A production method of nano-steel electroslag remelting

Abstract

The application discloses a nano-steel electroslag remelting electroslag slag system ratio and belongs to the technical field of electroslag remelting. The chemical elements of the electrode ingot are controlled according to mass percentage as follows: C: 0.035-0.055%, Si: 0.15-0.35%, Mn: 0.65-0.95%, P: 0.030% or less, S: 0.020% or less, Cr: 0.3-0.6%, Ni: 4.0-4.5%, Ti: 0.015-0.035%, Al: 0.015-0.055%, Nb: 0.035-0.065%, Cu: 0.95-1.30% and Mo: 0.45-0.65%, and the balance is iron and inevitable impurities. The chemical elements of the electroslag remelting slag system include CaF2, CaO, MgO, Al2O3, TiO2 and La2O3. The obtained nano-steel is uniform in chemical composition of each part and low in non-metallic inclusion quantity.

Description

Technical Field

[0001] This invention belongs to the field of electroslag remelting technology and relates to a production method for electroslag remelting of nano-steel. Background Technology

[0002] Nanostructured steel typically refers to high-strength steel with a nanoscale structure, exhibiting nanoscale characteristics such as a large interfacial area to volume ratio (Sv) exceeding 0.04 nm to 1 nm. Traditional nanostructured steels usually possess ultrafine grains and low uniform tensile elongation.

[0003] Nanosteel possesses significant advantages and promising applications. Its high strength and lightweight properties make it a key research focus in the automotive manufacturing sector, as it can replace existing materials to make cars lighter, safer, and more durable. The strength and stability of nanosteel can meet the material requirements of the aerospace industry. Its high strength can be applied to wind turbines, solar cells, electric vehicle batteries, fuel cells, and other fields in the new energy industry, greatly improving their efficiency and lifespan.

[0004] Electroslag remelting is a key smelting process for producing high-end special steels and alloys, offering significant advantages in ingot quality and yield. Currently, the production process for nanosteel involves smelting and refining, ingot casting / continuous casting, rolling, and heat treatment. Overcoming key technological challenges in producing high-quality nanosteel through electroslag remelting is an effective means to increase market share. Summary of the Invention

[0005] The present invention aims to provide a production method for electroslag remelting of nanosteel, which can improve the overall yield of electroslag ingots and refine the grain size of nanosteel.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows:

[0007] A method for producing nano-steel by electroslag remelting includes the following steps:

[0008] (1) Electrode ingot smelting and preparation: The chemical elements of the electrode ingot are controlled by mass percentage as follows: C: 0.035-0.055%, Si: 0.15-0.35%, Mn: 0.65-0.95%, P≤0.030%, S≤0.020%, Cr: 0.3-0.6%, Ni: 4.0-4.5%, Ti: 0.015-0.035%, Al: 0.015-0.055%, Nb: 0.035-0.065%, Cu: 0.95-1.30%, Mo: 0.45-0.65%, with the balance being iron and unavoidable impurities;

[0009] (2) Preparation of electroslag remelting slag system: The electroslag remelting slag system is heated from room temperature to 800-900℃ and kept at that temperature for 4.5-5.5h; the chemical elements of the electroslag remelting slag system include: CaF2, CaO, MgO, Al2O3, TiO2, La2O3;

[0010] (3) Preparation of protective gas: Argon gas is introduced into the equipment before and after the start of electroslag treatment to serve as a protective atmosphere;

[0011] (4) Assemble the equipment for electroslag remelting.

[0012] The electroslag remelting slag system has a viscosity of 0.055–0.060 Pa·S at 1500℃ and a viscosity of 0.045–0.050 Pa·S at 1600℃.

[0013] The addition rate of the electroslag remelting slag system during the arc initiation period is 1.5–2.0 kg / min, and the addition rate during the stabilization period is 2.5–3.0 kg / min.

[0014] The flow rate of argon gas during the electroslag remelting slag-forming period is 180–220 L / min, the flow rate of argon gas during the remelting period is 120–150 L / min, and the flow rate of argon gas during the feeding period is 50–100 L / min.

