High-toughness and high-crack-resistance gas shielded welding flux-cored wire and preparation method thereof

Abstract

The invention provides a high-toughness and high-crack-resistance gas shielded welding flux-cored wire and a preparation method of the high-toughness and high-crack-resistance gas shielded welding flux-cored wire. The flux-cored wire comprises a steel strip and a flux core filled in the steel strip, the flux core comprises, by weight, 5 parts to 10 parts of ferromanganese, 3 parts to 8 parts of ferrosilicon, 1 part to 3 parts of ferromolybdenum, 0.5 part to 1.5 parts of aluminum powder, 0.5 part to 1.5 parts of ferrotitanium, 1 part to 3 parts of potassium titanate, 1 part to 3 parts of sodium fluosilicate, 1 part to 5 parts of marble, 1 part to 5 parts of dolomite, 5 parts to 15 parts of fluorite, 0.1 part to 0.5 part of graphite, 0.05 part to 0.15 part of Ni-Ce-La rare earth alloy and 50 parts to 70 parts of reduced iron powder. According to the flux-cored wire, the formula of the flux powder is reasonably designed, and all the components have a synergistic effect, so that the flux-cored wire can obtain good tissue and performance after welding, the problems that an existing flux-cored wire is low in deposition efficiency, large in welding spatter, unstable in weld metal mechanical property and the like are solved, and the welding quality and the production efficiency are improved.

Description

Technical Field

[0001] The invention belongs to the field of welding wire production, and in particular relates to a high-toughness, high-cracking-resistance gas shielded flux-cored welding wire and a preparation method thereof. Background Art

[0002] Gas shielded welding (GMW) is a highly efficient and high-quality welding method that is widely used in modern manufacturing. Flux-cored wire, as an important welding material for GMW, has a significant impact on welding quality and efficiency.

[0003] Currently, existing gas shielded flux-cored welding wires on the market have numerous problems. Some flux-cored wires have low deposition efficiency, which results in extended welding cycles and increased production costs. Some wires produce significant spatter during welding, which not only affects the appearance of the welded joint but also wastes welding materials. Furthermore, the weld metal mechanical properties of some wires are unstable, particularly low-temperature impact toughness, making them unable to meet the requirements for high-strength, high-toughness, and other special operating conditions. These issues have limited the application and development of gas shielded welding technology in a wider range of fields. Therefore, the development of a high-performance gas shielded flux-cored welding wire and its manufacturing method is of great practical significance. Summary of the Invention

[0004] In view of this, the present invention aims to propose a high-toughness, high-crack-resistant gas shielded welding flux-cored wire and its preparation method, so as to solve the problems of low deposition efficiency, large welding spatter, unstable mechanical properties of weld metal, etc. of existing flux-cored welding wire, improve welding quality and production efficiency, and meet welding requirements under different working conditions.

[0005] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0006] A high-toughness, high-crack-resistance gas shielded welding flux-cored wire comprises a steel strip and a flux core filled inside the steel strip; wherein the flux core comprises, by weight: 5-10 parts of ferromanganese, 3-8 parts of ferrosilicon, 1-3 parts of ferromolybdenum, 0.5-1.5 parts of aluminum powder, 0.5-1.5 parts of ferrotitanium, 1-3 parts of potassium titanate, 1-3 parts of sodium fluorosilicate, 1-5 parts of marble, 1-5 parts of dolomite, 5-15 parts of fluorite, 0.1-0.5 parts of graphite, 0.05-0.15 parts of Ni-Ce-La rare earth alloy, and 50-70 parts of reduced iron powder.

