Production method of electrode flat steel square billet

Abstract

The invention provides a production method of an electrode flat steel square billet, which comprises the following steps of: sequentially carrying out converter semi-steel smelting, LF electric heating refining, RH vacuum treatment, bloom continuous casting and stacking slow cooling on raw materials of the electrode flat steel square billet to obtain the electrode flat steel square billet; and after the RH vacuum treatment, the molten steel discharged from the RH station is subjected to standing for 5-6 min under the condition that the temperature of the molten steel is kept to be larger than or equal to 1575 DEG C on a continuous casting platform, and then bloom continuous casting is carried out. Compared with the prior art, the production method provided by the invention adopts specific process steps, conditions and parameters to realize overall better interaction, can realize high-quality stable continuous casting of the super-electrode flat steel square billet, and the obtained product is good in macroscopic quality, and meanwhile, various properties meet standard requirements, the key index, namely the resistivity, is integrally controlled to be 11.0-12.7 mu omega.cm.

Description

Technical Field

[0001] The invention relates to the technical field of steel smelting, and more specifically to a method for producing an electrode flat steel billet. Background Art

[0002] In the production process of aluminum, electrolytic preparation is the main aluminum production process in my country, and a large amount of electricity is consumed in its production process. Therefore, electrolytic aluminum is one of the high-energy-consuming basic industries in my country's industrial production, and electricity costs occupy a dominant position, accounting for more than 40%. At present, the average direct electricity consumption per ton of aluminum in my country is about 13,000 KWh, while the theoretical direct electricity consumption per ton of aluminum is about 6,300 kWh, and the electricity utilization rate is about 48%, with a large space for energy saving and consumption reduction. Under the background of "dual carbon", energy saving and consumption reduction in aluminum production will play a leading role. Cathode flat steel, as an important component of the electrolytic cell in the production process of aluminum electrolysis, is generally used as the cathode of the electrolytic cell, which can play a role in evenly dividing the current and improving the current in the aluminum liquid. The quality of the electrode flat steel directly affects the production quality and energy consumption of aluminum electrolysis. Among them, the resistivity of the electrode flat steel is a key factor. The electrode flat steel with low resistivity can reduce the heat generated during the conduction process and improve the efficiency of electricity utilization.

[0003] The resistivity of electrode flat steel for electrolytic aluminum is mainly affected by internal factors such as chemical composition, purity, and organizational structure of the flat steel. With the continuous improvement of energy-saving and consumption-reducing requirements, traditional Q235A / B and Q195A / B cathode flat steels are gradually being eliminated and replaced by high-conductivity and ultra-high-conductivity electrode flat steels with lower resistivity.

[0004] In terms of chemical composition, there is a positive linear relationship between the increment of each element and the change in resistivity. The specific relationship is (i.e., at 20°C, the resistivity increase corresponding to each 1% increase in the mass percentage of the element, Ω·m):

[0005] Δρ=34.1·C+13.1·Si+5.1·Mn+11.1·P+12.1·S+12.1·Al+14.2·N.

[0006] It can be seen that the influences are C, N, Si, S, Al, P, and Mn from large to small. The C element has the greatest influence on the resistivity, followed by the N element and the Si element. Therefore, many scholars in the industry have carried out a lot of research, mainly focusing on the control of low alloy content to ensure a lower resistivity. In the steelmaking process, the removal of C is mainly through carbon-oxygen reaction. The extremely low C content often leads to a higher a[O] in the molten steel, and the removal of [O] is bound to produce deoxidation products. Excessive deoxidation products will produce nodules on the inner wall of the refractory material of the continuous casting nozzle, deteriorating the continuous casting process, and in severe cases, interrupting the casting; and the increase of alloy components used to balance the oxygen element in the molten steel will be unfavorable for the low resistivity control of the electrode flat steel. Molten steel with too high a[O] is prone to bubble defects, and the quality of the ingot is greatly reduced. In actual production, the principle of controlling bubble defects is often adopted, resulting in inefficient production; that is, the process of "slab continuous casting-cutting-rolling" is adopted for production; although the products produced achieve low-consumption production of electrolytic aluminum, it leads to high-energy consumption production of electrode flat steel, and the energy-saving and consumption-reduction performance of the entire process is obviously insufficient.

[0007] At present, the research on the production process of electrode flat steel billets is mainly focused on molten steel smelting, flat steel casting equipment technology, and research on improving the electrical conductivity of flat steel, but the existing technology does not involve the continuous casting technology of electrode flat steel billets.