[0015] The voltage during the arc initiation period of the electroslag remelting is 16-18V and the current is 1.6-1.8kA; the voltage during the slag formation period is 16-28V and the current is 1.6-2.4kA; the voltage during the remelting period is 28-32V and the current is 2.4-2.7kA; and the voltage during the feeding period is 23-32V and the current is 2.0-2.6kA.

[0016] The electroslag remelting slag system comprises the following components by mass percentage: CaF2: 43-53%, CaO: 12-17%, Al2O3: 15-25%, TiO2: 5-8%, MgO: 1-2%, La2O3: 5-7%, SiO2 ≤ 0.5%, with the remainder being unavoidable impurities.

[0017] Compared with existing technologies, this invention has the following advantages: The electroslag remelting slag system used in this invention incorporates 1-2% MgO, which forms a semi-solidified slag film on its surface after melting. This effectively prevents the transfer of oxygen, hydrogen, nitrogen, etc., from the gas into the slag, while also slowing down the decrease in slag pool temperature. Adding 5-8% TiO2 to the slag system effectively reduces the burn-off of Ti elements in the electrodes, increasing Ti yield and saving costs. Adding 5-7% La2O3 to the slag system effectively pins the movement of grain boundaries (GBs), thereby achieving the effect of refining and stabilizing grains.

[0018] This invention reduces defects such as slag grooves, ripples, and roughness on the surface of nanosteel ingots, thereby improving the yield of nanosteel. The produced nanosteel has a uniform chemical composition in all parts, refines the nanosteel structure, effectively reduces the amount of non-metallic inclusions, and improves the purity of the steel. Attached Figure Description

[0019] Figure 1 These are microstructure morphology diagrams of the electroslag ingots obtained in Example 1 and Comparative Example 1 of the present invention;

[0020] Figure 2 These are microstructure images of the electroslag ingots obtained in Example 2 and Comparative Example 2 of the present invention.

[0021] Figure 3 These are microstructure images of the electroslag ingots obtained in Example 3 and Comparative Example 3 of the present invention.

[0022] Figure 4 These are microstructure images of the electroslag ingots obtained in Example 4 and Comparative Example 4 of the present invention.

[0023] Figure 5 These are microstructure images of the electroslag ingots obtained in Example 5 and Comparative Example 5 of the present invention.

[0024] Figure 6 These are microstructure images of the electroslag ingots obtained in Example 6 and Comparative Example 6 of the present invention.

[0025] Figure 7 The surface quality diagrams are of the electroslag ingots obtained in Example 1 and Comparative Example 1 of this invention.

[0026] Figure 8 The surface quality diagrams are of the electroslag ingots obtained in Example 2 and Comparative Example 2 of this invention.

[0027] Figure 9 The surface quality diagrams are of the electroslag ingots obtained in Example 3 and Comparative Example 3 of this invention.

[0028] Figure 10 The surface quality diagrams are of the electroslag ingots obtained in Example 4 and Comparative Example 4 of this invention.

[0029] Figure 11 The surface quality diagrams are of the electroslag ingots obtained in Example 5 and Comparative Example 5 of the present invention.

[0030] Figure 12 The surface quality diagrams are of the electroslag ingots obtained in Example 6 and Comparative Example 6 of the present invention. Detailed Implementation

[0031] Example 1: The production method of nano-steel electroslag remelting in this example includes the following steps:

[0032] (1) Electrode ingot preparation: The chemical element percentage of the electrode ingot is controlled as follows: C: 0.035%, Si: 0.15%, Mn: 0.65%, P≤0.015%, S≤0.015%, Cr: 0.3%, Ni: 4.0%, Ti: 0.015%, Al: 0.015%, Nb: 0.035%, Cu: 0.95%, Mo: 0.45%, with the balance being iron and unavoidable impurities;

[0033] (2) Preparation of electroslag remelting slag system: Before smelting, weigh the electroslag remelting slag system according to the following ratio and mix them to prepare an electroslag billet: CaF2: 43%, CaO: 17%, Al2O3: 25%, TiO2: 8%, MgO: 1%, La2O3: 6%, SiO2≤0.5%; use a muffle furnace to heat from room temperature to 900℃ and hold for 5.5h;

[0034] The addition rate of electroslag remelting slag during the arc initiation period is 1.5 kg / min, and the addition rate during the stabilization period is 3.0 kg / min.

