Flux-cored welding wire and preparation method thereof

Abstract

The present invention provides a flux-cored welding wire and a preparation method thereof, comprising: a steel strip and a flux core, wherein the flux core is filled in the steel strip; the flux core comprises the following raw materials in percentage by mass: 7-10% low-carbon ferrochrome, 3-5% high-carbon ferrochrome, 7-10% metallic manganese, 5-7% ferromolybdenum, 4-6% rutile, 40-55% fluorite, 3-5% quartz, 1-2% potassium feldspar, 1-2% potassium fluozirconate, 2-3% calcium silicate powder, 3-5% magnesium powder, 3-4% 45% ferrosilicon, and the balance is atomized iron powder. The flux-cored welding wire provided by the present invention can, during welding, improve slag fluidity, reduce slag spatter, and enhance arc stability, thereby optimizing welding process performance; and can also enhance the high-temperature oxidation resistance and corrosion resistance of the high-deposited metal, resulting in a weld with excellent thermal crack resistance and low-temperature toughness, thereby making the weld of heat-resistant steel more adaptable to harsh environments of high temperature, high pressure, and steam corrosion.

Description

Technical Field

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

[0002] With the steady development of my country's economy, people's demand for electricity in their daily lives continues to increase, and thermal power generation occupies a dominant position in my country's power supply structure. The development of efficient, energy-saving, clean, and large-capacity thermal power generation technology is a key trend in my country's power development. Given that boiler tubes in thermal power plants operate for long periods of time in harsh environments such as high temperature, high pressure, and steam corrosion, heat-resistant steel is often used as the material for these tubes. The structure of such steel will undergo graphitization and creep over time, and its high-temperature strength will gradually deteriorate with use. The welds on the pipes are often structurally weak points, and they will usually become brittle before the pipes themselves, thus affecting the safe use of the boiler.

[0003] Therefore, in order to improve the safety of boiler use, it is necessary to provide a flux-cored welding wire and a preparation method thereof to improve the critical strength of heat-resistant steel welding welds in high pressure, high humidity and high corrosion environments, thereby solving the above technical problems. Summary of the Invention

[0004] In view of the above shortcomings of the prior art, the present invention provides a flux-cored welding wire and a preparation method thereof to solve the technical problem that the deposited metal of the existing flux-cored welding wire has poor corrosion resistance and low-temperature toughness.

[0005] To achieve the above-mentioned and other related purposes, the present invention provides a flux-cored welding wire, comprising: a steel strip and a flux core, wherein the flux core is filled in the steel strip; the flux core comprises the following raw materials in the following mass percentages:

[0006] Low carbon ferrochrome 7-10%, high carbon ferrochrome 3-5%, metallic manganese 7-10%, ferromolybdenum 5-7%, rutile 4-6%, fluorite 40-55%, quartz 3-5%, potassium feldspar 1-2%, potassium fluozirconate 1-2%, calcium silicate powder 2-3%, magnesium powder 3-5%, 45 ferrosilicon 3-4%, and the balance is atomized iron powder.

[0007] In one example of the present invention, the chromium content in the micro-carbon ferrochrome is greater than or equal to 70wt%, and the carbon content in the micro-carbon ferrochrome is less than or equal to 0.06wt%; the chromium content in the high-carbon ferrochrome is greater than or equal to 70wt%, and the carbon content in the high-carbon ferrochrome is greater than or equal to 8.2wt%; the manganese content in the metallic manganese is greater than or equal to 99.8wt%; the titanium dioxide content in the rutile is greater than or equal to 95wt%; the calcium fluoride content in the fluorite is greater than or equal to 95wt%; the silicon content in the 45 ferrosilicon is 42-47wt%; and the iron content in the atomized iron powder is greater than or equal to 98wt%.

[0008] In one example of the present invention, the steel strip is a carbon steel strip; the carbon content of the carbon steel strip is 0.04-0.10wt%, the silicon content of the carbon steel strip is less than or equal to 0.80wt%, the phosphorus content of the carbon steel strip is less than or equal to 0.03wt%, and the manganese content of the carbon steel strip is less than or equal to 1.25wt%.

