Crystallizer casting powder for continuous casting of high-pulling-speed electrical steel and application of crystallizer casting powder

Abstract

The invention provides crystallizer casting powder for continuous casting of high-pulling-speed electrical steel and application of the crystallizer casting powder, and the crystallizer casting powder comprises the following components in percentage by mass: 6.0-9.5% of MnO, 4.5-8.0% of FeO, 28-33% of SiO2, 30-35% of CaO, 4-6% of Al2O3, 8-9.5% of Na2O and the balance of inevitable impurities. The content of FeO and MnO is strictly controlled, so that the FeO and MnO generate a synergistic effect in function, and the FeO and MnO form a synergistic effect in a slag film, so that the radiation heat transfer capability of the casting powder is enhanced, the characteristic of high heat output in a crystallizer under the condition of high pulling speed (greater than or equal to 5.5 m / min) is effectively adapted, and the stability of heat flow in a meniscus area is guaranteed. Moreover, the preparation method is simple and convenient to operate, and the production cost is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of metallurgical continuous casting, in particular to a mold flux for high-speed continuous casting of electrical steel and application thereof. BACKGROUND

[0002] With the continuous development of continuous casting technology, high-speed (≥5.5 m / min) continuous casting has become an important means to improve the production efficiency of electrical steel. However, under high-speed conditions, the heat flux density fluctuation in the meniscus region of the mold is significantly intensified, leading to unstable heat transfer behavior, and thus causing a series of problems of casting quality and equipment damage risk. Specifically, the heat flux density fluctuation in the meniscus region usually exceeds ±20 kW / m², causing local overheating or undercooling, which seriously affects the surface quality of the casting, and defects such as longitudinal cracks and corner cracks occur frequently. In addition, under high-speed conditions, the copper plate of the mold bears more severe thermal cycling, and the propagation speed of thermal fatigue cracks is accelerated, significantly shortening the service life of the copper plate. In current industrial applications, the service life of the copper plate is generally 6000-8000 tons, and frequent replacement not only increases maintenance costs, but also affects the continuity and stability of continuous casting production.

[0003] The prior art mainly adjusts the chemical composition and physical properties of the mold flux to improve its heat resistance regulation ability, trying to effectively control the heat flux density. However, the traditional mold flux has limited radiation heat transfer regulation ability at high temperature, and it is difficult to stabilize the heat flux density in the meniscus region under high-speed conditions; at the same time, its role in slowing down the propagation of thermal fatigue cracks in the copper plate is also not obvious. Based on this, the present application provides a mold flux for high-speed continuous casting of electrical steel, aiming to solve the technical problem of cracks caused by copper plate thermal fatigue. SUMMARY

[0004] The main purpose of the present application is to provide a mold flux for high-speed continuous casting of electrical steel and application thereof, to solve the technical problem of cracks caused by copper plate thermal fatigue.

[0005] To achieve the above-mentioned purpose, the present application provides a mold flux for high-speed continuous casting of electrical steel, the composition of the mold flux for high-speed continuous casting of electrical steel, in mass percentage, comprises: MnO 6.0-9.5%, FeO 4.5-8.0%, SiO2 28-33%, CaO 30-35%, Al2O3 4-6%, Na2O 8-9.5%, and the rest is inevitable impurities.

[0006] According to the embodiment of the present application, the mass percentage of MnO and FeO in the mold flux for high-speed continuous casting of electrical steel is 0.8-1.5.

[0007] According to the embodiment of the present application, the viscosity of the mold flux for high-speed casting of electrical steel at 1300 DEG C is 0.15-0.25 Pa s.

[0008] According to the embodiment of the present application, the radiation heat transfer coefficient of the mold flux for high-speed casting of electrical steel is ≤0.5 W / (m K).

[0009] According to the embodiment of the present application, the melting point of the mold flux for high-speed casting of electrical steel is 1000-1050 DEG C.

[0010] According to the embodiment of the present application, the additional amount of MnO is adjusted in real time according to the casting speed.

