A method for producing stainless steel powder by atomization using AOD refining and induction furnace

Abstract

This invention relates to the field of metal powder preparation technology, specifically a method for producing stainless steel powder using a combination of AOD refining and induction furnace atomization. This method eliminates the traditional LF furnace temperature and composition adjustment process after AOD deep decarburization, and also eliminates the tundish graphite electrode plasma heating or double graphite electrode electroslag heating process. Instead, a large and a small induction furnace handle the receiving, heating, holding, precise temperature control, and stable flow supply of molten steel, which is then atomized through nozzles to produce powder. This method avoids the 0.03%–0.05% carbon increase in the LF process and the 0.01%–0.03% carbon increase in the tundish graphite electrode / electroslag heating process. It solves the problem that traditional processes cannot stably produce ultra-low carbon duplex stainless steel powder with a carbon content ≤0.03%, and has the advantages of a short process, no carbon increase, and suitability for continuous industrial production.

Description

Technical Field

[0001] This invention relates to the field of metal powder preparation technology, specifically a method for producing stainless steel powder by atomization using AOD refining and induction furnace combined. Background Technology

[0002] The demand for ultra-low carbon stainless steel powder (C≤0.03%) is growing in additive manufacturing, powder metallurgy, and high-end coatings. In industrial production, traditional atomization powdering processes have two inherent sources of carbon increase: approximately 0.03%–0.05% carbon increase from the LF furnace (ladle refining furnace) process, and approximately 0.02% cumulative carbon increase during the long powdering process (3-5 hours) using graphite electrodes or electroslag heating in the tundish. The combined effect of these two factors causes the final powder carbon content to exceed the ultra-low carbon control limit.

[0003] Existing technology CN114561510B (application number CN202210454529.5) discloses a method for online gas-phase carbon control in a steelmaking refining furnace or tundish. Its working principle is as follows: nitrogen (as a tracer gas), oxygen (as a reactant gas), and argon (as a protective gas) are introduced into the refining furnace or tundish through hollow graphite electrodes. The content of the outflowing gases is analyzed by a mass spectrometer, and the industrial control computer calculates and controls the oxygen flow rate based on the decarburization amount to ensure that the carbon increase in the molten steel is below 0.03%. This scheme represents a typical "post-event compensation" approach—accepting the predetermined carbon increase from the process and offsetting it through online chemical reaction in the gas phase.

[0004] However, this scheme still has fundamental flaws when applied to the industrial production of ultra-low carbon stainless steel powder: First, it does not eliminate the carbon enrichment source at the root. It assumes that the LF furnace and graphite electrode heating are necessary steps in the process and only performs passive decarburization after carbon enrichment occurs, making it difficult to guarantee control accuracy and stability. Second, it relies on mass spectrometer exhaust gas analysis for indirect calculation, which has a response lag and makes it difficult to achieve real-time and accurate control for long processes with continuous atomization for several hours.

[0005] Another prior art, CN111020402A (application number CN201811176073.0), discloses a method for manufacturing stainless steel powder using a vacuum induction gas atomization powder making device (VIGA). Although it uses induction heating to avoid graphite electrode contamination, the VIGA method is limited by batch vacuum induction melting and cannot directly utilize AOD refined molten steel from large steel enterprises. The raw materials rely on solid recycled materials or pure metals, which limits the scale of production capacity and increases the cost of raw materials.

[0006] In summary, no existing technology has proposed a complete process route that can directly use AOD-refined molten steel for atomization powder production with zero additional carbon addition throughout the entire process. Summary of the Invention

[0007] In order to overcome the defects in the prior art, the purpose of this invention is to provide a method for producing stainless steel powder by combining AOD refining with induction furnace atomization, so as to solve the problems mentioned in the background art.

