Smelting method of copper-clad steel with high stability

Abstract

The invention discloses a smelting method of copper-clad steel with high stability, and belongs to the technical field of ferrous metallurgy. The technical problems that in the prior art, a copper-clad steel smelting final product high-quality production process is unstable, the production control difficulty is higher, and actual requirements cannot be met are solved. According to the smelting method of the copper-clad steel with the high stability performance, the capacity of a top-bottom combined blown converter is not larger than 120 t, the smelting technological process comprises the steps of molten iron pre-desulfurization, converter steelmaking, LF furnace primary refining, RH furnace vacuum circulation degassing refining, LF furnace secondary refining and continuous casting, in addition, the smelting components of the product comprise smaller than or equal to 0.04% of C, smaller than or equal to 0.010% of Si, smaller than or equal to 0.02% of Cr and the balance Fe and inevitable impurities. The special copper-clad steel product smelted through the method is stable in component, smooth in pouring and excellent in product performance.

Description

Technical Field

[0001] The invention relates to the technical field of iron and steel metallurgy, and in particular to a copper-clad steel smelting method with high stability. Background Art

[0002] Copper clad steel refers to a composite wire with copper wrapped around steel wire, that is, a copper layer wrapped around the outer surface of the steel wire. It uses the skin effect of low-voltage high-frequency signals to travel along the surface in the high-frequency area. Therefore, as long as the thickness of the copper layer reaches a certain range, the signal of a certain frequency band can be guaranteed to be transmitted. Copper plays the role of conducting weak electrical signals, and steel wire plays a supporting role.

[0003] It has the high strength of steel and the excellent conductivity and corrosion resistance of copper. Compared with pure copper wire, it has many advantages: under the same cross-section and state (hard state), the mechanical strength of copper-clad steel wire is twice that of solid copper wire, and it can withstand large impacts and loads. When used in places with harsh environmental conditions and frequent movement, it has high reliability and fatigue resistance, and a relatively long service life; copper-clad steel wire uses steel instead of copper, which greatly reduces the consumption of pure copper, thereby reducing costs, reducing density, and saving scarce copper resources; copper-clad steel wire has less attenuation than pure copper wire at high frequencies, and has low signal loss and high transmission efficiency at high frequencies; copper-clad steel wire can be made into wires with different tensile strengths and electrical conductivity, and it can almost contain all the typical mechanical and electrical properties of copper alloys. Therefore, copper-clad steel wire is a very practical and valuable conductive material.

[0004] Patent CN102134629B discloses a smelting method of low silicon and ultra-low sulfur steel, which mainly produces low silicon and ultra-low sulfur steel through the process of "full three removals" pretreatment of molten iron-decarbonization converter smelting-LF refining process, and its composition C≤0.04%, Si≤0.03%. Patent CN 106834591A discloses a smelting method of copper ladle, which adopts the method of converter-LF furnace-small square billet continuous casting, and its product composition C≤0.04%, Si≤0.04%. At the same time, the above two products do not have clear requirements for Cr, and the composition control of Si is significantly greater than the requirements of this product. It is well known that the lower the content requirements of Si and Cr in the steelmaking process, the more difficult it is to control production, especially when Si≤0.010% and Cr≤0.02%, it will cause the copper clad steel smelting high-quality final product quality manufacturing difficulty, the process is unstable, and it cannot meet actual needs. Summary of the invention

[0005] In view of the shortcomings and deficiencies in the prior art, the present invention provides a copper-clad steel smelting method with scientific and stable production process, smelting components of the final product C≤0.04%, Si≤0.010%, Cr≤0.02%, and high stability performance for producing products with stable quality and excellent performance.