[0011] The additional amount of MnO is calculated according to the following formula: The additional amount of MnO = 0.4 x (V-5.0).

[0012] Wherein, the additional amount of MnO is expressed as a percentage relative to the total mass of the mold flux for high-speed casting of electrical steel.

[0013] The unit of the additional amount of MnO is %; V is the casting speed, and the unit is m / min.

[0014] According to the embodiment of the present application, the addition amount of FeO is adjusted according to the heat flux density of the meniscus region.

[0015] When the heat flux density of the meniscus region Q>35 kW / m 2 , the addition amount of FeO is the upper limit value.

[0016] The upper limit value is 7-8%.

[0017] According to the embodiment of the present application, the mold flux for high-speed casting of electrical steel is directionally supplemented to the meniscus region by a gas mist spraying method to maintain the stability of the thermal resistance layer.

[0018] The spraying speed of the gas mist spraying method is 0.8-1.2 kg / min.

[0019] The amount of the directionally supplemented mold flux for high-speed casting of electrical steel per ton of high-speed electrical steel is 0.25-0.4 kg.

[0020] The present application also provides an application of the mold flux for high-speed casting of electrical steel as described above, and the mold flux for high-speed casting of electrical steel is used in a continuous casting process with a casting speed ≥5.5 m / min.

[0021] According to the embodiments of the present application, the heat flux density fluctuation of the meniscus region is controlled within ±10 kW / m 2 The surface temperature gradient of the crystallizer copper plate is ≤15℃ / mm.

[0022] Compared with the prior art, the present application has the following beneficial effects: The above-mentioned mold flux for high-speed continuous casting of electrical steel and application thereof, by regulating and controlling the chemical composition of the mold flux for high-speed continuous casting of electrical steel, especially strictly controlling the content of FeO and MnO, produces a synergistic effect in function, and the two form a synergistic effect in the slag film, enhancing the radiation heat transfer capacity of the mold flux, effectively adapting to the characteristics of high heat output in the crystallizer under high-speed casting (≥5.5 m / min), and ensuring the stability of the heat flux in the meniscus region. The synergistic effect of MnO and FeO disperses in the glass matrix to form a microcrystalline phase, forming a "glass-microcrystalline" composite slag film structure. Among them, the glass phase provides good lubricity, reducing the frictional resistance between the casting blank and the crystallizer wall; the microcrystalline phase enhances the thermal stability of the slag film, effectively controls the heat flux density, prevents the heat flux from fluctuating sharply, and reduces the occurrence of copper plate thermal fatigue cracks.

[0023] Moreover, the preparation method of the present application is simple, convenient to operate, reduces production cost, and is suitable for industrial large-scale production. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from the structures shown in the drawings without creative labor.

[0025] Figure 1 is the surface graph of the copper plate after pouring the mold flux for high-speed continuous casting of electrical steel prepared in Example 1 of the present application; Figure 2 is the surface graph of the copper plate after pouring the mold flux for high-speed continuous casting of electrical steel prepared in Example 1 of the present application; Figure 3 is the surface graph of the copper plate after pouring the existing CaO-SiO2-based mold flux. DETAILED DESCRIPTION

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0028] To achieve the above objectives, the present invention provides a mold flux for high-speed continuous casting of electrical steel. The composition of the mold flux for high-speed continuous casting of electrical steel, by mass percentage, includes: MnO 6.0~9.5%, FeO 4.5~8.0%, SiO2 28~33%, CaO 30~35%, Al2O3 4~6%, Na2O 8~9.5%, with the remainder being unavoidable impurities.

[0029] In some embodiments, the composition of the mold flux for high-speed continuous casting of electrical steel, by mass percentage, includes: MnO 8~8.5%, FeO 5~8.0%, SiO2 28~33%, CaO 30~35%, Al2O3 4~6%, Na2O 8~9%, with the remainder being unavoidable impurities.

[0030] In some embodiments, the total content of MnO and FeO is 12-16% by mass percentage, and the FeO content is not less than 70% of the MnO content.

