphite is ≥ 95wt%, and a certain amount of carbon element is transferred to the weld to improve the mechanical properties of the deposited metal. The weight percentage of graphite in the flux core of the present invention is 1.5 to 2.5 parts, for example, the weight percentage of graphite can be any value within the range of 1.5 to 2.5 parts, such as 1.5 parts, 2 parts or 2.5 parts.

[0026] Aluminum-magnesium alloy, aluminum powder, aluminum iron: magnesium element can act as a deoxidizing and denitrifying agent, reduce the oxygen and nitrogen content of the weld, and ensure the mechanical properties of the deposited metal. Adding aluminum-magnesium alloy, aluminum powder, aluminum iron and adjusting their proportions can reduce spatter and improve welding processability. The weight proportion of aluminum-magnesium alloy in the flux core of the present invention is 20 to 30 parts, for example, the weight proportion of aluminum-magnesium alloy can be any value within the range of 20 to 30 parts, such as 20 parts, 25 parts or 30 parts; the weight proportion of aluminum powder is 10 to 20 parts, for example, the weight proportion of aluminum powder can be any value within the range of 10 to 20 parts, such as 10 parts, 15 parts or 20 parts; the weight proportion of aluminum iron is 2 to 4 parts, for example, the weight proportion of aluminum iron can be any value within the range of 2 to 4 parts, such as 2 parts, 3 parts or 4 parts.

[0027] Silicon calcium alloy: The calcium content in the silicon calcium alloy is ≥28wt%, and the silicon content is 55-65wt%. The silicon calcium alloy is used as a deoxidizer to transfer a certain amount of silicon elements to the weld to improve the mechanical properties of the deposited metal. The weight proportion of the silicon calcium alloy in the flux core of the present invention is 1-3 parts, for example, the weight proportion of the silicon calcium alloy can be any value within the range of 1-3 parts, such as 1 part, 2 parts or 3 parts.

[0028] Iron powder: Improve arc state and increase welding efficiency.

[0029] In one embodiment, the purity of aluminum powder is ≥97wt%; the purity of barium fluoride is ≥98wt%; the purity of barium carbonate is ≥98wt%; the purity of potassium fluoride is ≥94wt%; the purity of aluminum-magnesium alloy is ≥96wt%, the aluminum content is 47-53wt%, and the magnesium content is ≥47wt%.

[0030] See also Figure 1 The present invention provides a method for preparing a self-shielded flux-cored welding wire, comprising the following steps:

[0031] S1. Mix the above components evenly to prepare a drug core;

[0032] S2, rolling the steel strip into a U-shaped groove, and filling the mixed core into the U-shaped groove to close it;

[0033] S3. The steel strip filled with the flux core is drawn and reduced in diameter to the required specification to obtain a self-shielded flux cored welding wire.

[0034] In step S1, based on the weight of the flux core being 100 parts, the components in the flux core are as follows: 25-40 parts of barium fluoride, 5-10 parts of fluorite, 1-3 parts of rare earth fluoride, 1-3 parts of potassium fluoride, 1.5-3.5 parts of barium carbonate, 3-8 parts of marble, 1.5-2.5 parts of graphite, 20-30 parts of aluminum-magnesium alloy, 10-20 parts of aluminum powder, 2-4 parts of aluminum-iron, 1-3 parts of silicon-calcium alloy, and the balance is iron powder. Among them, the particle size of barium fluoride is preferably 100 mesh, the particle size of fluorite is preferably 80 mesh, the particle size of graphite is preferably 200 mesh, and the particle size of other components in the flux core is 60 mesh. Mixing components of different particle sizes in the flux core can make the new filling more uniform and compact, and improve the welding performance of the welding wire.

[0035] Before mixing, each component is dried. Barium fluoride, fluorite and graphite are preferably dried at 600° C. for 4 hours to remove crystal water of barium fluoride, fluorite and graphite. Other components are preferably dried at 200° C. for 2 hours to remove adsorbed water on the surface.

[0036] In step S2, the steel strip is a cold-rolled low-carbon steel strip, wherein the carbon content of the steel strip is ≤0.04wt%, the manganese content is ≤0.25wt%, the silicon content is ≤0.05wt%, the sulfur content is ≤0.02wt%, the phosphorus content is ≤0.02wt%, and the remainder is iron and some inevitable impurities; the filling rate of the self-shielding flux-cored welding wire, that is, the weight of the flux core is 8% to 14% of the total weight of the self-shielding flux-cored welding wire, that is, the filling rate of the flux core can be any value within the range of 8% to 14%, such as 8%, 10% or 14%.

[0037] In step S3, the diameter of the self-shielded flux-cored welding wire is 0.6-1.6 mm. For example, the diameter of the self-shielded flux-cored welding wire can be any value within the range of 0.6-1.6 mm, such as 0.6 mm, 1 mm or 1.6 mm.