[0006] To achieve the above objectives, the present invention is implemented by the following technical scheme: The copper-clad steel smelting method with high stability provided by the present invention, the smelting process includes molten iron pre-desulfurization → converter steelmaking → LF furnace preliminary refining → RH furnace vacuum cycle degassing refining → LF furnace secondary refining → continuous casting, and the specific steps include the following:

[0007] S1 / Pre-desulfurization of hot metal: pre-treat hot metal from blast furnace to reduce the sulfur content in hot metal to meet the quality requirements of steel in subsequent smelting processes. After the hot metal composition is qualified, slag is removed;

[0008] S2 / converter steelmaking, adding the pre-treated molten iron into the converter, slag making, oxygen blowing, steel tapping, the end point control target: C ≤ 0.080%, Cr ≤ 0.015%, steel tapping temperature 1610 ~ 1670 ℃;

[0009] S3 / LF furnace for preliminary refining. After the LF furnace arrives at the station, lime is added to synthesize slag without using fluorite. After the electrochemical slag is sent, calcium carbide and aluminum particles are used for deoxidation. The gray slag is tapped to the RH furnace;

[0010] S4 / RH furnace vacuum cycle degassing and refining, RH furnace refractory uses chrome-free refractory bricks, vacuum degree 8 ~ 15KPa, oxygen is blown from the gun, the oxygen blowing amount is calculated according to the carbon content and initial oxygen content, oxygen blowing ends and the cycle is circulated until the oxygen content of the molten steel is 180 ~ 450ppm, and then it continues to be maintained under high vacuum until the oxygen is fixed, aluminum particles are added according to the oxygen content, and the cycle ends after the aluminum particles are added;

[0011] S5 / LF furnace secondary refining, after returning to LF furnace, lime is added, synthetic slag is synthesized, power is continued to be supplied and aluminum particles are used for deoxidation, white slag is tapped, and the molten steel reaches the target temperature. According to the amount of molten steel, 1.5-2.5m / ton seamless calcium wire is fed, and the steel is soft-blown. After the soft-blowing is completed, the steel is poured;

[0012] S6 / continuous casting, the casting is protected throughout the casting process, the continuous casting tundish uses carbon-free insulation covering, and the crystallizer uses ultra-low carbon special protective slag.

[0013] Preferably, in step S1, the molten iron is desulfurized until the sulfur content of the molten iron is less than or equal to 0.003%, and the steel is tapped after the slag is cleaned.

[0014] Preferably, in step S2, the converter steelmaking: the converter capacity is not more than 120t; top and bottom combined blowing converter smelting is adopted;

[0015] Use scrap steel with low Cr content, and alloys such as medium carbon ferromanganese, aluminum ingots, and aluminum particles; use a ladle that can hold low silicon and low chromium molten steel, and the ladle wall and edge are clean;

[0016] After 10 to 50 tons of steel is tapped, 0.6 to 1.0 kg / ton of aluminum ingots is added. After 1 / 3 of the molten steel is tapped, 1.8 to 3.0 kg / ton of medium carbon ferromanganese is added. Use a slide plate and slag stopper to double slag. After tapping is completed, 2.0 to 3.0 kg / ton of top slag is added.

[0017] Preferably, in step S3, the LF furnace is initially refined, 7.0-9.0 kg / ton of lime and 3.0-4.5 kg / ton of synthetic slag are added after the LF furnace arrives at the station, and calcium carbide and aluminum particles are deoxidized in batches during power supply of the LF furnace.

[0018] Preferably, in step S4, the RH furnace is vacuum cycled for degassing and refining, the oxygen blowing amount is calculated according to the carbon content and the initial oxygen content, the oxygen content of the molten steel is 180-450 ppm after the oxygen blowing cycle ends for 3 minutes, and then the molten steel is kept in a high vacuum state, that is, the pressure is 133 Pa or less for 8-10 minutes.

[0019] The vacuum is maintained for 5 minutes to determine the oxygen content, and aluminum particles are added after maintaining the vacuum for 8 to 10 minutes according to the oxygen content. The cycle is then completed after 5 to 8 minutes.

[0020] Preferably, in step S5, the LF furnace is subjected to secondary refining, and after returning to the LF furnace, 1.5 to 3.0 kg / ton of lime and 1.5 to 2.5 kg / ton of synthetic slag are added, power is continued to be supplied and aluminum particles are used for deoxidation, white slag is tapped, and the molten steel is tapped after reaching the target temperature. According to the amount of molten steel, 1.5 to 2.5 m / ton of seamless calcium wire is fed, and the steel is soft-blown for tapping. After the soft blowing is completed, steel is poured.

