Hardfacing flux-cored wire for repairing surface of single-tooth roller

Abstract

The invention relates to the technical field of welding materials, in particular to a hardfacing flux-cored wire for repairing the surface of a single-tooth roller. According to the specific technical scheme, the flux core is prepared from, by mass, 5%-15% of graphite, 20%-60% of high-carbon ferrochrome, 3%-10% of silicon carbide, 2%-15% of tungsten carbide, 1%-6% of electrolytic manganese, 5%-20% of ferromolybdenum and the balance Fe powder. According to the flux-cored wire, surfacing alloy obtained through electric arc surfacing is good in surfacing manufacturability, weld joint forming is attractive, the number of surface air holes is small, and the flux-cored wire further has high hardness and abrasion resistance.

Description

Technical Field

[0001] The invention relates to the technical field of welding materials, and in particular to a wear-resistant surfacing flux-cored welding wire for repairing the surface of a single tooth roller. Background Art

[0002] As an indispensable key equipment in the modern steel industry, the single-tooth roller crusher plays a vital role in the crushing and processing of materials such as sintered ore and blast furnace slag. During long-term operation, this equipment continues to withstand severe wear from high-temperature sintered materials. Its main failure mechanisms can be summarized as follows: (1) The high-temperature sintered materials continue to contact and rub against the hobbing surface, resulting in the gradual loss of tooth surface material, which ultimately destroys the integrity of the roller tooth structure; (2) Under the working environment, the oxide scale on the roller surface periodically peels off, causing a significant increase in surface roughness, which in turn forms a vicious cycle and accelerates the wear process; (3) Under the action of long-term alternating loads, the continuous friction and wear between the tooth roller and the material causes stress concentration, which ultimately leads to the fracture of the tooth roller structure. These failure modes not only affect the service life of the equipment, but are also directly related to the continuity and economy of steel production.

[0003] In response to the serious wear problem of single-tooth roller crusher under harsh working conditions, surfacing repair technology has become the industry's preferred solution due to its process reliability and cost-effectiveness. In engineering practice, the main surfacing repair materials are nickel-based, cobalt-based and iron-based surfacing alloys. Cobalt-based surfacing alloys are known for their excellent wear resistance and are especially suitable for high-stress wear environments. However, their high material cost limits large-scale applications, and the welding process requirements are harsh, which significantly increases the process complexity. Nickel-based surfacing alloys are most outstanding in terms of resistance to metal-to-metal friction and wear. They also have excellent high-temperature resistance (working temperature can reach above 800°C) and oxidation resistance, and are particularly suitable for high-temperature wear conditions. However, their high procurement cost makes them mainly used for the repair of key components, and their economic efficiency is poor. In contrast, iron-based surfacing alloys have become the most widely used surfacing materials in industry due to their excellent wear resistance and good cost-effectiveness. Among them, Fe-Cr-C alloys are favored due to their unique microstructure design. M7C3 and M7C3 can be formed in the Fe-Cr-C alloy surfacing layer. 23 High-hardness carbide hard phases such as C6 and M3C form a three-dimensional wear-resistant skeleton structure, which can not only effectively hinder the cutting action of abrasive particles, but also achieve excellent impact wear resistance, greatly reducing repair costs while ensuring wear resistance.

[0004] While traditional Fe-Cr-C cladding alloys exhibit good wear resistance under general operating conditions, their wear and impact resistance remain insufficient under the high-stress, high-impact wear conditions experienced by single-tooth roller crushers, making them difficult to meet practical repair requirements. To address this technical bottleneck, the present invention optimizes and modifies traditional Fe-Cr-C alloys through a multi-element alloying design. By introducing strong carbide-forming elements such as Mo and W, the alloy's wear and impact resistance are significantly improved. Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the present invention provides a wear-resistant surfacing flux-cored welding wire for single-tooth roller surface repair. The surfacing alloy obtained by arc surfacing through the flux-cored welding wire provided by the present invention not only has good surfacing processability, beautiful weld formation, and a small number of surface pores, but also has high hardness and wear resistance.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0007] The present invention discloses a drug core, which comprises the following components in percentage by mass:

[0008] Graphite 5-15%, high carbon ferrochrome 20-60%, silicon carbide 3-10%, tungsten carbide 2-15%, electrolytic manganese 1-6%, ferromolybdenum 5-20%, and the balance is Fe powder.