[0009] In one example of the present invention, the particle size of the drug core is 40-200 mesh.

[0010] In an example of the present invention, the diameter of the flux-cored welding wire is 1.2-1.6 mm.

[0011] In an example of the present invention, the flux core accounts for 14-16% of the flux-cored welding wire by mass.

[0012] The present invention also provides a method for preparing the flux-cored welding wire described in any of the above examples, the method comprising:

[0013] Mix and prepare the core powder according to the raw material components;

[0014] wrapping the core powder in a steel strip;

[0015] The steel strip is drawn to a preset size to obtain a flux-cored welding wire.

[0016] In one example of the present invention, the preparation method further includes: drying the raw materials before configuring the core powder; wherein the drying temperature of each raw material is 195-205° C., and the drying time of each raw material is 60 to 100 minutes.

[0017] In one example of the present invention, wrapping the core powder in a steel strip includes: rolling the steel strip into a U-shaped groove; filling the core powder into the U-shaped groove, and then butt-welding the openings of the U-shaped groove.

[0018] In an example of the present invention, in the butt welding of the openings of the U-shaped groove, high-frequency welding technology is used to butt weld the openings of the U-shaped groove.

[0019] The present invention also provides an application of the flux-cored welding wire described in any of the above examples or the flux-cored welding wire prepared by the preparation method described in any of the above examples in the field of thermal power generation.

[0020] The present invention provides a flux-cored welding wire and a preparation method thereof. The flux-cored welding wire comprises a flux core containing a certain proportion of micro-carbon ferrochrome, metallic manganese, fluorite, rutile, quartz, magnesium powder, calcium silicon powder, ferrosilicon, and 45% ferrosilicon. During welding, the flux-cored welding wire utilizes the micro-carbon ferrochrome, metallic manganese, magnesium powder, ferrosilicon, calcium silicon powder, and 45% ferrosilicon to reduce the oxygen and sulfur contents in the weld, thereby improving the high-temperature oxidation resistance and corrosion resistance of the high-deposited metal and imparting excellent thermal crack resistance and low-temperature toughness to the weld. Furthermore, the flux-cored welding wire utilizes a combination of alkaline slag materials such as fluorite with rutile and quartz to improve slag fluidity, reduce slag spatter, and enhance arc stability, thereby optimizing welding process performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 1 is a schematic flow chart of a method for preparing a flux-cored welding wire according to an embodiment of the present invention;

[0023] Figure 2 FIG. 1 is a flow chart of step S2 in one embodiment of the present invention. DETAILED DESCRIPTION

[0024] The following describes the embodiments of the present invention through specific examples. 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 based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following examples and the features in the examples can be combined with each other unless they conflict. It should also be understood that the terms used in the examples of the present invention are for the purpose of describing specific embodiments, not for the purpose of limiting the scope of protection of the present invention. The test methods for which specific conditions are not specified in the following examples are generally carried out under conventional conditions or under the conditions recommended by the manufacturers.

[0025] When numerical ranges are given in the examples, it should be understood that unless otherwise specified herein, both endpoints of each numerical range and any value between the two endpoints may be used. Unless otherwise defined, all technical and scientific terms used herein are consistent with the prior art as understood by those skilled in the art and the description of the present invention. Any prior art methods, devices, and materials similar or equivalent to those described in the examples of the present invention may also be used to implement the present invention.

[0026] The present invention provides a flux-cored welding wire and a preparation method thereof. The flux-cored welding wire can, on the one hand, improve slag fluidity, reduce slag spatter, and enhance arc stability during welding, thereby optimizing welding process performance. On the other hand, it can enhance the high-temperature oxidation resistance and corrosion resistance of highly deposited metal, so that the weld has excellent resistance to thermal cracking and low-temperature toughness, thereby making the weld of heat-resistant steel more adaptable to the harsh environment of high temperature, high pressure, and steam corrosion.

