Flux-cored wire and preparation method and application thereof

Abstract

The invention 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 belt and a flux core wrapped in the steel belt, and the flux core comprises, by mass, 33%-35% of micro-carbon ferrochrome, 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 ferrotitanium, 1%-2% of ferrosilicon and the balance iron powder. The flux-cored wire can be suitable for all-position welding, is stable in welding arc, easy in slag removal, smooth in wire feeding and attractive in weld joint forming, has better hardness and excellent impact resistance and crack resistance, has the weld joint hardness up to 68 HRC, is applied to turbine blade repair, and can greatly prolong the service life of turbine blades.

Description

Technical Field

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

[0002] Water turbines and auxiliary machinery are important hydropower equipment and an indispensable part of the hydropower industry. They are important equipment for making full use of clean and renewable energy to achieve energy conservation and emission reduction and reduce environmental pollution. Their technological development is in line with the development scale of my country's hydropower industry. Driven by the strong demand for electricity in my country, my country's water turbine and auxiliary machinery manufacturing industry has entered a period of rapid development. Its economic scale and technical level have been significantly improved, and my country's water turbine manufacturing technology has reached the world's advanced level. However, when the turbine runner blades are running, the blades are the key components in the turbine responsible for converting the kinetic energy of water into mechanical energy. Therefore, any damage to the blades will have a significant impact on the performance of the turbine. Wear is a common form of blade damage, which may cause changes in the shape and size of the blades, thereby affecting the efficiency and stability of the turbine.

[0003] There are many reasons for turbine blade wear, mainly including mechanical wear, chemical corrosion and thermal stress. Mechanical wear is usually caused by the friction between solid particles such as mud, impurities and the blade surface. Chemical corrosion is caused by the reaction between chemicals in the water and the blade material, resulting in material loss. Thermal stress is because the blades are subjected to uneven heat loads when rotating at high speed, resulting in uneven expansion and contraction of the material, stress concentration, and ultimately wear or breakage. In order to prevent damage to other parts of the turbine due to blade wear, the worn parts need to be repaired in time. Summary of the invention

[0004] In view of the above problems existing in the prior art, the present invention provides a flux-cored welding wire and a preparation method and use thereof, which are used to repair the worn parts of turbine blades.

[0005] To achieve the above-mentioned purpose and other related purposes, the first aspect of the present invention provides a flux-cored welding wire, which comprises a steel strip and a flux core wrapped in the steel strip. The flux core comprises the following components, calculated by mass percentage of the flux core, and the mass percentage of each component is: 33% to 35% of micro-carbon ferrochrome, 21% to 23% of calcium fluoride, 11% to 13% of nickel powder, 12% to 14% of rutile, 7% to 9% of iron-molybdenum alloy, 3% to 5% of manganese powder, 2% to 4% of ferrotitanium alloy, 1% to 2% of ferrosilicon alloy, and the rest is 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 particle size of the micro-carbon ferrochrome is 80 mesh to 120 mesh, the particle size of the nickel powder is 60 mesh to 80 mesh, the particle size of the iron-molybdenum alloy is 60 mesh to 120 mesh, the particle size of the manganese powder is 60 mesh to 80 mesh, and the particle size of the titanium-iron alloy is 80 mesh to 100 mesh.

[0008] In one embodiment of the present invention, the steel strip is a stainless steel 410 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 9.7-10.3 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 ratio;

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

[0014] Rolling the steel strip into a U-shaped groove, and filling the core into the U-shaped groove to close it;

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

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

[0017] A third aspect of the present invention provides a use of a flux-cored welding wire, wherein the flux-cored welding wire is suitable for repairing turbine blades.

[0018] The wear-resistant surfacing flux-cored welding wire provided by the present invention has micro-carbon ferrochrome, iron-molybdenum alloy, titanium-iron alloy and manganese powder added to the flux core to infiltrate the weld metal, wherein the chromium element, titanium element, manganese element and molybdenum element can improve the hardness of the weld, and the nickel element, molybdenum element and titanium element can also refine the grain structure and improve the toughness of the weld. Compared with the same type of welding wire, the wear-resistant surfacing flux-cored welding wire prepared by the present invention has excellent welding process, stable arc combustion, good weld bead forming, small smoke and less spatter, dense surfacing layer without shrinkage, can continuously perform multi-layer welding, and has high hardness and excellent impact resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] 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 in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other embodiments can be obtained based on these drawings without paying creative work.

[0020] Figure 1 FIG. 1 is a flow chart of the preparation of the flux-cored welding wire in one embodiment of the present invention. DETAILED DESCRIPTION

[0021] 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.

[0022] When numerical ranges are given in the embodiments, it should be understood that unless otherwise specified in the present invention, both endpoints of each numerical range and any value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present invention are familiar to those skilled in the art and the description of the present invention, and any method, device and material of the prior art similar or equivalent to the method, device and material in the embodiments of the present invention can also be used to implement the present invention.