[0009] Preferably, the mass fraction of chromium in the high-carbon ferrochrome is 68%, and the mass fraction of carbon is 8%; the mass fraction of silicon in the silicon carbide is 70%, and the mass fraction of carbon is 30%; the mass fraction of tungsten in the tungsten carbide powder is 94%, and the mass fraction of carbon is 6%; the mass fraction of molybdenum in the ferromolybdenum is 60%; the mass fraction of manganese in the electrolytic manganese is greater than 90%; and the mass fraction of carbon in the graphite is greater than 99.5%.

[0010] Preferably, in terms of mass percentage, the components include 5-15% graphite, 30-50% high carbon ferrochrome, 3-6% silicon carbide, 5-10% tungsten carbide, 2-5% electrolytic manganese, 8-15% ferromolybdenum, and the rest is Fe powder.

[0011] Preferably, the particle size of the high carbon ferrochrome is 30-50 mesh, the particle sizes of the ferromolybdenum and tungsten carbide are both 80-100 mesh, the particle size of the electrolytic manganese is 60-80 mesh, the particle size of the silicon carbide is 70-90 mesh, the particle size of the graphite is 40-60 mesh; and the particle size of the Fe powder is 100-150 mesh.

[0012] Correspondingly, a wear-resistant surfacing flux-cored welding wire for single-tooth roller surface repair is provided, wherein the raw material of the flux-cored welding wire includes the flux core.

[0013] Preferably, the filling rate of the flux core in the flux-cored welding wire is 40-60%.

[0014] Accordingly, a method for preparing a wear-resistant surfacing flux-cored wire for repairing the surface of a single tooth roller comprises wrapping the flux core with a metal shell.

[0015] Accordingly, a welding method for reducing welding pores in a surfacing layer of a single-tooth roller surface repair is provided, wherein the wear-resistant surfacing flux-cored wire for single-tooth roller surface repair is used for welding, and the welding process is a plasma arc surfacing process.

[0016] Preferably, the plasma arc surfacing process parameters are: voltage: 25-30V, current: 300-500A, wire feeding speed: 8-9m / min, atmosphere: 80% Ar+20% CO2 mixed gas, gas flow: 15-20L / min, wire elongation: 15-20mm.

[0017] Preferably, after welding is completed, the mass percentage of alloying elements in the obtained surfacing alloy is within the following ranges: C: 2-8%; Cr: 10-40%; Mo: 2-7%; Mn: 0.5-3%; Si: 0.5-2%; W: 1-6%; Fe and unavoidable impurities: balance.

[0018] The present invention has the following beneficial effects:

[0019] The wear-resistant surfacing flux-cored welding wire for single-tooth roller surface repair provided by the present invention meets the use performance of new wear-resistant and impact-resistant materials.

