A high-toughness, high-resistance gas shielded welding flux-cored wire and a preparation method thereof

Abstract

The application provides a high-toughness and high-anti-crack gas shielded welding flux-cored wire and a preparation method thereof. The flux-cored wire comprises a steel belt and a flux filled in the steel belt, and the flux comprises, by weight fraction, 5-10 parts of manganese iron, 3-8 parts of silicon iron, 1-3 parts of molybdenum iron, 0.5-1.5 parts of aluminum powder, 0.5-1.5 parts of titanium iron, 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 a Ni-Ce-La rare earth alloy and 50-70 parts of reduced iron powder. The flux-cored wire is prepared by reasonably designing the powder formula, and the components synergize with each other, so that the flux-cored wire can obtain good structure and performance after welding. The problems of low deposition efficiency, large welding spatter and unstable mechanical properties of weld metal of the existing flux-cored wire are solved, and the welding quality and production efficiency are improved.

Description

Technical Field

[0001] This invention belongs to the field of welding wire production, and in particular relates to a high-toughness, high-crack-resistant gas shielded welding flux-cored wire and its preparation method. Background Technology

[0002] Gas shielded welding (GSW) is a highly efficient and high-quality welding method widely used in modern manufacturing. Flux-cored welding wire, as a crucial welding material in GSW, has a vital impact on welding quality and efficiency.

[0003] Currently, existing gas-shielded welding flux-cored wires on the market have many problems. Some flux-cored wires have low welding deposition efficiency, leading to longer welding production cycles and increased production costs; some wires exhibit significant spatter during welding, affecting not only the appearance quality of the weld joint but also wasting welding materials; furthermore, the weld metal mechanical properties of some wires are unstable, especially their low-temperature impact toughness, failing to meet the requirements of high-strength, high-toughness applications. These problems limit the application and development of gas-shielded welding technology in a wider range of fields. Therefore, developing a high-performance gas-shielded welding flux-cored wire and its manufacturing method is of significant practical importance. 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, and unstable mechanical properties of weld metal of existing flux-cored welding wires, improve welding quality and production efficiency, and meet the welding needs under different working conditions.

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

[0006] A high-toughness, high-crack-resistant gas-shielded welding flux-cored wire includes a steel strip and a flux core filled inside the steel strip; wherein the flux core comprises, by weight, the following components: 5-10 parts ferromanganese, 3-8 parts ferrosilicon, 1-3 parts ferromolybdenum, 0.5-1.5 parts aluminum powder, 0.5-1.5 parts ferrotitanium, 1-3 parts potassium titanate, 1-3 parts sodium fluorosilicate, 1-5 parts marble, 1-5 parts dolomite, 5-15 parts fluorite, 0.1-0.5 parts graphite, 0.05-0.15 parts Ni-Ce-La rare earth alloy, and 50-70 parts 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 act as alloying reinforcing agents. Manganese plays a role in solid solution strengthening in the weld, and can also combine with sulfur to form manganese sulfide, reducing the hot brittleness effect of sulfur on the weld metal and improving the strength and toughness of the weld. Silicon is an effective deoxidizer, which can improve the purity of the weld metal, and can also work synergistically 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 a relatively small impact on toughness. Appropriate addition of ferromolybdenum helps to improve the overall performance of the flux-cored welding wire while ensuring tensile strength. Experiments showed that when the addition ratio of these three alloys is 1.5-3:1-2.5:1, the low-temperature impact absorption energy of the deposited metal at -40℃ all reach over 100J, demonstrating excellent low-temperature impact performance.

[0008] Furthermore, the mass ratio of aluminum powder to ferrotitanium is 1:1. Aluminum powder and ferrotitanium act as deoxidizers; aluminum, a strong deoxidizer, effectively removes oxygen from the weld, reduces oxide inclusions, and improves the toughness of the weld metal. Titanium not only deoxidizes but also combines with nitrogen to form titanium nitride, refining the grains and improving the microstructure of the weld metal, thereby increasing the strength and toughness of the weld. Experiments showed that when the ratio of aluminum powder to ferrotitanium is 1:1, the weld formation is aesthetically pleasing and free of porosity.