[0008] For example:

[0009] CN113913698B discloses a high-strength and high-conductivity flat steel and its manufacturing method and application, and specifically discloses that the high-strength and high-conductivity flat steel is composed of C≤0.006%, Si≤0.05%, 0.15%≤Mn≤0.20%, P≤0.02%, S≤0.004%, Ti≤0.05%, and the balance Fe in terms of weight percentage; the manufacturing method of the high-strength and high-conductivity flat steel comprises the following steps: step 1, smelting the molten steel in a converter: feeding AlFe alloy and Al wire into the molten steel for smelting, and when tapping the steel Add synthetic slag for slag washing; Step 2, LF refining: the material smelted in the converter is refined and desulfurized, and fed to SiCa wire and Ti wire; Step 3, after LF refining, RH vacuum degassing, casting into continuous casting billet, and then rolling to obtain; In the step 2, continuous casting refining is adopted in a tundish, and the temperature of the tundish is 1535~1555℃; the Ti wire is a titanium iron alloy wire; the titanium iron alloy includes 20±3wt% Ti and 80±3wt% Fe; the synthetic slag includes 65~66% CaO, 16~17% Al by weight 2 O 3 , 4~5% SiO 2, 2~3% MgO, 0.04~0.05% S and 0.005~0.015% P; the feeding amount of the Ti wire is 10kg±0.5kg per ton of molten steel; the feeding amount of the AlFe alloy is 1.5~3.5kg / t; the feeding rate of the Al wire is ≥5m / min; the feeding rate of the SiCa wire is ≥4m / min; the amount of the synthetic slag accounts for 0.3~0.4% of the mass of the molten steel during tapping.

[0010] CN218252228U discloses a device for correcting the straightness of an electrode flat steel, and specifically discloses: a workbench (1) and an auxiliary pressing frame (2) mounted on the workbench (1), the auxiliary pressing frame (2) being provided with a straightness auxiliary correction mechanism, the workbench (1) being provided with a feed end (3) and a discharge end (4) opposite to each other, the workbench (1) being provided with a transmission part, the transmission part being provided at positions corresponding to the feed end (3) and the discharge end (4), the feed end (3) and the discharge end (4) being provided with a transmission part. (4) is provided with a hydraulic correction part, the hydraulic correction part is arranged on the workbench (1), the straightness auxiliary correction mechanism includes a reference data reading part and an auxiliary correction part, the reference data reading part is installed on the side of the auxiliary pressing frame (2), the auxiliary correction part is slidably arranged under the auxiliary pressing frame (2), the reference data reading part is provided with a scale for reading the specific bending length of the electrode flat steel, and the auxiliary correction part is a pad block that can increase, decrease and superimpose to adjust the straightness of the electrode flat steel.

[0011] CN116083780A discloses a production method of ultra-low carbon and ultra-low silicon manganese electrode flat steel, and specifically discloses that the ultra-low carbon and ultra-low silicon manganese electrode flat steel is obtained by subjecting the molten iron fed into the furnace to converter steelmaking; subjecting the molten steel after the converter is tapped to LF furnace refining twice; subjecting the refined molten steel to RH vacuum treatment; and then subjecting the molten steel to continuous casting and rolling. The technology can eliminate bubbles under the skin of the continuous casting billet, ensure the castability of the molten steel, and the cast billet can be directly rolled into the electrode flat steel, thus solving the problem that the ultra-low carbon and ultra-low silicon manganese electrode flat steel is extremely difficult to produce by using the square billet continuous casting process, and realizing the control of the carbon content ≤0.003%, the silicon content ≤0.006%, the manganese content ≤0.03%, the T[O] ≤0.0020%, and the resistivity (at 20°C) ≤1.3×10~(-7)Ω·m in the ultra-low carbon and ultra-low silicon manganese electrode flat steel, thereby greatly saving electric energy in the production process of electrolytic aluminum and realizing a substantial reduction in production costs.

[0012] CN116657022A discloses an electrode flat steel with both low resistivity and high carburization resistance and a preparation method thereof, and specifically discloses the following steps: (1) smelting and casting pure iron and pure copper in sequence to obtain an alloy ingot; the composition of the alloy ingot comprises, by mass percentage, C 0.03-0.06%, Cu 0.4-2.4% and the remainder Fe; (2) subjecting the alloy ingot obtained in the step (1) to oxidation treatment to obtain an electrode flat steel with both low resistivity and high carburization resistance; the oxidation treatment atmosphere is an oxidizing atmosphere, the oxidation treatment holding temperature is 1020-1080°C, and the oxidation treatment holding time is ≥30min; the electrode flat steel provided by the invention has a resistivity of <1.4×10~(-7)Ω·m and excellent carburization resistance.