[0020] The present invention provides a wear-resistant surfacing flux-cored welding wire for surface repair of a single tooth roller, which can form a composite microstructure with excellent wear resistance on the surface of the substrate through an arc surfacing process. Metallographic analysis shows that the surfacing layer is mainly composed of a martensite matrix, residual austenite and a carbide-reinforced phase (M7C3 and MC type). This multi-phase synergistic microstructure gives the material good mechanical properties. Traditional Fe-Cr-C based surfacing alloys show obvious performance deficiencies under high stress and high impact wear conditions of long-term service of single tooth rollers, which are mainly reflected in the rapid attenuation of wear resistance and unsatisfactory repair effects. To this end, the present invention innovatively introduces strong carbide-forming elements such as Mo and W on the basis of the Fe-Cr-C alloy system for alloying modification. Among them, the addition of Mo element can promote the nucleation and precipitation of carbides in the alloy, which not only increases the amount of hard phases, but also effectively refines the grain size and improves the uniformity of the structure. The W element significantly improves the wear resistance of the material by solid solution strengthening and the formation of special carbides. This carbide-reinforced iron-based alloy represents the development direction of a new generation of wear-resistant materials. Its microstructural characteristics are characterized by a uniform distribution of fine carbide-reinforced phases within a martensitic matrix. This unique microstructure offers dual advantages: on the one hand, the dispersed hard carbide phase effectively hinders the cutting action of abrasive particles, providing excellent wear resistance; on the other hand, the synergistic effect of the martensitic matrix and carbides enables the material to maintain high hardness while also possessing good impact resistance, meeting the repair requirements of single-tooth roller crushers. Furthermore, the presence of retained austenite helps alleviate stress concentration. The service life of single-tooth rollers repaired with this welding wire is significantly improved compared to traditional Fe-Cr-C alloy cladding coatings, meeting the steel industry's requirements for long-life and high-reliability critical equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The flow chart for the preparation of wear-resistant surfacing flux-cored wire for single-tooth roller surface repair;

[0022] Figure 2 The surfacing surface morphology of the surfacing alloy prepared in Example 5;

[0023] Figure 3 This is the wear depth diagram of the surfacing alloy prepared in Example 5. DETAILED DESCRIPTION

[0024] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0025] Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art.

[0026] The present invention discloses a drug core, which comprises the following components in percentage by mass:

[0027] Graphite 5-15%, high-carbon ferrochrome 20-60%, silicon carbide 3-10%, tungsten carbide 2-15%, electrolytic manganese 1-6%, ferromolybdenum 5-20%, and the balance is iron powder. As a preferred solution, graphite 5-15%, high-carbon ferrochrome 30-50%, silicon carbide 3-6%, tungsten carbide 5-10%, electrolytic manganese 2-5%, ferromolybdenum 8-15%, and the balance is iron powder. The high-carbon ferrochrome has a particle size of 30-50 mesh, the ferromolybdenum and tungsten carbide have particle sizes of 80-100 mesh, the electrolytic manganese has a particle size of 60-80 mesh, the silicon carbide has a particle size of 70-90 mesh, the graphite has a particle size of 40-60 mesh, and the iron powder has a particle size of 100-150 mesh.

[0028] Furthermore, the mass fraction of chromium in the high-carbon ferrochrome is 68%, and the mass fraction of carbon is 8%; the mass fraction of silicon in the silicon carbide is 70%, and the mass fraction of carbon is 30%; the mass fraction of tungsten in the tungsten carbide powder is 94%, and the mass fraction of carbon is 6%; the mass fraction of molybdenum in the ferromolybdenum is 60%; the mass fraction of manganese in the electrolytic manganese is greater than 90%; and the mass fraction of carbon in the graphite is greater than 99.5%.

[0029] The present invention discloses a wear-resistant flux-cored welding wire for surface repair of single-tooth rollers. The raw material of the flux-cored welding wire includes the aforementioned flux core. The flux core fill rate of the flux-cored welding wire is 40-60%, which is the percentage of the area occupied by the flux core to the total cross-sectional area of ​​the welding wire. As a preferred embodiment, the flux core fill rate is 40-55%, and in a further preferred embodiment, the flux core fill rate is 45-50%.

[0030] The preparation process of a wear-resistant surfacing flux-cored welding wire for single-tooth roller surface repair includes the following steps:

[0031] (1) Powder selection and drying: Select alloy powder according to the core composition and dry each powder in advance. The drying equipment is a vacuum drying oven, the drying temperature is 150℃, and the drying time is 2 hours.

[0032] (2) Powder screening: In order to ensure the consistency of the particle size of the same powder, each powder needs to be screened through a sieve.

