A flux-cored wire and a method of manufacturing and use thereof

Abstract

The application provides a flux-cored wire and a preparation method and application thereof, and particularly relates to the field of welding materials. The flux-cored wire comprises a steel strip and a flux wrapped in the steel strip, and the flux comprises the following components and the mass percentage of each component is as follows: micro-carbon chromium iron 33-35%, calcium fluoride 21-23%, nickel powder 11-13%, rutile 12-14%, iron-molybdenum alloy 7-9%, manganese powder 3-5%, titanium-iron alloy 2-4%, silicon-iron alloy 1-2%, and the rest is iron powder. The flux-cored wire of the application can be applied to all-position welding, and has the advantages of stable welding arc, easy deslagging, smooth wire feeding, beautiful weld forming, good hardness, excellent impact resistance and crack resistance, and the hardness of the weld can be as high as 68HRC. The application of the flux-cored wire to the repair of turbine blades can greatly improve the service life of the turbine blades.

Description

Technical Field

[0001] This invention relates to the field of welding materials technology, specifically to a flux-cored welding wire, its preparation method, and its applications. Background Technology

[0002] Hydropower turbines and auxiliary equipment are essential components of the hydropower industry, playing a crucial role in fully utilizing clean and renewable energy to achieve energy conservation, emission reduction, and environmental pollution control. Their technological development is commensurate with the scale of my country's hydropower industry. Driven by strong electricity demand in my country, the manufacturing industry of hydropower turbines and auxiliary equipment has entered a period of rapid development, with significant improvements in both economic scale and technological level. my country's hydropower turbine manufacturing technology has reached world-class levels. However, during turbine runner operation, the blades are key components responsible for converting the kinetic energy of water into mechanical energy. Therefore, any damage to the blades will significantly affect the turbine's performance. Wear is a common form of blade damage, potentially leading to changes in blade shape and size, thereby affecting the turbine's efficiency and stability.

[0003] The causes of turbine blade wear are diverse, mainly including mechanical wear, chemical corrosion, and thermal stress. Mechanical wear is usually caused by friction between solid particles such as silt and impurities and the blade surface. Chemical corrosion occurs when chemicals in the water react with the blade material, leading to material loss. Thermal stress results from uneven thermal loads on the blades during high-speed rotation, causing uneven expansion and contraction of the material, resulting in stress concentration and ultimately wear or breakage. To prevent damage to other parts of the turbine due to blade wear, timely repair of the worn areas is necessary. Summary of the Invention

[0004] In view of the problems existing in the prior art, the present invention provides a flux-cored welding wire, its preparation method and application, for repairing worn parts of turbine blades.

[0005] To achieve the above and other related objectives, the first aspect of the present invention provides a flux-cored welding wire, the flux-cored welding wire comprising a steel strip and a flux core encased within the steel strip, wherein the flux core comprises the following components and the mass percentage of each component is as follows: 33%–35% micro-carbon ferrochrome, 21%–23% calcium fluoride, 11%–13% nickel powder, 12%–14% rutile, 7%–9% iron-molybdenum alloy, 3%–5% manganese powder, 2%–4% ferrotitanium alloy, 1%–2% ferrosilicon alloy, and the remainder being iron powder.

[0006] In one embodiment of the present invention, the chromium content in the micro-carbon ferrochrome is 70% to 72%, the nickel content in the nickel powder is ≥99%, the molybdenum content in the iron-molybdenum alloy is ≥55%, the manganese content in the manganese powder is ≥99%, and the titanium content in the titanium-iron alloy is 70% to 75%.

[0007] In one embodiment of the present invention, the micro-carbon ferrochrome has a particle size of 80-120 mesh, the nickel powder has a particle size of 60-80 mesh, the iron-molybdenum alloy has a particle size of 60-120 mesh, the manganese powder has a particle size of 60-80 mesh, and the titanium-iron alloy has a particle size of 80-100 mesh.

[0008] In one embodiment of the present invention, the steel strip is a 410 stainless steel strip.

[0009] In one embodiment of the present invention, the thickness of the steel strip is 0.4 mm and the width of the steel strip is 9.7 to 10.3 mm.

[0010] In one embodiment of the present invention, the weight of the flux core accounts for 25-30% of the total weight of the flux-cored welding wire.