[0021] Preferably, after soft blowing for ≥15 min, the ladle is hoisted to continuous casting according to the production rhythm.

[0022] Preferably, in step S6, continuous casting is performed, and the cross-section of the ingot is 180 mm×240 mm.

[0023] Preferably, in step S6, the continuous casting is performed at a ladle temperature of 1570-1580°C, a casting speed of 1.10-1.30 m / min, and a crystallizer water volume of 140±5 m 3 / h, crystallizer electromagnetic stirring 300A / 5Hz, end electromagnetic stirring 350A / 6Hz, secondary cooling water volume 0.34~0.36L / kg, use light pressure, among which 1#, 2#, 3#, and 4# rollers press down 1.8mm, 2mm, 2mm, and 2mm respectively, with a total pressure reduction of 7.8mm.

[0024] Preferably, the components of the obtained special copper-clad steel final product are C≤0.04%, Si≤0.010%, and Cr≤0.02%.

[0025] The present invention provides a copper-clad steel smelting method with high stability. It has the following beneficial effects:

[0026] The copper-clad steel smelting method with high stability of the present invention has a scientific and stable production process, and convenient and accurate operation and control. Through the entire process flow of molten iron pre-desulfurization → converter steelmaking → LF furnace preliminary refining → RH furnace vacuum cycle degassing refining → LF furnace secondary refining → continuous casting, each step synergizes to enhance the efficiency, so that the smelting composition of the final product finally obtained reaches C≤0.04%, Si≤0.010%, Cr≤0.02%, and high-quality and excellent performance products can be stably produced in batches. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0028] Example 1

[0029] A copper-clad steel smelting method with high stability performance uses a 100t top and bottom combined blowing converter. The specific process flow is as follows: the smelting process flow includes molten iron pre-desulfurization → converter steelmaking → LF furnace preliminary refining → RH furnace vacuum cycle degassing refining → LF furnace secondary refining → continuous casting. The specific steps include: product composition C: ≤0.04%, Si: ≤0.010%, Cr: ≤0.02%, stable composition, smooth production and excellent product performance.

[0030] This is achieved specifically through the following technical solutions:

[0031] S1. Pre-desulfurization of molten iron: pre-treat the blast furnace molten iron. After the molten iron composition is qualified, the final sulfur content of the molten iron is 0.003%. Steel is tapped after the slag is cleaned.

[0032] S2. For converter steelmaking, use scrap steel produced by our factory, control the converter end composition and tapping temperature, control the amount of slag when tapping, and add appropriate amount of alloy and top slag.

[0033] The pretreated molten iron is added to the converter, and top and bottom combined blowing converter is used for smelting, slag making, oxygen blowing and steel tapping. The end point control target is: converter end point C 0.0046%, Mn 0.08%, P 0.008%, S 0.004%, Ni 0.009%, Cr0.007%, Cu 0.018%, steel tapping temperature 1644℃, 230kg of medium carbon ferromanganese, 90kg of aluminum ingot and 215kg of top slag are added during steel tapping.

[0034] S3. LF furnace is used for preliminary refining. After the LF furnace arrives at the station, 810kg of lime and 355kg of synthetic slag are added. During power transmission, 50kg of calcium carbide and 40kg of aluminum particles are removed in batches until gray-white slag is used for steelmaking. The steelmaking temperature is 1710℃ and the oxygen content is 33ppm. The ladle is then hoisted to the RH furnace.

[0035] S4.RH furnace vacuum cycle degassing refining, after arriving at RH furnace, RH furnace refractory materials use chrome-free refractory bricks, vacuum degree 8 ~ 15KPa, oxygen blowing gun, according to the carbon content, the initial oxygen content of molten steel calculated oxygen blowing amount, RH furnace oxygen blowing 170m 3 At the end of oxygen blowing, the oxygen content was 264ppm, the cumulative vacuum time was 43min, 55kg of aluminum particles were added, and the end content of Al was 0.027%, O 7.1ppm, and temperature was 1625℃, and then returned to the LF furnace.