[0008] To achieve the above objectives, the present invention provides a method for producing stainless steel powder by atomization using AOD refining and induction furnace combined, comprising the following steps:

[0009] S1. Use an AOD refining furnace to decarburize and adjust the composition of stainless steel mother liquor to obtain AOD final molten steel with a carbon content ≤0.03%;

[0010] S2. After the steel is tapped from the AOD furnace, the molten steel is directly transferred into a large induction furnace for receiving, heating and heat preservation in an environment without graphite electrodes and without electroslag heating. The capacity of the large induction furnace is matched with the capacity of the AOD refining furnace.

[0011] S3. Transfer the molten steel in the large induction furnace to the small induction furnace in batches, and perform precise temperature control and steady flow control on the molten steel. The capacity of the small induction furnace is determined according to the atomization powder production speed, which is 3 to 10 times the powder production per minute.

[0012] S4. The molten steel in the small induction furnace flows out through the nozzle and is atomized into powder under a protective atmosphere to obtain ultra-low carbon stainless steel powder.

[0013] S5. The entire process eliminates the LF furnace refining process and the intermediate ladle graphite electrode / electroslag heating process, and the low-carbon results of the AOD final molten steel are retained at the atomization terminal.

[0014] As a further improvement to this technical solution, the large induction furnace mentioned in step S2 is a coreless induction furnace or a cored induction furnace, with a capacity of 5 to 120 tons, a heating power of 1000 to 15000 kW, and a holding temperature of molten steel in the large induction furnace of 1500 to 1650℃.

[0015] As a further improvement to this technical solution, the capacity of the small induction furnace in step S3 is 100-1000 kg, the heating power is 50-500 kW, and the tapping temperature of the molten steel in the small induction furnace is 1520-1680℃.

[0016] As a further improvement to this technical solution, in step S3, the small induction furnace adopts a bottom-pouring or tilting steel tapping structure. By adjusting the induction heating power and the opening of the tapping port, the flow rate and temperature of the molten steel are controlled to achieve a stable supply of liquid to the nozzle.

[0017] As a further improvement to this technical solution, the atomization powder preparation in step S4 adopts gas atomization, water atomization or water-gas combined atomization method, the atomization medium is argon, nitrogen or their mixture, and the atomization pressure is 1 to 8 MPa.

[0018] As a further improvement to this technical solution, the LF furnace refining process in step S5 is cancelled to eliminate the 0.03% to 0.05% carbon increase introduced into the molten steel by the LF process, and the tundish graphite electrode / electroslag heating process is cancelled to eliminate the 0.01% to 0.03% carbon increase introduced into the molten steel by the graphite electrode.

[0019] As a further improvement to this technical solution, in step S1, the AOD refining adopts a top and bottom blowing method, the blowing gas is a mixture of oxygen and argon, and the AOD tapping temperature is controlled at 1600-1750℃.

[0020] As a further improvement to this technical solution, the ultra-low carbon stainless steel powder is duplex stainless steel powder, austenitic stainless steel powder or ferritic stainless steel powder, with the final powder having a carbon content ≤0.03% and an oxygen content ≤0.005%.

[0021] As a further improvement to this technical solution, the final product of the duplex stainless steel powder has a carbon content of ≤0.025%, an atomized powder sphericity of ≥90%, and a particle size distribution of 15~150μm.

[0022] As a further improvement to this technical solution, the transfer of molten steel from the large induction furnace to the small induction furnace adopts an intermediate ladle or guide pipe method, and inert gas is introduced during the transfer process to protect against secondary oxidation and temperature drop of the molten steel.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] 1. This method of using AOD refining and induction furnace in combination to produce stainless steel powder avoids secondary carbon addition at the source by eliminating the LF furnace and the graphite electrode / electroslag heating process in the tundish. It establishes a two-stage induction heating system with a large induction furnace and a small induction furnace, so that the carbon content of the final powder is stably controlled at ≤0.03%, which completely solves the fundamental problem that traditional processes cannot stably produce ultra-low carbon stainless steel powder.