[0031] In some embodiments, strictly limiting the total content of MnO and FeO, and specifying that the FeO content is not less than 70% of the MnO content, ensures that MnO and FeO have a synergistic effect in function, rather than canceling each other out. FeO is translucent to infrared radiation at high temperatures, meaning it enhances radiative heat transfer. Simultaneously, FeO promotes the formation of a crystalline phase in the protective slag; MnO also regulates heat transfer, but it tends to promote the formation of a glassy phase. At high casting speeds, the crystallizer needs to rapidly dissipate a large amount of heat, but this process must be controllable and uniform.

[0032] The Al2O3 content is strictly controlled at 4-6% to avoid sudden viscosity changes caused by the adsorption of Al2O3 inclusions in the steel by the protective slag at high casting speeds, thereby reducing slag inclusions under the billet and lowering the defect rate.

[0033] Na2O and SiO2 form low-melting-point sodium silicate (Na2O·2SiO2), which can maintain extremely low viscosity in the liquid slag film layer, ensuring stable frictional resistance when the casting speed fluctuates, and preventing sticking and leakage of high-speed electrical steel due to lubrication interruption.

[0034] In some embodiments, ensuring the total content of MnO and FeO is crucial for achieving a fine balance between lubrication, thermal conductivity, and reactivity, especially for the two core operating conditions of high casting speed and electrical steel. If the total content of MnO and FeO is too high, it will excessively reduce viscosity and melting point, leading to lubrication failure, and excessively increase heat transfer, causing thermal stress cracks. If the total content of MnO and FeO is too low, the viscosity and melting point of the protective slag will be too high, resulting in insufficient lubrication and increasing the risk of steel leakage at high casting speeds.

[0035] In some embodiments, MnO and FeO act as strong fluxing agents, significantly reducing the melting point of the slag system (≤1100℃) and reducing high-temperature viscosity, ensuring that the slag can still quickly fill the gap between the billet and the copper plate when the casting speed is ≥5.5 m / min, forming a uniform slag film.

[0036] In some embodiments, 50W1300 non-oriented electrical steel (for high-speed electrical steel) is produced using a CSP thin slab continuous casting machine, with a continuous casting speed of 5.5~10 m / min and a slab thickness of 60~70 mm.

[0037] In some embodiments, 50W1300 non-oriented electrical steel (for high-speed electrical steel) is produced using a CSP thin slab continuous casting machine with a casting speed of 5.5~6.5 m / min and a slab thickness of 60~70 mm.

[0038] The aforementioned mold flux for high-speed continuous casting of electrical steel utilizes a mold flux with a suitable chemical composition, particularly by strictly controlling the content of FeO and MnO. This results in a synergistic effect, where the two elements work together in the slag film to enhance the radiative heat transfer capacity of the mold flux. This effectively adapts to the high heat output characteristics within the mold under high casting speeds (≥5.5 m / min) and ensures the stability of heat flow in the meniscus region. The synergistic effect of MnO and FeO disperses within the glass matrix to form a microcrystalline phase, constructing a "glass-microcrystalline" composite slag film structure. The glass phase provides excellent lubrication, reducing frictional resistance between the cast billet and the mold wall; the microcrystalline phase enhances the thermal stability of the slag film, effectively controlling heat flux density, preventing drastic heat flow fluctuations, and reducing the occurrence of thermal fatigue cracks in the copper plate.

[0039] Moreover, the preparation method of the present invention is simple, easy to operate, reduces production costs, and is suitable for large-scale industrial production.

[0040] In some embodiments, the mass percentage of MnO to FeO in the mold flux used for high-speed continuous casting of electrical steel is 0.8 to 1.5.

[0041] In the mold flux used for high-speed continuous casting of electrical steel, the mass percentage of MnO and FeO is 0.9~1.3.