[0036] S5.LF furnace secondary refining, after returning to LF furnace, lime is added cumulatively 200kg, synthetic slag 220kg, continue to supply power and use aluminum particles for deoxidation and slag making, 15min, white slag steel is tapped, the slag is white and at the right temperature, then the steel is treated with calcium, the tapping temperature is 1635℃, 220m of seamless calcium wire is fed, tapping is soft blown for 18min, and then the steel is hoisted to the continuous casting platform.

[0037] S6. Continuous casting, the cross section of the ingot is 180mm×240mm. After the soft blowing is completed, the ladle is hoisted to the continuous casting for pouring. The ingot is protected during the whole casting process. The continuous casting tundish uses carbon-free insulation covering, and the crystallizer uses ultra-low carbon special protective slag. The tundish temperature is 1576℃, the pulling speed is controlled at 1.10m / min, and the water volume of the crystallizer is 145m 3 / h, crystallizer electromagnetic stirring 300A / 5Hz, end electromagnetic stirring 350A / 6Hz, secondary cooling water volume 0.35L / kg, use light pressure, where 1#, 2#, 3#, and 4# rollers press down 1.8mm, 2mm, 2mm, and 2mm respectively, with a designed total pressure reduction of 7.8mm to produce a copper-clad steel final product with high stability.

[0038] After testing, the chemical composition of the copper-clad steel final product QGT04Si01 is as follows by weight: C 0.01%, Si 0.01%, Mn 0.26%, P 0.009%, S 0.003%, Ni 0.01%, Cr 0.02%, Cu 0.02%, Al 0.037%, and the balance is iron.

[0039] Example 2

[0040] A copper-clad steel smelting method with high stability performance uses a 100t top and bottom combined blowing converter. The specific process flow is as follows: the smelting process flow includes molten iron pre-desulfurization → converter steelmaking → LF furnace preliminary refining → RH furnace vacuum cycle degassing refining → LF furnace secondary refining → continuous casting. The specific steps include: product composition C: ≤0.04%, Si: ≤0.010%, Cr: ≤0.02%, stable composition, smooth production and excellent product performance.

[0041] This is achieved specifically through the following technical solutions:

[0042] S1. Pre-desulfurization of molten iron: pre-treat the blast furnace molten iron. After the molten iron composition is qualified, the final sulfur content of the molten iron is 0.002%. Steel is tapped after the slag is cleaned.

[0043] S2. For converter steelmaking, use scrap steel produced by our factory, control the converter end composition and tapping temperature, control the amount of slag when tapping, and add appropriate amount of alloy and top slag.

[0044] The pretreated molten iron is added to the converter, and top and bottom combined blowing converter is used for smelting, slag making, oxygen blowing and steel tapping. The end point control target is: converter end point C 0.0040%, Mn 0.06%, P 0.007%, S 0.005%, Ni 0.012%, Cr0.007%, Cu 0.008%, steel tapping temperature 1636℃, 280kg of medium carbon ferromanganese, 98kg of aluminum ingot and 220kg of top slag are added during steel tapping.

[0045] S3. LF furnace is used for preliminary refining. After the LF furnace arrives at the station, 808kg of lime and 357kg of synthetic slag are added. During power transmission, 40kg of calcium carbide and 35kg of aluminum particles are removed in batches until gray-white slag is produced. The steelmaking temperature is 1700℃ and the oxygen content is 64ppm. The ladle is then hoisted to the RH furnace.

[0046] S4.RH furnace vacuum cycle degassing refining, after arriving at RH furnace, RH furnace refractory materials use chrome-free refractory bricks, vacuum degree 8 ~ 15KPa, oxygen blowing gun, according to the carbon content, the initial oxygen content of molten steel calculated oxygen blowing amount, RH furnace oxygen blowing 160m 3 At the end of oxygen blowing, the oxygen content was 339ppm, the cumulative vacuum time was 45min, 65kg of aluminum particles were added, and the end content of Al was 0.025%, O 6.7ppm, and temperature was 1619℃, and then returned to the LF furnace.

