Hard alloy welding powder for hardfacing of valve sealing surface and preparation method therefor

Abstract

Disclosed in the present application are a hard alloy welding powder for hardfacing of valve sealing surfaces and a preparation method therefor. The welding powder comprises the following components in percentage by mass: 1.20-1.40% of C element, 2.70-3.5% of Si element, 3.00-4.50% of Mn element, 24.00-26.00% of Cr element, 2.00-2.20% of Mo element, 3.50-4.50% of Ni element, less than or equal to 0.20% of Co element, less than or equal to 0.02% of B element, less than or equal to 0.10% of N element, and the balance of Fe element. The preparation method comprises: weighing raw materials, mixing the raw materials, and smelting same to obtain molten alloy; and atomizing the molten alloy by means of gas to produce powder, and screening same to obtain hard alloy welding powder. The present application strictly limits the content of Co element, and properties such as hardness can meet design requirements; the preparation method has a simple and reliable process.

Description

Hard alloy welding powder for surface cladding of valve sealing surfaces and its preparation method Technical Field

[0001] This application belongs to the field of welding technology, and relates to a welding powder and its preparation method, particularly to a hard alloy welding powder for surface overlay welding of valve sealing surfaces and its preparation method. Background Technology

[0002] Currently, specialized welding materials are used for the sealing surfaces of nuclear power plant valves, with cobalt-based Stellite alloy being the most mature and widely used. Among these, ERCoCr-A (US standard system, AWS A5.21) is the most prevalent. Specific parameters are shown in the table below:

[0003] Table 1. Mass fraction of ERCoCr-A elements

[0004]

[0005] Cobalt-based Stellite alloy valve sealing surfaces experience wear and corrosion during use, resulting in small amounts of cobalt-based alloy debris entering the primary circuit medium. This cobalt (59Co, a stable isotope) is irradiated by neutrons as it flows through the reactor core, transforming into the highly radioactive isotope 60Co, which becomes the primary source of radiation. The cobalt content of the welded sealing surfaces of nuclear island valves accounts for approximately 60-70% of the total cobalt content in the primary circuit equipment. Therefore, the cobalt-based alloy material of the nuclear island valve sealing surfaces is the most significant factor affecting the occupational radiation dose levels of nuclear power plant operation and maintenance personnel. Summary of the Invention

[0006] The technical problem to be solved by this application is to provide a cemented carbide welding powder that strictly limits the Co element content while meeting the design requirements in light of the above-mentioned defects of the prior art.

[0007] The further technical problem to be solved by this application is to provide a simple and reliable preparation method.

[0008] The technical solution adopted by this application to solve its technical problem is:

[0009] A hard alloy welding powder for surface surfacing of valve sealing surfaces is constructed, comprising the following components by mass percentage: C 1.20~1.40%, Si 2.70~3.5%, Mn 3.00~4.50%, Cr 24.00~26.00%, Mo 2.00~2.20%, Ni 3.50~4.50%, Co ≤0.20%, B ≤0.02%, N ≤0.10%, with the balance being Fe.

[0010] Furthermore, the hard alloy welding powder used for surface overlay welding of valve sealing surfaces preferably includes the following components by mass percentage: 1.30~1.35% C, 2.70~3.10% Si, 3.10~3.50% Mn, 24.00~25.00% Cr, 2.05~2.15% Mo, 3.80~4.40% Ni, ≤0.20% Co, ≤0.015% B, ≤0.06% N, with the balance being Fe.

[0011] Furthermore, the hard alloy welding powder used for surface overlay welding of valve sealing surfaces preferably includes the following components by mass percentage: 1.32% C, 2.75% Si, 3.19% Mn, 24.37% Cr, 2.06% Mo, 3.87% Ni, ≤0.20% Co, ≤0.011% B, ≤0.06% N, with the balance being Fe.