[0035] (3) Preparation of protective gas: Ar gas is introduced into the equipment to serve as a protective atmosphere. The gas flow rate during the slag formation period is 200 L / min, the gas flow rate during the remelting period is 150 L / min, and the gas flow rate during the feeding period is 60 L / min.

[0036] (4) Electroslag remelting: The equipment is assembled for electroslag remelting. The voltage is controlled at 16V and the current is controlled at 1.7kA during the arc initiation period; the voltage is controlled at 22V and the current is controlled at 2.0kA during the slag formation period; the voltage is controlled at 30V and the current is controlled at 2.4kA during the melting period; and the voltage is controlled at 25V and the current is controlled at 2.2kA during the feeding period.

[0037] Comparative Example 1: A comparative method for producing nano-steel by electroslag remelting, comprising the following steps:

[0038] (1) Electrode ingot preparation: The chemical element percentage of the electrode ingot is controlled as follows: C: 0.035%, Si: 0.15%, Mn: 0.65%, P≤0.015%, S≤0.015%, Cr: 0.3%, Ni: 4.0%, Ti: 0.015%, Al: 0.015%, Nb: 0.035%, Cu: 0.95%, Mo: 0.45%, with the balance being iron and unavoidable impurities;

[0039] (2) Preparation of electroslag remelting slag system: Before smelting, weigh the electroslag remelting slag system according to the following ratio and mix them to make an electroslag billet: CaF2: 65%, CaO: 15%, Al2O3: 20%. Use a muffle furnace to raise the temperature from room temperature to 900℃ and keep it at that temperature for 5.5h.

[0040] (3) Preparation of protective gas: Ar gas is introduced into the equipment to serve as a protective atmosphere, and the flow rate is set to 200L / min;

[0041] (4) Electroslag remelting: The assembly equipment is used for electroslag remelting. The voltage for electroslag remelting is controlled at 20V and the current is controlled at 2.5kA.

[0042] The ingots obtained from the examples and comparative examples were analyzed. The results of the number of non-metallic inclusions at different locations are shown in Table 1, the results of chemical element detection at different locations are shown in Table 2, and the results of the microstructure morphology detection of the electroslag ingots are as follows: Figure 1 As shown, the surface quality test results of electroslag ingots are as follows: Figure 7 As shown.

[0043] As shown in Table 1, the number density of non-metallic inclusions at the bottom, middle, and top of the electroslag in Example 1 was reduced by 32.8%, 35.8%, and 40.3%, respectively, compared to Comparative Example 1.

[0044] Depend on Figure 1 It can be seen that the present invention significantly refines the microstructure and grain size of the electroslag ingot. From Figure 7 It can be seen that the electroslag ingot produced by the present invention has no obvious defects such as slag grooves, ripples, or surface roughness, which effectively improves the surface quality of the electroslag ingot.

[0045] Table 1 Results of the number of non-metallic inclusions at different locations

[0046]

[0047] Table 2. Results of typical chemical element detection at different locations

[0048]

[0049] Example 2: The production method of nano-steel electroslag remelting in this example includes the following steps:

[0050] (1) Electrode ingot preparation: The chemical element percentage of the electrode ingot is controlled as follows: C: 0.035%, Si: 0.15%, Mn: 0.65%, P≤0.015%, S≤0.015%, Cr: 0.3%, Ni: 4.0%, Ti: 0.015%, Al: 0.015%, Nb: 0.035%, Cu: 0.95%, Mo: 0.45%, with the balance being iron and unavoidable impurities;

[0051] (2) Preparation of electroslag remelting slag system: Before smelting, weigh the electroslag remelting slag system according to the following ratio and mix them to prepare an electroslag billet: CaF2: 53%, CaO: 17%, Al2O3: 15%, TiO2: 8%, MgO: 2%, La2O3: 5%, SiO2≤0.5%; use a muffle furnace to raise the temperature from room temperature to 850℃ and hold for 4.5h;

[0052] The electroslag remelting slag is added at a rate of 2.0 kg / min during the arc initiation period and 2.5 kg / min during the stabilization period.