[0013] However, the above-mentioned prior art does not involve the continuous casting technology of electrode flat steel billets. Summary of the invention

[0014] In view of this, the object of the present invention is to provide a method for producing electrode flat steel billets, which can achieve high-quality and stable continuous casting of super electrode flat steel billets, and the obtained products have good low-multiple quality, and various performances meet the standard requirements well, among which the key indicator of resistivity is overall controlled at 11.0~12.7μΩ·cm.

[0015] The present invention provides a method for producing an electrode flat steel billet, comprising the following steps:

[0016] The electrode flat steel billet raw material is sequentially subjected to converter semi-steel smelting, LF electric heating refining, RH vacuum treatment, large square billet continuous casting and stacking slow cooling to obtain the electrode flat steel billet;

[0017] After the RH vacuum treatment, the molten steel after the RH station is first placed on the continuous casting platform with the temperature of the molten steel kept at ≥1575°C for 5min-6min, and then the large square billet is continuously cast.

[0018] Preferably, the smelting chemical composition of the electrode flat steel billet raw material, measured in mass percentage, consists of the following elements: C 0.02%~0.04%, Si 0.02%~0.07%, Mn 0.28%~0.40%, P≤0.015%, S≤0.008%, Als 0.010%~0.020%, O≤30ppm, N≤60ppm, and the rest is Fe and other inevitable impurities.

[0019] Preferably, a[O] in the molten steel after the RH vacuum treatment is controlled at 20ppm-30ppm, and the contents of other chemical components meet the requirements of the finished product.

[0020] Preferably, the cross-sectional dimensions of the large square billet are 320 mm×410 mm or 360 mm×450 mm.

[0021] Preferably, the large square billet continuous casting adopts straight-through long nozzle casting, and the inner diameter of the nozzle is 50mm~60mm.

[0022] Preferably, the superheat of the molten steel in the bloom continuous casting process is overall controlled at 20°C to 40°C.

[0023] Preferably, the large square billet continuous casting adopts a dynamic matching casting speed and electromagnetic stirring process.

[0024] Preferably, the dynamic matching casting speed and electromagnetic stirring process are specifically as follows:

[0025] Superheat 20℃~25℃, matching continuous casting speed 2.7t / min, crystallizer electromagnetic stirring current intensity 350A~450A, solidification end electromagnetic stirring current intensity 100A~150A;

[0026] Superheat 26~35℃, matching continuous casting speed 2.5t / min~2.6t / min, crystallizer electromagnetic stirring current intensity 350A~400A, solidification end electromagnetic stirring current intensity 150A~200A;

[0027] The superheat is 36~40℃, the matching continuous casting speed is 2.4t / min~2.5t / min, the electromagnetic stirring current intensity of the crystallizer is 300A~350A, and the electromagnetic stirring current intensity at the end of solidification is 200A~250A.

[0028] Preferably, the second cooling of the continuous casting of the large square billet adopts strong cooling, and the specific water volume is 0.35~0.37L / kg 钢 .

[0029] Preferably, the endpoint C of the converter semi-steel smelting is ≤0.030%, the tapping temperature is ≥1650°C, the alloy is added according to the target alloy and content in the steel, and 300kg~500kg of active lime is quantitatively added;

[0030] During the LF electric heating refining, 1000kg-1200kg of slag is added, and argon is blown and stirred throughout the process. During the argon blowing process, the steel liquid surface is strictly prohibited from violently churning, and the [Als]% in the steel liquid is controlled to be 0.025%-0.035%, and the temperature at the end of LF is controlled to be 1590°C-1594°C;

[0031] When the surface temperature of the continuous casting billet is greater than 600° C., the stacking slow cooling is started, and the slow cooling time is greater than or equal to 18 hours.