[0011] A second aspect of the present invention provides a method for preparing a flux-cored welding wire, comprising the following steps:

[0012] Weigh the core powder according to the specified ratio;

[0013] The core powder is mixed evenly to obtain the core;

[0014] The steel strip is rolled into a U-shaped groove, and the core is filled into the U-shaped groove and then closed.

[0015] The steel strip filled with the flux core is drawn and reduced in diameter to the required specification to obtain the flux-cored welding wire.

[0016] In one embodiment of the present invention, the diameter of the flux-cored wire is 1.4 to 3.2 mm.

[0017] A third aspect of the present invention provides an application of a flux-cored welding wire suitable for the repair of turbine blades.

[0018] The wear-resistant surfacing flux-cored welding wire provided by this invention incorporates micro-carbon ferrochrome, iron-molybdenum alloy, titanium-iron alloy, and manganese powder into the flux core to alloy the weld metal. Chromium, titanium, manganese, and molybdenum elements enhance weld hardness, while nickel, molybdenum, and titanium refine the grain structure and improve weld toughness. Compared to similar welding wires, the wear-resistant surfacing flux-cored welding wire prepared by this invention exhibits superior welding process, stable arc combustion, good weld bead formation, less smoke and spatter, a dense weld overlay without shrinkage porosity, and allows for continuous multi-layer welding. It also possesses high hardness and excellent impact resistance. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a flowchart illustrating the preparation process of the flux-cored welding wire in one embodiment of the present invention. Detailed Implementation

[0021] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features can be combined with each other. It should also be understood that the terminology used in the embodiments of the present invention is for describing specific implementation schemes and not for limiting the scope of protection of the present invention. Test methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or according to the conditions recommended by the respective manufacturers.

[0022] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention, as well as the prior art known to those skilled in the art and the description of the invention, may be implemented using any prior art methods, devices, and materials similar to or equivalent to the methods, devices, and materials in the embodiments of the present invention.

[0023] It should be noted that the terms such as "upper", "lower", "left", "right", "middle" and "one" used in this specification are only for clarity of description and are not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered as part of the scope of the invention.

[0024] This invention provides a flux-cored welding wire, comprising a steel strip and a flux core encased within the steel strip. The flux core comprises the following components by mass percentage: 33%–35% micro-carbon ferrochrome, 21%–23% calcium fluoride, 11%–13% nickel powder, 12%–14% rutile, 7%–9% iron-molybdenum alloy, 3%–5% manganese powder, 2%–4% ferrotitanium alloy, 1%–2% ferrosilicon alloy, and the remainder being iron powder.

[0025] The functions of each component in the core are as follows:

[0026] Micro-carbon ferrochrome: Micro-carbon ferrochrome contains 70%–72% chromium and is mainly used for alloying. Adding a certain amount of micro-carbon ferrochrome can improve the hardenability and hardness of the weld; it also forms chromium carbides, improving the wear resistance of the weld. In the flux core of this invention, the mass percentage of micro-carbon ferrochrome is 33%–35%, for example, any value within the range of 33%–35%, such as 33%, 34%, or 35%.

[0027] Calcium fluoride: The calcium fluoride content must be ≥98%. Its main uses are gas generation and hydrogen removal. Adding an appropriate amount of calcium fluoride can significantly reduce the hydrogen content in the weld. The F2 produced by high-temperature decomposition can also further protect the weld metal. The mass percentage of calcium fluoride in the flux core of this invention is 21% to 23%, for example, it can be any value within the range of 21% to 23%, such as 21%, 22%, or 23%.

[0028] Rutile: The TiO2 content in rutile is ≥95%, and its main uses are slag formation, air blocking, and weld bead protection. The mass percentage of rutile in the flux core of this invention is 12% to 14%, for example, the mass percentage of rutile can be any value within the range of 12% to 14%, such as 12%, 13%, or 14%.

[0029] Manganese powder: The manganese content in the manganese powder is ≥99%. Its main function is as a deoxidizer and alloying agent. Excessive use will increase welding spatter. The mass percentage of metallic manganese in the flux-cored wire of this invention is 3% to 5%. For example, the mass percentage of manganese powder can be any value within the range of 3% to 5%, such as 3%, 4% or 5%.

[0030] Titanium-iron alloy: The titanium content in the titanium-iron alloy is 70%-75%, and it is mainly used as a deoxidizer. Excessive titanium content will increase spatter. The mass percentage of titanium-iron alloy in the flux-cored wire of this invention is 2% to 4%. For example, the mass percentage of titanium-iron alloy can be any value within the range of 2% to 4%, such as 2%, 3%, or 4%.