[0053] (3) Preparation of protective gas: Ar gas is introduced into the equipment to serve as a protective atmosphere. The gas flow rate during the slag formation period is 220 L / min, the gas flow rate during the remelting period is 120 L / min, and the gas flow rate during the feeding period is 60 L / min.

[0054] (4) Electroslag remelting: The equipment is assembled for electroslag remelting. The voltage is controlled at 18V and the current is controlled at 1.8kA during the arc initiation period; the voltage is controlled at 25V and the current is controlled at 2.2kA during the slag formation period; the voltage is controlled at 32V and the current is controlled at 2.7kA during the melting period; and the voltage is controlled at 28V and the current is controlled at 2.6kA during the feeding period.

[0055] Comparative Example 2: A method for producing comparative nano-steel by electroslag remelting, comprising the following steps:

[0056] (1) Electrode ingot preparation: The chemical element percentage of the electrode ingot is controlled as follows: C: 0.035%, Si: 0.15%, Mn: 0.65%, P≤0.015%, S≤0.015%, Cr: 0.3%, Ni: 4.0%, Ti: 0.015%, Al: 0.015%, Nb: 0.035%, Cu: 0.95%, Mo: 0.45%, with the balance being iron and unavoidable impurities;

[0057] (2) Preparation of electroslag remelting slag system: Before smelting, weigh the electroslag remelting slag system according to the following ratio and mix them to make an electroslag billet: CaF2: 65%, CaO: 15%, Al2O3: 20%. Use a muffle furnace to raise the temperature from room temperature to 900℃ and keep it at that temperature for 5.5h.

[0058] (3) Preparation of protective gas: Ar gas is introduced into the equipment to serve as a protective atmosphere, and the flow rate is set to 200L / min;

[0059] (4) Electroslag remelting: The assembly equipment is used for electroslag remelting. The voltage for electroslag remelting is controlled at 20V and the current is controlled at 2.5kA.

[0060] The ingots obtained from the examples and comparative examples were analyzed. The results of the number of non-metallic inclusions at different locations are shown in Table 3, the results of chemical element detection at different locations are shown in Table 4, and the results of the microstructure morphology detection of the electroslag ingots are as follows: Figure 2 As shown.

[0061] As shown in Table 3, the number density of non-metallic inclusions at the bottom, middle, and top of the electroslag in Example 2 was reduced by 25.8%, 34.2%, and 35.7% respectively compared to Comparative Example 2.

[0062] Depend on Figure 2It can be seen that the present invention significantly refines the microstructure and grain size of electroslag ingots.

[0063] Table 3 Results of the number of non-metallic inclusions at different locations

[0064]

[0065] Table 4. Results of typical chemical element detection at different locations

[0066]

[0067] Example 3: The production method of nano-steel electroslag remelting in this example includes the following steps:

[0068] (1) Electrode ingot preparation: The chemical element percentage of the electrode ingot is controlled as follows: C: 0.035%, Si: 0.15%, Mn: 0.65%, P≤0.015%, S≤0.015%, Cr: 0.3%, Ni: 4.0%, Ti: 0.015%, Al: 0.015%, Nb: 0.035%, Cu: 0.95%, Mo: 0.45%, with the balance being iron and unavoidable impurities;

[0069] (2) Preparation of electroslag remelting slag system: Before smelting, weigh the electroslag remelting slag system according to the following ratio and mix them to prepare an electroslag billet: CaF2: 50%, CaO: 12%, Al2O3: 24%, TiO2: 5%, MgO: 2%, La2O3: 7%, SiO2≤0.5%; use a muffle furnace to heat from room temperature to 800℃ and hold for 4.5h;

[0070] The electroslag remelting slag is added at a rate of 1.5 kg / min during the arc initiation period and 2.5 kg / min during the stabilization period.

[0071] (3) Preparation of protective gas: Ar gas is introduced into the equipment to serve as a protective atmosphere. The gas flow rate during the slag formation period is 180 L / min, the gas flow rate during the remelting period is 120 L / min, and the gas flow rate during the feeding period is 50 L / min.

[0072] (4) Electroslag remelting: The equipment is assembled for electroslag remelting. The voltage is controlled at 16V and the current is controlled at 1.6kA during the arc initiation period; the voltage is controlled at 16V and the current is controlled at 1.6kA during the slag formation period; the voltage is controlled at 28V and the current is controlled at 2.4kA during the melting period; and the voltage is controlled at 23V and the current is controlled at 2.0kA during the feeding period.

