Smelting method of iron-nickel-based alloy

Abstract

The invention relates to the field of smelting, in particular to a smelting method of an iron-nickel-based alloy. The method comprises the following steps: smelting in an electric furnace; refining in an AOD furnace; refining in an LF furnace; refining in a VOD furnace; casting ingots; due to process adjustment of all the steps, electroslag remelting operation is not needed after the VOD furnace refining step, the obtained molten steel can be directly cast, the process steps are shortened, and the production efficiency is improved. As the electroslag remelting process flow is reduced, the smelting process disclosed by the invention can reduce the electroslag cost by 2000-3500 yuan / ton, and also can avoid 3-5% metal loss caused by head and tail cutting and surface polishing treatment on the consumable electrode before electroslag remelting; and the situation that components at the head and the tail of the steel ingot are not uniform due to element burning loss in the electroslag remelting process is effectively avoided.

Description

Technical Field

[0001] The invention relates to the field of smelting, and in particular to a smelting method of an iron-nickel based alloy. Background Art

[0002] A286 alloy is an iron-nickel based deformation high temperature alloy containing Ti, Al and other trace alloying elements. The γ' phase Ni is precipitated by heat treatment after deformation. 3 (Ti, Al), thereby achieving precipitation hardening. A286 alloy has good comprehensive mechanical properties and corrosion resistance, and its operating temperature range is -253℃~650℃. Due to its excellent performance, A286 alloy is widely used in aerospace, energy, chemical and other fields. In the aerospace field, A286 alloy is often used to manufacture high-temperature load-bearing parts of aircraft engines that work for a long time below 650℃, such as turbine discs, compressor discs, rotor blades and fasteners. These components not only need to operate at high temperatures, but also often face various dynamic loads and vibration challenges. The excellent performance of A286 alloy ensures the safe and efficient operation of these components.

[0003] The current smelting method commonly used for existing A286 alloy products is electric furnace + refining to produce electrode rods, and then electroslag remelting after flattening the head and tail of the electrode rods and polishing the surface. Its production process is long, the yield rate is low, and the manufacturing cost is high. In addition, since A286 alloy is aluminum-titanium steel, the inevitable aluminum-titanium burning loss during the electroslag remelting process leads to uneven composition of the head and tail of the produced steel ingots. Summary of the invention

[0004] The present invention proposes a short-process smelting process of electric furnace + refining + ingot casting for A286 alloy, which reduces the electroslag remelting link, improves production efficiency and reduces smelting costs. By reasonably setting the process, the smelted alloy structure and performance are guaranteed to be equivalent to those of the electroslag remelting process, and the process can ensure the uniformity of the ingot composition.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions: A smelting method for an iron-nickel based alloy comprises the following steps: electric furnace smelting; AOD furnace refining; LF furnace refining; VOD furnace refining; ingot casting; after the VOD furnace refining step, the obtained molten steel can be directly cast into ingots without the need for electroslag remelting.

[0006] Preferably, the electric furnace smelting steps are as follows: 1) When the melting temperature of the charge is greater than 1550℃, an appropriate amount of carbonized rice husk can be added to the furnace to prevent slag crusting; 2) Take samples and analyze all elements to provide reference for the initial adjustment of AOD composition; 3) Steel tapping temperature T≥1650℃, C≥1.2%.

[0007] Further preferably, in the electric furnace smelting step 1), the addition amount of the carbonized rice husk is 20 - 40 kg per 20 t of molten steel.

[0008] Preferably, in the AOD furnace refining step, during the reduction period, full Al reduction is first adopted without adding Si; during the secondary reduction, reducing slag materials such as 300 - 400 kg of quicklime per 20 t of molten steel, 100 - 300 kg of fluorite per 20 t of molten steel, and 2 - 4 kg of Al ingots or Al particles per ton of molten steel are added.