[0009] Furthermore, the mass ratio of potassium titanate to sodium fluorosilicate is 2:1. Potassium titanate and fluorosilicate act as arc stabilizers; potassium titanate stabilizes the arc, making the welding process smoother, which is beneficial for improving welding quality and reducing welding defects. Sodium fluorosilicate works synergistically with potassium titanate to further enhance arc stability. Simultaneously, fluorine improves the fluidity of the weld metal during welding, enhancing weld formation quality. This invention found that a 2:1 ratio of potassium titanate to sodium fluorosilicate results in the most stable welding arc and minimal spatter.

[0010] Furthermore, the mass ratio of marble to dolomite is 1:1. Before use, the marble requires baking at 500℃ for 2 hours, and the fluorite requires baking at 800℃ for 2 hours. Marble and dolomite act as slag-forming agents. At high temperatures, marble decomposes into CaO and CO2. CO2 forms a protective gas that inhibits oxidation, while CaO, as an alkaline oxide, removes sulfur and phosphorus from the molten pool, reducing the risk of hot cracking and embrittlement in the weld. Dolomite decomposes to produce CaO, MgO, and CO2. MgO, as an inert oxide, increases the melting point of the slag, slows the solidification rate, and promotes a full reaction between the molten pool metal and the slag. Mg can transition into the weld, acting as a deoxidizer and forming a fine-grained structure (such as acicular ferrite), thus improving toughness. This invention found that a 1:1 ratio of marble to dolomite results in excellent welding technology and the easiest slag removal.

[0011] Furthermore, the Ni-Ce-La rare earth alloy is an alloy formed by adding rare earth elements Ce and La to nickel as the base material. The mass ratio of Ce to La added is 1:1. In the Ni-Ce-La rare earth alloy, the mass percentages of Ce and La are 0.05%-0.10%, respectively. The comprehensive performance is enhanced by the 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. This reduces non-metallic inclusions in the weld and purifies the molten pool. Rare earth elements can refine grains, improve the morphology and distribution of inclusions in the weld metal, and enhance the weld's toughness and crack resistance. Rare earth compounds can reduce the surface tension of the slag, improve the droplet transition morphology, reduce spatter, stabilize arc combustion, and improve welding processability.

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

[0014] Reduced iron powder, as the main filler component of the flux, can adjust the density and flowability of the flux, while providing a certain iron-based component to the weld metal to ensure the basic strength of the weld.

[0015] Furthermore, the steel strip is made of low-carbon steel, 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 filler for the flux core is 15%-20%. Low-carbon steel strip has good formability and weldability, providing a stable coating structure for the flux core without excessively affecting the carbon content of the weld metal, which helps ensure the toughness of the weld.

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

[0017] 1) Pre-treat the steel strip, including removing oil, removing rust, and annealing.

[0018] 2) Weigh the raw materials for the core, first bake the marble and fluorite, then crush each raw material separately, add the crushed powder to the powder mixer and mix thoroughly;

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

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

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

[0022] Furthermore, in step 2), the particle size of the pulverized medicine powder 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 existing technologies, the high-toughness, high-crack-resistant gas-shielded welding flux-cored wire and its preparation method described in this invention have the following advantages:

[0025] (1) The high-toughness, high-crack-resistance gas-shielded welding flux-cored wire of the present invention achieves good microstructure and performance after welding through the rational design of the flux powder formula and the synergistic effect between the components. While meeting the requirement of tensile strength of 500MPa, it also has high toughness, with an impact toughness value of over 80J at -20℃ and over 60J at -40℃, which greatly improves the reliability and safety of the welded joint 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-resistant gas-shielded welding flux-cored wire of the present invention can stabilize the arc, reduce welding spatter, and make the welding process more stable and smooth, with good welding performance. At the same time, the good weld formation quality reduces subsequent grinding, cleaning and other processes, improves welding efficiency and reduces labor intensity.