[0073] Comparative Example 3: A comparative method for producing nano-steel by electroslag remelting, comprising the following steps:

[0074] (1) Electrode ingot preparation: The chemical element percentage of the electrode ingot is controlled as follows: C: 0.035%, Si: 0.15%, Mn: 0.65%, P≤0.015%, S≤0.015%, Cr: 0.3%, Ni: 4.0%, Ti: 0.015%, Al: 0.015%, Nb: 0.035%, Cu: 0.95%, Mo: 0.45%, with the balance being iron and unavoidable impurities;

[0075] (2) Preparation of electroslag remelting slag system: Before smelting, weigh the electroslag remelting slag system according to the following ratio and mix them to make an electroslag billet: CaF2: 65%, CaO: 15%, Al2O3: 20%. Use a muffle furnace to raise the temperature from room temperature to 900℃ and keep it at that temperature for 5.5h.

[0076] (3) Preparation of protective gas: Ar gas is introduced into the equipment to serve as a protective atmosphere, and the flow rate is set to 200L / min;

[0077] (4) Electroslag remelting: The assembly equipment is used for electroslag remelting. The voltage for electroslag remelting is controlled at 20V and the current is controlled at 2.5kA.

[0078] The ingots obtained from the examples and comparative examples were analyzed. The results of the number of non-metallic inclusions at different locations are shown in Table 5, the results of chemical element detection at different locations are shown in Table 6, and the results of the microstructure morphology detection of the electroslag ingots are as follows: Figure 3 As shown, the surface quality test results of electroslag ingots are as follows: Figure 9 As shown.

[0079] As shown in Table 5, the number density of non-metallic inclusions at the bottom, middle, and top of the electroslag in Example 3 was reduced by 71.8%, 22.4%, and 30.2% respectively compared to Comparative Example 3.

[0080] Depend on Figure 3 It can be seen that the present invention significantly refines the microstructure and grain size of the electroslag ingot. From Figure 9 It can be seen that the electroslag ingot produced by the present invention has no obvious defects such as slag grooves, ripples, or surface roughness, which effectively improves the surface quality of the electroslag ingot.

[0081] Table 5 Results of the number of non-metallic inclusions at different locations

[0082]

[0083] Table 6. Results of typical chemical element detection at different locations

[0084]

[0085] Example 4: The production method of nano-steel electroslag remelting in this example includes the following steps:

[0086] (1) Electrode ingot preparation: The chemical element percentage of the electrode ingot is controlled as follows: C: 0.035%, Si: 0.15%, Mn: 0.65%, P≤0.015%, S≤0.015%, Cr: 0.3%, Ni: 4.0%, Ti: 0.015%, Al: 0.015%, Nb: 0.035%, Cu: 0.95%, Mo: 0.45%, with the balance being iron and unavoidable impurities;

[0087] (2) Preparation of electroslag remelting slag system: Before smelting, weigh the electroslag remelting slag system according to the following ratio to prepare an electroslag billet: CaF2: 50%, CaO: 16%, Al2O3: 18.5%, TiO2: 7%, MgO: 1.5%, La2O3: 7%, SiO2≤0.05%; use a muffle furnace to raise the temperature from room temperature to 800℃ and hold for 4.5h;

[0088] The addition rate of electroslag remelting slag during the arc initiation period is 2.0 kg / min, and the addition rate during the stabilization period is 3.0 kg / min.

[0089] (3) Preparation of protective gas: Ar gas is introduced into the equipment to serve as a protective atmosphere. The gas flow rate during the slag formation period is 220 L / min, the gas flow rate during the remelting period is 150 L / min, and the gas flow rate during the feeding period is 100 L / min.

[0090] (4) Electroslag remelting: The equipment is assembled for electroslag remelting. The voltage is controlled at 18V and the current is controlled at 1.8kA during the arc initiation period; the voltage is controlled at 28V and the current is controlled at 2.4kA during the slag formation period; the voltage is controlled at 32V and the current is controlled at 2.7kA during the melting period; and the voltage is controlled at 32V and the current is controlled at 2.6kA during the feeding period.