[0031] Ferrosilicon alloy: The silicon content in ferrosilicon alloy is 45% to 48%, mainly used as a deoxidizer. Silicon can improve the hardness and strength of the weld, promote ferrite grain coarsening, reduce coercivity, reduce the anisotropy tendency of crystals, promote columnar crystal growth, and reduce plasticity. In the flux-cored wire of this invention, the mass percentage of ferrosilicon is 1% to 2%, for example, the mass percentage of ferrovanadium can be any value within the range of 1% to 2%, such as 1%, 1.5%, or 2%.

[0032] In one embodiment, the particle size of the micro-carbon ferrochrome is 80-120 mesh, the particle size of the nickel powder is 60-80 mesh, the particle size of the iron-molybdenum alloy is 60-120 mesh, the particle size of the manganese powder is 60-80 mesh, and the particle size of the titanium-iron alloy is 80-100 mesh. Taking micro-carbon ferrochrome as an example, 80-mesh and 120-mesh sieves can be used to screen it. Specifically, a 120-mesh sieve is placed below an 80-mesh sieve, and the micro-carbon ferrochrome is poured into the 80-mesh sieve. The particles remaining in the 120-mesh sieve are the 80-120 mesh particles. The same method is used to screen the nickel powder, iron-molybdenum alloy, manganese powder, and titanium-iron alloy respectively.

[0033] Please see Figure 1 This invention provides a method for preparing flux-cored welding wire, comprising the following steps:

[0034] S1. Weigh the core powder according to the specified ratio;

[0035] S2. Mix the core powder evenly to obtain the core;

[0036] S3. Roll the steel strip into a U-shaped groove, fill the core material into the U-shaped groove, and close it;

[0037] S4. The steel strip filled with flux is drawn and reduced to the required diameter to obtain flux-cored welding wire.

[0038] In step S1, the components of the core are weighed according to the following proportions: 33%–35% micro-carbon ferrochrome, 21%–23% calcium fluoride, 11%–13% nickel powder, 12%–14% rutile, 7%–9% iron-molybdenum alloy, 3%–5% manganese powder, 2%–4% ferrotitanium alloy, 1%–2% ferrosilicon alloy, and the remainder being iron powder. In one embodiment, the particle size of the micro-carbon ferrochrome is 80–120 mesh, the particle size of the nickel powder is 60–80 mesh, the particle size of the iron-molybdenum alloy is 60–120 mesh, the particle size of the manganese powder is 60–80 mesh, and the particle size of the ferrotitanium alloy is 80–100 mesh.

[0039] In step S2, when mixing the drug core powder, a conventional stirring and mixing device in the art is selected. For example, a tilting pot is selected, and in order to ensure that the components of the drug core are mixed evenly, the stirring time is at least 30 minutes.

[0040] In step S3, the steel strip is 410 stainless steel strip with a thickness of 0.4 mm and a width of 9.7–10.3 mm. The filler content and weight of the flux-cored wire account for 25–30% of the total weight of the flux-cored wire, for example, any value within the range of 25%–30%, such as 25%, 28%, or 30%.

[0041] The wear-resistant flux-cored welding wire prepared by this invention has excellent welding process, stable arc combustion, good weld bead formation, little smoke and spatter, dense weld overlay without shrinkage porosity, and can be continuously welded in multiple layers. It also has high hardness and excellent impact resistance.

[0042] The technical solution of the present invention will be described in detail below through several specific embodiments. Unless otherwise stated, the raw materials and reagents used in the following embodiments are all commercially available products, or can be prepared by conventional methods in the art, and the instruments used in the embodiments are all commercially available.

[0043] Example 1

[0044] The flux-cored welding wire of this embodiment includes a steel strip and a flux core wrapped within the steel strip. The flux core comprises the following components by mass percentage: 33% micro-carbon ferrochrome, 21% calcium fluoride, 13% nickel powder, 13% rutile, 9% iron-molybdenum alloy, 3% manganese powder, 4% ferrotitanium alloy, 1% ferrosilicon alloy, and the remainder is iron powder. The above powders are mixed evenly to obtain the flux core. The steel strip is rolled into a U-shaped groove, and the flux core is filled into the U-shaped groove and closed. The steel strip filled with the flux core is drawn and reduced in diameter to the required specification to obtain the flux-cored welding wire.