[0025] 2. The method of using AOD refining and induction furnace in combination to produce stainless steel powder is simplified to "AOD → large induction furnace → small induction furnace → atomization", which reduces the one-time steel molten material transfer and secondary temperature adjustment, thereby reducing heat loss and the risk of secondary oxidation. Attached Figure Description

[0026] The accompanying drawings described herein are for illustrative purposes only. The shapes and proportions of the components in the drawings are merely schematic and intended to aid in understanding the invention. They are not intended to specifically limit the shapes and proportions of the components of the invention.

[0027] Figure 1 This is a schematic diagram of the preparation of stainless steel mother liquor using the AOD refining furnace of the present invention;

[0028] Figure 2 This is a schematic diagram illustrating the preparation of ultra-low carbon stainless steel powder according to the present invention;

[0029] Figure 3 This is a general flowchart of the preparation process of ultra-low carbon stainless steel powder according to the present invention;

[0030] Figure 4 This is a bar chart comparing the carbon content of the powders used in this invention.

[0031] The meanings of the labels in the diagram are as follows:

[0032] 100. AOD refining furnace; 200. Large induction furnace; 300. Small induction furnace. Detailed Implementation

[0033] The specific embodiments described herein are for illustrative purposes only. Under the guidance of this invention, any possible variations of the invention by those skilled in the art should be considered within its scope. The directional terms used herein are based on the orientations shown in the accompanying drawings and are for ease of description and simplification; therefore, they should not be construed as limitations on the invention. Furthermore, in the description of this invention, "a number" means two or more, unless otherwise explicitly specified.

[0034] Please see Figures 1-4 As shown, the present invention provides a method for producing stainless steel powder by atomization using AOD refining and induction furnace combined, comprising the following steps:

[0035] S1. Use an AOD refining furnace 100 to decarburize and adjust the composition of stainless steel mother liquor to obtain AOD final steel liquor with a carbon content ≤0.03%;

[0036] After the steel is tapped from S2 and AOD, the molten steel is directly transferred into the large induction furnace 200. It is then subjected to receiving, heating and heat preservation treatment in an environment without graphite electrodes and without electroslag heating. The capacity of the large induction furnace 200 is matched with the capacity of the AOD refining furnace 100.

[0037] S3. Transfer the molten steel in the large induction furnace 200 to the small induction furnace 300 in batches. Perform precise temperature control and steady flow control on the molten steel. The capacity of the small induction furnace 300 is determined according to the atomization powder production speed, which is 3 to 10 times the powder production per minute.

[0038] S4. The molten steel in the small induction furnace 300 flows out through the nozzle and is atomized into powder under a protective atmosphere to obtain ultra-low carbon stainless steel powder.

[0039] S5. The entire process eliminates the LF furnace refining process and the tundish graphite electrode / electroslag heating process, and the low-carbon results of the AOD final molten steel are retained at the atomization terminal. Since the small induction furnace 300 itself has a precise temperature control function, the molten steel can be directly atomized through the nozzle without passing through the tundish with graphite electrode or electroslag heating device. This fundamentally eliminates the carbon pollution of molten steel caused by graphite electrode heating.

[0040] In step S1, AOD refining employs a top-and-bottom blowing method, using a mixture of oxygen and argon as the blowing gas. The AOD tapping temperature is controlled between 1600 and 1750°C. The ultra-low carbon stainless steel powder is duplex stainless steel powder, austenitic stainless steel powder, or ferritic stainless steel powder, with a final powder carbon content ≤0.03% and an oxygen content ≤0.005%. The final product of this duplex stainless steel powder has a carbon content ≤0.025%, an atomized powder sphericity ≥90%, and a particle size distribution of 15–150 μm.

[0041] In step S2, the large induction furnace 200 is either a coreless or cored induction furnace with a capacity of 5–120 tons and a heating power of 1000–15000 kW. The holding temperature of the molten steel in the large induction furnace 200 is 1500–1650℃. Using the large induction furnace 200 can replace the LF furnace in completing the temperature adjustment and molten steel holding functions, without bearing the inherent carbon increase risk associated with the LF furnace. The large induction furnace 200 uses electromagnetic induction heating, with the heat source being the induced current. It completely avoids contact between graphite electrodes or carbon-containing materials and the molten steel, and there is no carbon source input during the heating process.