[0027] The flux-cored welding wire comprises a steel strip and a flux core filled within the steel strip. The flux core comprises the following raw materials, in percentage by mass: 7-10% low-carbon ferrochrome, 3-5% high-carbon ferrochrome, 7-10% metallic manganese, 5-7% ferromolybdenum, 4-6% rutile, 40-55% fluorite, 3-5% quartz, 1-2% potassium feldspar, 1-2% potassium fluorozirconate, 2-3% calcium silicate powder, 3-5% magnesium powder, 3-4% 45% ferrosilicon, and the balance is atomized iron powder.

[0028] The functions of the raw material components of the drug core are described in detail as follows:

[0029] Micro-carbon ferrochrome: As an alloying additive in the flux core, micro-carbon ferrochrome transfers chromium into the weld during welding, thereby increasing the chromium content in the deposited metal and easily forming a chromium oxide protective film on the surface of the weld material, giving the weld material excellent resistance to both room-temperature and high-temperature oxidation and corrosion. Furthermore, compared to metallic chromium, micro-carbon ferrochrome improves slag fluidity and reduces slag spatter during flux-cored welding, thereby optimizing welding process performance. The mass percentage of micro-carbon ferrochrome in the flux core is 7% to 10%. For example, the mass percentage of micro-carbon ferrochrome in the flux core can be 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, or 10%.

[0030] High-carbon ferrochrome: As an alloying additive in the flux core, high-carbon ferrochrome transfers chromium and carbon into the weld during welding. The synergistic effect of carbon and chromium further enhances the hardness of the resulting weld. High-carbon ferrochrome accounts for 3% to 5% by weight of the flux core. For example, the weight percentage of high-carbon ferrochrome in the flux core can be 3%, 3.5%, 4%, 4.5%, or 5%.

[0031] Manganese metal: Manganese metal acts as a deoxidizer and desulfurizer in the flux core. During welding, manganese metal works synergistically with silicon to deoxidize, effectively reducing the oxygen content in the weld. Manganese metal combines with sulfur to form manganese sulfide, preventing the formation of low-melting-point iron sulfide in the weld, preventing the weld metal from developing hot cracks and improving the weld's resistance to hot cracking. Furthermore, manganese metal combines with iron to form a solid solution, increasing the strength and hardness of the ferrite and austenite in the deposited metal. The mass percentage of manganese metal in the flux core ranges from 7% to 10%. For example, the mass percentage of manganese metal in the flux core can be 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, or 10%.

[0032] Fluorite: Fluorite, primarily composed of calcium fluoride, reduces the amount of hydrogen diffused in the weld during welding, adjusts the pH of the weld slag, enhances slag fluidity, reduces slag spatter, improves weld slag removal and formation, and contributes to improved weld toughness and acid corrosion resistance. Fluorite can make up 40% to 55% of the flux core by weight. For example, the weight percentage of fluorite in the flux core can be 40%, 42%, 45%, 47%, 50%, 52%, or 55%.

[0033] Rutile: Rutile, primarily composed of titanium dioxide, acts as a slag-forming agent in the flux core. During welding, rutile significantly reduces slag viscosity and surface tension, improving slag fluidity and coverage. It also stabilizes the welding arc, reduces slag spatter, and increases wire deposition speed. The weight percentage of rutile in the flux core ranges from 4% to 6%. For example, the weight percentage of rutile in the flux core can be 4%, 4.5%, 4.7%, 5%, 5.3%, 5.5%, 5.7%, or 6%. Adding these appropriate proportions of rutile to the flux core ensures that the flux-cored wire can weld heat-resistant steel in all positions.

[0034] Quartz: Quartz is primarily composed of silicon dioxide. Quartz in the flux core adjusts the physical properties of the slag, forming the slag and reducing the slag's basicity during welding. The mass percentage of quartz in the flux core ranges from 3% to 5%. For example, the mass percentage of quartz in the flux core can be 3%, 3.5%, 4%, 4.5%, or 5%.