[0045] In this embodiment, the width of the steel strip is 10.3 mm, the flux core accounts for 25% of the total mass of the flux-cored welding wire, and the diameter of the flux-cored welding wire is 1.4 mm.

[0046] Example 2

[0047] The flux-cored welding wire of this embodiment includes a steel strip and a flux core wrapped within the steel strip. The flux core comprises the following components by mass percentage: 34% micro-carbon ferrochrome, 22% calcium fluoride, 11% nickel powder, 14% rutile, 7% iron-molybdenum alloy, 5% manganese powder, 2% ferrotitanium alloy, 1.5% ferrosilicon alloy, and the remainder is iron powder. The above powders are mixed evenly to obtain the flux core. The steel strip is rolled into a U-shaped groove, and the flux core is filled into the U-shaped groove and closed. The steel strip filled with the flux core is drawn and reduced in diameter to the required specification to obtain the flux-cored welding wire.

[0048] In this embodiment, the width of the steel strip is 10mm, the flux core accounts for 28% of the total mass of the flux-cored welding wire, and the diameter of the flux-cored welding wire is 3.2mm.

[0049] Example 3

[0050] The flux-cored welding wire of this embodiment includes a steel strip and a flux core wrapped within the steel strip. The flux core comprises the following components by mass percentage: 35% micro-carbon ferrochrome, 23% calcium fluoride, 12% nickel powder, 12% rutile, 8% iron-molybdenum alloy, 4% manganese powder, 3% ferrotitanium alloy, 2% ferrosilicon alloy, and the remainder is iron powder. The above powders are mixed evenly to obtain the flux core. The steel strip is rolled into a U-shaped groove, and the flux core is filled into the U-shaped groove and closed. The steel strip filled with the flux core is drawn and reduced in diameter to the required specification to obtain the flux-cored welding wire.

[0051] In this embodiment, the width of the steel strip is 9.7 mm, the flux core accounts for 30% of the total mass of the flux-cored wire, and the diameter of the flux-cored wire is 2.0 mm.

[0052] Example 4

[0053] The flux-cored welding wire of this embodiment includes a steel strip and a flux core wrapped within the steel strip. The flux core comprises the following components by mass percentage: 35% micro-carbon ferrochrome, 21% calcium fluoride, 12% nickel powder, 13% rutile, 8% iron-molybdenum alloy, 4% manganese powder, 2% titanium-iron alloy, 3% silicon-iron alloy, and the remainder is iron powder. The above powders are mixed evenly to obtain the flux core. The steel strip is rolled into a U-shaped groove, and the flux core is filled into the U-shaped groove and closed. The steel strip filled with the flux core is drawn and reduced in diameter to the required specification to obtain the flux-cored welding wire.

[0054] In this embodiment, the width of the steel strip is 10mm, the flux core accounts for 26% of the total mass of the flux-cored welding wire, and the diameter of the flux-cored welding wire is 2.5mm.

[0055] Example 5

[0056] The flux-cored welding wire of this embodiment includes a steel strip and a flux core wrapped within the steel strip. The flux core comprises the following components by mass percentage: 33% micro-carbon ferrochrome, 22% calcium fluoride, 14% nickel powder, 12% rutile, 9% iron-molybdenum alloy, 3% manganese powder, 2% ferrotitanium alloy, 2% ferrosilicon alloy, and the remainder is iron powder. The above powders are mixed evenly to obtain the flux core. The steel strip is rolled into a U-shaped groove, and the flux core is filled into the U-shaped groove and closed. The steel strip filled with the flux core is drawn and reduced in diameter to the required specification to obtain the flux-cored welding wire.

[0057] In this embodiment, the width of the steel strip is 10.3 mm, the flux core accounts for 27% of the total mass of the flux-cored wire, and the diameter of the flux-cored wire is 2.5 mm.

[0058] In Examples 1 to 5, the steel strip of the flux-cored welding wire is made of stainless steel 410 strip. The particle size of the micro-carbon ferrochrome in the flux core is 80-120 mesh, the particle size of the nickel powder is 60-80 mesh, the particle size of the iron-molybdenum alloy is 60-120 mesh, the particle size of the manganese powder is 60-80 mesh, and the particle size of the titanium-iron alloy is 80-100 mesh.