[0009] Further preferably, the AOD furnace refining step is as follows: 1) Before charging the molten steel, the temperature of the AOD furnace is ≥800 °C; the gas supply parameters should satisfy P 氧 ≥1.5 MPa, P 氩 ≥1.5 MPa; 2) Before charging the molten steel, Ar = 500 - 700 Nm 3 ∕h, and the cooling gas flow rate is 130 - 350 Nm 3 ∕h; 3) After the molten steel is charged into the AOD furnace, sample and analyze after blowing Ti and Si. When Ti ≤ 0.25% and Si ≤ 0.25%, slag removal treatment is carried out; 4) During the AOD decarbonization period, the total gas flow rate is controlled at 1100 - 1500 Nm 3 ∕h; 5) When C ≤ 0.3%, add Al for reduction. During the reduction period, full Al reduction is adopted without adding Si; 6) After the reduction is completed, tilt the furnace to measure the temperature, take samples, and remove slag ≥90%. During the secondary reduction, adding reducing slag materials such as 300 - 400 kg of quicklime per 20 t of molten steel, 100 - 300 kg of fluorite per 20 t of molten steel, and 2 - 4 kg of Al ingots or Al particles per ton of molten steel, and the reduction time > 5 minutes; 7) The target control of the tapping composition is: C: 0.150 - 0.30%; P: ≤0.035%; S: ≤0.003%; Si: ≤0.20%; Cr: 13.0 - 14.5%; Ni: 24.0 - 24.5%; Mo: 1.05 - 1.12%.

[0010] Preferably, the LF furnace refining includes the following steps: 1) After the molten steel arrives, adjust the argon flow rate and supply power to raise the temperature. During the temperature - raising process, add lime and fluorite according to the actual situation to adjust the fluidity of the furnace slag; 2) Add an appropriate amount of aluminum particles for diffusion deoxidation, requiring less addition and frequent addition to maintain a reducing atmosphere in the ladle; wait until the furnace slag turns white for more than 10 minutes and the temperature ≥1580 °C, stir with large - volume argon for more than 3 minutes and take a full - analysis sample. After the sample is returned, adjust the composition according to the following target values: C: 0.150 - 0.30%; Mn: 1.0 - 1.1%; Ni: 24.5 - 25.0%; Cr: 14.0 - 14.5%; Mo: 1.05 - 1.12%; V: 0.20 - 0.30%; 3) After the molten steel composition meets the requirements described in step 2), S ≤ 0.002%, ladle slag skimming is carried out, and the ladle temperature ≥ 1650 °C.

[0011] Preferably, the VOD furnace refining includes the following steps: 1) Skim the slag before entering the ladle to ensure that the exposed molten steel area ≥ 70%; 2) Carry out vacuum oxygen blowing operation after covering; 3) After stopping oxygen, break the vacuum and measure the temperature, add slag-making materials and deoxidizers: lime 30 - 40 kg / t of molten steel; calcium silicide 1 - 3 kg / t of molten steel, aluminum pellets 6 - 8 kg / t of molten steel; 4) After adding the slag materials, turn back the ladle cover car, evacuate and degas after covering, and keep the pressure ≤ 67 Pa for a holding time ≥ 15 minutes; 5) Measure the temperature after breaking the vacuum, return to the LF furnace for reduction with Al powder or calcium silicide powder, the white slag time ≥ 20 min, take gas samples, the target O ≤ 20 ppm, if the temperature ≥ 1630 °C, then lift out and skim the slag, skim the slag until the slag thickness ≤ 100 mm, feed Al, and then add metallic titanium (adjusted according to the internal control standard), stir with argon for 5 minutes after adding metallic titanium and take a full analysis sample; 6) After the composition is qualified, soft blow, insert ferroboron wrapped with aluminum foil 10 minutes before tapping; 7) Tapping.

[0012] More preferably, in step 5) of the VOD furnace refining, feed Al according to the internal control standard, in step 6), add ferroboron wrapped with aluminum foil according to the internal control standard, and the internal control standard: C: ≤ 0.03%; Mn: ≤ 1.30%; Si: ≤ 0.5%; S: ≤ 0.002%; P: ≤ 0.035%; Cr: 13.5 - 15.0%; Al: 0.13 - 0.28%; Ti: 2.00 - 2.30%; Ni: 24.3 - 25.0%; B: 0.004 - 0.007%; Mo: 1.05 - 1.15%; V: 0.20 - 0.30%; the balance is Fe.

[0013] More preferably, the soft blow time in step 6) of the VOD furnace refining ≥ 20 min.

[0014] More preferably, in step 7) of the VOD furnace refining, the tapping temperature: 1520 °C - 1540 °C.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The process of the present invention reduces the electroslag remelting process flow, shortens the process steps, and improves production efficiency.