[0032] The present invention provides a production method of electrode flat steel billet, comprising the following steps: subjecting the electrode flat steel billet raw material to converter semi-steel smelting, LF electric heating refining, RH vacuum treatment, large billet continuous casting and stacking slow cooling in sequence to obtain electrode flat steel billet; after the RH vacuum treatment, the molten steel after RH exiting the station is first placed on a continuous casting platform to maintain the molten steel temperature ≥1575°C for 5min~6min, and then large billet continuous casting is performed. Compared with the prior art, the production method provided by the present invention adopts specific process steps, conditions and parameters to achieve overall good interaction, can realize high-quality and stable continuous casting of super electrode flat steel billet, and the obtained product has good low-multiple quality, and at the same time, various performances meet the standard requirements well, wherein the key indicator of resistivity is overall controlled at 11.0~12.7μΩ·cm. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a typical low-magnification photo of the finished product obtained in Example 1 of the present invention;

[0034] Figure 2 This is a typical low-magnification photo of the finished product obtained in Example 2 of the present invention;

[0035] Figure 3 This is a typical low-magnification photo of the finished product obtained in Example 3 of the present invention. DETAILED DESCRIPTION

[0036] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] The present invention provides a method for producing an electrode flat steel billet, comprising the following steps:

[0038] The electrode flat steel billet raw material is sequentially subjected to converter semi-steel smelting, LF electric heating refining, RH vacuum treatment, large square billet continuous casting and stacking slow cooling to obtain the electrode flat steel billet;

[0039] After the RH vacuum treatment, the molten steel after the RH station is first placed on the continuous casting platform with the temperature of the molten steel kept at ≥1575°C for 5min-6min, and then the large square billet is continuously cast.

[0040] In the present invention, the smelting chemical composition of the electrode flat steel billet raw material, in terms of mass percentage, is preferably composed of the following elements: C 0.02%~0.04%, Si 0.02%~0.07%, Mn 0.28%~0.40%, P≤0.015%, S≤0.008%, Als 0.010%~0.020%, O≤30ppm, N≤60ppm, and the rest is Fe and other inevitable impurities.

[0041] The technical problem to be solved by the present invention with respect to the above-mentioned electrode flat steel square billet raw materials is: to provide a continuous casting technology for electrode flat steel square billets; generally speaking, the more deoxidation products there are in the molten steel during continuous casting production, the more likely it is that the inner wall of the nozzle will stick, deteriorating the flow strands and the flow field, while the continuous casting of molten steel with a low alloy component is likely to produce bubble defects in the ingot; more importantly, in the process of continuous casting of square billets, the cross-sectional dimensions of the ingot are small, the corresponding cross-sectional dimensions of the ingot channel are small, and the influence effect of the adhesion inclusions on the inner wall of the ingot increases sharply; furthermore, in the casting process of steels with a low alloy content, the liquidus temperature is high and the solid-liquidus temperature difference is small, resulting in a large temperature gradient in the casting process, rapid dendrite growth, developed columnar crystals, and a large tendency for intermediate cracks and center cracks in the ingot; and in the process of electromagnetic stirring to inhibit the growth of columnar crystals, the molten steel has a low viscosity and good fluidity, and the stirring and scouring is more intense, which is likely to produce a white bright band.

[0042] Therefore, how to reduce the adhesion of deoxidation inclusions on the inner wall of the nozzle in the continuous casting process and control the solidification heat transfer and dendrite growth of the billet is the key to the continuous casting of ultra-high conductivity electrode flat steel. By adopting the production method provided by the present invention, the high-quality and stable continuous casting of super electrode flat steel billets is successfully achieved; wherein, by fully standing, the floating removal of deoxidation products is more thorough, and the negative impact of the nozzle nodules of the billet continuous casting with a smaller cross-sectional size than the slab is greatly reduced. More importantly, it is highly sensitive to the solidification heat transfer characteristics, and accurate dynamic process matching is formulated. By integrating the superheat of the casting steel liquid, combined electromagnetic stirring, casting speed and secondary cooling intensity dynamic fine deployment, the precise solidification control of the ultra-high conductivity electrode flat steel billet is achieved, the low-multiple quality of the billet is good, and the various properties of the flat steel obtained by rolling meet the standard requirements well, wherein the key indicator of resistivity is overall controlled at 11.0~12.7μΩ·cm.

[0043] In the present invention, after the RH vacuum treatment, the molten steel after the RH exits the station is first placed on a continuous casting platform with the temperature of the molten steel kept at ≥1575°C for 5min-6min, and then the large square billet is continuously cast.

[0044] In the present invention, a[O] in the molten steel after RH vacuum treatment is preferably controlled at 20ppm-30ppm, and the contents of other chemical components meet the requirements of the finished product.

[0045] In the present invention, the cross-sectional dimensions of the bloom are preferably 320 mm×410 mm or 360 mm×450 mm.