[0007] Furthermore, the mass ratio of ferromanganese, ferrosilicon and ferromolybdenum is (1.5-3):(1-2.5):1. Ferromanganese, ferrosilicon and ferromolybdenum are alloy strengtheners. Manganese can play a role of solid solution strengthening in the weld. At the same time, it can also combine with sulfur to form manganese sulfide, reducing the thermal brittleness of sulfur on the weld metal and improving the strength and toughness of the weld. Silicon is an effective deoxidizer that can improve the purity of the weld metal. At the same time, it can also synergize with manganese to further improve the strength and toughness of the weld. Molybdenum can improve the strength and high-temperature performance of the weld metal, while having little effect on the reduction of toughness. The appropriate addition of ferromolybdenum helps to improve the comprehensive performance of the flux-cored welding wire while ensuring the tensile strength. Through experiments, it was found that when the addition ratio of these three alloys was 1.5-3:1-2.5:1, the low-temperature impact absorption energy of the deposited metal at -40°C reached more than 100J, and the low-temperature impact performance was excellent.

[0008] Furthermore, the mass ratio of aluminum powder to ferrotitanium is 1:1. Aluminum powder and ferrotitanium act as deoxidizers. Aluminum is a strong deoxidizer, effectively removing oxygen from the weld, reducing oxide inclusions, and improving the toughness of the weld metal. Titanium not only deoxidizes, but also combines with nitrogen to form titanium nitride, refining the grain size and improving the weld metal structure, thereby increasing the weld's strength and toughness. Experiments have shown that a 1:1 ratio of aluminum powder to ferrotitanium results in a beautiful weld with no porosity.

[0009] Furthermore, the mass ratio of potassium titanate to sodium fluorosilicate is 2:1. Potassium titanate and fluorosilicic acid act as arc stabilizers. Potassium titanate stabilizes the arc, making the welding process smoother, which helps improve welding quality and reduce welding defects. Sodium fluorosilicate and potassium titanate work synergistically to further enhance arc stability. Fluorine improves the fluidity of the weld metal during welding, improving weld quality. The present invention discovered that a 2:1 ratio of potassium titanate to sodium fluorosilicate produces the most stable welding arc and minimizes spatter.

[0010] Furthermore, the mass ratio of marble and dolomite is 1:1. Marble needs to be baked at 500℃×2h before use, and fluorite needs to be baked at 800℃×2h before use. Marble and dolomite act as slagging agents. Marble decomposes into CaO and CO2 at high temperature. CO2 forms a protective gas to inhibit oxidation. CaO, as an alkaline oxide, removes sulfur and phosphorus from the molten pool, reducing the risk of hot cracking and embrittlement of the weld. Dolomite decomposes to produce CaO, MgO and CO2. MgO, as an inert oxide, increases the melting point of the slag, slows down the solidification rate, and promotes the full reaction of the molten pool metal and the slag. The Mg element can transition to the weld, play a deoxidation role, and form a fine-grained structure (such as acicular ferrite) to improve toughness. The present invention finds that when the ratio of marble and dolomite is 1:1, the welding process is excellent and slag removal is easiest.

[0011] Furthermore, the Ni-Ce-La rare earth alloy is an alloy formed by adding rare earth elements Ce and La to nickel as a matrix, wherein the mass ratio of added Ce and La is 1:1. The mass percentages of Ce and La in the Ni-Ce-La rare earth alloy are 0.05%-0.10% respectively, and the comprehensive performance is enhanced by composite rare earth.

[0012] Rare earth elements have a strong affinity for oxygen and sulfur, forming high-melting-point, low-solubility rare earth oxides and sulfides, which reduce non-metallic inclusions in welds and purify the molten pool. Rare earth elements refine grain size, improve the morphology and distribution of inclusions in the weld metal, and enhance weld toughness and crack resistance. Rare earth compounds reduce slag surface tension, improve droplet transfer morphology, and reduce spatter. They also stabilize arc combustion and improve welding processability.

[0013] An appropriate amount of graphite can provide a certain carbon source for the weld metal, which has little effect on the toughness while ensuring the strength of the weld, and can also improve the welding process performance.

[0014] As the main filling component of the powder, reduced iron powder can adjust the density and fluidity of the powder, while providing a certain iron-based component for the weld metal to ensure the basic strength of the weld.