[0016] The process of the present invention reduces the electroslag remelting process flow and reduces the electroslag cost by 2000 - 3500 yuan per ton.

[0017] Before electroslag remelting, it is necessary to cut the head and tail of the consumable electrode and polish the surface, with a metal utilization rate loss of about 3 - 5%. The smelting process proposed in this solution can well avoid the above metal losses.

[0018] The process proposed by the present invention effectively avoids the uneven composition of the head and tail of the ingot caused by element burning loss during the electroslag remelting process. Specific Embodiments

[0019] The following will further describe the present invention in combination with specific embodiments, and the advantages and features of the present invention will become clearer as the description progresses. However, the embodiments are only exemplary and do not constitute any limitation to the scope of the present invention. Those skilled in the art should understand that without departing from the spirit and scope of the present invention, the details and forms of the technical solutions of the present invention can be modified or replaced, but such modifications and replacements all fall within the protection scope of the present invention.

[0020] The chemical composition standard of A286 alloy is: C: ≤0.08%; Mn: ≤2.00%; Si: ≤1.0%; S: ≤0.03%; P: ≤0.04%; Cr: 13.50 - 16.00%; Al: ≤0.35%; Ti: 1.85 - 2.35%; Ni: 24.00 - 27.00%; B: 0.001 - 0.010%; Mo: 1.00 - 1.50%; Fe: balance; V: 0.10 - 0.50%.

[0021] The internal control standard of the chemical composition of A286 alloy in the embodiments of the present application is: C: ≤0.03%; Mn: ≤1.30%; Si: ≤0.5%; S: ≤0.002%; P: ≤0.035%; Cr: 13.5 - 15.0%; Al: 0.13 - 0.28%; Ti: 2.00 - 2.30%; Ni: 24.3 - 25.0%; B: 0.004 - 0.007%; Mo: 1.05 - 1.15%; V: 0.20 - 0.30%; the balance is Fe.

[0022] Example 1 A method for smelting a Fe - Ni - based alloy, comprising the following steps: (1) Electric furnace smelting 1) The full melting temperature of the furnace charge: 1580°C. Add carbonized rice husk to the furnace at a dosage of 25 kg / 20 t of molten steel to avoid slag crust formation.

[0023] (2) Tapping temperature T: 1680 °C, C: 1.4%.

[0024] (2) AOD furnace refining (1) The temperature of the AOD furnace before charging the molten steel is 900 °C. The gas supply parameters should meet P 氧 : 1.6 MPa, P 氩 : 1.6 MPa.

[0025] (2) Before charging the molten steel, Ar = 600 Nm 3 / h, and the cooling gas flow rate is 180 Nm 3 / h.

[0026] (3) After the molten steel is charged into the AOD furnace, samples are taken for analysis after blowing Ti and Si. Ti: 0.1%; Si: 0.13%; Skimming treatment.

[0027] (4) During AOD decarburization, the total gas flow rate is controlled at 1300 Nm 3 / h.

[0028] (5) C: 0.25%, adding Al: 100 kg for reduction.

[0029] (6) After the reduction is completed, 90% of the slag is skimmed. For the secondary reduction, 350 kg of quicklime, 200 kg of fluorite, and 80 kg of Al ingots are added as the reducing slag materials, and the reduction time is 8 minutes.

[0030] (7) AOD tapping composition: C: 0.20%; P: 0.03%; S: 0.002%; Si: 0.2%; Cr: 13.8%; Ni: 24.2%; Mo: 1.10%.

[0031] (3) LF furnace refining (1) After the molten steel arrives, adjust the argon flow rate to increase the temperature by power supply and adjust the fluidity of the slag.

[0032] (2) Add 20 kg of aluminum pellets appropriately for diffusion deoxidation to maintain a reducing atmosphere in the ladle. The slag turns white for 12 minutes, and the temperature is 1600 °C. Stir with large argon for 3 minutes to take a complete analysis sample.

[0033] (3) LF tapping composition: C: 0.21%; Mn: 1.1%; Ni: 24.5%; Cr: 14.0%; Mo: 1.05%; V: 0.20%. S: 0.001%, lift the ladle to skim the slag, and the ladle temperature is 1658 °C.

[0034] (4) VOD furnace refining (1) Skim the slag before charging into the ladle, exposing 80% of the molten steel area.