[0047] S5.LF furnace secondary refining, after returning to LF furnace, 235kg of lime is added cumulatively, 250kg of synthetic slag is added, power is continued and aluminum particles are used for deoxidation and slag making, 17 minutes, white slag is tapped, the steel slag is white and at the right temperature, then calcium treatment is performed, the tapping temperature is 1632℃, 215m of seamless calcium wire is fed, tapping is soft blown for 20 minutes, and then the steel is hoisted to the continuous casting platform.

[0048] S6. Continuous casting, the cross section of the ingot is 180mm×240mm. After the soft blowing is completed, the ladle is hoisted to the continuous casting for pouring. The ingot is protected during the whole casting process. The continuous casting tundish uses carbon-free insulation covering, and the crystallizer uses ultra-low carbon special protective slag. The tundish temperature is 1571℃, the pulling speed is controlled at 1.10m / min, and the water volume of the crystallizer is 144m 3 / h, crystallizer electromagnetic stirring 300A / 5Hz, end electromagnetic stirring 350A / 6Hz, secondary cooling water volume 0.35L / kg, use light pressure, where 1#, 2#, 3#, and 4# rollers press down 1.8mm, 2mm, 2mm, and 2mm respectively, with a designed total pressure reduction of 7.8mm to produce a copper-clad steel final product with high stability.

[0049] After testing, the chemical composition of the copper-clad steel final product QGT04Si01 is as follows by weight: C 0.01%, Si 0.01%, Mn 0.24%, P 0.008%, S 0.003%, Ni 0.013%, Cr 0.014%, Cu 0.01%, Al 0.033%, and the balance is iron.

[0050] In summary, the copper-clad steel smelting method with high stability of the present invention has a scientific and stable production process, and convenient and precise operation and control. Through the entire process flow of molten iron pre-desulfurization → converter steelmaking → LF furnace preliminary refining → RH furnace vacuum cycle degassing refining → LF furnace secondary refining → continuous casting, each step synergizes to achieve the final product The smelting composition reaches C≤0.04%, Si≤0.010%, Cr≤0.02%, meeting actual needs.

[0051] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for smelting copper-clad steel with high stability, characterized in that: The smelting process includes hot metal pre-desulfurization → converter steelmaking → LF furnace preliminary refining → RH furnace vacuum cycle degassing refining → LF furnace secondary refining → continuous casting. The specific steps include the following: S1 / Pre-desulfurization of hot metal: pre-treat hot metal from blast furnace to reduce the sulfur content in hot metal to meet the quality requirements of steel in subsequent smelting processes. After the hot metal composition is qualified, slag is removed; S2 / converter steelmaking, adding the pre-treated molten iron into the converter, slag making, oxygen blowing, steel tapping, the end point control target: C ≤ 0.080%, Cr ≤ 0.015%, steel tapping temperature 1610 ~ 1670 ℃; S3 / LF furnace for preliminary refining. After the LF furnace arrives at the station, lime is added to synthesize slag without using fluorite. After the electrochemical slag is sent, calcium carbide and aluminum particles are used for deoxidation. The gray slag is tapped to the RH furnace; S4 / RH furnace vacuum cycle degassing and refining, RH furnace refractory uses chrome-free refractory bricks, vacuum degree 8 ~ 15KPa, oxygen is blown from the gun, the oxygen blowing amount is calculated according to the carbon content and initial oxygen content, oxygen blowing ends and the cycle is circulated until the oxygen content of the molten steel is 180 ~ 450ppm, and then it continues to be maintained under high vacuum until the oxygen is fixed, aluminum particles are added according to the oxygen content, and the cycle ends after the aluminum particles are added; S5 / LF furnace secondary refining, after returning to LF furnace, lime is added, synthetic slag is synthesized, power is continued to be supplied and aluminum particles are used for deoxidation, white slag is tapped, and the molten steel reaches the target temperature. According to the amount of molten steel, 1.5-2.5m / ton seamless calcium wire is fed, and the steel is soft-blown. After the soft-blowing is completed, the steel is poured; S6 / continuous casting, the casting is protected throughout the casting process, the continuous casting tundish uses carbon-free insulation covering, and the crystallizer uses ultra-low carbon special protective slag.