[0091] Comparative Example 4: A comparative method for producing nano-steel by electroslag remelting, comprising the following steps:

[0092] (1) Electrode ingot preparation: The chemical element percentage of the electrode ingot is controlled as follows: C: 0.035%, Si: 0.15%, Mn: 0.65%, P≤0.015%, S≤0.015%, Cr: 0.3%, Ni: 4.0%, Ti: 0.015%, Al: 0.015%, Nb: 0.035%, Cu: 0.95%, Mo: 0.45%, with the balance being iron and unavoidable impurities;

[0093] (2) Preparation of electroslag remelting slag system: Before smelting, weigh the electroslag remelting slag system according to the following ratio and mix them to make an electroslag billet: CaF2: 65%, CaO: 15%, Al2O3: 20%. Use a muffle furnace to raise the temperature from room temperature to 900℃ and keep it at that temperature for 5.5h.

[0094] (3) Preparation of protective gas: Ar gas is introduced into the equipment to serve as a protective atmosphere, and the flow rate is set to 200L / min;

[0095] (4) Electroslag remelting: The assembly equipment is used for electroslag remelting. The voltage for electroslag remelting is controlled at 20V and the current is controlled at 2.5kA.

[0096] The ingots obtained from the examples and comparative examples were analyzed. The results of the number of non-metallic inclusions at different locations are shown in Table 7, the results of chemical element detection at different locations are shown in Table 8, and the results of the microstructure morphology detection of the electroslag ingots are as follows: Figure 4 As shown.

[0097] As shown in Table 7, the number density of non-metallic inclusions at the bottom, middle, and top of the electroslag in Example 4 was reduced by 52.4%, 23.2%, and 27.6% respectively compared to Comparative Example 4.

[0098] Depend on Figure 4 It can be seen that the present invention significantly refines the microstructure and grain size of electroslag ingots.

[0099] Table 7 Results of the number of non-metallic inclusions at different locations

[0100]

[0101] Table 8. Results of typical chemical element detection at different locations

[0102]

[0103] Example 5: The production method of nano-steel electroslag remelting in this example includes the following steps:

[0104] (1) Electrode ingot preparation: The chemical element percentage of the electrode ingot is controlled as follows: C: 0.040%, Si: 0.20%, Mn: 0.80%, P≤0.03%, S≤0.02%, Cr: 0.35%, Ni: 4.2%, Ti: 0.020%, Al: 0.030%, Nb: 0.050%, Cu: 1.05%, Mo: 0.53%, with the balance being iron and unavoidable impurities;

[0105] (2) Preparation of electroslag remelting slag system: Before smelting, weigh the electroslag remelting slag system according to the following ratio and mix them to prepare an electroslag billet: CaF2: 47%, CaO: 17%, Al2O3: 22%, TiO2: 8%, MgO: 1%, La2O3: 5%, SiO2≤0.5%; use a muffle furnace to raise the temperature from room temperature to 850℃ and hold for 5h;

[0106] The addition rate of electroslag remelting slag during the arc initiation period is 1.7 kg / min, and the addition rate during the stabilization period is 2.7 kg / min.

[0107] (3) Preparation of protective gas: Ar gas is introduced into the equipment to serve as a protective atmosphere. The gas flow rate during the slag formation period is 200 L / min, the gas flow rate during the remelting period is 135 L / min, and the gas flow rate during the feeding period is 75 L / min.

[0108] (4) Electroslag remelting: The equipment is assembled for electroslag remelting. The voltage is controlled at 17V and the current is controlled at 1.7kA during the arc initiation period; the voltage is controlled at 20V and the current is controlled at 2.0kA during the slag formation period; the voltage is controlled at 30V and the current is controlled at 2.6kA during the melting period; and the voltage is controlled at 28V and the current is controlled at 2.3kA during the feeding period.