[0035] Ferromolybdenum: Ferromolybdenum is an alloy composed of molybdenum and iron. As an alloying additive, ferromolybdenum transfers molybdenum into the weld during the welding process. Molybdenum can mitigate or eliminate the temper brittleness caused by other alloying elements, significantly improving the weld's impact toughness and enhancing its strength, corrosion resistance, wear resistance, and thermal cracking resistance. Ferromolybdenum can account for 5% to 7% by weight of the flux core. For example, the weight percentage of ferromolybdenum in the flux core can be 5%, 5.5%, 6%, 6.5%, or 7%.

[0036] Potassium feldspar: Potassium feldspar plays a role in slag formation, arc stabilization, and reducing the surface tension of the liquid metal during welding. It can improve slag fluidity and adjust slag viscosity and temperature. The mass percentage of potassium feldspar in the flux core is 1% to 2%. For example, the mass percentage of potassium feldspar in the flux core can be 1%, 1.2%, 1.4%, 1.5%, 1.7%, or 2%.

[0037] Potassium fluorozirconate: As a potassium fluoride, potassium fluorozirconate stabilizes the welding arc in the flux core. Adding a small amount to the flux core can effectively optimize the welding process. The mass percentage of potassium fluorozirconate in the flux core ranges from 1% to 2%. For example, the mass percentage of potassium fluorozirconate in the flux core can be 1%, 1.2%, 1.4%, 1.5%, 1.7%, or 2%.

[0038] Calcium silicate powder: Calcium silicate powder acts as a calcium additive, deoxidizer, desulfurizer, and modifier for non-metallic inclusions in the flux core. An appropriate amount of calcium silicate powder can increase the calcium and silicon content in the flux-cored wire. The calcium and silicon in the flux core have a strong affinity for oxygen, sulfur, and nitrogen, reducing the oxygen and sulfur content in the deposited metal during welding. Deoxidation and desulfurization products easily float up and are removed, effectively reducing the likelihood of welding defects such as porosity and slag inclusions in the weld layer. The weight percentage of calcium silicate powder in the flux core is 2% to 3%. For example, the weight percentage of calcium silicate powder in the flux core can be 2%, 2.2%, 2.5%, 2.7%, or 3%.

[0039] Magnesium powder: Magnesium powder acts as a flux core and alloying additive. It transitions into the weld during welding to improve the alloying properties of the deposited metal and enhance the strength and corrosion resistance of the weld material. The weight percentage of magnesium powder in the flux core ranges from 3% to 5%. For example, the weight percentage of magnesium powder in the flux core can be 3%, 3.5%, 4%, 4.5%, or 5%.

[0040] 45% Ferrosilicon: 45% Ferrosilicon has a silicon content of 42-47%. As a deoxidizer in the flux core, 45% Ferrosilicon increases the melting point and hardness of the weld metal during welding, imparting improved corrosion and high-temperature resistance. The mass fraction of 45% Ferrosilicon in the flux core ranges from 42% to 47%. For example, the mass fraction of 45% Ferrosilicon in the flux core can be 42%, 43%, 44%, 45%, 46%, or 47%.

[0041] Atomized iron powder: The spherical shape of atomized iron powder enhances the overall fluidity of the flux core powder, ensuring uniform filling and molding. Adding atomized iron powder to the flux core provides a small amount of oxygen during welding, effectively increasing the core's conductivity, stabilizing the arc and improving welding efficiency, thereby improving the arc state and regulating the fluidity of the molten iron. Any remaining material in the flux core other than the aforementioned can be filled with atomized iron powder.

[0042] In some embodiments, the chromium content of the low-carbon ferrochrome is greater than or equal to 70 wt %, and the carbon content of the low-carbon ferrochrome is less than or equal to 0.06 wt %. In one embodiment, the carbon content of the low-carbon ferrochrome is 0.02-0.06 wt %, for example, the carbon content of the low-carbon ferrochrome can be 0.02 wt %, 0.03 wt %, 0.04 wt %, 0.05 wt %, or 0.06 wt %. The chromium content of the high-carbon ferrochrome is greater than or equal to 70 wt %, and the carbon content of the high-carbon ferrochrome is greater than or equal to 8.2 wt %. In one embodiment, the carbon content of the high-carbon ferrochrome is 8.2-10 wt %, for example, the carbon content of the high-carbon ferrochrome can be 8.2 wt %, 8.4 wt %, 8.5 wt %, 8.8 wt %, 9.0 wt %, 9.2 wt %, 9.4 wt %, 9.6 wt %, 9.8 wt %, or 10 wt %.