[0042] In step S3, the small induction furnace 300 has a capacity of 100–1000 kg, a heating power of 50–500 kW, and a tapping temperature of molten steel of 1520–1680 °C. The small induction furnace 300 in step S3 adopts a bottom-pouring or tilting tapping structure. The flow rate and temperature of the molten steel are controlled by adjusting the induction heating power and the tapping port opening, achieving a stable supply of molten steel to the nozzle. A two-stage induction heating system consisting of the large induction furnace 200 and the small induction furnace 300 is established. This two-stage system meets the requirements of industrial-scale mass production for molten steel reserves while ensuring precise control of the supply flow rate and temperature in the atomization process.

[0043] In step S4, the atomization powder preparation adopts gas atomization, water atomization or water-gas combined atomization method, the atomization medium is argon, nitrogen or their mixture, and the atomization pressure is 1 to 8 MPa.

[0044] In step S5, the LF furnace refining process is cancelled to eliminate the 0.03% to 0.05% carbon increase introduced into the molten steel by the LF process, and the tundish graphite electrode / electroslag heating process is cancelled to eliminate the 0.01% to 0.03% carbon increase introduced into the molten steel by the graphite electrode.

[0045] In addition, the transfer of molten steel from the large induction furnace 200 to the small induction furnace 300 adopts the intermediate ladle or guide pipe method, and inert gas is introduced during the transfer process to prevent secondary oxidation and temperature drop of the molten steel.

[0046] Existing technologies involve partial optimization or carbon increase compensation based on the traditional "AOD→LF→intermediate package (graphite electrode / electroslag heating)→atomization" route. However, this invention directly eliminates the key process that leads to carbon increase, establishing a new powder production route with no carbon pollution throughout the entire process. Through the new route of "AOD deep decarburization→large induction furnace insulation→small induction furnace temperature control→atomization powder production", this invention achieves full-process carbon isolation from the AOD endpoint to the atomization terminal.

[0047] The present invention will be further described in detail below with reference to specific embodiments and comparative examples. Unless otherwise specified, the experimental methods described in the following embodiments are conventional methods; the materials and equipment, unless otherwise specified, are commercially available.

[0048] Example 1 (Production of 2205 duplex stainless steel powder)

[0049] Step 1: AOD Refining; 45 tons of stainless steel mother liquor pre-melted in the electric arc furnace are added to AOD refining furnace 100, and decarburization refining is carried out using top and bottom blowing of O2-Ar mixed gas. The blowing process is divided into oxidation and reduction stages: during the oxidation stage, the O2 / Ar ratio is gradually reduced according to the carbon content, and decarburization is carried out to 0.02%; during the reduction stage, ferrosilicon and aluminum are added for deoxidation and alloying. The final AOD steel composition (mass percentage): C 0.020%, Cr 22.5%, Ni 5.8%, Mo 3.1%, N 0.16%, Mn 1.2%, Si 0.5%, P≤0.03%, S≤0.02%, balance Fe; tapping temperature 1680℃.

[0050] Step 2: The large induction furnace is used for heat preservation. After tapping from the AOD (Alternating Dry Ore) furnace, the molten steel is directly transferred to a 45-ton coreless large induction furnace (model 200). The large induction furnace has a power of 8000kW, a frequency of 250Hz, and a magnesia refractory lining. Induction heating is started to adjust the temperature of the molten steel to 1580–1620℃ and maintain this temperature. During the heat preservation period, the molten steel achieves temperature and composition homogenization under the action of induction stirring.