[0027] (3) The high toughness and high crack resistance gas shielded welding flux-cored wire formulation 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, production efficiency is improved and scrap rate is reduced, thereby effectively controlling production costs and improving the market competitiveness of the product.

[0028] (4) The preparation method of the high toughness and high crack resistance gas shielded welding flux-cored wire described in this invention has clear process parameters and operating specifications for each step from steel strip pretreatment to finished product inspection. It is easy to realize industrial production, and the production process is stable and the product quality is consistent, which can meet the needs of large-scale production. Detailed Implementation

[0029] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0030] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0031] Example 1

[0032] A high-toughness, high-crack-resistant gas shielded welding flux-cored wire includes a steel strip and a flux core filled inside 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 components and weight proportions of the core are shown in Table 1.

[0034] Preparation method:

[0035] 1) Steel strip pretreatment: Clean 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 during the rolling process, improve the plasticity and formability of the steel strip, and then cool naturally.

[0036] 2) Preparation of medicinal powder: Marble needs to be baked at 500℃ for 2 hours before use, and fluorite needs to be baked at 800℃ for 2 hours before use. After crushing all kinds of medicinal powder raw materials to 100 mesh as required, they are mixed 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 uniformly mixed powder is evenly filled into the U-shaped steel strip by a powder feeder. The powder feeder is controlled to make the powder filling rate reach 17%.

[0038] 4) Joining and Drawing: The U-shaped steel strip filled with flux powder is joined by a joining device to form a circular flux-cored welding wire blank. The blank is then subjected to rough drawing and fine drawing. Rough drawing uses a larger drawing force to initially reduce the diameter of the welding wire blank, while fine drawing uses a smaller drawing force to precisely control the diameter of the welding wire to achieve 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 welding 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, a rough drawing is performed first at a speed of 2 m / s, followed by a fine drawing, with the wire diameter controlled at 1.4 mm and the drawing speed at 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-resistant gas shielded welding flux-cored wire includes a steel strip and a flux core filled inside 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 components and weight proportions of the 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 then cooled naturally.

[0046] 2) Preparation of powder: Marble needs to be baked at 500℃ for 2 hours before use, and fluorite needs to be baked at 800℃ for 2 hours before use. The raw materials for the powder 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 uniformly mixed powder is evenly filled into the U-shaped steel strip by a powder feeder. The powder feeder is controlled to ensure that the powder filling rate reaches 18%.

[0048] 4) Joining and drawing: The U-shaped steel strip filled with flux powder is joined by a joining device to form a circular flux-cored wire blank; then the blank is coarsely drawn and finely drawn in sequence. The coarse drawing speed is 2.5m / s, and the fine drawing controls the wire diameter to 1.4mm and the speed to 1.8m / s.

[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-resistant gas shielded welding flux-cored wire includes a steel strip and a flux core filled inside 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 components and weight proportions of the 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 then cooled naturally.

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

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

[0057] 4) Joining and drawing: The U-shaped steel strip filled with flux powder is joined by a joining device to form a circular flux-cored wire blank; then the blank is coarsely drawn and finely drawn in sequence. The coarse drawing speed is 2.5m / s, and the fine drawing controls the wire diameter to 1.4mm and the speed to 1.8m / s.

[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-resistant gas shielded welding flux-cored wire includes a steel strip and a flux core filled inside 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 components and weight proportions of the 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 then cooled naturally.

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

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

[0066] 4) Joining and drawing: The U-shaped steel strip filled with flux powder is joined by a joining device to form a circular flux-cored wire blank; then the blank is coarsely drawn and finely drawn in sequence. The coarse drawing speed is 2.5m / s, and the fine drawing controls the wire diameter to 1.6mm and the speed to 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. Composition and weight fractions of the core in the examples.