[0015] Furthermore, the steel strip is low-carbon, with a carbon content controlled between 0.05% and 0.10%, a thickness of 0.5-1.0mm, and a width of 10mm. The filler material in the flux core is 15%-20%. Low-carbon steel strip offers excellent formability and weldability, providing a stable coating structure for the flux core without significantly affecting the carbon content of the weld metal, thereby ensuring weld toughness.

[0016] The present invention also provides a method for preparing the high-toughness, high-crack-resistance gas shielded welding flux-cored wire as described above, the method comprising the following steps:

[0017] 1) Pre-treatment of the steel strip, including degreasing, derusting and annealing;

[0018] 2) Weigh the core materials, bake the marble and fluorite first, then grind each raw material separately, add the ground powder into a powder mixer and mix thoroughly;

[0019] 3) The pre-treated steel strip is rolled into a U-shape by a wire forming machine, and the mixed powder is evenly filled into the U-shaped steel strip through a powder feeder. During the filling process, the powder filling rate is controlled between 15% and 20%, and the filling rate is stable by adjusting the powder feeding speed and the steel strip running speed.

[0020] 4) The U-shaped steel strip filled with powder is closed by a closing device to form a circular flux-cored welding wire blank; the blank is then coarse-drawn and fine-drawn in sequence to obtain the welding wire of the required size.

[0021] Furthermore, the specific steps of step 1) pretreatment of the steel strip include: cleaning the selected low-carbon steel strip to remove oil, rust and other impurities on the surface, and then annealing the steel strip to eliminate the internal stress generated during the rolling process and improve the plasticity and formability of the steel strip. The annealing temperature is controlled at 600-700°C, the holding time is 30-60 minutes, and then naturally cooled in air.

[0022] Furthermore, the particle size of the powder after pulverization in step 2) is 60-200 mesh, and the mixing time is 30-60 minutes;

[0023] In step 4), the pulling speed is 1-3 m / s.

[0024] Compared with the prior art, the high-toughness, high-crack-resistant gas shielded welding flux-cored wire and its preparation method of the present invention have the following advantages:

[0025] (1) The high-toughness, high-crack-resistance gas shielded welding flux-cored wire of the present invention achieves excellent microstructure and performance after welding by rationally designing the powder formula and synergizing the various components. While meeting the tensile strength requirement of 500 MPa, it also has high toughness, with an impact toughness value exceeding 80 J at -20°C and exceeding 60 J at -40°C. This greatly improves the reliability and safety of welded joints under complex working conditions and is suitable for various welded structures with high strength and toughness requirements.

[0026] (2) The arc stabilizer and other additives added to the high-toughness, high-crack-resistance gas shielded flux-cored welding wire of the present invention stabilize the arc, reduce weld spatter, and make the welding process smoother and more fluid, with excellent welding process performance. Furthermore, the excellent weld seam quality reduces subsequent grinding and cleaning processes, improving welding efficiency and reducing labor intensity.

[0027] (3) The high-toughness, high-crack-resistance gas shielded flux-cored welding wire formula of the present invention minimizes the use of expensive alloying elements while ensuring performance. By optimizing the proportion of each component and the manufacturing process, the production efficiency is improved and the scrap rate is reduced, thereby effectively controlling the production cost and improving the market competitiveness of the product.

[0028] (4) The preparation method of the high-toughness, high-cracking-resistant gas shielded welding flux-cored wire described in the present invention has clear process parameters and operating specifications in each link from steel strip pretreatment to finished product inspection, which is easy to realize industrial production, and the production process is stable, the product quality consistency is good, and it can meet the needs of large-scale production. DETAILED DESCRIPTION

[0029] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0030] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0031] Example 1

[0032] A high-toughness, high-crack-resistance gas shielded welding flux-cored wire comprises a steel strip and a flux core filled in the steel strip; the steel strip is a low-carbon steel strip with a carbon content of 0.06%, a thickness of 0.5 mm and a width of 10 mm.