[0043] In some embodiments, the steel strip is a carbon steel strip, and the steel strip includes the following raw material components in the following mass percentages: the carbon content of the carbon steel strip is 0.04 to 0.10 wt%, for example, the carbon content of the carbon steel strip can be 0.04 wt%, 0.05 wt%, 0.06 wt%, 0.08 wt% or 0.10 wt%; the silicon content of the carbon steel strip is less than or equal to 0.80 wt%; the phosphorus content of the carbon steel strip is less than or equal to 0.03 wt%; the manganese content of the carbon steel strip is less than or equal to 1.25 wt%; and the balance is iron and unavoidable impurities.

[0044] In some embodiments, the manganese content in the manganese metal is greater than or equal to 99.8 wt %, the titanium dioxide content in the rutile is greater than or equal to 95 wt %, the calcium fluoride content in the fluorite is greater than or equal to 95 wt %, and the iron content in the atomized iron powder is greater than or equal to 98 wt %.

[0045] In some embodiments, the particle size of the core is 40-200 mesh, and the particle size of the core can be any value within the range of 40-200 mesh. Particle size refers to the size of the raw material particles. The larger the mesh number, the finer the particles. For example, in the core, the mesh number of the micro-carbon ferrochrome is 80 mesh, and the particle size satisfies that the powder passing through 80 mesh is greater than or equal to 95%; the powder passing through 200 mesh is less than or equal to 10%; the mesh number of the high-carbon ferrochrome is 40 mesh, and the particle size satisfies that the powder passing through 40 mesh is greater than or equal to 95%; the powder passing through 200 mesh is less than or equal to 20%; the mesh number of the metallic manganese is 60 mesh, and the particle size satisfies that the powder passing through 60 mesh is greater than or equal to 95%; the powder passing through 200 mesh is less than or equal to 20%;

[0046] In some embodiments, the flux core accounts for 14-16% by mass of the flux-cored welding wire. For example, the flux core may account for 14%, 14.5%, 15%, 15.5% or 16% by mass.

[0047] In some embodiments, the diameter of the flux-cored welding wire is 1.2-1.6 mm. The diameter of the flux-cored welding wire can be any value within the range of 1.2-1.6 mm, for example, the diameter of the flux-cored welding wire can be 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, or 1.6 mm.

[0048] like Figure 1 As shown, the present invention also provides a method for preparing the flux-cored welding wire described in any one of the above embodiments, the preparation method comprising the following steps:

[0049] S1. Mix and prepare core powder according to the raw material components;

[0050] S2, wrapping the core powder in a steel strip;

[0051] S3. Drawing the steel strip to a preset size to obtain a flux-cored welding wire.

[0052] In step S1, the raw material components in the core are mixed in the following mass percentages: low-carbon ferrochrome 7-10%, high-carbon ferrochrome 3-5%, metallic manganese 7-10%, ferromolybdenum 5-7%, rutile 4-6%, fluorite 40-55%, quartz 3-5%, potassium feldspar 1-2%, potassium fluorozirconate 1-2%, calcium silicate powder 2-3%, magnesium powder 3-5%, 45% ferrosilicon 3-4%, and the remainder is atomized iron powder to prepare the core powder.

[0053] In some embodiments, the preparation method further includes: drying the raw materials before preparing the core powder; drying each raw material at a temperature of 195-205°C for 60-100 minutes, and taking it out after the drying furnace cools to room temperature to obtain the dried raw materials.

[0054] like Figure 2 As shown, in some embodiments, step S2 includes the following steps:

[0055] S21, rolling the steel strip into a U-shaped groove;

[0056] S22, mixing the core powder evenly and filling it into the U-shaped groove, and then butt-welding the openings of the U-shaped groove.