[0051] Step 3: Precise temperature and flow control in the small induction furnace. Molten steel from the large induction furnace is transferred in batches to a small induction furnace (300) with a capacity of 500 kg, via an intermediate ladle under argon protection. The small induction furnace has a power of 250 kW and a frequency of 1000 Hz. The molten steel is precisely heated to the required atomization temperature of 1650–1670 °C. The tapping temperature from the small induction furnace (300) is 1660 °C ± 5 °C. It employs a bottom-pouring structure, and the molten steel flow rate is precisely controlled by adjusting the induction power.

[0052] Step 4: Atomization Powder Preparation. Molten steel enters the tightly coupled gas atomizing nozzle through the bottom guide pipe of the small induction furnace 300. High-purity argon is used as the atomizing medium, with an atomization pressure of 5.0 MPa and a molten steel flow rate of 3.5 kg / min. The atomized powder is separated by cyclone separation and sieving to obtain 2205 duplex stainless steel powder of the target particle size. Throughout the entire process, from AOD tapping to the end of atomization, all refractory materials in contact with the molten steel are low-carbon magnesia or high-alumina materials, and graphite electrodes are not involved.

[0053] Example 2 (Production of 316L austenitic stainless steel powder)

[0054] Step 1: AOD Refining. 316L stainless steel was refined in a 60-ton AOD furnace. The final AOD molten steel composition (mass percentage) was: C 0.018%, Cr 17.2%, Ni 12.5%, Mo 2.5%, Mn 1.5%, Si 0.6%, P≤0.03%, S≤0.02%, with the balance being Fe. The tapping temperature was 1700℃.

[0055] Step 2: Insulation in the large induction furnace. After tapping from AOD, the steel is transferred to a 60-ton cored induction furnace with a power of 5000kW and an insulation temperature of 1550~1590℃.

[0056] Step 3: Precise temperature control in the small induction furnace. The small induction furnace has a capacity of 800kg, a power of 300kW, and a tapping temperature of 1640℃±5℃.

[0057] Step 4: Atomization powder preparation. Nitrogen atomization was used at a pressure of 4.5 MPa and a steel flow rate of 4.0 kg / min. 316L austenitic stainless steel powder was obtained.

[0058] Example 3 (Production of 304L austenitic stainless steel powder, with slightly higher initial carbon content to verify decarburization retention capability)

[0059] Step 1: AOD refining. AOD final steel composition (mass percentage): C 0.028%, Cr 18.5%, Ni 8.5%, Mn 1.4%, Si 0.5%, balance Fe. Tapping temperature: 1690℃.

[0060] Step 2: Insulation in the large induction furnace. Transfer to a 30-ton coreless induction furnace with a power of 6000kW, an insulation temperature of 1570~1610℃, and an insulation time of 2.5h.

[0061] Step 3: Precise temperature control in a small induction furnace. Capacity 300kg, power 150kW, tapping temperature 1650℃.

[0062] Step 4: Atomization powder preparation. Argon gas atomization, atomization pressure 5.5 MPa, molten steel flow rate 2.8 kg / min. This embodiment aims to verify that when the carbon content at the AOD endpoint is close to the upper limit (0.028%), the entire process without carbon addition can still ensure that the carbon content of the powder product meets the standard.

[0063] Comparative Example 1 (Traditional process: AOD+LF+intermediate tundish graphite electrode plasma heating)

[0064] To compare the technical effects of the present invention, the same grade 2205 duplex stainless steel powder was prepared using a traditional process route.

[0065] After AOD refining, the molten steel is transferred to an LF furnace for temperature adjustment and composition fine-tuning. The LF furnace uses graphite electrodes for heating, with a heating power of 3500kW and a treatment time of 45 minutes. After LF treatment, the molten steel is transferred to an 8-ton tundish, where it is reheated and kept warm using graphite electrode plasma heating (power 500kW, lasting approximately 4 hours), and then atomized into powder. The remaining atomization parameters are the same as in Example 1.