[0012] A method for preparing hard alloy welding powder for surface overlay welding of valve sealing surfaces includes the following steps:

[0013] S1. Weighing materials: using single crystal silicon, electrolytic manganese, pure metallic chromium, pure metallic nickel, pure metallic molybdenum and pure metallic iron as raw materials;

[0014] S2, Smelting: The raw materials obtained in step S1 are mixed and smelted to obtain an alloy liquid with qualified chemical composition, which then proceeds to step S3.

[0015] S3. Atomization: The alloy liquid obtained in step S2, which meets the requirements of each element composition of the welding powder, is atomized to obtain mixed powders of different fineness.

[0016] S4. Sieving: The mixed powder obtained in step S3 is sieved to obtain solder powder of a specified mesh size.

[0017] Furthermore, in the method for preparing the cemented carbide welding powder, preferably in step S1, the amount of the raw materials is calculated according to the following mass percentages of elements: Si 2.70~3.5%, Mn 3.00~4.50%, Cr 24.00~26.00%, Mo 2.00~2.20%, Ni 3.50~4.50%, with the balance being Fe.

[0018] Further, in the method for preparing the cemented carbide welding powder, preferably in step S1, the amount of the raw materials is calculated according to the following mass percentages of elements: Si 2.70~3.10%, Mn 3.10~3.50%, Cr 24.00~25.00%, Mo 2.05~2.15%, Ni 3.80~4.40%, Co ≤0.20%, B ≤0.015%, N ≤0.06%, and the balance is Fe.

[0019] Furthermore, in the method for preparing the cemented carbide welding powder, preferably in step S1, the amount of the raw materials is calculated according to the following mass percentages of elements: Si 2.75%, Mn 3.19%, Cr 24.37%, Mo 2.06%, Ni 3.87%, Co ≤0.20%, B ≤0.011%, N ≤0.06%, and the balance is Fe.

[0020] Furthermore, in the method for preparing the cemented carbide welding powder, preferably in step S2, the melting is carried out using a medium-frequency furnace or an AOD refining furnace, and the melting temperature is controlled at 1400~1500℃ for 30-40 minutes.

[0021] Furthermore, in the method for preparing the cemented carbide welding powder, preferably in step S2, after melting to obtain an alloy liquid, the chemical composition of the alloy liquid is tested. If it meets the requirements of each element of the welding powder, the chemical composition is qualified, and then proceed to step S3. If not, the same proportion of raw materials is added, and the melting is carried out again. The chemical composition of the alloy liquid is tested again. If not, the same proportion of raw materials is added and the melting is repeated until the chemical composition is qualified.

[0022] Furthermore, in the method for preparing the cemented carbide welding powder, preferably in step S2, the qualified chemical composition means that it meets the requirements of each element composition of the welding powder.

[0023] Furthermore, in the method for preparing the cemented carbide welding powder, preferably in step S3, the gas atomization is performed by using an ultra-low temperature gas atomization medium to flush the molten liquid and directly form powder.

[0024] Furthermore, in the method for preparing the cemented carbide welding powder, preferably in step S3, the cryogenic gas atomizing medium is cryogenic nitrogen, helium, or argon.

[0025] Furthermore, in the method for preparing the cemented carbide welding powder, preferably in step S3, the ultra-low temperature gas atomizing medium is obtained by vaporizing a liquid medium.

[0026] Furthermore, in the method for preparing the cemented carbide welding powder, preferably in step S4, the specified mesh size is 100~270 mesh.

[0027] Implementing this application has the following beneficial effects:

[0028] This application's cemented carbide welding powder is specifically designed for surface cladding of valve sealing surfaces. It strictly limits the Co content, with a Co content ≤0.20%, far lower than the 60-70% content in existing technologies. When debris and corrosive substances generated from wear and corrosion of the alloy valve sealing surface enter the primary circuit medium during use, the very low Co content will not form an irradiation source, thus avoiding any impact on the occupational radiation dose levels of nuclear power plant operation and maintenance personnel. It also complies with the new technical specifications for valves, which explicitly state that "for valves using reactor coolant as the medium, cobalt-free alloys are recommended for the cemented carbide surface material of the valve seat and valve disc; in non-radioactive systems, cobalt-based alloys can be used for the cemented carbide surface of the valve seat and valve disc." Furthermore, besides the strict control of cobalt content, other technical indicators of this welding powder, such as hardness and welding quality, meet welding requirements.