[0057] In some embodiments, in step S2, the flux core powder mixed in step S1 is wrapped in a steel strip using a rolling mill, wherein the flux core filling rate in the steel strip is 14% to 16%, and the flux core filling rate is the mass percentage of the flux core relative to the flux cored wire.

[0058] In some embodiments, in step S21 , a carbon steel strip is used as the practical steel strip to be processed.

[0059] In some embodiments, in step S22, the openings of the U-shaped groove are butt-welded using high-frequency welding technology.

[0060] In step S3, the steel strip is drawn to a preset size so that the diameter of the steel strip reaches 1.2 to 1.6 mm, thereby obtaining a flux-cored welding wire.

[0061] The present invention also provides the use of the flux-cored welding wire described in any of the above embodiments, or the flux-cored welding wire prepared by the preparation method described in any of the embodiments, in the thermal power industry, particularly in the welding of heat-resistant steel. This flux-cored welding wire, when used in conjunction with RMD (short-circuit control) or pulse technology, can weld heat-resistant steel in all positions. The flux-cored welding wire has excellent welding process, stable arc, minimal spatter, easy slag removal, and aesthetically pleasing weld seam formation for heat-resistant steel used in thermal power boilers. The resulting heat-resistant steel welds have excellent high-temperature oxidation resistance, corrosion resistance, and low-temperature toughness, allowing the heat-resistant steel welding materials to adapt to harsh environments characterized by high temperature, high pressure, and high corrosion.

[0062] The technical solutions of the present invention are described in detail below through several specific examples and comparative examples. Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by conventional methods in the art.

[0063] Example 1

[0064] This embodiment provides a flux-cored welding wire, which includes a steel strip and a flux core filled in the steel strip. The filling rate of the flux core in the flux-cored welding wire is 14%. The flux core includes the following components, measured by mass percentage: 7% low-carbon ferrochrome, 3% high-carbon ferrochrome, 8% metallic manganese, 7% ferromolybdenum, 6% rutile, 42% fluorite, 4% quartz, 1% potassium feldspar, 1% potassium fluorozirconate, 2% calcium silicate powder, 3% magnesium powder, 3% 45% ferrosilicon, and 13% atomized iron powder. The preparation method of the flux-cored welding wire includes the following steps:

[0065] S1. Weigh the raw materials according to the above raw material components, dry the raw materials and evenly mix them to obtain a core powder; wherein the raw materials are dried at a drying temperature of 195° C. for 60 minutes;

[0066] S2. Cut the carbon steel strip to a width of 14 mm, clean it, and roll it into a U-shaped groove; fill the U-shaped groove of the carbon steel strip with flux core powder, and then butt-weld the U-shaped groove opening of the carbon steel strip using high-frequency welding technology;

[0067] S3. After the carbon steel strip is rolled and reduced in diameter, it is drawn into a wire drawing machine to a diameter of 1.2 mm to obtain a flux-cored welding wire.

[0068] Example 2

[0069] This embodiment provides a flux-cored welding wire, which includes a steel strip and a flux core filled in the steel strip. The filling rate of the flux core in the flux-cored welding wire is 15%. The flux core includes the following components, measured by mass percentage: 10% low-carbon ferrochrome, 5% high-carbon ferrochrome, 7% metallic manganese, 5% ferromolybdenum, 4% rutile, 44% fluorite, 3% quartz, 2% potassium feldspar, 1% potassium fluorozirconate, 2% calcium silicate powder, 4% magnesium powder, 3% 45% ferrosilicon, and 10% atomized iron powder. The preparation method of the flux-cored welding wire includes the following steps:

[0070] S1. Weigh the raw materials according to the above raw material components, dry the raw materials and evenly mix them to obtain a core powder; wherein the raw materials are dried at a drying temperature of 200° C. for 80 minutes;

[0071] S2. Cut the carbon steel strip to a width of 14 mm, clean it, and roll it into a U-shaped groove; fill the U-shaped groove of the carbon steel strip with flux core powder, and then butt-weld the U-shaped groove opening of the carbon steel strip using high-frequency welding technology;

[0072] S3. After the carbon steel strip is rolled and reduced in diameter, it is drawn into a wire drawing machine to a diameter of 1.4 mm to obtain a flux-cored welding wire.