[0046] In the present invention, the continuous casting of the large square billet preferably adopts straight-through long nozzle casting, and the inner diameter of the nozzle is preferably 50mm-60mm; the superheat of the molten steel in the continuous casting process of the large square billet is overall controlled at 20℃~40℃.

[0047] In the present invention, the bloom continuous casting preferably adopts a dynamic matching casting speed and electromagnetic stirring process; the dynamic matching casting speed and electromagnetic stirring process are preferably specifically:

[0048] Superheat 20℃~25℃, matching continuous casting speed 2.7t / min, crystallizer electromagnetic stirring current intensity 350A~450A, solidification end electromagnetic stirring current intensity 100A~150A;

[0049] Superheat 26~35℃, matching continuous casting speed 2.5t / min~2.6t / min, crystallizer electromagnetic stirring current intensity 350A~400A, solidification end electromagnetic stirring current intensity 150A~200A;

[0050] The superheat is 36~40℃, the matching continuous casting speed is 2.4t / min~2.5t / min, the electromagnetic stirring current intensity of the crystallizer is 300A~350A, and the electromagnetic stirring current intensity at the end of solidification is 200A~250A.

[0051] In the present invention, the second cooling of the large square billet continuous casting is preferably strong cooling, and the specific water volume is preferably 0.35~0.37L / kg 钢 .

[0052] In addition to the above-mentioned key technical points which must be implemented as required, the present invention requires that other continuous casting system processes and other process processes be implemented in coordination with conventional operations.

[0053] In the present invention, the endpoint C of the converter semi-steel smelting is preferably ≤0.030%, the tapping temperature is preferably ≥1650°C, the alloy is added according to the target alloy and content in the steel, and preferably 300kg~500kg of active lime is added quantitatively.

[0054] In the present invention, 1000kg-1200kg of slag is preferably added during the LF electric heating refining process, argon blowing and stirring are performed throughout the process, and the molten steel surface is strictly prohibited from violently churning during the argon blowing process. The [Als]% in the molten steel is preferably controlled to be 0.025%-0.035%, and the temperature at the end of LF is preferably controlled to be 1590°C-1594°C.

[0055] In the present invention, the stacking slow cooling is preferably started when the surface temperature of the continuous casting billet is >600°C, and the slow cooling time is preferably ≥18h.

[0056] The present invention provides a production method of electrode flat steel billet, comprising the following steps: subjecting the electrode flat steel billet raw material to converter semi-steel smelting, LF electric heating refining, RH vacuum treatment, large billet continuous casting and stacking slow cooling in sequence to obtain electrode flat steel billet; after the RH vacuum treatment, the molten steel after RH exiting the station is first placed on a continuous casting platform to maintain the molten steel temperature ≥1575°C for 5min~6min, and then large billet continuous casting is performed. Compared with the prior art, the production method provided by the present invention adopts specific process steps, conditions and parameters to achieve overall good interaction, can realize high-quality and stable continuous casting of super electrode flat steel billet, and the obtained product has good low-multiple quality, and at the same time, various performances meet the standard requirements well, wherein the key indicator of resistivity is overall controlled at 11.0~12.7μΩ·cm.

[0057] In order to further illustrate the present invention, the following examples are used to explain it in detail. The grade of the electrode flat steel produced in the following examples of the present invention is SAE1006.

[0058] Example 1

[0059] This embodiment is that an enterprise adopts the production method provided by the present invention to carry out continuous casting production of SAE1006 electrode flat steel square billets, and the continuous casting cross-sectional size is 320mm×410mm; the process technology flow executed is: converter semi-steel smelting→LF electric heating refining→RH vacuum treatment→large square billet (cross-sectional size: 320mm×410mm) continuous casting→stacking slow cooling; the chemical composition of the produced SAE1006 electrode flat steel is: C 0.03%, Si 0.05%, Mn 0.33%, P 0.010%, S 0.006%, Als 0.017%, O22ppm, N 46ppm, and the rest is Fe and other inevitable impurities.