[0042] In some embodiments, if the MnO content is much higher than the FeO content, the protective slag will become overly vitrified, resulting in high thermal resistance and potentially insufficient heat transfer. However, adjusting the appropriate MnO and FeO content ensures sufficient radiative heat transfer to accommodate the high heat output at high drawing speeds. Furthermore, the synergistic effect of MnO and FeO creates a stable slag film structure with microcrystals dispersed within a glass matrix. The glass phase provides good lubrication, while the microcrystalline phase stabilizes and controls heat flow, preventing drastic fluctuations in heat flow.

[0043] In some embodiments, the mold flux used for high-speed continuous casting of electrical steel has a viscosity of 0.15~0.25 Pa·s at 1300°C.

[0044] In some embodiments, the mold flux used for high-speed continuous casting of electrical steel has a viscosity of 0.15~0.2 Pa·s at 1300°C.

[0045] In some embodiments, the mold flux used for high-speed continuous casting of electrical steel has a viscosity of 0.15~0.18 Pa·s at 1300°C.

[0046] In some embodiments, the low viscosity of the mold flux used for continuous casting of high-speed electrical steel at 1300°C can promote uniform slag film spreading, suppress local thick slag spots, reduce the standard deviation of heat flux density distribution, and thus reduce the generation of surface longitudinal cracks in high-speed electrical steel.

[0047] In some embodiments, the radiative heat transfer coefficient of the mold flux used for high-speed continuous casting of electrical steel is ≤0.5 W / (m·K).

[0048] In some embodiments, the radiative heat transfer coefficient of the mold flux used for high-speed continuous casting of electrical steel is 0.1~0.5 W / (m·K).

[0049] In some embodiments, the radiative heat transfer coefficient of the mold flux used for high-speed continuous casting of electrical steel is 0.3~0.5 W / (m·K).

[0050] In some embodiments, the radiative heat transfer coefficient of the mold flux used for high-speed continuous casting of electrical steel is 0.35~0.45 W / (m·K).

[0051] In some embodiments, adjusting the radiative heat transfer coefficient of the mold flux used in high-speed continuous casting of electrical steel can significantly reduce the heat flux density in the upper part of the mold, reduce the temperature gradient of the primary billet shell, and reduce thermal stress, thereby significantly reducing the incidence of defects such as longitudinal and transverse cracks on the surface of the billet.

[0052] Moreover, protective slags with lower radiative heat transfer coefficients are usually accompanied by lower melting points and viscosity, which helps to form a more stable and uniform slag film, improves crystallizer lubrication, and reduces the risk of sticking and steel leakage.

[0053] Under high-speed continuous casting conditions, protective slag with a lower radiation heat transfer coefficient can better control heat transfer, reduce problems such as uneven billet shell thickness and steel leakage caused by excessive heat transfer, and improve the operating rate and safety of the continuous casting machine.

[0054] In some embodiments, the melting point of the mold flux used for high-speed continuous casting of electrical steel is 1000~1050℃.

[0055] In some embodiments, the melting point of the mold flux used for high-speed continuous casting of electrical steel is 1010~1030℃.

[0056] In some embodiments, strictly controlling the melting point of the mold flux used for high-speed continuous casting of electrical steel can simultaneously achieve "low heat transfer, low cracking, and low slag consumption" without sacrificing lubrication.

[0057] In some embodiments, the amount of MnO added is adjusted in real time according to the continuous casting speed.

[0058] The amount of MnO added is calculated according to the following formula: The amount of MnO added is 0.4 × (V - 5.0).

[0059] The amount of MnO added is expressed as a percentage of the total mass of the mold flux used for high-speed continuous casting of electrical steel.

[0060] The unit for the amount of MnO added is %.

[0061] V represents the continuous casting speed, measured in m / min.

[0062] In some embodiments, by controlling the amount of MnO added, the crystallinity of the slag film can be increased "instantly" under high-speed continuous casting conditions of ≥5.5m / min, thereby achieving a dynamic balance between heat transfer and lubrication and reducing the risk of surface cracks and sticking / steel leakage in high-speed electrical steel.

[0063] In some embodiments, the amount of FeO added is adjusted according to the heat flux density of the meniscus region.