2. A copper-clad steel smelting method with high stability according to claim 1, characterized in that: In step S1, the molten iron is desulfurized until the sulfur content of the molten iron is less than or equal to 0.003%, and the steel is tapped after the slag is removed.

3. A copper-clad steel smelting method with high stability according to claim 1, characterized in that: In step S2, converter steelmaking: the converter capacity is not more than 120t; top and bottom combined blowing converter smelting is adopted; Use scrap steel with low Cr content, and alloys such as medium carbon ferromanganese, aluminum ingots, and aluminum particles; use a ladle that holds low silicon and low chromium molten steel, and the ladle wall and edge are clean; After 10 to 50 tons of steel is tapped, 0.6 to 1.0 kg / ton of aluminum ingots is added. After 1 / 3 of the molten steel is tapped, 1.8 to 3.0 kg / ton of medium carbon ferromanganese is added. Use a slide plate and slag stopper to double slag. After tapping is completed, 2.0 to 3.0 kg / ton of top slag is added.

4. A copper-clad steel smelting method with high stability according to claim 1, characterized in that: In step S3, the LF furnace is initially refined. After the LF furnace arrives at the station, 7.0-9.0 kg / ton of lime and 3.0-4.5 kg / ton of synthetic slag are added. During the power supply period of the LF furnace, calcium carbide and aluminum particles are deoxidized in batches.

5. A copper-clad steel smelting method with high stability according to claim 1, characterized in that: In step S4, the RH furnace is vacuum cycled for degassing and refining. The oxygen blowing amount is calculated according to the carbon content and the initial oxygen content. The oxygen content of the molten steel is 180-450 ppm after the oxygen blowing cycle ends for 3 minutes. Then, the molten steel is kept in a high vacuum state, i.e., the pressure is 133 Pa or less for 8-10 minutes. The vacuum is maintained for 5 minutes to determine the oxygen content, and aluminum particles are added after maintaining the vacuum for 8 to 10 minutes according to the oxygen content. The cycle is then completed after 5 to 8 minutes.

6. A copper-clad steel smelting method with high stability according to claim 1, characterized in that: In step S5, the LF furnace is subjected to secondary refining, and after returning to the LF furnace, 1.5-3.0 kg / ton of lime and 1.5-2.5 kg / ton of synthetic slag are added, and power is continued to be supplied while aluminum particles are used for deoxidation. White slag is used for steelmaking, and steel is tapped after the molten steel reaches the target temperature. According to the amount of molten steel, 1.5-2.5 m / ton of seamless calcium wire is fed, and soft blowing is performed for steel tapping. After the soft blowing is completed, steel is poured.

7. A copper-clad steel smelting method with high stability according to claim 6, characterized in that: After soft blowing for ≥15min, the ladle is hoisted to continuous casting according to the production rhythm.

8. A copper-clad steel smelting method with high stability according to claim 6, characterized in that: In step S6, continuous casting is performed, and the cross-section of the ingot is 180 mm×240 mm.

9. A copper-clad steel smelting method with high stability according to claim 7, characterized in that: In step S6, continuous casting is performed, the ladle temperature is 1570-1580°C, the casting speed is 1.10-1.30 m / min, and the crystallizer water volume is 140±5 m 3 / h, crystallizer electromagnetic stirring 300A / 5Hz, end electromagnetic stirring 350A / 6Hz, secondary cooling water volume 0.34~0.36L / kg, use light pressure, among which 1#, 2#, 3#, and 4# rollers press down 1.8mm, 2mm, 2mm, and 2mm respectively, with a total pressure reduction of 7.8mm.

10. A method for smelting copper-clad steel with high stability according to any one of claims 1 to 9, characterized in that: The components of the obtained special copper-clad steel final product are C≤0.04%, Si≤0.010%, and Cr≤0.02%.