[0060] The key technical parameters involved in the present invention are actually implemented as follows: (1) a[O] in the molten steel after RH vacuum treatment is controlled at 15-18 ppm, and the contents of other chemical components meet the requirements of the finished product, namely C 0.03%, Si 0.05%, Mn 0.33%, P 0.010%, S0.006%, Als 0.017%, and N 46 ppm; (2) Furthermore, the molten steel after RH exits the station is placed on the continuous casting platform to maintain the molten steel temperature ≥1575°C for a standing time of 5-6 minutes; (3) a straight-through long nozzle is used for casting, and the inner diameter of the nozzle is 50-52 mm; (4) the superheat of the molten steel during the casting process is controlled at 20-40°C as a whole; the casting speed and electromagnetic stirring process are dynamically matched: the superheat is 20-25°C, the matching continuous casting speed is 2.7 t / min, the crystallizer electromagnetic stirring current intensity is 440-450A, and the solidification end electromagnetic stirring current Strength 140~150A; superheat 26~35℃, matching continuous casting speed 2.5~2.6t / min, crystallizer electromagnetic stirring current intensity 390~400A, solidification end electromagnetic stirring current intensity 190~200A; superheat 36~40℃, matching continuous casting speed 2.4~2.5t / min, crystallizer electromagnetic stirring current intensity 340~350A, solidification end electromagnetic stirring current intensity 240~250A; secondary cooling adopts strong cooling, specific water volume 0.36~0.37L / kg steel.

[0061] In addition to the above-mentioned key technical points which must be implemented as required, the present invention requires that other continuous casting system processes and other process processes be implemented in coordination with conventional operations, such as converter semi-steel smelting: end point C≤0.030%, tapping temperature≥1650°C, alloys are added according to the target alloy and content in the steel, and 400kg of active lime is added quantitatively; LF refining: 1100kg of special slag is added, argon is blown and stirred throughout the process, violent churning of the molten steel surface is strictly prohibited during the argon blowing process, the [Als]% in the molten steel is controlled at 0.035%, and the temperature at the end of LF is controlled at 1590°C; stacking slow cooling is started when the surface temperature of the continuous casting billet is greater than 600°C, and the slow cooling time is ≥18h.

[0062] The SAE1006 electrode flat steel ingot with a cross section of 320mm×410mm obtained from the test was subjected to pickling low-power inspection. The typical result photos are shown in Figure 1 The results show that the low-power quality of the ingot is good, among which the proportion of 0.5 level of central looseness of the ingot reaches 98%, there are no intermediate cracks, no subcutaneous bubbles, and the proportion of 0.5 level of central segregation is 95%; the resistivity of the flat steel obtained by rolling is 12.5μΩ·cm at 20℃.

[0063] Example 2

[0064] This embodiment is that an enterprise adopts the production method provided by the present invention to carry out continuous casting production of SAE1006 electrode flat steel billets, and the continuous casting cross-sectional size is 360mm×450mm; the process technology flow executed is: converter semi-steel smelting → LF electric heating refining → RH vacuum treatment → large square billet (cross-sectional size: 360mm×450mm) continuous casting → stacking slow cooling; the chemical composition of the produced SAE1006 electrode flat steel is: C 0.02%, Si 0.07%, Mn 0.40%, P 0.015%, S 0.008%, Als 0.020%, O30ppm, N 60ppm, and the rest is Fe and other inevitable impurities.

[0065] The key technical parameters involved in the present invention are actually implemented as follows: (1) a[O] in the molten steel after RH vacuum treatment is controlled at 18-20 ppm, and the contents of other chemical components meet the requirements of the finished product, namely C 0.02%, Si 0.07%, Mn 0.40%, P 0.015%, S0.008%, Als 0.020%, and N 60 ppm; (2) Furthermore, the molten steel after RH exits the station is placed on the continuous casting platform under the condition of keeping the molten steel temperature ≥1575°C for a standing time of 5-6 minutes; (3) a straight-through long nozzle is used for casting, and the inner diameter of the nozzle is 58-60 mm; (4) the superheat of the molten steel during the casting process is controlled at 20-40°C as a whole; the casting speed and electromagnetic stirring process are dynamically matched: the superheat is 20-25°C, the continuous casting speed is matched to 2.7 t / min, the electromagnetic stirring current intensity of the crystallizer is 350-360A, and the electromagnetic stirring current at the end of solidification is 2.7 t / min. Strength 100~110A; superheat 26~35℃, matching continuous casting speed 2.5~2.6t / min, crystallizer electromagnetic stirring current intensity 350~370A, solidification end electromagnetic stirring current intensity 150~160A; superheat 36~40℃, matching continuous casting speed 2.4~2.5t / min, crystallizer electromagnetic stirring current intensity 300~310A, solidification end electromagnetic stirring current intensity 200~210A; secondary cooling adopts strong cooling, specific water volume 0.35~0.37L / kg steel.