[0066] Comparative Example 2 (AOD + Large Induction Furnace + Intermediate Ladle Graphite Electrode Heating)

[0067] To further verify the necessity of eliminating the tundish graphite electrode heating, Comparative Example 2 was designed: after AOD tapping, the steel is directly transferred to a large induction furnace (same as step 2 in Example 1), but subsequently undergoes tundish graphite electrode plasma heating (same as the tundish heating method in Comparative Example 1) before atomization powder production. This scheme simulates a scenario where process improvements are made only in the LF stage without changing the tundish heating method, and is used to verify the independent carbonization effect of the tundish graphite electrode heating stage.

[0068] Comparison table of carbon content and key indicators of each embodiment and comparative example

[0069] Results analysis:

[0070] project Process route steel grades AOD endpoint C (%) C (%) after large induction furnace C (%) after small induction furnace / intermediate drum Powder C (%) Powder O (%) Is it qualified (C≤0.03%)? Example 1 Complete route of the invention 2205 0.020 0.020 0.020 0.020 0.0032 qualified Example 2 Complete route of the invention 316L 0.018 0.018 0.018 0.019 0.0028 qualified Example 3 Complete route of the invention 304L 0.028 0.028 0.028 0.028 0.0030 qualified Comparative Example 1 AOD→LF→Intermediate Packet Graphite Electrode→Atomization (Traditional Route) 2205 0.020 After LF: 0.055 After intermediate packaging: 0.075 0.075 0.0035 Unqualified Comparative Example 2 AOD → Large Induction Furnace → Intermediate Graphite Electrode → Atomization (LF only cancelled) 2205 0.020 0.020 After intermediate packaging: 0.040 0.040 0.0033 Unqualified

[0071] The comparison table shows that:

[0072] (1) Examples 1-3 all successfully controlled the carbon content of the powder to ≤0.03%. From the AOD endpoint to the final powder, the carbon content hardly increased, which fully verified the technical effect of the present invention that there is no additional carbon increase throughout the entire process. In Example 3, the carbon content at the AOD endpoint was 0.028%, and it remained stable at 0.028% after the entire process, proving that the method can reliably maintain the low carbon results of AOD.

[0073] (2) In Comparative Example 1, the final carbon content of AOD was 0.020%, but after treatment in the LF furnace, the carbon content increased to 0.055% (an increase of 0.035%). After being heated by plasma at the graphite electrode in the tundish for 4 hours, the carbon content increased to 0.075% (an additional increase of 0.020%), and the final carbon content of the powder reached 0.075%, far exceeding the acceptable upper limit of 0.03%. This fully verifies that the dual carbon increase effect caused by the LF process and the graphite electrode heating in the tundish in the traditional process is the root cause of the failure of ultra-low carbon control.

[0074] (3) Although Comparative Example 2 eliminated the LF furnace and directly fed the AOD steel into the large induction furnace for heat preservation (without carbon increase), it still underwent subsequent plasma heating with graphite electrodes in the tundish. Ultimately, the powder carbon content increased to 0.040%, a carbon increase of approximately 0.020%, and the product was also substandard. This confirms that tundish graphite electrode heating has an independent and significant carbon increase effect on molten steel, and the accumulated carbon increase in its long-term heating environment is sufficient to cause the ultra-low carbon product to fail. This further illustrates the necessity of simultaneously eliminating the dual processes of LF and tundish graphite electrode heating in this invention.

[0075] In summary, the full-process data and comparative verification of this invention fully demonstrate that the new process route of AOD → large induction furnace → small induction furnace → atomization powder production can stably produce ultra-low carbon stainless steel powder with a carbon content of ≤0.03% by eliminating the two major carbon-increasing sources of LF and intermediate ladle graphite electrode / electroslag heating from the root, thus solving the inherent problems of traditional processes.