[0029] The preparation method of this application uses various metal raw materials. After the raw materials are uniformly mixed, they are melted into an alloy liquid, then atomized into a mixed powder, and sieved to obtain welding powder of a specified mesh size. The entire preparation process is simple, reliable and easy to operate. Attached Figure Description

[0030] To more clearly illustrate the technical solution of this application, the following description will be provided in conjunction with the accompanying drawings and embodiments. It should be understood that the following drawings only show some embodiments of this application and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort. In the drawings:

[0031] Figure 1 is a weld overlay pattern of a weld overlay test according to an embodiment of this application;

[0032] Figure 2 is a schematic diagram of the test location for the welding test in an embodiment of this application;

[0033] Figure 3 is a macroscopic metallographic image of the weld seam in Embodiment 1 of this application;

[0034] Figure 4 is a macroscopic metallographic image of the weld seam in Embodiment 2 of this application;

[0035] Figure 5 is a macroscopic metallographic image of the weld in Embodiment 3 of this application. Detailed Implementation

[0036] To provide a clearer understanding of the technical features, objectives, and effects of this application, the specific embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0037] In the following description, specific details are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details.

[0038] This application describes a cemented carbide welding powder specifically designed for surface cladding of valve sealing surfaces. It must not only meet the technical requirements of conventional welding powders but also comply with the specific requirements related to nuclear power. Therefore, addressing the issues with existing cobalt-based Stellite welding materials, the Co content is strictly limited to ≤0.20%. The specific welding powder technical solution is as follows:

[0039] A hard alloy welding powder for surface surfacing of valve sealing surfaces comprises the following components by weight percentage: 1.20~1.40% C, 2.70~3.5% Si, 3.00~4.50% Mn, 24.00~26.00% Cr, 2.00~2.20% Mo, 3.50~4.50% Ni, ≤0.20% Co, ≤0.02% B, ≤0.10% N, with the balance being Fe.

[0040] In the above-mentioned welding powder composition, the Co content is ≤0.20%, which is far lower than the 60-70% content in existing technologies. During valve use, if wear and corrosion occur, the resulting debris and corrosion products entering the primary circuit medium will not form an irradiation source due to the very low Co content, thus avoiding any impact on the occupational radiation dose levels of nuclear power plant operation and maintenance personnel. Furthermore, in addition to strictly controlling the cobalt content, the welding powder of this application complies with Table 2 of standard RCC-MS8000 (2007 edition) for other technical indicators.

[0041] Specifically, this application preferably includes the following components by mass percentage: 1.30-1.35% C, 2.70-3.10% Si, 3.10-3.50% Mn, 24.00-25.00% Cr, 2.05-2.15% Mo, 3.80-4.40% Ni, ≤0.20% Co, ≤0.015% B, ≤0.06% N, with the balance being Fe.

[0042] The optimal composition includes the following components by mass percentage: 1.32% C, 2.75% Si, 3.19% Mn, 24.37% Cr, 2.06% Mo, 3.87% Ni, ≤0.20% Co, ≤0.011% B, ≤0.06% N, with the balance being Fe.

[0043] A method for preparing hard alloy welding powder for surface overlay welding of valve sealing surfaces includes the following steps:

[0044] S1. Weighing: The raw materials are single-crystal silicon, electrolytic manganese, pure chromium, pure nickel, pure molybdenum, and pure iron. The amounts of the raw materials are calculated as the following mass percentages of elements: Si 2.70~3.5%, Mn 3.00~4.50%, Cr 24.00~26.00%, Mo 2.00~2.20%, Ni 3.50~4.50%, with the balance being Fe. Among the above elemental composition, Fe, Si, Mn, Cr, Mo, and Ni are the main components, and the remainder are impurities derived from the main components of the raw materials.