[0033] (3) Powder preparation and mixing: Powder preparation is carried out based on the filling rate of each flux-cored wire and the mass percentage of each powder. After powder preparation, the different powders need to be evenly mixed to ensure uniformity of the components in the flux-cored wire.

[0034] (4) Belt selection: Select stainless steel belt as the metal shell. The thickness of the steel belt is 0.3mm and the width is 12mm.

[0035] (5) Drawing: The steel strip passes through the forming rollers and changes from a flat surface to a U-shape. At this time, the prepared core powder is fed into the U-shaped steel strip through a conveyor belt. After the U-shaped steel strip carrying the powder passes through the closing rollers continuously, the steel strip changes from a U-shape to an O-shape, and the steel strip closes, tightly wrapping the core powder. Figure 1 shown.

[0036] (6) Reduction and packaging: The drawn flux-cored wire is passed through a drawing die of a certain diameter to achieve the required diameter of the finished product. The reduced flux-cored wire is loaded into an I-shaped wheel and sealed for storage before use.

[0037] The present invention also provides a welding method for reducing welding pores in a single-tooth roller surface repair surfacing layer, using the wear-resistant surfacing flux-cored wire for single-tooth roller surface repair for welding, and the welding process is a plasma arc surfacing process.

[0038] The plasma arc cladding process parameters are: voltage: 25-30V, current: 300-500A, wire feed speed: 8-9m / min, atmosphere: 80% Ar + 20% CO2 mixture, gas flow rate: 15-20L / min, and wire extension: 15-20mm. After welding, the resulting cladding alloy has the following alloying element weight percentages: C: 2-8%; Cr: 10-40%; Mo: 2-7%; Mn: 0.5-3%; Si: 0.5-2%; W: 1-6%; and Fe and unavoidable impurities: the remainder.

[0039] In the present invention, the various elements function as follows:

[0040] C: Carbon and chromium are alloying elements that significantly influence the microstructure of high-chromium cast iron. As the mass fraction of carbon and chromium increases, the microstructure of high-chromium cast iron shifts from hypoeutectic to hypereutectic, and the primary phase transforms from austenite to M7C3 carbide. The high hardness of the M7C3 carbide hard phase significantly improves the wear resistance of the weld overlay.

[0041] Cr: Chromium plays a decisive role in the type of carbides, mainly forming M3C, M7C3, M 23 C6 carbide. Among them, M7C3 carbide has extremely high hardness and is evenly distributed in the matrix as hard particles, significantly improving the hardness and wear resistance of the material. At the same time, the Cr element can increase the strength of steel and improve the hardenability of the alloy.

[0042] Mo: Mo can improve the hardenability of alloy steel, inhibit the transformation of pearlite and ferrite, and allow more austenite to transform into martensite during quenching; at the same time, it improves the strength and tempering resistance of martensite through solid solution strengthening and carbide formation.

[0043] W: The W element significantly improves the tempering stability, red hardness (for example, high-speed steel maintains high hardness at 600°C) and high-temperature strength of steel by forming stable carbides (such as W2C) and solid solution strengthening; its carbides can also improve wear resistance, making it particularly suitable for high-temperature and high-wear environments such as cutting tools.

[0044] Mn, Si: Use manganese and silicon to jointly deoxidize and increase the element transition coefficient.

[0045] Fe: Fill the margin.

[0046] In order to better understand the present invention, the present invention will be further described below with reference to specific embodiments.

[0047] In the following examples, all the raw materials used can be obtained from commercial sources.

[0048] 1. In the following embodiments, the outer sheath of the flux-cored welding wire is made of a stainless steel strip with a thickness of 0.3 mm and a width of 12 mm. The core components of the flux-cored welding wire are specifically described in the embodiments. The steel strip is rolled into a U-shape after passing through rollers. The various powders in the formula are weighed, dried, and mixed in advance according to the designed proportions, and then mechanically added to the steel strip. The U-shaped steel strip is closed after passing through subsequent rollers. The closed steel strip is repeatedly drawn and reduced in diameter using a drawing die to produce a flux-cored welding wire with a diameter of 2.8 mm, thereby obtaining a wear-resistant surfacing flux-cored welding wire for single-tooth roller surface repair.