[0064] When the heat flux density Q in the meniscus region is greater than 35 kW / m 2 At that time, the amount of FeO added is its upper limit.

[0065] The upper limit is 7-8%.

[0066] In some embodiments, the heat flux density in the meniscus region exceeds 35 kW / m². 2 Under high heat load conditions, by precisely controlling the amount of FeO added to its upper limit (7~8%), local excess heat can be effectively absorbed, the solidified shell overheating can be suppressed, the surface grains can be refined, the incidence of surface cracks and inclusions can be significantly reduced, the stability of continuous casting process and the quality of billet can be improved, and the stable production of high-quality continuous casting billets can be achieved.

[0067] In some embodiments, the mold flux for high-speed continuous casting of electrical steel is directionally replenished to the curved liquid surface area by aerosol spraying in order to maintain the stability of the thermal resistance layer.

[0068] The spraying speed of the aerosol spraying method is 0.8~1.2 kg / min.

[0069] In each ton of high-speed electrical steel casting, the amount of mold flux specifically added for high-speed electrical steel continuous casting is 0.25~0.4 kg.

[0070] In some embodiments, the spraying speed of the aerosol spraying method is 0.9~1.1 kg / min.

[0071] In each ton of high-speed electrical steel casting, the amount of mold flux specifically added for continuous casting of high-speed electrical steel casting is 0.28~0.35 kg.

[0072] In some embodiments, the mold flux for high-speed continuous casting of electrical steel is directionally replenished to the curved liquid surface area by aerosol spraying. This can precisely maintain the stability of the thermal resistance layer structure of the slag film, suppress heat flux density fluctuations, significantly reduce surface cracks and vibration marks, improve continuous casting stability and billet surface quality, and achieve efficient utilization of the mold flux.

[0073] The present invention also provides an application of the mold flux for high-speed continuous casting of electrical steel as described above, wherein the mold flux for high-speed continuous casting of electrical steel is used in continuous casting processes with casting speed ≥ 5.5 m / min.

[0074] In some embodiments, the mold flux used in high-speed continuous casting of electrical steel can effectively delay thermal fatigue cracks in copper plates, increasing their service life from 6,000-8,000 tons to over 12,500 tons.

[0075] In some embodiments, the longitudinal crack defect rate of the mold flux used for high-speed continuous casting of electrical steel is reduced to below 0.3%, and the crack occurrence rate is reduced to 2-7%.

[0076] In some embodiments, the longitudinal crack defect rate of the cast billet in the mold flux used for high-speed continuous casting of electrical steel is reduced to 0.1-0.3%, and the crack occurrence rate is reduced to 2-6%.

[0077] In some embodiments, the longitudinal crack defect rate of the cast billet in the mold flux used for high-speed continuous casting of electrical steel is reduced to 0.1-0.3%, and the crack occurrence rate is reduced to 2-4%.

[0078] In some embodiments, the maintenance cost per ton of high-speed electrical steel is reduced by 5.5 to 6 yuan, resulting in significant economic benefits.

[0079] In some embodiments, the heat flux density fluctuation in the meniscus region is controlled within ±10 kW / m². 2 Within this range, the temperature gradient on the surface of the copper plate in the crystallizer is ≤15℃ / mm.

[0080] In some embodiments, controlling the heat flux density fluctuation in the meniscus region can ensure that the nascent billet shell can grow uniformly and stably in the crystallizer, avoid longitudinal cracks on the billet surface, and improve the surface quality of the billet.

[0081] In some embodiments, regulating the temperature gradient on the surface of the copper plate in the crystallizer effectively reduces thermal stress concentration caused by local overheating or uneven cooling, significantly reducing the generation of hot cracks in the copper plate. Simultaneously, it prevents billet cracks caused by excessive local stress in the billet shell due to temperature gradients, ensuring the integrity of the billet. Furthermore, stable meniscus heat flow and a uniform temperature field greatly reduce drastic fluctuations in the molten steel surface within the crystallizer. This creates a more stable solidification environment, making the continuous casting process more stable and smooth, reducing the risk of production accidents such as leaks, and improving production continuity.