[0069]

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

[0071]

[0072]

[0073] Table 3 Welding process test results of the embodiments

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

[0075] 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 Components and Weight Parts

[0077]

[0078]

[0079]

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

[0081]

[0082]

[0083] Table 6 Welding process test results of the embodiments

[0084]

[0085] The above comparison shows that the welding wires prepared according to Examples 1-4 of the present invention can obtain good microstructure and properties 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℃ and more than 60 J at a low temperature of -40℃, which greatly improves the reliability and safety of the welded joint under complex working conditions and is suitable for various welded structures with high requirements for strength and toughness.

[0086] In contrast, when the proportions of ferromanganese, ferrosilicon, and ferromolybdenum in Comparative Example 1 are not met, when the proportions of aluminum powder and ferrotitanium in Comparative Example 2 are not met, when the proportions of potassium titanate and sodium fluorosilicate in Comparative Example 3 are not met, when the proportions of marble and dolomite in Comparative Example 4 are not met, when the graphite content in Comparative Examples 5-6 meets the requirements, when the proportions of Ni-Ce-La rare earth alloy in Comparative Examples 7-8 are not met, and when the proportions of Ni, Ce, and La in Comparative Example 9 are not met, 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 within the protection scope of the present invention.

Claims

1. A method for preparing a high-toughness, high-crack-resistance gas-shielded welding flux-cored wire, wherein the 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 core, by weight, comprises: 5-10 parts ferromanganese, 3-8 parts ferrosilicon, 1-3 parts ferromolybdenum, 0.5-1.5 parts aluminum powder, 0.5-1.5 parts ferrotitanium, 1-3 parts potassium titanate, 1-3 parts sodium fluorosilicate, 1-5 parts marble, 1-5 parts dolomite, 5-15 parts fluorite, 0.1-0.5 parts graphite, 0.05-0.15 parts Ni-Ce-La rare earth alloy, and 50-70 parts reduced iron powder; the mass ratio of ferromanganese, ferrosilicon, and ferromolybdenum is (1.5-3):(1-2.5):1; the mass ratio of marble to dolomite is 1:1, and the marble needs to be heated to 500℃ before use. The fluorite needs to be baked at 800℃ for 2 hours before use; the Ni-Ce-La rare earth alloy is an alloy formed by adding rare earth elements Ce and La to nickel as the base, with a Ce to La mass ratio of 1:1, and the mass percentages of Ce and La in the Ni-Ce-La rare earth alloy are 0.05%-0.10% respectively; the steel strip is a low carbon steel strip with a carbon content controlled between 0.05%-0.10%, a thickness of 0.5-1.0 mm, and a width of 10 mm; the filling rate of the core is 15%-20%; the method is characterized by the following steps: 1) Pre-treat the steel strip, including removing oil, removing rust, and annealing. 2) Weigh the raw materials for the core, first bake the marble and fluorite, then crush each raw material separately, add the crushed powder to the powder mixer and mix thoroughly; 3) The pretreated steel strip is rolled into a U-shape using a welding wire forming machine, and the uniformly mixed powder is evenly filled into the U-shaped steel strip using a powder feeder. 4) The U-shaped steel strip filled with flux powder is joined together by a joining device to form a circular flux-cored welding wire blank; then the blank is coarsely drawn and finely drawn in sequence to obtain the welding wire of the required size; The specific steps of step 1) steel strip pretreatment include: cleaning the selected low carbon steel strip to remove surface oil, rust and other impurities, and then annealing it to eliminate the internal stress generated during the rolling process, improve the plasticity and formability of the steel strip. The annealing temperature is controlled at 600-700℃, the holding time is 30-60 minutes, and then it is naturally cooled in the air.

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

1.

3. The method for preparing the high-toughness, high-crack-resistant 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.

4. The method for preparing the high-toughness, high-crack-resistant gas-shielded welding flux-cored wire according to claim 1, characterized in that: In step 2), the particle size of the pulverized medicine powder 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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