[0059] The content of each component in the flux-cored welding wires of Examples 1 to 5 is shown in Table 1, and the parameters of the flux-cored welding wires are shown in Table 2. The chemical composition of the deposited metal and welding processability tests were conducted on the flux-cored welding wires provided in Examples 1 to 5 according to GB / T 5293. The chemical composition of the deposited metal is shown in Table 3. The hardness and relative corrosion rate of the deposited metal were tested. The relative corrosion rate test conditions were as follows: the deposited metal was placed in a solution with a concentration of 1.0 × 10⁻⁶... -2 In a mol / L NaHSO3 solution with a pH of 4.6, the solution was kept at 25℃ and 45% humidity for 72 hours. The relative corrosion rate was calculated using the following formula: Relative corrosion rate (%) = (Original weight - Weight after corrosion) / Original weight × 100%. The welding performance, hardness of the weld metal, and corrosion rate of the weld metal are shown in Table 4.

[0060] Table 1. Contents of each component in the flux-cored wires prepared in Examples 1 to 5

[0061]

[0062]

[0063] Table 2 Parameters of flux-cored welding wires prepared in Examples 1 to 5

[0064]

[0065] Table 3 Chemical composition of the weld metal of flux-cored wires prepared in Examples 1 to 5

[0066]

[0067] Table 4 Welding performance of flux-cored welding wires prepared in Examples 1 to 5

[0068]

[0069] The experimental results of Examples 1 to 5 show that the invented wear-resistant flux-cored welding wire has good welding processability, good hardness, wear resistance and crack resistance, and the HRC hardness of the deposited metal is uniform and stable.

[0070] The wear-resistant flux-cored welding wire provided by this invention incorporates micro-carbon ferrochrome, iron-molybdenum alloy, titanium-iron alloy, and manganese powder into the flux core to alloy the weld metal. Chromium, titanium, manganese, and molybdenum elements enhance weld hardness, while nickel, molybdenum, and titanium refine the grain structure and improve weld toughness. Compared to similar welding wires, the wear-resistant flux-cored welding wire prepared by this invention exhibits superior welding process, stable arc combustion, good weld bead formation, less smoke and spatter, and a dense weld layer without shrinkage porosity. It allows for continuous multi-layer welding and possesses high hardness and excellent impact resistance. Therefore, this invention effectively overcomes some practical problems in the prior art, thus possessing high utilization value and practical significance.

[0071] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can 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 those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A flux-cored welding wire characterized by, The steel strip and the core wire are composed of the following components in percentage by mass of the core wire: 33-35% of micro-carbon chromium iron, 21-23% of calcium fluoride, 11-13% of nickel powder, 12-14% of rutile, 7-9% of iron-molybdenum alloy, 3-5% of manganese powder, 2-4% of titanium-iron alloy, 1-2% of silicon-iron alloy, and the rest of iron powder.

2. The flux cored welding wire of claim 1, wherein The content of chromium in the micro-carbon chromium iron is 70-72%, the content of nickel in the nickel powder is ≥99%, the content of molybdenum in the iron-molybdenum alloy is ≥55%, the content of manganese in the manganese powder is ≥99%, and the content of titanium in the titanium-iron alloy is 70-75%.

3. The flux cored wire of claim 1 wherein, The particle size of the micro-carbon chromium iron is 80-120 mesh, the particle size of the nickel powder is 60-80 mesh, the particle size of the iron-molybdenum alloy is 60-120 mesh, the particle size of the manganese powder is 60-80 mesh, and the particle size of the titanium-iron alloy is 80-100 mesh.

4. The flux cored wire of claim 1 wherein, The steel strip is stainless steel 410.

5. The flux cored wire of claim 1 wherein, The thickness of the steel strip is 0.4 mm, and the width of the steel strip is 9.7-10.3 mm.

6. The flux cored wire of claim 1 wherein, The weight of the core wire accounts for 25-30% of the total weight of the core wire.

7. A method of making the flux cored wire of any one of claims 1 to 6, characterized in that, The method comprises the following steps: The core wire powder is weighed according to the proportion; The core wire is prepared by uniformly mixing the core wire powder; The steel strip is rolled into a U-shaped groove, and the core wire is filled into the U-shaped groove and closed; The steel strip filled with the core wire is drawn to the required specification to prepare the core wire.

8. The preparation method according to claim 7, wherein the diameter of the core wire is 1.4-3.2 mm.

9. Use of the flux-cored wire according to any one of claims 1 to 6, characterized in that, The core wire is suitable for repairing the water turbine blade.

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