[0082] To further illustrate the present invention, the following examples are provided: Example 1 50W1300 non-oriented electrical steel (for high-speed electrical steel casting) was produced using a CSP thin slab continuous casting machine at a casting speed of 5.8 m / min and a slab thickness of 65 mm. The composition of the mold flux used in the high-speed electrical steel continuous casting, by mass percentage, was: MnO 8.2%, FeO 6.5%, SiO2 30.1%, CaO 32.0%, Al2O 35.1%, Na2O 8.5%, with the remainder being unavoidable impurities.

[0083] In the mold flux used for high-speed continuous casting of electrical steel, the mass percentage of MnO to FeO is 1.26.

[0084] During continuous casting, the composition is dynamically adjusted based on the casting speed and heat flow monitoring results. MnO is added directionally to the mold flux used in high-speed electrical steel continuous casting via an aerosol spraying system, with an addition amount of 0.32%. The spraying speed is 1.0 kg / min; the amount of mold flux added directionally to each ton of high-speed electrical steel is 0.31 kg.

[0085] Tests showed that the mold flux used for high-speed continuous casting of electrical steel had a viscosity of 0.16 Pa·s at 1300℃, a melting point of 1021℃, a radiative heat transfer coefficient of 0.43 W / (m·K), a copper plate surface temperature gradient of ≤15℃ / mm, a copper plate lifespan extended to 12,500 tons, a crack incidence rate of 3%, and a longitudinal crack defect rate of 0.1%.

[0086] Example 2 Compared to Example 1, the composition of the mold flux used in high-speed continuous casting of electrical steel was changed. Specifically, the composition of the mold flux for high-speed continuous casting of electrical steel, by mass percentage, is: MnO 8.4%, FeO 7.5%, SiO2 29.6%, CaO 31.8%, Al2O 34.8%, Na2O 8.4%, with the remainder being unavoidable impurities. The mass percentage of MnO to FeO is 1.12, and other steps are the same as in Example 1.

[0087] Tests showed that the mold flux used for high-speed continuous casting of electrical steel had a viscosity of 0.18 Pa·s at 1300℃ and a melting point of 1015℃. The radiative heat transfer coefficient of the mold flux used for high-speed continuous casting of electrical steel was 0.47 W / (m·K). The surface temperature gradient of the copper plate was ≤9℃ / mm. The copper plate life was extended to 9200 tons, the crack incidence rate was 5%, and the longitudinal crack defect rate was 0.8%.

[0088] Example 3 Compared to Example 1, the composition of the mold flux used in high-speed continuous casting of electrical steel was changed. Specifically, the composition of the mold flux for high-speed continuous casting of electrical steel, by mass percentage, is: MnO 8.3%, FeO 5.92%, SiO2 30.6%, CaO 32.5%, Al2O 34.5%, Na2O 8.8%, with the remainder being unavoidable impurities. The mass percentage of MnO to FeO is 1.4, and other steps are the same as in Example 1.

[0089] Tests showed that the mold flux used for high-speed continuous casting of electrical steel had a viscosity of 0.13 Pa·s at 1300℃, a melting point of 1045℃, a radiative heat transfer coefficient of 0.41 W / (m·K), a copper plate surface temperature gradient of ≤11℃ / mm, a copper plate lifespan extended to 9400 tons, a crack incidence rate of 3.8%, and a longitudinal crack defect rate of 0.6%.

[0090] Comparative Example 1 Compared to Example 1, the composition of the mold flux used for high-speed continuous casting of electrical steel was changed.

[0091] The composition of the mold flux used in high-speed continuous casting of electrical steel, by mass percentage, is: MnO 9.2%, FeO 12.1%, SiO2 31.8%, CaO 34.2%, Al2O 34.7%, Na2O 8.6%, with the remainder being unavoidable impurities. The mass percentage of MnO to FeO is 0.76, and the other steps are the same as in Example 1.