[0033] The composition and weight of the drug core are shown in Table 1.

[0034] Preparation method:

[0035] 1) Steel strip pretreatment: Wash the low carbon steel strip in alkaline solution for 10 minutes to remove oil stains, then anneal at 650℃ for 45 minutes to eliminate the internal stress generated in the rolling process, improve the plasticity and formability of the steel strip, and cool naturally.

[0036] 2) Preparation of medicinal powder: Marble needs to be baked at 500℃×2h before use, and fluorite needs to be baked at 800℃×2h before use. After the various medicinal powder raw materials are crushed to 100 mesh as required, mix them in a powder mixer for 45 minutes.

[0037] 3) Powder filling: The steel strip is rolled into a U-shape by a wire forming machine, and the mixed powder is evenly filled into the U-shaped steel strip through a powder feeder. The powder feeder is controlled to make the powder filling rate reach 17%.

[0038] 4) Closing and Drawing: After filling the powder, the U-shaped steel strip is closed by a closing device to form a round flux-cored wire blank. The blank is then subjected to rough drawing and fine drawing. Rough drawing uses a higher pulling force to initially reduce the diameter of the wire blank, while fine drawing uses a lower pulling force to precisely control the wire diameter to the predetermined specifications, such as 0.9mm, 1.0mm, 1.2mm, 1.4mm, 1.6mm, etc. During the drawing process, it is important to control the drawing speed and lubrication conditions to ensure the surface quality and internal structural stability of the wire. The drawing speed is generally controlled between 1-3m / s, and a special wire drawing lubricant is used for lubrication.

[0039] In this embodiment, rough drawing is performed first, with a drawing speed of 2 m / s, and then fine drawing is performed, with the welding wire diameter controlled to be 1.4 mm and the drawing speed to be 1.5 m / s.

[0040] The performance test results are shown in Table 2, and the welding process test results are shown in Table 3.

[0041] Example 2

[0042] A high-toughness, high-crack-resistance gas shielded welding flux-cored wire comprises a steel strip and a flux core filled in the steel strip; the steel strip is a low-carbon steel strip with a carbon content of 0.08%, a thickness of 0.5 mm and a width of 10 mm.

[0043] The composition and weight of the drug core are shown in Table 1.

[0044] Preparation method:

[0045] 1) Steel strip pretreatment: After the steel strip is pickled in acid to remove rust, it is annealed at 680℃ for 50 minutes and cooled naturally.

[0046] 2) Preparation of medicinal powder: Marble needs to be baked at 500℃×2h before use, and fluorite needs to be baked at 800℃×2h before use. The medicinal powder raw materials are crushed to 120 mesh and then mixed for 50 minutes.

[0047] 3) Powder filling: The steel strip is rolled into a U-shape by a wire forming machine, and the mixed powder is evenly filled into the U-shaped steel strip through a powder feeder. The powder feeder is controlled to make the powder filling rate reach 18%.

[0048] 4) Closing and drawing: The U-shaped steel strip filled with powder is closed by a closing device to form a round flux-cored welding wire billet; the billet is then subjected to rough drawing and fine drawing in sequence, with a rough drawing speed of 2.5m / s and a fine drawing speed of 1.4mm in diameter.

[0049] The performance test results are shown in Table 2, and the welding process test results are shown in Table 3.

[0050] Example 3

[0051] A high-toughness, high-crack-resistance gas shielded welding flux-cored wire comprises a steel strip and a flux core filled in the steel strip; the steel strip is a low-carbon steel strip with a carbon content of 0.08%, a thickness of 0.7 mm and a width of 10 mm.

[0052] The composition and weight of the drug core are shown in Table 1.

[0053] Preparation method:

[0054] 1) Steel strip pretreatment: After the steel strip is pickled in acid to remove rust, it is annealed at 680℃ for 50 minutes and cooled naturally.