[0109] Comparative Example 5: A comparative method for producing nano-steel by electroslag remelting, comprising the following steps:

[0110] (1) Electrode ingot preparation: The chemical element percentage of the electrode ingot is controlled as follows: C: 0.040%, Si: 0.20%, Mn: 0.80%, P≤0.03%, S≤0.02%, Cr: 0.35%, Ni: 4.2%, Ti: 0.020%, Al: 0.030%, Nb: 0.050%, Cu: 1.05%, Mo: 0.53%, with the balance being iron and unavoidable impurities;

[0111] (2) Preparation of electroslag remelting slag system: Before smelting, weigh the electroslag remelting slag system according to the following ratio and mix them to make an electroslag billet: CaF2: 65%, CaO: 15%, Al2O3: 20%. Use a muffle furnace to raise the temperature from room temperature to 900℃ and keep it at that temperature for 5.5h.

[0112] (3) Preparation of protective gas: Ar gas is introduced into the equipment to serve as a protective atmosphere, and the flow rate is set to 200L / min;

[0113] (4) Electroslag remelting: The assembly equipment is used for electroslag remelting. The voltage for electroslag remelting is controlled at 20V and the current is controlled at 2.5kA.

[0114] Depend on Figure 5 It can be seen that the present invention significantly refines the microstructure and grain size of the electroslag ingot. From Figure 11 It can be seen that the electroslag ingot produced by the present invention has no obvious defects such as slag grooves, ripples, or surface roughness, which effectively improves the surface quality of the electroslag ingot.

[0115] The ingots obtained from the examples and comparative examples were analyzed. The results of the number of non-metallic inclusions at different locations are shown in Table 9, the results of chemical element detection at different locations are shown in Table 10, and the results of the microstructure morphology detection of the electroslag ingots are as follows: Figure 5 As shown.

[0116] As shown in Table 9, the number density of non-metallic inclusions at the bottom, middle, and top of the electroslag in Example 5 was reduced by 37.0%, 20.4%, and 12.4% respectively compared to Comparative Example 5.

[0117] Depend on Figure 5 It can be seen that the present invention significantly refines the microstructure and grain size of electroslag ingots.

[0118] Table 9 Results of the number of non-metallic inclusions at different locations

[0119]

[0120] Table 10 Results of typical chemical element detection at different locations

[0121]

[0122] Example 6: The production method of nano-steel electroslag remelting in this example includes the following steps:

[0123] (1) Electrode ingot preparation: The chemical element percentage of the electrode ingot is controlled as follows: C: 0.045%, Si: 0.22%, Mn: 0.85%, P≤0.03%, S≤0.02%, Cr: 0.40%, Ni: 4.3%, Ti: 0.025%, Al: 0.035%, Nb: 0.055%, Cu: 1.1%, Mo: 0.54%, with the balance being iron and unavoidable impurities;

[0124] (2) Preparation of electroslag remelting slag system: Before smelting, weigh the electroslag remelting slag system according to the following ratio and mix them to prepare an electroslag billet: CaF2: 52%, CaO: 14%, Al2O3: 20%, TiO2: 7%, MgO: 1%, La2O3: 6%, SiO2≤0.5%; use a muffle furnace to heat from room temperature to 900℃ and hold for 5.5h;

[0125] The electroslag remelting slag is added at a rate of 1.5 kg / min during the arc initiation period and 2.5 kg / min during the stabilization period.

[0126] (3) Preparation of protective gas: Ar gas is introduced into the equipment to serve as a protective atmosphere. The gas flow rate during the slag formation period is 180 L / min, the gas flow rate during the remelting period is 120 L / min, and the gas flow rate during the feeding period is 50 L / min.

[0127] (4) Electroslag remelting: The equipment is assembled for electroslag remelting. The voltage is controlled at 16V and the current is controlled at 1.6kA during the arc initiation period; the voltage is controlled at 16V and the current is controlled at 1.6kA during the slag formation period; the voltage is controlled at 28V and the current is controlled at 2.4kA during the melting period; and the voltage is controlled at 23V and the current is controlled at 2.0kA during the feeding period.

[0128] Comparative Example 6: A comparative method for producing nano-steel by electroslag remelting, comprising the following steps:

[0129] (1) Electrode ingot preparation: The chemical element percentage of the electrode ingot is controlled as follows: C: 0.040%, Si: 0.20%, Mn: 0.80%, P≤0.03%, S≤0.02%, Cr: 0.35%, Ni: 4.2%, Ti: 0.020%, Al: 0.030%, Nb: 0.050%, Cu: 1.05%, Mo: 0.53%, with the balance being iron and unavoidable impurities;

[0130] (2) Preparation of electroslag remelting slag system: Before smelting, weigh the electroslag remelting slag system according to the following ratio and mix them to make an electroslag billet: CaF2: 65%, CaO: 15%, Al2O3: 20%. Use a muffle furnace to raise the temperature from room temperature to 900℃ and keep it at that temperature for 5.5h.