[0073] Example 3

[0074] This embodiment provides a flux-cored welding wire, which includes a steel strip and a flux core filled in the steel strip. The filling rate of the flux core in the flux-cored welding wire is 16%. The flux core includes the following components, measured by mass percentage: 7% low-carbon ferrochrome, 3% high-carbon ferrochrome, 8% metallic manganese, 6% ferromolybdenum, 4% rutile, 50% fluorite, 4% quartz, 1% potassium feldspar, 2% potassium fluorozirconate, 3% calcium silicate powder, 5% magnesium powder, 3% 45% ferrosilicon, and 4% atomized iron powder. The preparation method of the flux-cored welding wire includes the following steps:

[0075] S1. Weigh the raw materials according to the above raw material components, dry the raw materials and evenly mix them to obtain a core powder; wherein the raw materials are dried at a drying temperature of 205° C. for 90 minutes;

[0076] S2. Cut the carbon steel strip to a width of 14 mm, clean it, and roll it into a U-shaped groove; fill the U-shaped groove of the carbon steel strip with flux core powder, and then butt-weld the U-shaped groove opening of the carbon steel strip using high-frequency welding technology;

[0077] S3. After the carbon steel strip is rolled and reduced in diameter, it is drawn into a wire drawing machine to a diameter of 1.5 mm to obtain a flux-cored welding wire.

[0078] Example 4

[0079] This embodiment provides a flux-cored welding wire, which includes a steel strip and a flux core filled in the steel strip. The filling rate of the flux core in the flux-cored welding wire is 16%. The flux core includes the following components, measured by mass percentage: 9% low-carbon ferrochrome, 4% high-carbon ferrochrome, 10% metallic manganese, 6% ferromolybdenum, 5% rutile, 40% fluorite, 5% quartz, 1% potassium feldspar, 2% potassium fluorozirconate, 2% calcium silicate powder, 4% magnesium powder, 4% 45% ferrosilicon, and 8% atomized iron powder. The preparation method of the flux-cored welding wire includes the following steps:

[0080] S1. Weigh the raw materials according to the above raw material components, dry the raw materials and evenly mix them to obtain a core powder; wherein the raw materials are dried at a drying temperature of 200° C. for 100 minutes;

[0081] S2. Cut the carbon steel strip to a width of 14 mm, clean it, and roll it into a U-shaped groove; fill the U-shaped groove of the carbon steel strip with flux core powder, and then butt-weld the U-shaped groove opening of the carbon steel strip using high-frequency welding technology;

[0082] S3. After the carbon steel strip is rolled and reduced in diameter, it is drawn into a wire drawing machine to a diameter of 1.6 mm to obtain a flux-cored welding wire.

[0083] To further verify the efficacy of the present invention, welding processability tests were conducted on the flux-cored welding wires provided in Examples 1 to 4 above according to relevant standards and specifications. The flux-cored welding wires provided in Examples 1 to 4 were used to weld heat-resistant steel, respectively. The welding parameters of the welding tests are shown in Table 1, and the material parameters and mechanical properties of the measured weld deposited metal are shown in Tables 2 and 3, respectively.

[0084] Table 1: Welding parameters for welding tests in Examples 1 to 4

[0085] Example Welding current (A) Welding voltage (V) Shielding gas Example 1 160～220 24-28 carbon dioxide Example 2 180～240 26～30 carbon dioxide Example 3 200～260 28～32 carbon dioxide Example 4 220～280 29～34 carbon dioxide

[0086] Table 2: Material parameters of flux-cored wire deposited metal in Examples 1 to 4

[0087]

[0088] Table 3: Mechanical properties of metal deposits from flux-cored wire welding in Examples 1 to 4

[0089]

[0090] The test results of Examples 1 to 4 show that the welds of heat-resistant steel welded with the flux-cored wire provided by the present invention have a tensile strength greater than 600 MPa, a yield strength greater than 500 MPa, an elongation greater than 20%, and an impact energy greater than 80 J at 0°C after being subjected to a high-temperature environment. This indicates that the welds of heat-resistant steel welded with the flux-cored wire provided by the present invention have excellent high-temperature oxidation resistance and corrosion resistance, and can be used for Cr-Mo steel pipe fittings with higher requirements for crack resistance or impact toughness.