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

[0024] The invention provides a flux-cored welding wire, comprising a steel strip and a flux core wrapped in the steel strip. The flux core comprises the following components, calculated by mass percentage of the flux core, and the mass percentage of each component is: 33% to 35% of micro-carbon ferrochrome, 21% to 23% of calcium fluoride, 11% to 13% of nickel powder, 12% to 14% of rutile, 7% to 9% of iron-molybdenum alloy, 3% to 5% of manganese powder, 2% to 4% of ferrotitanium alloy, 1% to 2% of ferrosilicon alloy, and the rest is iron powder.

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

[0026] Micro-carbon ferrochrome: The chromium content of micro-carbon ferrochrome is 70% to 72%. It is mainly used for alloying. Adding a certain amount of micro-carbon ferrochrome can improve the hardenability of the weld and the hardness of the weld; form chromium carbides and improve the wear resistance of the weld. The mass percentage of micro-carbon ferrochrome in the flux core of the present invention is 33% to 35%, for example, the mass percentage of micro-carbon ferrochrome can be any value within the range of 33% to 35%, such as 33%, 34% or 35%.

[0027] Calcium fluoride: The calcium fluoride content is required to be ≥98%. Its main purpose is to generate gas and remove hydrogen. 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 deposited metal. The mass percentage of calcium fluoride in the flux core of the present invention is 21% to 23%. For example, the mass percentage of calcium fluoride 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 purpose is to make slag, block air, and protect the weld. The mass percentage of rutile in the flux core of the present invention is 12% to 14%, for example, the mass percentage of rutile can be any value within the range of 12%, 13% or 14%, etc.

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

[0030] Ferro-titanium alloy: The titanium content of ferro-titanium alloy is 70%-75%, which is mainly used as a deoxidizer. Too much of it will increase spatter. The mass percentage of ferro-titanium alloy in the flux-cored welding wire of the present invention is 2% to 4%, for example, the mass percentage of ferro-titanium 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%, which is mainly used as a deoxidizer. Silicon can improve the hardness and strength of the weld, promote the coarsening of ferrite grains, reduce coercivity, reduce the anisotropy tendency of crystals, promote the growth of columnar crystals, and reduce plasticity. The mass percentage of ferrosilicon in the flux-cored welding wire of the present invention is 1% to 2%, and the mass percentage of ferrovanadium, for example, 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 micro-carbon ferrochrome is 80-120 mesh, the particle size of nickel powder is 60-80 mesh, the particle size of iron-molybdenum alloy is 60-120 mesh, the particle size of manganese powder is 60-80 mesh, and the particle size of titanium-iron alloy is 80-100 mesh. Taking micro-carbon ferrochrome as an example, for example, 80-mesh and 120-mesh sieves can be used to screen micro-carbon ferrochrome. Specifically as follows: place a sieve with a mesh number of 120 mesh below a sieve with a mesh number of 80 mesh, pour the micro-carbon ferrochrome into the sieve with a mesh number of 80 mesh, and the particles left in the sieve with a mesh number of 120 mesh are 80-120 mesh particles. Use the same method to screen nickel powder, iron-molybdenum alloy, manganese powder and titanium-iron alloy respectively.

[0033] See also Figure 1 The present invention provides a method for preparing a flux-cored welding wire, comprising the following steps:

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

[0035] S2, mixing the core powder evenly to obtain the core;

[0036] S3, rolling the steel strip into a U-shaped groove, and filling the core into the U-shaped groove, and closing it;

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

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

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

[0040] In step S3, the steel strip is a stainless steel strip of 410, the thickness of the steel strip is 0.4 mm, and the width of the steel strip is 9.7-10.3 mm. The filling rate of the flux-cored welding wire and the weight of the flux core account for 25-30% of the total weight of the flux-cored welding wire, for example, any value of 25%, 28% or 30% or the like.

[0041] The wear-resistant surfacing flux-cored welding wire prepared by the invention has excellent welding process, stable arc combustion, good weld bead forming, small smoke and dust, less splash, dense surfacing layer without shrinkage, can continuously perform multi-layer welding, and has high hardness and excellent impact resistance.

[0042] The technical scheme of the present invention is described in detail below through several specific examples. Unless otherwise specified, the raw materials and reagents used in the following examples are all commercially available products, or can be prepared by conventional methods in the art, and the instruments used in the examples 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 in the steel strip. The flux core includes the following components in terms of mass percentage of the flux core: 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 rest is iron powder. The above powders are evenly mixed to obtain a 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 to a desired specification to obtain a 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 in the steel strip. The flux core includes the following components in terms of mass percentage of the flux core: 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 rest is iron powder. The above powders are evenly mixed to obtain a 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 to the required specifications to obtain the flux-cored welding wire.

[0048] In this embodiment, the width of the steel strip is 10 mm, 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 3.2 mm.