[0038] The self-shielded flux-cored welding wire of the present invention adopts direct current positive connection during welding, and does not need shielding gas for protection.

[0039] The present invention is described in detail below through some specific examples. The drugs used in the following examples can all be obtained through common commercial means.

[0040] Example 1

[0041] The self-shielded flux-cored welding wire of this embodiment includes a steel strip and a flux core filled in the steel strip, wherein the flux core includes the following components and the weight proportions of each component are: 40 parts of barium fluoride, 5 parts of fluorite, 2 parts of rare earth fluoride, 3 parts of potassium fluoride, 1.5 parts of barium carbonate, 4.5 parts of marble, 1.5 parts of graphite, 20 parts of aluminum-magnesium alloy, 15 parts of aluminum powder, 2 parts of aluminum-iron, 3 parts of silicon-calcium alloy, and 2.5 parts of iron powder. The filling rate of the flux core is 14%.

[0042] Example 2

[0043] The self-shielded flux-cored welding wire of this embodiment includes a steel strip and a flux core filled in the steel strip, wherein the flux core includes the following components and the weight proportions of each component are respectively: 25 parts of barium fluoride, 7.6 parts of fluorite, 1 part of rare earth fluoride, 1.8 parts of potassium fluoride, 2.5 parts of barium carbonate, 8 parts of marble, 1.8 parts of graphite, 25.5 parts of aluminum-magnesium alloy, 20 parts of aluminum powder, 3 parts of aluminum-iron, 1 part of silicon-calcium alloy, and 2.8 parts of iron powder. The filling rate of the flux core is 11%.

[0044] Example 3

[0045] The self-shielded flux-cored welding wire of this embodiment includes a steel strip and a flux core filled in the steel strip, wherein the flux core includes the following components and the weight proportions of each component are: 28.5 parts of barium fluoride, 10 parts of fluorite, 3 parts of rare earth fluoride, 1 part of potassium fluoride, 3.5 parts of barium carbonate, 3 parts of marble, 2.5 parts of graphite, 30 parts of aluminum-magnesium alloy, 10 parts of aluminum powder, 4 parts of aluminum-iron, 1.5 parts of silicon-calcium alloy, and 3 parts of iron powder. The filling rate of the flux core is 8%.

[0046] Comparative Example 1

[0047] The flux-cored welding wire of this comparative example comprises a steel strip and a flux core filled in the steel strip, wherein the flux core comprises the following components and the weight proportions of the components are respectively: 18 parts of barium fluoride, 7.5 parts of fluorite, 2.6 parts of rare earth fluoride, 2.1 parts of potassium fluoride, 2 parts of barium carbonate, 8 parts of marble, 0.5 parts of graphite, 4.5 parts of metal manganese, 26 parts of aluminum-magnesium alloy, 15 parts of aluminum powder, 4 parts of aluminum-iron, 2.6 parts of silicon-calcium alloy, and 7.2 parts of iron powder. The filling rate is 10.2%.

[0048] Comparative Example 2

[0049] The flux-cored welding wire of this comparative example comprises a steel strip and a flux core filled in the steel strip, wherein the flux core comprises the following components and the weight proportions of the components are respectively: 43 parts of barium fluoride, 2 parts of fluorite, 1 part of rare earth fluoride, 2.5 parts of potassium fluoride, 2 parts of barium carbonate, 5 parts of marble, 1 part of graphite, 22 parts of aluminum-magnesium alloy, 16 parts of aluminum powder, 1 part of aluminum-iron, 0.5 parts of silicon-calcium alloy, and 4 parts of iron powder. The filling rate is 10.4%.

[0050] The contents of the components in the flux core of the self-shielded flux-cored welding wires of Examples 1 to 3 and the flux-cored welding wires of Comparative Examples 1 and 2 are shown in Table 1. The welding performance of the self-shielded flux-cored welding wires of Examples 1 to 3 and the flux-cored welding wires of Comparative Examples 1 and 2 was tested according to relevant standards and specifications. The welding performance is shown in Table 2, and the mechanical properties of the deposited metal are shown in Table 3.

[0051] Table 1 Core components of self-shielded flux-cored welding wires of Examples 1 to 3 and flux-cored welding wires of Comparative Examples 1 and 2

[0052]

[0053]

[0054] Table 2 Welding performance

[0055] The welding performance of Examples 1 to 3 and Comparative Examples 1 and 2 was tested, and the welding conditions were: welding was performed using a Tribet NBC200 welding machine, the power polarity was DC positive connection, the welding voltage was 18-20V, and the welding current was 130-150A.

[0056]

[0057] Table 3 Mechanical properties of deposited metal

[0058] The mechanical properties test pieces of deposited metal are prepared according to GB / T 25774.1, and the tensile test of deposited metal is carried out according to GB / T2652.