[0049] 2. In the core powder, the particle size of the high carbon ferrochrome is 30-50 mesh; the particle sizes of the ferromolybdenum and tungsten carbide are both 80-100 mesh; the particle size of manganese is 60-80 mesh; the particle size of silicon carbide is 70-90 mesh; the particle size of graphite is 40-60 mesh; and the particle size of Fe powder is 100-150 mesh.

[0050] The mass fraction of chromium in the high-carbon ferrochrome is 68%, and the mass fraction of carbon is 8%; the mass fraction of silicon in the silicon carbide is 70%, and the mass fraction of carbon is 30%; the mass fraction of tungsten in the tungsten carbide powder is 94%, and the mass fraction of carbon is 6%; the mass fraction of molybdenum in the ferromolybdenum is 60%; the mass fraction of manganese in the manganese raw material is greater than 90%; and the mass fraction of carbon in the graphite is greater than 99.5%.

[0051] 3. Arc surfacing was used to prepare the surfacing alloy. The welding parameters were: voltage: 25-30 V, current: 300-500 A, wire feed speed: 8-9 m / min, atmosphere: 80% Ar + 20% CO₂ mixture, gas flow rate: 15-20 L / min, and wire elongation: 15-20 mm. The surfacing alloy prepared in this example was subjected to hardness testing, abrasive wear testing, friction wear testing, and impact testing. The specific test steps are as follows:

[0052] (1) The Rockwell hardness of the cladding alloy was tested using an HR-150A electric Brinell hardness tester. The indenter was a diamond cone indenter with a load of 150 kg, a loading time of 5 s, and a recovery time of 3 s. The distance between two adjacent test points was 5 mm, and the number of test points was 10. The final hardness of the cladding alloy was the average of the data from the 10 test points.

[0053] (2) Abrasive wear tests were conducted using an MLS-225 wet sand rubber wheel abrasive wear tester. The wear specimen size was 57 mm × 25 mm × 10 mm. The main test parameters included: rubber wheel diameter of 176 mm, rubber wheel speed of 240 rpm, rubber wheel hardness of 60 Shore hardness, quartz sand of 40-70 mesh selected as abrasive, loading load of 100 N, 1000 g of water and 1500 g of quartz sand added during the test. Before each test, a pre-grinding at 2000 rpm was performed to prevent the surface roughness of the specimen from affecting the wear results. After pre-grinding, the specimen was weighed as the weight before wear; the specimen was immersed in an ethanol solution at 8000 rpm, ultrasonically cleaned, and then dried with a hair dryer. The specimen was weighed using a Beijing Sartorius precision balance with an accuracy of 0.0001 g. Three tests were conducted on each specimen, and the average value of the specimen loss weight was taken as the reference standard for wear resistance.

[0054] (3) Friction and wear tests were conducted using an MS-HT1000 friction and wear testing machine. The wear specimen size was 20 mm × 20 mm × 7 mm, and the test parameters were: φ4 silicon carbide, load 2000 g, friction radius 6 mm, rotation speed 300 r / min, test temperature room temperature, and time 60 min. To reduce experimental error, three tests were conducted on each specimen. After the test, an OLMPUS-4100 laser confocal scanning microscope was used to obtain the three-dimensional morphology of the specimen wear scar and calculate the wear volume of the specimen. The wear scar morphology was observed using a field emission scanning electron microscope.

[0055] (4) A self-designed drop hammer impact tester was used to test the impact resistance of the surfacing alloy. The impact specimen was 57mm×25mm×15mm in size. The specimen was placed in the groove below the punch and then clamped with a fixture before impact. The punch tip had a certain angle. The impact energy could be adjusted by adjusting the height of the punch through the screw. The hammer of the impact tester was 10kg, with a maximum impact load of 80J and an impact angle of 171°. In order to simulate the impact force of a single tooth roller under actual working conditions, the impact energy was set to 10J in this test. The toughness of the surfacing alloy was comprehensively measured by the actual impact angle θ. The impact angle was measured using the image processing software Image-pro.