[0035] (2) After covering, perform vacuum oxygen blowing operation. 3) After stopping oxygen supply, evacuate the air and measure the temperature, then add slag-making materials and deoxidizers: 600 kg of lime; 40 kg of calcium silicide lumps, and 120 kg of aluminum pellets.

[0036] 4) After adding the slag materials, turn back the ladle cover car, cover the ladle and then evacuate and degas under vacuum. Maintain at 65 Pa for 15 minutes. 5) After evacuating the air, measure the temperature, return to the LF furnace and add 12 kg of Al powder for reduction. The white slag time is 20 min. Take a gas sample, O: 20 ppm, temperature 1635 °C. Lift out and skim the slag until the slag thickness is 80 mm. Feed Al into the furnace according to the internal control standard, and add metallic titanium after feeding Al.

[0037] 6) After the composition is qualified, soft blow for 24 min, and insert ferroboron wrapped with aluminum foil (added according to the internal control standard) 10 min before tapping.

[0038] 7) Tapping temperature: 1530 °C.

[0039] 8) The total furnace charge is 20 t, and 10 ingots of 2 t are cast.

[0040] Example 2 A method for smelting a Fe-Ni-based alloy, comprising the following steps: (1) Electric furnace smelting 1) The full melting temperature of the furnace charge: 1585 °C. Add 27 kg of carbonized rice husk into the furnace to prevent the slag from crusting.

[0041] 2) Tapping temperature T: 1683 °C, C: 1.5%.

[0042] (2) AOD furnace refining 1) The furnace temperature of the AOD furnace before steel charging is 910 °C. The gas supply parameters should meet P 氧 : 1.6 MPa, P 氩 : 1.6 MPa.

[0043] 2) Before steel charging, Ar = 600 Nm 3 ∕h, and the cooling gas flow rate is 200 Nm 3 ∕h.

[0044] 3) After the molten steel is charged into the AOD furnace, blow Ti and Si and then take a sample for analysis, Ti: 0.12%; Si: 0.11%, and carry out slag skimming treatment.

[0045] 4) During AOD decarburization, the total gas flow rate is controlled at 1300 Nm 3 ∕h.

[0046] 5) C: 0.24%, add 100 kg of Al for reduction.

[0047] 6) 90% of the slag is removed after the reduction is completed. For the secondary reduction, 350 kg of quicklime, 200 kg of fluorite, and 80 kg of Al ingots are added as the reduction slag materials. The reduction time is 10 minutes.

[0048] 7) The chemical composition of the molten steel tapped from AOD is as follows: C: 0.21%; P: 0.03%; S: 0.002%; Si: 0.2%; Cr: 13.9%; Ni: 24.3%; Mo: 1.10%.

[0049] (3)Refining in LF furnace 1) After the molten steel arrives, adjust the argon flow rate to increase the temperature by applying power and adjust the fluidity of the slag.

[0050] 2) Add 20 kg of aluminum pellets for diffusion deoxidation to maintain a reducing atmosphere in the ladle. The slag turns white in 12 minutes and the temperature is 1600 °C. Take a complete analysis sample after stirring with large argon flow for 4 minutes.

[0051] 3) The chemical composition of the molten steel tapped from LF is as follows: C: 0.21%; Mn: 1.1%; Ni: 24.5%; Cr: 14.0%; Mo: 1.10%; V: 0.20%. S: 0.001%. Lift the ladle to remove the slag. The temperature of the lifted ladle is 1658 °C.

[0052] (4)Refining in VOD furnace 1) Remove the slag before entering the ladle, exposing 80% of the molten steel surface area.

[0053] 2) After covering, perform vacuum oxygen blowing operation.

[0054] 3) After stopping the oxygen, break the vacuum and measure the temperature. Add slag-making materials and deoxidizers: 600 kg of lime; 40 kg of calcium silicide, and 120 kg of aluminum pellets.

[0055] 4) After adding the slag materials, drive the ladle cover car back, cover the ladle and then evacuate for vacuum degassing. Maintain the pressure at 65 Pa for 18 minutes. 5) After breaking the vacuum, measure the temperature. Return to the LF furnace and add 15 kg of Al powder for reduction. The white slag time is 21 min. Take a gas sample. O: 18 ppm. Lift out the ladle and remove the slag when the temperature is 1638 °C. Remove the slag until the slag thickness is 80 mm. Feed Al into the furnace according to the internal control standard. After feeding Al, add metallic titanium.