[0059]

[0060] From the test results in Table 2 and Table 3, it can be seen that the self-shielded flux-cored welding wires of Examples 1 to 3 have good arc stability, good spatter, and good weld formability and slag removal properties, while the flux-cored welding wires of Comparative Examples 1 and 2 have poor arc stability, large spatter, and poor weld formability and slag removal properties. Examples 1 to 3 have good tensile strength and yield strength, while the tensile strength and yield strength of the flux-cored welding wire of Comparative Example 2 are poor. Although the flux-cored welding wire prepared in Comparative Example 1 has good tensile strength and yield strength, since metal manganese is added to the flux core of the flux-cored welding wire of Comparative Example 1, the manganese content in the smoke of the flux-cored welding wire of Comparative Example 1 is too high during welding.

[0061] The self-shielded flux-cored welding wire of the present invention can ensure that the weld has sufficient strength and plasticity by adding a certain proportion of carbon, silicon and rare earth elements to interact with each other. By adding a variety of fluorides and carbonates, the welding wire itself generates a gas-protected molten pool during welding, which has good anti-pore ability, and no gas protection is required during welding, which greatly reduces carbon emissions. In addition, the fluorine element generated by the decomposition of fluorides combines with the hydrogen element of the molten pool to volatilize as hydrogen fluoride gas, so that the weld has ultra-low diffusible hydrogen; adding a certain amount of fluorite and potassium fluoride can improve slag removal and arc stability, so that the self-shielded flux-cored welding wire of the present invention has a stable arc, easy slag removal, and beautiful shape during welding. Therefore, the present invention effectively overcomes some practical problems in the prior art and has high utilization value and use significance.

[0062] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A self-shielded flux-cored welding wire, characterized in that: The invention comprises a steel strip and a core filled in the steel strip. The core is composed of the following components in parts by weight based on 100 parts by weight of the core: 25-40 parts of barium fluoride, 5-10 parts of fluorite, 1-3 parts of rare earth fluoride, 1-3 parts of potassium fluoride, 1.5-3.5 parts of barium carbonate, 3-8 parts of marble, 1.5-2.5 parts of graphite, 20-30 parts of aluminum-magnesium alloy, 10-20 parts of aluminum powder, 2-4 parts of aluminum-iron, 1-3 parts of silicon-calcium alloy, and the balance is iron powder.

2. The self-shielded flux-cored welding wire according to claim 1, characterized in that: The calcium fluoride content in the fluorite is ≥98wt%; the carbon content in the graphite is ≥95wt%; the calcium carbonate content in the marble is ≥98wt%; The calcium content of the silicon-calcium alloy is ≥28wt%, and the silicon content is 55-65wt%.

3. The self-shielded flux-cored welding wire according to claim 1, characterized in that: The content of rare earth oxide in the rare earth fluoride is ≥83wt%, and the content of fluorine is ≥26wt%; the content of cerium dioxide in the rare earth oxide is ≥45wt%.

4. The self-shielded flux-cored welding wire according to claim 1, characterized in that: The purity of the aluminum powder is ≥97wt%; the purity of the barium fluoride is ≥98wt%; the purity of the barium carbonate is ≥98wt%; the purity of the potassium fluoride is ≥94wt%; the purity of the aluminum-magnesium alloy is ≥96wt%, the aluminum content is 47-53wt%, and the magnesium content is ≥47wt%.

5. The self-shielded flux-cored welding wire according to claim 1, characterized in that: The steel strip is a cold-rolled low-carbon steel strip, wherein the carbon content is ≤0.04wt%, the manganese content is ≤0.25wt%, the silicon content is ≤0.05wt%, the sulfur content is ≤0.02wt%, the phosphorus content is ≤0.02wt%, and the remainder is iron and some inevitable impurities.

6. The self-shielded flux-cored welding wire according to claim 1, characterized in that: The weight of the flux core is 8% to 14% of the total weight of the self-shielding flux cored welding wire.

7. The self-shielded flux-cored welding wire according to claim 1, characterized in that: The diameter of the self-shielded flux-cored welding wire is 0.6 mm to 1.6 mm.

8. The self-shielded flux-cored welding wire according to claim 1, characterized in that: The self-shielded flux-cored welding wire adopts direct current positive connection during welding.

9. A method for preparing a self-shielded flux-cored welding wire, characterized in that: The steps include: The components according to claim 1 are mixed uniformly to prepare a drug core; The steel strip is rolled into a U-shaped groove, and the uniformly mixed core is filled into the U-shaped groove to close it; The steel strip filled with flux core is drawn and reduced to the required specifications to obtain a self-shielded flux cored welding wire.

10. The preparation method according to claim 9, characterized in that: Each component is dried before being mixed evenly.

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