[0066] In addition to the above-mentioned key technical points which must be implemented as required, the present invention requires that other continuous casting system processes and processes of other processes be implemented in coordination with conventional operations, such as converter semi-steel smelting: end point C≤0.030%, tapping temperature≥1650°C, alloys are added according to the target alloy and content in the steel, and 400kg of active lime is added quantitatively; LF refining: 1100kg of special slag is added, argon is blown and stirred throughout the process, violent churning of the molten steel surface is strictly prohibited during the argon blowing process, [Als]% in the molten steel is controlled at 0.025%, and the temperature at the end of LF is controlled at 1594°C; stacking slow cooling is started when the surface temperature of the continuous casting billet is greater than 600°C, and the slow cooling time is ≥18h.

[0067] The SAE1006 electrode flat steel ingot with a cross section of 360mm×450mm obtained from the test was pickled and tested at low magnification. The typical result photos are as follows: Figure 2 The results show that the low-power quality of the ingot is good, among which the proportion of 0.5 level of central looseness of the ingot reaches 94%, there are no intermediate cracks, no subcutaneous bubbles, and the proportion of 0.5 level of central segregation is 92%; the resistivity of the flat steel obtained by rolling is 12.7μΩ·cm at 20℃.

[0068] Example 3

[0069] This embodiment is that an enterprise adopts the production method provided by the present invention to carry out continuous casting production of SAE1006 electrode flat steel billets, and the continuous casting cross-sectional size is 320mm×410mm; the process technology flow executed is: converter semi-steel smelting→LF electric heating refining→RH vacuum treatment→large square billet (cross-sectional size: 320mm×410mm) continuous casting→stacking slow cooling; the chemical composition of the produced SAE1006 electrode flat steel is: C 0.04%, Si 0.02%, Mn 0.28%, P 0.008%, S 0.006%, Als 0.010%, O23ppm, N 39ppm, and the rest is Fe and other inevitable impurities.

[0070] The key technical parameters involved in the present invention are actually implemented as follows: (1) a[O] in the molten steel after RH vacuum treatment is controlled at 20-30ppm, and the contents of other chemical components meet the requirements of the finished product, namely C 0.04%, Si 0.02%, Mn 0.28%, P 0.008%, S0.006%, Als 0.010%, and N 39ppm; (2) Furthermore, the molten steel after RH exits the station is placed on the continuous casting platform under the condition of keeping the molten steel temperature ≥1575°C for 6 minutes; (3) a straight-through long nozzle is used for casting, and the inner diameter of the nozzle is 50-51mm; (4) the superheat of the molten steel during the casting process is controlled at 20-40°C as a whole; the casting speed and electromagnetic stirring process are dynamically matched: the superheat is 20-25°C, the matching continuous casting speed is 2.7t / min, the electromagnetic stirring current intensity of the crystallizer is 400-420A, and the electromagnetic stirring current intensity at the end of solidification is 400-420A. 120~130A; superheat 26~35℃, matching continuous casting speed 2.5~2.6t / min, crystallizer electromagnetic stirring current intensity 370~380A, solidification end electromagnetic stirring current intensity 170~180A; superheat 36~40℃, matching continuous casting speed 2.4~2.5t / min, crystallizer electromagnetic stirring current intensity 330~340A, solidification end electromagnetic stirring current intensity 230~240A; secondary cooling adopts strong cooling, specific water volume 0.365~0.370L / kg steel.

[0071] In addition to the above-mentioned key technical points which must be implemented as required, the present invention requires that other continuous casting system processes and other process processes be implemented in coordination with conventional operations, such as converter semi-steel smelting: end point C≤0.030%, tapping temperature≥1650°C, alloys are added according to the target alloy and content in the steel, and 400kg of active lime is added quantitatively; LF refining: 1100kg of special slag is added, argon is blown and stirred throughout the process, violent churning of the molten steel surface is strictly prohibited during the argon blowing process, the [Als]% in the molten steel is controlled at 0.035%, and the temperature at the end of LF is controlled at 1590°C; stacking slow cooling is started when the surface temperature of the continuous casting billet is greater than 600°C, and the slow cooling time is ≥18h.

[0072] The SAE1006 electrode flat steel ingot with a cross section of 320mm×410mm obtained from the test was subjected to pickling low-power inspection. The typical result photos are shown in Figure 3 The results show that the low-power quality of the ingot is good, among which the proportion of 0.5 level of central looseness of the ingot reaches 97%, there is no intermediate crack, no subcutaneous bubble, and the proportion of 0.5 level of central segregation is 97%; the resistivity of the flat steel obtained by rolling is 11.0μΩ·cm at 20℃.