[0056] 6) After the chemical composition is qualified, perform soft blowing for 25 min. Insert ferroboron wrapped with aluminum foil (added according to the internal control standard) 10 minutes before tapping.

[0057] 7) Tapping temperature: 1535 °C.

[0058] 8) The total furnace charge is 20 t, and 10 ingots of 2 t are cast.

[0059] The process route of the comparative example is electric furnace + AOD + LF + VOD + electroslag remelting. The steps of electric furnace + AOD + LF + VOD are the same as those in Example 1 and will not be repeated below. The main process parameters of electroslag remelting (based on a 2t electroslag ingot) 1) Slag system: CaF 2 : Al 2 O 3 : CaO = 75%: 15%: 10%.

[0060] 2) Slag amount: 72 - 80 kg.

[0061] 3) Electrical parameters: Voltage: 60 - 66 V, Current: 8300 - 9300 A.

[0062] 4) The following shows the electroslag remelting parameters of the comparative example.

[0063] Comparative Example 1: The slag system is CaF 2 : Al 2 O 3 : CaO = 75%: 15%: 10%, the slag amount is 72 kg, the voltage is 65 V, and the current is 8400 A; Comparative Example 2: The slag system is CaF 2 : Al 2 O 3 : CaO = 75%: 15%: 10%, the slag amount is 76 kg, the voltage is 64 V, and the current is 8800 A; Details not described above except for process parameters are conventional operations in this industry and will not be elaborated here.

[0064] The following shows the comparison of case results: 1. Comparison of inclusion levels is shown in Table 1; 2. Comparison of easily burned components is shown in Table 2; 3. Ingot yield and cost. The example is produced by the process of the present invention, and the comparative example is produced by the traditional smelting method of electroslag remelting.

[0065] Table 1. Comparison of inclusion levels

[0066] Table 1 shows that the inclusions in the steel ingots produced by the present invention are comparable to those produced through the electroslag remelting process.

[0067] Table 2. Comparison of easily burned components

[0068] Table 2 shows that the composition of the steel ingots produced by the present invention avoids the phenomenon of uneven composition at the head and tail of the steel ingot caused by the inconsistent burning loss law of easily burned elements in the electroslag remelting process at the head and tail of the steel ingot.

[0069] Ingot yield and cost The smelting method of Comparative Example 1 first produces consumable electrode bars and then undergoes electroslag remelting. Before electroslag remelting, the consumable electrodes need to be cut at both ends and the surface polished, resulting in a metal utilization rate loss of about 3-5%. Moreover, the cost per ton of steel after electroslag remelting is 2,000-3,500 yuan. The smelting process proposed in this solution can well avoid the above metal losses and smelting costs, while reducing the process flow and improving the process production efficiency.

Claims

1. A method for smelting an iron-nickel based alloy, characterized in that: The following steps are involved: Electric furnace smelting; AOD furnace refining; LF furnace refining; VOD furnace refining; ingot casting; after the VOD furnace refining step, there is no need for electroslag remelting operation, and the obtained molten steel can be directly cast into ingots.

2. The smelting method of an iron-nickel based alloy according to claim 1, characterized in that: The electric furnace smelting steps are as follows: 1) The full melting temperature of the charge is > 1550°C, and carbonized rice husks are added to the furnace to avoid slag crusting; 2) Take samples and analyze all elements to provide reference for the initial adjustment of AOD composition; 3) Steel tapping temperature T≥1650℃, C≥1.2%.

3. The smelting method of an iron-nickel based alloy according to claim 2, characterized in that: In the electric furnace smelting step 1), the amount of carbonized rice husk added is 20-40 kg / 20 t of molten steel.

4. The method for smelting an iron-nickel-based alloy according to claim 1, characterized in that: In the AOD furnace refining step, full Al reduction is first adopted in the reduction period without adding Si; 300-400 kg / 20 t molten steel of reducing slag lime, 100-300 kg / 20 t molten steel of fluorite, and 2-4 kg / t molten steel of Al ingots or Al particles are added in the secondary reduction.