[0056] Example 1

[0057] The flux core is weighed according to the following percentages: graphite 8%, high carbon ferrochrome 30%, silicon carbide 3.5%, tungsten carbide 5%, electrolytic manganese 2.5%, ferromolybdenum 8%, and the rest is Fe powder.

[0058] According to the surfacing process disclosed above, a surfacing alloy is prepared. The mass percentage of alloying elements in the obtained surfacing alloy is C: 5.5%; Cr: 18.5%; Mo: 2.1%; Mn: 1.1%; W: 1%; Si: 0.8%; Fe and unavoidable impurities: balance.

[0059] The Rockwell hardness of the surfacing alloy is 60.1HRC; in the abrasive wear test, the wear loss weight is 0.6162g; in the friction wear test, the wear depth is 12.6μm; and the impact angle is 55.3°.

[0060] Example 2

[0061] The flux core is weighed according to the following percentages: graphite 8%, high carbon ferrochrome 35%, silicon carbide 3.5%, tungsten carbide 4.5%, electrolytic manganese 2.5%, ferromolybdenum 10%, and the rest is Fe powder.

[0062] According to the surfacing process disclosed above, a surfacing alloy is prepared. The mass percentage of alloying elements in the obtained surfacing alloy is C: 5.5%; Cr: 20.0%; Mo: 2.8%; Mn: 1.1%; W: 2%; Si: 0.8%; Fe and unavoidable impurities: balance.

[0063] The Rockwell hardness of the surfacing alloy is 63.7HRC; in the abrasive wear test, the wear loss weight is 0.4927g; in the friction wear test, the wear depth is 9.7μm; and the impact angle is 50.5°.

[0064] Example 3

[0065] The flux core is weighed according to the following percentages: graphite 8%, high carbon ferrochrome 35%, silicon carbide 3.5%, tungsten carbide 7.0%, electrolytic manganese 2.5%, ferromolybdenum 12%, and the rest is Fe powder.

[0066] According to the surfacing process disclosed above, a surfacing alloy is prepared. The mass percentage of alloying elements in the obtained surfacing alloy is C: 5.5%; Cr: 20.0%; Mo: 3.0%; Mn: 1.1%; W: 3.0%; Si: 0.8%; Fe and unavoidable impurities: balance.

[0067] The Rockwell hardness of the surfacing alloy is 65.5HRC; in the abrasive wear test, the wear loss weight is 0.4177g; in the friction wear test, the wear depth is 8.8μm; and the impact angle is 42.9°.

[0068] Example 4

[0069] The flux core is weighed according to the following percentages: graphite 6%, high carbon ferrochrome 45%, silicon carbide 4.5%, tungsten carbide 9%, electrolytic manganese 2.5%, ferromolybdenum 12%, and the rest is Fe powder.

[0070] According to the surfacing process disclosed above, a surfacing alloy is prepared. The mass percentage of alloying elements in the obtained surfacing alloy is C: 5.0%; Cr: 23.0%; Mo: 3.2%; Mn: 1.1%; W: 3.5%; Si: 1.5%; Fe and unavoidable impurities: balance.

[0071] The surfacing process has little spatter, good flatness, and no tiny cracks; the Rockwell hardness of the surfacing alloy is 68.1HRC; in the abrasive wear test, the wear loss weight is 0.3404g; the friction depth is 7.2μm; and the impact angle is 37.1°.

[0072] Example 5

[0073] The flux core is weighed according to the following percentages: graphite 8%, high carbon ferrochrome 45%, silicon carbide 4.5%, tungsten carbide 9%, electrolytic manganese 2.5%, ferromolybdenum 15%, and the rest is Fe powder.