[0045] Preferably, the amount of the raw materials is calculated as the following mass percentage of elements: 2.70~3.10% Si, 3.10~3.50% Mn, 24.00~25.00% Cr, 2.05~2.15% Mo, 3.80~4.40% Ni, with the balance being Fe.

[0046] The optimal amount of the raw materials is calculated as the following element mass percentages: 2.75% Si, 3.19% Mn, 24.37% Cr, 2.06% Mo, 3.87% Ni, with the balance being Fe.

[0047] S2, Melting: The raw materials obtained in step S1 are mixed and melted to obtain an alloy liquid with qualified chemical composition, which then proceeds to step S3. Specifically, after melting, the alloy liquid is tested for chemical composition. If it meets the requirements for each element of the solder powder, it is considered chemically qualified and proceeds to step S3. If not, raw materials are added in the same proportion, and the melting and melting are repeated. The chemical composition of the alloy liquid is tested again. If not, the process of adding raw materials in the same proportion and melting is repeated until the chemical composition is qualified. Qualified chemical composition means meeting the requirements for each element of the solder powder.

[0048] Specifically, the smelting is carried out using a medium-frequency furnace or an AOD refining furnace, with the smelting temperature controlled at 1400~1500℃ and maintained for 30-40 minutes. Any value within this smelting temperature range meets the requirements of this application. For example, controlling the smelting temperature at 1400℃, 1420℃, 1450℃, 1470℃, 1490℃, or 1500℃ can all achieve the present invention. Maintaining the temperature within the above range also meets the requirements of this application. For example, maintaining the temperature for 30, 32, 35, 38, or 40 minutes can all achieve the present invention.

[0049] In this step, the raw materials are proportioned according to elemental ratios, which basically meet the requirements for solder powder composition. However, due to the presence of small amounts of impurities in the raw materials, such as Co, B, N, and C, the content of these impurities is relatively high, or they accumulate after mixing, causing them to exceed the solder powder composition ratio requirements. Therefore, it is necessary to add various raw materials in the same proportion and continue melting until the chemical composition is qualified. This application maintains the solder powder composition ratio while reducing the proportion of impurities. Only after passing the test can the next step be carried out.

[0050] S3. Atomization: The alloy liquid obtained in step S2, which meets the requirements for the elemental composition of the welding powder, is atomized to obtain mixed powders of different fineness. Specifically, the atomization is performed by using an ultra-low temperature atomizing medium to flush the molten liquid, directly forming powder. The ultra-low temperature atomizing medium can be ultra-low temperature nitrogen, helium, or argon. All three ultra-low temperature atomizing media are applicable to this application and can be vaporized using existing liquid media. Preferred is vaporized liquid nitrogen at -196℃.

[0051] S4. Sieving: The mixed powder obtained in step S3 is sieved to obtain welding powder of a specified mesh size. The specified mesh size is 100~270 mesh.

[0052] This application will be described in detail through the following specific embodiments:

[0053] Example 1: A hard alloy welding powder for surface overlay welding of valve sealing surfaces, comprising the following components by weight percentage:

[0054]

[0055] Preparation method: S1. Weighing raw materials: Weigh single crystal silicon, electrolytic manganese, pure chromium, pure nickel, pure molybdenum and pure iron. The amount of the raw materials is calculated according to the mass percentage of Fe, Si, Mn, Cr, Mo and Ni elements in the table above, that is, the content of each element in the table is converted into the amount of each raw material and then weighed.

[0056] S2. Melting: The raw materials obtained in step S1 are mixed and melted in a medium-frequency furnace at a temperature controlled at 1420℃ for 30 minutes to obtain a liquid alloy. The chemical composition of the liquid alloy is tested and found to meet the elemental composition requirements of the welding powder in the table above. The method for testing the chemical composition is a conventional technique and will not be described in detail here.

[0057] S3. Atomization: The alloy liquid obtained in step S2 is atomized by rinsing the molten liquid with vaporized liquid nitrogen at -196°C to form powder, resulting in mixed powders of different fineness.

[0058] S4. Sieving: The mixed powder obtained in step S3 is sieved using a powder sieve to obtain cemented carbide welding powder with a fineness of 150 mesh. Here, 100 mesh refers to the fact that the vast majority of particles in the powder have a fineness of 150 mesh, and the same applies below.