[0049] Example 3

[0050] The flux-cored welding wire of this embodiment includes a steel strip and a flux core wrapped in the steel strip. The flux core includes the following components in terms of mass percentage of the flux core: 35% of micro-carbon ferrochrome, 23% of calcium fluoride, 12% of nickel powder, 12% of rutile, 8% of iron-molybdenum alloy, 4% of manganese powder, 3% of ferrotitanium alloy, 2% of ferrosilicon alloy, and the rest is iron powder. The above powders are evenly mixed to obtain a 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 to a desired specification to obtain a 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 welding wire, and the diameter of the flux-cored welding 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 in the steel strip. The flux core includes the following components in terms of mass percentage of the flux core: 35% of micro-carbon ferrochrome, 21% of calcium fluoride, 12% of nickel powder, 13% of rutile, 8% of iron-molybdenum alloy, 4% of manganese powder, 2% of ferrotitanium alloy, 3% of ferrosilicon alloy, and the rest is iron powder. The above powders are evenly mixed to obtain a 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 to the required specifications to obtain a flux-cored welding wire.

[0054] In this embodiment, the width of the steel strip is 10 mm, 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 2.5 mm.

[0055] Example 5

[0056] The flux-cored welding wire of this embodiment includes a steel strip and a flux core wrapped in the steel strip. The flux core includes the following components in terms of mass percentage of the flux core: 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 rest is iron powder. The above powders are evenly mixed to obtain a 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 to a desired specification to obtain a 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 welding wire, and the diameter of the flux-cored welding 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 steel strip, the particle size of the micro-carbon ferrochromium in the flux core is 80 mesh to 120 mesh, the particle size of the nickel powder is 60 mesh to 80 mesh, the particle size of the iron-molybdenum alloy is 60 mesh to 120 mesh, the particle size of the manganese powder is 60 mesh to 80 mesh, and the particle size of the titanium-iron alloy is 80 mesh to 100 mesh.

[0059] The contents of the components of the flux core in the flux cored welding wires of Examples 1 to 5 are 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 the welding processability test were performed 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 are as follows: the deposited metal is placed in a concentration of 1.0×10 -2 In a mol / L NaHSO3 solution, the pH value of the NaHSO3 solution is 4.6. Under the conditions of temperature of 25°C and humidity of 45%, it is maintained for 72 hours. The calculation formula of the relative corrosion rate is as follows: Relative corrosion rate (%) = (original weight - weight after corrosion) / original weight × 100%. The welding performance, hardness of the deposited metal and corrosion rate of the deposited metal are shown in Table 4.

[0060] Table 1 Content of each component of flux-cored welding wire prepared in Examples 1 to 5

[0061]

[0062]

[0063] Table 2 Flux-cored welding wire parameters prepared in Examples 1 to 5

[0064]

[0065] Table 3 Chemical composition of deposited metal of flux-cored welding wire prepared in Examples 1 to 5

[0066]

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

[0068]

[0069] The experimental results of Examples 1 to 5 show that the wear-resistant surfacing flux-cored welding wire of the present invention 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 surfacing flux-cored welding wire provided by the present invention adds micro-carbon ferrochrome, iron-molybdenum alloy, ferrotitanium alloy and manganese powder to the flux core to infiltrate the weld metal, wherein the chromium element, titanium element, manganese element and molybdenum element can improve the hardness of the weld, and the nickel element, molybdenum element and titanium element can also refine the grain structure and improve the toughness of the weld. Compared with the same type of welding wire, the wear-resistant surfacing flux-cored welding wire prepared by the present invention has excellent welding process, stable arc combustion, good weld bead forming, small smoke and less spatter, dense surfacing layer without shrinkage, can continuously perform multi-layer welding, and has high hardness and excellent impact resistance. Therefore, the present invention effectively overcomes some practical problems in the prior art and has high utilization value and use significance.

[0071] 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 flux-cored welding wire, characterized in that: The invention comprises a steel strip and a flux core wrapped in the steel strip. The flux core comprises the following components in percentage by mass: 33% to 35% of micro-carbon ferrochrome, 21% to 23% of calcium fluoride, 11% to 13% of nickel powder, 12% to 14% of rutile, 7% to 9% of iron-molybdenum alloy, 3% to 5% of manganese powder, 2% to 4% of ferrotitanium alloy, 1% to 2% of ferrosilicon alloy, and the rest is iron powder.

2. The flux-cored welding wire according to claim 1, characterized in that: 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%.

3. The flux-cored welding wire according to claim 1, characterized in that: 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.

4. The flux-cored welding wire according to claim 1, characterized in that: The steel strip is a stainless steel 410 steel strip.

5. The flux-cored welding wire according to claim 1, characterized in that: 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 welding wire according to claim 1, characterized in that: The weight of the flux core accounts for 25-30% of the total weight of the flux cored welding wire.

7. A method for preparing a flux-cored welding wire according to any one of claims 1 to 6, characterized in that: The steps include: Weigh the core powder according to the ratio; The drug core powder is mixed evenly to obtain the drug core; Rolling the steel strip into a U-shaped groove, and filling the core into the U-shaped groove to close it; The steel strip filled with the flux core is drawn and reduced in diameter to a desired specification to obtain the flux cored welding wire.

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

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

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