[0074] According to the surfacing process disclosed above, a surfacing alloy is prepared. The mass percentage of alloying elements in the obtained surfacing alloy is C: 5.5%; Cr: 23.0%; Mo: 3.5%; Mn: 1.1%; W: 4%; Si: 1.5%; Fe and unavoidable impurities: balance.

[0075] The surfacing process has less spatter, bright surfacing alloy surface, high flatness, no cracks, and few surface pores. Figure 2As shown in the figure, the Rockwell hardness of the surfacing alloy is 69.3HRC; in the abrasive wear test, the wear loss weight is 0.2520g; in the friction wear test, the wear depth is 6.8μm (as shown in the figure, Figure 3 ); the impact angle is 32.5°.

[0076] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A drug core, characterized in that: Calculated by mass percentage, it includes the following components: Graphite 5-15%, high carbon ferrochrome 20-60%, silicon carbide 3-10%, tungsten carbide 2-15%, electrolytic manganese 1-6%, ferromolybdenum 5-20%, and the balance is Fe powder.

2. The drug core according to claim 1, characterized in that: The mass fraction of chromium in the high-carbon ferrochrome is 68%, and the mass fraction of carbon is 8%; the mass fraction of silicon in the silicon carbide is 70%, and the mass fraction of carbon is 30%; the mass fraction of tungsten in the tungsten carbide powder is 94%, and the mass fraction of carbon is 6%; the mass fraction of molybdenum in the ferromolybdenum is 60%; the mass fraction of manganese in the electrolytic manganese is greater than 90%; and the mass fraction of carbon in the graphite is greater than 99.5%.

3. The drug core according to claim 1, characterized in that: Calculated by mass percentage, the ingredients include 5-15% graphite, 30-50% high carbon ferrochrome, 3-6% silicon carbide, 5-10% tungsten carbide, 2-5% electrolytic manganese, 8-15% ferromolybdenum, and the rest is Fe powder.

4. The drug core according to claim 1, characterized in that: The particle size of the high carbon ferrochrome is 30-50 mesh, the particle sizes of the ferromolybdenum and tungsten carbide are both 80-100 mesh, the particle size of the electrolytic manganese is 60-80 mesh, the particle size of the silicon carbide is 70-90 mesh, the particle size of the graphite is 40-60 mesh; and the particle size of the Fe powder is 100-150 mesh.

5. A wear-resistant surfacing flux-cored welding wire for single-tooth roller surface repair, characterized by: The raw material of the flux-cored welding wire includes the flux core according to any one of claims 1 to 4.

6. The wear-resistant surfacing flux-cored welding wire for single-tooth roller surface repair according to claim 5, characterized in that: The filling rate of the flux core in the flux cored welding wire is 40-60%.

7. A method for preparing the wear-resistant surfacing flux-cored welding wire for single-tooth roller surface repair according to claim 5 or 6, characterized in that: The drug core is wrapped with a metal shell.

8. A welding method for reducing welding porosity in a surface repair surfacing layer of a single tooth roller, characterized in that: The wear-resistant surfacing flux-cored wire for surface repair of a single tooth roller prepared by the preparation method according to claim 7 is used for welding, and the welding process is a plasma arc surfacing process.

9. The welding method for reducing welding porosity in a surface repair cladding layer of a single toothed roller according to claim 8, characterized in that: The plasma arc surfacing process parameters are: voltage: 25-30V, current: 300-500A, wire feeding speed: 8-9m / min, atmosphere: 80% Ar+20% CO2 mixed gas, gas flow: 15-20L / min, and wire elongation: 15-20mm.

10. A welding method for reducing welding porosity in a surface repair surfacing layer of a single toothed roller according to claim 9, characterized in that: After welding is completed, the mass percentage of alloying elements in the obtained surfacing alloy is within the following ranges: C: 2-8%; Cr: 10-40%; Mo: 2-7%; Mn: 0.5-3%; Si: 0.5-2%; W: 1-6%; Fe and unavoidable impurities: balance.

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