[0059] Example 2: A hard alloy welding powder for surface overlay welding of valve sealing surfaces, comprising the following components by mass percentage:

[0060]

[0061] Preparation method: S1. Weighing raw materials: Weigh single crystal silicon, electrolytic manganese, pure chromium, pure nickel, pure molybdenum and pure iron. The amount of the raw materials is calculated according to the mass percentage of Fe, Si, Mn, Cr, Mo and Ni elements in the table above, that is, the content of each element in the table is converted into the amount of each raw material and then weighed.

[0062] S2. Melting: The raw materials obtained in step S1 are mixed and melted in a medium-frequency furnace. The melting temperature is controlled at 1400℃ and maintained for 40 minutes to obtain a liquid alloy. The chemical composition of the liquid alloy is tested and meets the requirements of each element in the welding powder in the table above. The method for testing the chemical composition is a conventional technique and will not be described in detail here.

[0063] S3. Atomization: The alloy liquid obtained in step S2 is atomized by rinsing the molten liquid with vaporized liquid nitrogen at -196°C to form powder, resulting in mixed powders of different fineness.

[0064] S4. Sieving: The mixed powder obtained in step S3 is sieved through a powder sieve to obtain cemented carbide welding powder with a fineness of 270 mesh.

[0065] Example 3: A hard alloy welding powder for surface overlay welding of valve sealing surfaces, comprising the following components by weight percentage:

[0066]

[0067] Preparation method: S1. Weighing raw materials: Weigh single crystal silicon, electrolytic manganese, pure chromium, pure nickel, pure molybdenum and pure iron. The amount of the raw materials is calculated according to the mass percentage of Fe, Si, Mn, Cr, Mo and Ni elements in the table above, that is, the content of each element in the table is converted into the amount of each raw material and then weighed.

[0068] S2. Melting: The raw materials obtained in step S1 are mixed and melted in a medium-frequency furnace. The melting temperature is controlled at 1500℃ and maintained for 35 minutes to obtain a liquid alloy. The chemical composition of the liquid alloy is tested and meets the requirements of each element in the welding powder in the table above. The method for testing the chemical composition is a conventional technique and will not be described in detail here.

[0069] S3. Atomization: The alloy liquid obtained in step S2 is atomized by rinsing the molten liquid with vaporized liquid nitrogen at -196°C to form powder, resulting in mixed powders of different fineness.

[0070] S4. Sieving: The mixed powder obtained in step S3 is sieved through a powder sieve to obtain cemented carbide welding powder with a fineness of 200 mesh.

[0071] Example 4: A hard alloy welding powder for surface overlay welding of valve sealing surfaces, comprising the following components by weight percentage:

[0072]

[0073] Preparation method: S1. Weighing raw materials: Weigh single crystal silicon, electrolytic manganese, pure chromium, pure nickel, pure molybdenum and pure iron. The amount of the raw materials is calculated according to the mass percentage of Fe, Si, Mn, Cr, Mo and Ni elements in the table above, that is, the content of each element in the table is converted into the amount of each raw material and then weighed.

[0074] S2. Melting: The raw materials obtained in step S1 are mixed and melted in an AOD refining furnace. The melting temperature is controlled at 1450℃ and maintained for 37 minutes to obtain a liquid alloy. The chemical composition of the liquid alloy is tested and meets the requirements of each element in the welding powder in the table above. The method for testing the chemical composition is a conventional technique and will not be described in detail here.

[0075] S3. Atomization: The alloy liquid obtained in step S2 is atomized by rinsing the molten liquid with liquid helium at a temperature below -100°C to form powder, resulting in mixed powders of different fineness.

[0076] S4. Sieving: The mixed powder obtained in step S3 is sieved through a powder sieve to obtain cemented carbide welding powder with a fineness of 150 mesh.