[0055] 2) Preparation of medicinal powder: Marble needs to be baked at 500℃×2h before use, and fluorite needs to be baked at 800℃×2h before use. The medicinal powder raw materials are crushed to 80 mesh and then mixed for 50 minutes.

[0056] 3) Powder filling: The steel strip is rolled into a U-shape by a wire forming machine, and the powder filling rate is controlled to be 18%.

[0057] 4) Closing and drawing: The U-shaped steel strip filled with powder is closed by a closing device to form a round flux-cored welding wire billet; the billet is then subjected to rough drawing and fine drawing in sequence, with a rough drawing speed of 2.5m / s and a fine drawing speed of 1.4mm in diameter.

[0058] The performance test results are shown in Table 2, and the welding process test results are shown in Table 3.

[0059] Example 4

[0060] A high-toughness, high-crack-resistance gas shielded welding flux-cored wire comprises a steel strip and a flux core filled in the steel strip; the steel strip is a low-carbon steel strip with a carbon content of 0.08%, a thickness of 0.5 mm and a width of 10 mm.

[0061] The composition and weight of the drug core are shown in Table 1.

[0062] Preparation method:

[0063] 1) Steel strip pretreatment: After the steel strip is pickled in acid to remove rust, it is annealed at 680℃ for 50 minutes and cooled naturally.

[0064] 2) Preparation of medicinal powder: Marble needs to be baked at 500℃×2h before use, and fluorite needs to be baked at 800℃×2h before use. The medicinal powder raw materials are crushed to 100 mesh and then mixed for 50 minutes.

[0065] 3) Powder filling: The steel strip is rolled into a U-shape by a wire forming machine, and the powder filling rate is controlled to be 18%.

[0066] 4) Closing and drawing: The U-shaped steel strip filled with powder is closed by a closing device to form a round flux-cored welding wire billet; the billet is then subjected to rough drawing and fine drawing in sequence, with a rough drawing speed of 2.5m / s and a fine drawing speed of 1.6mm for the wire diameter and a speed of 1.8m / s.

[0067] The performance test results are shown in Table 2, and the welding process test results are shown in Table 3.

[0068] Table 1 Example core composition and weight parts

[0069]

[0070] Table 2 Performance test results of the embodiment (protective gas 100% CO2)

[0071]

[0072]

[0073] Table 3 Example welding process test results

[0074] project Example 1 Example 2 Example 3 Example 4 Welding spatter rate (%) 4 3 3 3 Deposition efficiency (%) 92 95 97 98

[0075] In order to verify the importance of the composition of the flux-cored welding wire, the following comparative example was designed based on Example 1 for comparative verification.

[0076] Table 4 Comparative Example Core Composition and Weight

[0077]

[0078]

[0079]

[0080] Table 5 Performance test results of the embodiment (protective gas 100% CO2)

[0081]

[0082]

[0083] Table 6 Example welding process test results

[0084]

[0085] From the above comparison, it can be seen that the welding wires of Examples 1-4 prepared according to the present invention can obtain good structure and performance after welding, with a tensile strength greater than 500 MPa and high toughness. The impact toughness value can reach more than 80 J at a low temperature of -20°C, and can also reach more than 60 J at a low temperature of -40°C. It greatly improves the reliability and safety of the welded joints under complex working conditions and is suitable for various welding structures with high requirements on strength and toughness.

[0086] In contrast, when the ferromanganese, ferrosilicon and ferromolybdenum in comparative example 1 do not meet the proportion requirements, the aluminum powder and ferrotitanium in comparative example 2 do not meet the proportion requirements, the potassium titanate and sodium fluorosilicate in comparative example 3 do not meet the proportion requirements, the marble and dolomite in comparative example 4 do not meet the proportion requirements, the graphite content in comparative examples 5-6 meets the proportion requirements, the Ni-Ce-La rare earth alloy in comparative examples 7-8 does not meet the proportion requirements, and the ratio of Ni, Ce and La in comparative example 9 does not meet the requirements, the mechanical properties of the welding wire will be reduced to varying degrees, and the welding spatter rate will also increase to varying degrees, which is not conducive to improving welding efficiency.