[0131] (3) Preparation of protective gas: Ar gas is introduced into the equipment to serve as a protective atmosphere, and the flow rate is set to 200L / min;

[0132] (4) Electroslag remelting: The assembly equipment is used for electroslag remelting. The voltage for electroslag remelting is controlled at 20V and the current is controlled at 2.5kA.

[0133] Depend on Figure 6 It can be seen that the present invention significantly refines the microstructure and grain size of the electroslag ingot. From Figure 12 It can be seen that the electroslag ingot produced by the present invention has no obvious defects such as slag grooves, ripples, or surface roughness, which effectively improves the surface quality of the electroslag ingot.

[0134] The ingots obtained from the examples and comparative examples were analyzed. The results of the number of non-metallic inclusions at different locations are shown in Table 11, the results of chemical element detection at different locations are shown in Table 12, and the results of the microstructure morphology detection of the electroslag ingots are as follows: Figure 6 As shown.

[0135] As shown in Table 11, the number density of non-metallic inclusions at the bottom, middle, and top of the electroslag in Example 6 was reduced by 52.9%, 55.8%, and 61.7% respectively compared to Comparative Example 6.

[0136] Table 11 Results of the number of non-metallic inclusions at different locations

[0137]

[0138] Table 12 Results of typical chemical element detection at different locations

[0139]

Claims

1. A method for producing nano-steel by electroslag remelting, characterized in that, Includes the following steps: (1) Electrode ingot smelting and preparation: The chemical elements of the electrode ingot are controlled by mass percentage as follows: C: 0.035-0.055%, Si: 0.15-0.35%, Mn: 0.65-0.95%, P≤0.030%, S≤0.020%, Cr: 0.3-0.6%, Ni: 4.0-4.5%, Ti: 0.015-0.035%, Al: 0.015-0.055%, Nb: 0.035-0.065%, Cu: 0.95-1.30%, Mo: 0.45-0.65%, with the balance being iron and unavoidable impurities; (2) Preparation of electroslag remelting slag system: The electroslag remelting slag system is heated from room temperature to 800-900℃ and kept at that temperature for 4.5-5.5h; the electroslag remelting slag system includes the following components by mass percentage: CaF2: 43-53%, CaO: 12-17%, Al2O3: 15-25%, TiO2: 5-8%, MgO: 1-2%, La2O3: 5-7%, SiO2≤0.5%, and the remainder are unavoidable impurities; (3) Preparation of protective gas: Argon gas is introduced into the equipment before and after the start of electroslag treatment to serve as a protective atmosphere; (4) Assemble the equipment for electroslag remelting.

2. The method for producing nano-steel by electroslag remelting according to claim 1, characterized in that: The electroslag remelting slag system has a viscosity of 0.055–0.060 Pa·S at 1500℃ and a viscosity of 0.045–0.050 Pa·S at 1600℃.

3. The method for producing nano-steel by electroslag remelting according to claim 2, characterized in that: The addition rate of the electroslag remelting slag system during the arc initiation period is 1.5–2.0 kg / min, and the addition rate during the stabilization period is 2.5–3.0 kg / min.

4. The method for producing nano-steel by electroslag remelting according to claim 3, characterized in that: The flow rate of argon gas during the electroslag remelting slag-forming period is 180–220 L / min, the flow rate of argon gas during the remelting period is 120–150 L / min, and the flow rate of argon gas during the feeding period is 50–100 L / min.

5. The method for producing nano-steel by electroslag remelting according to claim 4, characterized in that: The voltage during the arc initiation period of the electroslag remelting is 16-18V and the current is 1.6-1.8kA; the voltage during the slag formation period is 16-28V and the current is 1.6-2.4kA; the voltage during the remelting period is 28-32V and the current is 2.4-2.7kA; and the voltage during the feeding period is 23-32V and the current is 2.0-2.6kA.

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