[0077] Example 5: A hard alloy welding powder for surface overlay welding of valve sealing surfaces, comprising the following components by weight percentage:

[0078]

[0079] Preparation method: S1. Weighing raw materials: Weigh single crystal silicon, electrolytic manganese, pure chromium, pure nickel, pure molybdenum and pure iron. The amount of the raw materials is calculated according to the mass percentage of Fe, Si, Mn, Cr, Mo and Ni elements in the table above, that is, the content of each element in the table is converted into the amount of each raw material and then weighed.

[0080] S2. Melting: The raw materials obtained in step S1 are mixed and melted in a medium-frequency furnace at a temperature controlled at 1420℃ for 33 minutes to obtain a liquid alloy. The chemical composition of the liquid alloy is tested and found to meet the elemental composition requirements of the welding powder in the table above. The method for testing the chemical composition is a conventional technique and will not be described in detail here.

[0081] S3. Atomization: The alloy liquid obtained in step S2 is atomized by rinsing the molten liquid with liquid argon at -185.8°C to form powder, resulting in mixed powders of different fineness.

[0082] S4. Sieving: The mixed powder obtained in step S3 is sieved through a powder sieve to obtain cemented carbide welding powder with a fineness of 100 mesh.

[0083] Test verification: The quality requirements for hard alloy welding powder used for surface cladding of valve sealing surfaces are in accordance with standard RCC-MS8000. The following tests, using Examples 1-3 as examples, demonstrate the cladding performance of the welding powder in this application, referencing the aforementioned standard requirements:

[0084] PAW plasma welding was used for surfacing tests, and the samples were manufactured as shown in Figures 1 and 2.

[0085] 1. Hardness test: Ten samples were prepared from each of the welding powders in Examples 1-3, and welding tests were conducted. The hardness of the weld was tested, and the average value of the test results was used to evaluate the welding powder.

[0086] Hardness test results (HRC)

[0087] As can be seen from the table, the weld hardness test results of the welding powder welding in this application meet the requirements of the RCC-MS8000 standard.

[0088] 2. Wear test: Wear test is performed on the welding material samples, and the wear rate is compared with that of cobalt-based welding materials of the same grade.

[0089] Comparison of sample wear rate (%)

[0090]

[0091] As can be seen from the table, the wear rate of the three samples in this application is much lower than that of existing cobalt-based welding powders at both room temperature and high temperature. Moreover, the hardness loss rate at high temperature is better than that of cobalt-based materials of the same grade. The low wear rate not only reduces the amount of welding powder alloy debris entering the primary circuit, but also reduces the total cobalt content.

[0092] 3. Welding quality inspection:

[0093] This application examines the welding quality using macroscopic metallographic photographs of Examples 1-3, obtaining the metallographic images shown in Figures 3-5. Specific results are as follows:

[0094] 1) Overall weld: The weld consists of two layers and has been tested and found to be free of cracks, incomplete penetration, lack of fusion, and porosity defects.

[0095] 2) Weld: No microcracks or deposit defects.

[0096] 3) Heat-affected zone: No microcracks or deposit defects.

[0097] 4) Base material: Free from microcracks and deposit defects.

[0098] In summary, it can be seen that the welding quality of this application is excellent.

[0099] It is understood that the above embodiments only illustrate preferred embodiments of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of this application. It should be noted that, for those skilled in the art, without departing from the concept of this application, the above technical features can be freely combined, and several modifications and improvements can be made, all of which fall within the protection scope of this application. Therefore, all equivalent transformations and modifications made within the scope of the claims of this application should fall within the coverage of the claims of this application.

Claims

1. A hard alloy welding powder for surface overlay welding of valve sealing surfaces, characterized in that, The composition includes the following elements by mass percentage: C 1.20~1.40%, Si 2.70~3.50%, Mn 3.00~4.50%, Cr 24.00~26.00%, Mo 2.00~2.20%, Ni 3.50~4.50%, Co ≤0.20%, B ≤0.02%, N ≤0.10%, and the balance is Fe.