[0091] The flux-cored welding wire provided by the present invention improves slag fluidity, reduces slag spatter, and enhances arc stability during welding, thereby optimizing welding process performance. It also enhances the high-temperature oxidation resistance and corrosion resistance of the deposited metal, resulting in welds with excellent thermal crack resistance and low-temperature toughness. This makes welds made of heat-resistant steel more adaptable to harsh environments such as high temperature, high pressure, and steam corrosion. Therefore, the present invention effectively overcomes several practical problems of the prior art and has high practical significance and value.

[0092] 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 skilled in 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 one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A flux-cored welding wire, characterized in that: include: steel strips; a core filled in the steel strip; The core comprises the following raw materials in percentage by mass: Low carbon ferrochrome 7-10%, high carbon ferrochrome 3-5%, metallic manganese 7-10%, ferromolybdenum 5-7%, rutile 4-6%, fluorite 40-55%, quartz 3-5%, potassium feldspar 1-2%, potassium fluozirconate 1-2%, calcium silicate powder 2-3%, magnesium powder 3-5%, 45 ferrosilicon 3-4%, and the balance is atomized iron powder.

2. The flux-cored welding wire according to claim 1, characterized in that The chromium content of the low-carbon ferrochrome is greater than or equal to 70wt%, and the carbon content of the low-carbon ferrochrome is less than or equal to 0.06wt%; the chromium content of the high-carbon ferrochrome is greater than or equal to 70wt%, and the carbon content of the high-carbon ferrochrome is greater than or equal to 8.2wt%; the manganese content of the metallic manganese is greater than or equal to 99.8wt%; the titanium dioxide content of the rutile is greater than or equal to 95wt%; the calcium fluoride content of the fluorite is greater than or equal to 95wt%; the silicon content of the 45 ferrosilicon is 42-47wt%; and the iron content of the atomized iron powder is greater than or equal to 98wt%.

3. The flux-cored welding wire according to claim 1, wherein: The steel strip is a carbon steel strip; the carbon content of the carbon steel strip is 0.04-0.10wt%, the silicon content of the carbon steel strip is less than or equal to 0.80wt%, the phosphorus content of the carbon steel strip is less than or equal to 0.03wt%, and the manganese content of the carbon steel strip is less than or equal to 1.25wt%.

4. The flux-cored welding wire according to claim 1, wherein: The particle size of the drug core is 40 to 200 meshes.

5. The flux-cored welding wire according to claim 1, wherein: The diameter of the flux-cored welding wire is 1.2-1.6 mm.

6. The flux-cored welding wire according to claim 1, wherein: The flux core accounts for 14-16% of the flux cored welding wire by mass.

7. A method for preparing the flux-cored welding wire according to any one of claims 1 to 6, characterized in that: include: Mix the raw material components according to claim 1 to prepare the core powder; wrapping the core powder in a steel strip; The steel strip is drawn to a preset size to obtain a flux-cored welding wire.

8. The preparation method according to claim 7, characterized in that The preparation method further comprises: drying the raw materials before preparing the core powder; wherein the drying temperature of each raw material is 195-205° C., and the drying time of each raw material is 60-100 minutes.

9. The preparation method according to claim 7, characterized in that The step of wrapping the core powder in a steel strip comprises: rolling the steel strip into a U-shaped groove; The core powder is filled into the U-shaped groove, and then the openings of the U-shaped groove are butt-welded.

10. The preparation method according to claim 9, characterized in that In the butt welding of the openings of the U-shaped groove, high-frequency welding technology is used to butt weld the openings of the U-shaped groove.

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