[0076] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for atomizing stainless steel powder by using AOD refining and induction furnace, characterized in that, Includes the following steps: S1. Use an AOD refining furnace (100) to decarburize and adjust the composition of stainless steel mother liquor to obtain AOD final steel liquor with carbon content ≤0.03%; S2, After the AOD steel is tapped, the molten steel is directly transferred into the large induction furnace (200) and subjected to receiving, heating and heat preservation treatment in an environment without graphite electrodes and without electroslag heating. The capacity of the large induction furnace (200) is matched with the capacity of the AOD refining furnace (100). S3. The molten steel in the large induction furnace (200) is transferred to the small induction furnace (300) in batches. The molten steel is precisely temperature controlled and the flow is kept constant. The capacity of the small induction furnace (300) is determined according to the atomization powder production speed, which is 3 to 10 times the powder production per minute. S4. The molten steel in the small induction furnace (300) flows out through the nozzle and is atomized into powder under a protective atmosphere to obtain ultra-low carbon stainless steel powder. S5. The entire process eliminates the LF furnace refining process and the intermediate ladle graphite electrode / electroslag heating process, and the low-carbon results of the AOD final steel liquid are retained at the atomization terminal.

2. The method of claim 1, wherein the AOD refining and induction furnace combined atomization method for producing stainless steel powder is characterized by: The large induction furnace (200) mentioned in step S2 is a coreless induction furnace or a cored induction furnace, with a capacity of 5 to 120 tons, a heating power of 1000 to 15000 kW, and a holding temperature of molten steel in the large induction furnace (200) of 1500 to 1650 ℃.

3. The method for producing stainless steel powder by atomization using AOD refining and induction furnace combined according to claim 2, characterized in that: The small induction furnace (300) mentioned in step S3 has a capacity of 100-1000 kg, a heating power of 50-500 kW, and a tapping temperature of molten steel in the small induction furnace (300) of 1520-1680 °C.

4. The method for producing stainless steel powder by atomization using AOD refining and induction furnace combined according to claim 3, characterized in that: In step S3, the small induction furnace (300) adopts a bottom-pouring or tilting steel tapping structure. By adjusting the induction heating power and the opening of the tapping port, the flow rate and temperature of the molten steel are controlled to achieve stable liquid supply to the nozzle.

5. The method for producing stainless steel powder by atomization using AOD refining and induction furnace combined according to claim 4, characterized in that: The atomization powder preparation in step S4 adopts gas atomization, water atomization or water-gas combined atomization method, the atomization medium is argon, nitrogen or a mixture thereof, and the atomization pressure is 1 to 8 MPa.

6. The method for producing stainless steel powder by atomization using AOD refining and induction furnace combined according to claim 5, characterized in that: In step S5, the LF furnace refining process is cancelled to eliminate the 0.03% to 0.05% carbon increase introduced into the molten steel by the LF process, and the tundish graphite electrode / electroslag heating process is cancelled to eliminate the 0.01% to 0.03% carbon increase introduced into the molten steel by the graphite electrode.

7. The method for producing stainless steel powder by atomization using AOD refining and induction furnace combined according to claim 6, characterized in that: In step S1, AOD refining adopts a top and bottom blowing method, and the blowing gas is a mixture of oxygen and argon. The AOD tapping temperature is controlled at 1600-1750℃.

8. The method for producing stainless steel powder by atomization using AOD refining and induction furnace combined according to claim 7, characterized in that: The ultra-low carbon stainless steel powder is duplex stainless steel powder, austenitic stainless steel powder, or ferritic stainless steel powder, with a final powder carbon content ≤0.03% and oxygen content ≤0.005%.

9. The method for producing stainless steel powder by atomization using AOD refining and induction furnace combined according to claim 8, characterized in that: The final product of this duplex stainless steel powder has a carbon content of ≤0.025%, an atomized powder sphericity of ≥90%, and a particle size distribution of 15~150μm.

10. The method for producing stainless steel powder by atomization using AOD refining and induction furnace combined according to claim 9, characterized in that: The transfer of molten steel from the large induction furnace (200) to the small induction furnace (300) is carried out by means of an intermediate ladle or a guide pipe, and inert gas is introduced for protection during the transfer process.

Images