2. The hard alloy welding powder for surface overlay welding of valve sealing surfaces according to claim 1, characterized in that, The composition includes the following elements by mass percentage: C 1.30~1.35%, Si 2.70~3.10%, Mn 3.10~3.50%, Cr 24.00~25.00%, Mo 2.05~2.15%, Ni 3.80~4.40%, Co ≤0.20%, B ≤0.015%, N ≤0.06%, and the balance is Fe.

3. The hard alloy welding powder for surface overlay welding of valve sealing surfaces according to claim 1, characterized in that, The composition includes the following elements by mass percentage: C 1.32%, Si 2.75%, Mn 3.19%, Cr 24.37%, Mo 2.06%, Ni 3.87%, Co ≤0.20%, B ≤0.011%, N ≤0.06%, and the balance is Fe.

4. A method for preparing hard alloy welding powder for surface overlay welding of valve sealing surfaces, characterized in that, Includes the following steps: S1. Weighing materials: using single crystal silicon, electrolytic manganese, pure metallic chromium, pure metallic nickel, pure metallic molybdenum and pure metallic iron as raw materials; S2, Smelting: The raw materials obtained in step S1 are mixed and smelted to obtain an alloy liquid with qualified chemical composition, which then proceeds to step S3. S3. Atomization: The alloy liquid obtained in step S2, which meets the requirements of each element composition of the welding powder, is atomized to obtain mixed powders of different fineness. S4. Sieving: The mixed powder obtained in step S3 is sieved to obtain solder powder of a specified mesh size.

5. The method for preparing cemented carbide welding powder according to claim 4, characterized in that, In step S1, the mass ratio of the raw materials is calculated according to the following element mass percentages: Si 2.70~3.5%, Mn 3.00~4.50%, Cr 24.00~26.00%, Mo 2.00~2.20%, Ni 3.50~4.50%, with the balance being Fe.

6. The method for preparing cemented carbide welding powder according to claim 5, characterized in that, The raw materials are proportioned according to the following element mass percentages: Si 2.70~3.10%, Mn 3.10~3.50%, Cr 24.00~25.00%, Mo 2.05~2.15%, Ni 3.80~4.40%, Co ≤0.20%, B ≤0.015%, N ≤0.06%, with the balance being Fe.

7. The method for preparing cemented carbide welding powder according to claim 6, characterized in that, The raw materials are proportioned according to the following element mass percentages: Si 2.75%, Mn 3.19%, Cr 24.37%, Mo 2.06%, Ni 3.87%, Co ≤0.20%, B ≤0.011%, N ≤0.06%, with the balance being Fe.

8. The method for preparing cemented carbide welding powder according to claim 4, characterized in that, In step S2, the smelting is carried out using a medium-frequency furnace or an AOD refining furnace, with the smelting temperature controlled at 1400~1500℃ and maintained for 30-40 minutes.

9. The method for preparing cemented carbide welding powder according to claim 4, characterized in that, In step S2, after melting, an alloy liquid is obtained. The chemical composition of the alloy liquid is tested. If it meets the requirements of each element of the welding powder, the chemical composition is qualified. Then, proceed to step S3. If not, add raw materials in the same proportion and melt again. Test the chemical composition of the alloy liquid again. If not, repeat the process of adding raw materials in the same proportion and melting until the chemical composition is qualified.

10. The method for preparing cemented carbide welding powder according to claim 9, characterized in that, In step S2, "qualified chemical composition" means that the chemical composition meets the requirements of each element in the solder powder.

11. The method for preparing cemented carbide welding powder according to claim 4, characterized in that, In step S3, the gas atomization is performed by using an ultra-low temperature gas atomization medium to flush the molten liquid and directly form powder.

12. The method for preparing cemented carbide welding powder according to claim 11, characterized in that, In step S3, the cryogenic gas atomizing medium is cryogenic nitrogen, helium, or argon.

13. The method for preparing cemented carbide welding powder according to claim 11, characterized in that, In step S3, the ultra-low temperature atomizing medium is obtained by vaporizing a liquid medium.

14. The method for preparing cemented carbide welding powder according to claim 4, characterized in that, In step S4, the specified mesh size is 100 to 270 mesh.

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