5. The smelting method of an iron-nickel based alloy according to claim 4, characterized in that: The AOD furnace refining steps are as follows: 1) AOD furnace temperature before steel mixing ≥ 800℃; gas supply parameters should meet P 氧 ≥1.5MPa, P 氩 ≥1.5MPa; 2) Ar flow rate before adding steel is 500~700 Nm 3 ∕h, cooling air flow rate is 130~350 Nm 3 ∕h; 3) After the molten steel is added into the AOD furnace, Ti and Si are blown and then sampled for analysis. Ti≤0.25%, Si≤0.25% for slag removal; 4) During AOD decarburization, the total gas flow rate is controlled at 1100~1500 Nm 3 ∕h; 5) When C≤0.3%, add Al for reduction, and use full Al reduction during the reduction period without adding Si; 6) After the reduction is completed, the furnace is shaken to measure the temperature, sample, and remove slag ≥ 90%. For secondary reduction, 300-400 kg / 20t of molten steel of reducing slag, 100-300 kg / 20t of molten steel of fluorite, and 2-4 kg / t of molten steel of Al ingots or Al particles are added. The reduction time is > 5 minutes; 7) The target of steel composition control is: C: 0.150~0.30%; P: ≤0.035%; S: ≤0.003%; Si: ≤0.20%; Cr: 13.0~14.5%; Ni: 24.0~24.5%; Mo: 1.05~1.12%.

6. The smelting method of an iron-nickel based alloy according to claim 1, characterized in that: The LF furnace refining comprises the following steps: 1) After the molten steel is in place, adjust the argon flow rate to heat the furnace. During the heating process, add lime and fluorite to adjust the fluidity of the slag according to the actual situation; 2) Add appropriate amount of aluminum particles for diffusion deoxidation. It is required to add less and frequently to maintain the reducing atmosphere in the bag. When the slag turns white for more than 10 minutes and the temperature is ≥1580℃, stir with argon gas for more than 3 minutes to take a full analysis sample. After the sample is returned, adjust the composition according to the following target values: C: 0.150~0.30%; Mn: 1.0~1.1%; Ni: 24.5~25.0%; Cr: 14.0~14.5%; Mo: 1.05~1.12%; V: 0.20~0.30%; 3) After the composition of the molten steel meets the requirements of step 2), S≤0.002%, the ladle is deslagging, and the ladle temperature is ≥1650℃.

7. The method for smelting an iron-nickel-based alloy according to claim 1, characterized in that: The VOD furnace refining comprises the following steps: 1) Before entering the tank, remove the slag to ensure that the exposed molten steel area is ≥ 70%; 2) Perform vacuum oxygen blowing operation after covering; 3) After stopping the oxygen, measure the temperature in the air and add slag-making materials and deoxidizers: 30-40 kg / t of molten steel lime; 1-3 kg / t of molten steel calcium silicon blocks; 6-8 kg / t of molten steel aluminum particles; 4) After adding the slag, drive back to the tank cover car, cover it and vacuum degas, ≤67Pa for ≥15 minutes; 5) After breaking the air, measure the temperature, return the Al powder or calcium silicate powder to the LF furnace for reduction, the white slag time is ≥20min, take the gas sample, the target O≤20ppm, the temperature is ≥1630℃, then lift out the slag, and slag until the slag thickness is ≤100 mm, feed Al, and then add metal titanium, adjust it according to the internal control standard, and stir with argon for 5 minutes after adding metal titanium to take the full analysis sample; 6) After the composition is qualified, soft blowing is performed and ferroboron wrapped in aluminum foil is inserted 10 minutes before steelmaking; 7) Steel production.

8. The method for smelting an iron-nickel-based alloy according to claim 7, characterized in that: In the VOD furnace refining step 5), Al is fed according to the internal control standard. In step 6), the ferroboron wrapped in aluminum foil is added according to the internal control standard. The internal control standard is: C: ≤0.03%; Mn: ≤1.30%; Si: ≤0.5%; S: ≤0.002%; P: ≤0.035%; Cr: 13.5~15.0%; Al: 0.13~0.28%; Ti: 2.00~2.30%; Ni: 24.3~25.0%; B: 0.004~0.007%; Mo: 1.05~1.15%; V: 0.20~0.30%; the balance is Fe.

9. The method for smelting an iron-nickel-based alloy according to claim 7, characterized in that: The soft blowing time of the VOD furnace refining step 6) is ≥ 20 min.

10. The method for smelting an iron-nickel-based alloy according to claim 7, characterized in that: In the VOD furnace refining step 7), the tapping temperature is 1520°C to 1540°C.

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