[0073] The above-mentioned implementation examples illustrate that by adopting the production method provided by the present invention, high-quality and stable continuous casting of super electrode flat steel billets is successfully achieved; wherein, by fully standing, the deoxidation products are more thoroughly floated and removed, and the negative impact of nozzle nodules in continuous casting of billets with smaller cross-sectional sizes than slabs is greatly reduced. More importantly, the highly sensitive property of solidification heat transfer is formulated, and precise dynamic process matching is formulated. By integrating the superheat of the casting steel liquid, combined electromagnetic stirring, casting speed and secondary cooling intensity, precise solidification control of the ultra-high conductive electrode flat steel billet is achieved, the low-multiple quality of the billet is good, and the various properties of the flat steel obtained by rolling meet the standard requirements well, wherein the key indicator of resistivity is overall controlled at 11.0~12.7μΩ·cm.

[0074] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for producing an electrode flat steel billet, comprising the following steps: The electrode flat steel billet raw material is sequentially subjected to converter semi-steel smelting, LF electric heating refining, RH vacuum treatment, large square billet continuous casting and stacking slow cooling to obtain the electrode flat steel billet; After the RH vacuum treatment, the molten steel after the RH station is first placed on the continuous casting platform with the temperature of the molten steel kept at ≥1575°C for 5min-6min, and then the large square billet is continuously cast.

2. The method for producing an electrode flat steel billet according to claim 1, characterized in that: The smelting chemical composition of the electrode flat steel billet raw material, in terms of mass percentage, consists of the following elements: C 0.02%~0.04%, Si 0.02%~0.07%, Mn 0.28%~0.40%, P≤0.015%, S≤0.008%, Als 0.010%~0.020%, O≤30ppm, N≤60ppm, and the rest is Fe and other inevitable impurities.

3. The method for producing an electrode flat steel billet according to claim 1, characterized in that: The a[O] in the molten steel after the RH vacuum treatment is controlled at 20ppm-30ppm, and the contents of other chemical components meet the requirements of the finished product.

4. The method for producing an electrode flat steel billet according to claim 1, characterized in that: The cross-sectional dimensions of the large square billet are 320 mm×410 mm or 360 mm×450 mm.

5. The method for producing electrode flat steel billets according to claim 1, characterized in that: The large square billet continuous casting adopts straight-through long nozzle casting, and the inner diameter of the nozzle is 50mm~60mm.

6. The method for producing electrode flat steel billets according to claim 1, characterized in that: The superheat of the molten steel in the continuous casting process of the large square billet is controlled at 20°C to 40°C as a whole.

7. The method for producing an electrode flat steel billet according to claim 6, characterized in that: The large square bloom continuous casting adopts a dynamic matching casting speed and electromagnetic stirring process.

8. The method for producing electrode flat steel billets according to claim 7, characterized in that: The dynamic matching casting speed and electromagnetic stirring process are specifically as follows: Superheat 20℃~25℃, matching continuous casting speed 2.7t / min, crystallizer electromagnetic stirring current intensity 350A~450A, solidification end electromagnetic stirring current intensity 100A~150A; Superheat 26~35℃, matching continuous casting speed 2.5t / min~2.6t / min, crystallizer electromagnetic stirring current intensity 350A~400A, solidification end electromagnetic stirring current intensity 150A~200A; The superheat is 36~40℃, the matching continuous casting speed is 2.4t / min~2.5t / min, the electromagnetic stirring current intensity of the crystallizer is 300A~350A, and the electromagnetic stirring current intensity at the end of solidification is 200A~250A.

9. The method for producing electrode flat steel billets according to claim 1, characterized in that: The second cooling of the continuous casting of large square billets adopts strong cooling, and the specific water volume is 0.35~0.37L / kg 钢 .

10. The method for producing electrode flat steel billets according to claim 1, characterized in that: The endpoint C of the converter semi-steel smelting is ≤0.030%, the tapping temperature is ≥1650°C, the alloy is added according to the target alloy and content in the steel, and 300kg~500kg of active lime is quantitatively added; During the LF electric heating refining, 1000kg-1200kg of slag is added, and argon is blown and stirred throughout the process. During the argon blowing process, the steel liquid surface is strictly prohibited from violently churning, and the [Als]% in the steel liquid is controlled to be 0.025%-0.035%, and the temperature at the end of LF is controlled to be 1590°C-1594°C; When the surface temperature of the continuous casting billet is greater than 600° C., the stacking slow cooling is started, and the slow cooling time is greater than or equal to 18 hours.

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