[0087] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A high-toughness, high-crack-resistance gas shielded flux-cored welding wire, characterized by: The invention comprises a steel strip and a flux core filled inside the steel strip; wherein the flux core comprises, by weight: 5-10 parts of ferromanganese, 3-8 parts of ferrosilicon, 1-3 parts of ferromolybdenum, 0.5-1.5 parts of aluminum powder, 0.5-1.5 parts of ferrotitanium, 1-3 parts of potassium titanate, 1-3 parts of sodium fluorosilicate, 1-5 parts of marble, 1-5 parts of dolomite, 5-15 parts of fluorite, 0.1-0.5 parts of graphite, 0.05-0.15 parts of Ni-Ce-La rare earth alloy, and 50-70 parts of reduced iron powder.

2. The high-toughness, high-crack-resistance gas shielded welding flux-cored wire according to claim 1, characterized in that: The mass ratio of ferromanganese, ferrosilicon and ferromolybdenum is (1.5-3):(1-2.5):

1.

3. The high-toughness, high-crack-resistance gas shielded flux-cored welding wire according to claim 1, characterized in that: The mass ratio of aluminum powder to ferrotitanium is 1:

1.

4. The high-toughness, high-crack-resistance gas shielded welding flux-cored wire according to claim 1, characterized in that: The mass ratio of potassium titanate to sodium fluorosilicate is 2:

1.

5. The high-toughness, high-crack-resistance gas shielded welding flux-cored wire according to claim 1, characterized in that: The mass ratio of marble and dolomite is 1:

1. Marble needs to be baked at 500℃×2h before use, and fluorite needs to be baked at 800℃×2h before use.

6. The high-toughness, high-crack-resistance gas shielded flux-cored welding wire according to claim 1, characterized in that: Ni-Ce-La rare earth alloy is an alloy with nickel as the matrix and rare earth elements Ce and La added. The mass ratio of Ce and La added is 1:

1. The mass percentages of Ce and La in the Ni-Ce-La rare earth alloy are 0.05%-0.10% respectively.

7. The high-toughness, high-crack-resistance gas shielded flux-cored welding wire according to claim 1, characterized in that: The steel strip is a low-carbon steel strip with a carbon content controlled between 0.05% and 0.10%, a thickness of 0.5-1.0 mm, and a width of 10 mm; the filling material of the core is 15%-20%.

8. A method for preparing a high-toughness, high-crack-resistant gas shielded welding flux-cored wire according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: 1) Pre-treatment of the steel strip, including degreasing, derusting and annealing; 2) Weigh the core materials, bake the marble and fluorite first, then grind each raw material separately, add the ground powder into a powder mixer and mix thoroughly; 3) The pretreated steel strip is rolled into a U-shape by a wire forming machine, and the mixed powder is evenly filled into the U-shaped steel strip through a powder feeder; 4) The U-shaped steel strip filled with powder is closed by a closing device to form a circular flux-cored welding wire blank; the blank is then coarse-drawn and fine-drawn in sequence to obtain the welding wire of the required size.

9. The method for preparing the high-toughness, high-crack-resistance gas shielded welding flux-cored wire according to claim 8, characterized in that: Step 1) The specific steps of pre-treating the steel strip include: cleaning the selected low-carbon steel strip to remove oil, rust and other impurities on the surface, and then annealing the steel strip to eliminate the internal stress generated in the steel strip during the rolling process and improve the plasticity and formability of the steel strip. The annealing temperature is controlled at 600-700°C for 30-60 minutes, and then naturally cool in air.

10. The method for preparing the high-toughness, high-crack-resistance gas shielded welding flux-cored wire according to claim 8, characterized in that: The particle size of the powder after pulverization in step 2) is 60-200 mesh, and the mixing time is 30-60 minutes; In step 4), the pulling speed is 1-3 m / s.

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