[0092] Tests showed that the mold flux used for high-speed continuous casting of electrical steel had a viscosity of 0.19 Pa·s at 1300℃, a melting point of 1010℃, a radiative heat transfer coefficient of 0.52 W / (m·K), a copper plate surface temperature gradient of 18℃ / mm, a copper plate life of 6500 tons, a crack incidence rate of 8.5%, and a longitudinal crack defect rate of 1.8%.

[0093] Comparative Example 2 Compared to Example 1, the composition of the mold flux used for high-speed continuous casting of electrical steel was changed.

[0094] The composition of the mold flux used in high-speed continuous casting of electrical steel, by mass percentage, is: MnO 11.5%, FeO 7.3%, SiO2 31.2%, CaO 33.2%, Al2O 35.2%, Na2O 9.2%, with the remainder being unavoidable impurities. The mass percentage of MnO to FeO is 1.57, and the other steps are the same as in Example 1.

[0095] Tests showed that the mold flux used for high-speed continuous casting of electrical steel had a viscosity of 0.21 Pa·s at 1300℃, a melting point of 1015℃, a radiative heat transfer coefficient of 0.54 W / (m·K), a copper plate surface temperature gradient of 20℃ / mm, a copper plate life of 7200 tons, a crack incidence rate of 7.8%, and a longitudinal crack defect rate of 1.5%.

[0096] Analysis example: Figure 1This is a heat flow diagram of the mold flux for casting grade 1300 electrical steel in high-speed continuous casting, obtained in Example 1 of this invention. Figure 2 This is a surface view of the copper plate after casting with the mold protective slag for high-speed continuous casting of electrical steel obtained in Embodiment 1 of the present invention. It can be seen that there are cracks on the surface of the copper plate. Figure 3 This is a surface image of a copper plate after casting with an existing CaO-SiO2-based protective slag. Cracks can be seen on the surface of the steel plate.

[0097] Therefore, taking Example 1 as an example, the present invention needs to strictly limit the composition of the mold flux used for high-speed continuous casting of electrical steel, as well as the mass percentages of MnO and FeO. Through the cooperation of each step, the resulting mold flux for high-speed continuous casting of electrical steel has a viscosity of 0.15~0.25 Pa·s at 1300℃, a radiative heat transfer coefficient ≤0.5 W / (m·K), and a melting point of 1000~1050℃. This mold flux for high-speed continuous casting of electrical steel can control the heat flux density fluctuation in the meniscus region within ±10 kW / m when used in continuous casting processes with a casting speed ≥5.5 m / min. 2 Within this range, the surface temperature gradient of the copper plate in the crystallizer is ≤15℃ / mm, which significantly extends the life of the copper plate and reduces the crack rate.

[0098] The aforementioned mold flux for high-speed continuous casting of electrical steel and its application demonstrate how adjusting the chemical composition of the mold flux for high-speed continuous casting of electrical steel, particularly strictly controlling the content of FeO and MnO, can create a synergistic effect. The two elements work together in the slag film to enhance the radiative heat transfer capacity of the mold flux, effectively adapting to the high heat output characteristics within the mold under high casting speeds (≥5.5 m / min) and ensuring the stability of heat flow in the meniscus region. The synergistic effect of MnO and FeO disperses in the glass matrix to form a microcrystalline phase, constructing a "glass-microcrystalline" composite slag film structure. The glass phase provides good lubrication properties, reducing the frictional resistance between the billet and the mold wall; the microcrystalline phase enhances the thermal stability of the slag film, effectively controlling heat flux density, preventing drastic heat flow fluctuations, and reducing the occurrence of thermal fatigue cracks in the copper plate.

[0099] Moreover, the preparation method of the present invention is simple, easy to operate, reduces production costs, and is suitable for large-scale industrial production.

[0100] The above technical solutions of the present invention are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made under the technical concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A mold flux for high-speed continuous casting of electrical steel, characterized in that, The composition of the mold flux used for high-speed continuous casting of electrical steel, by mass percentage, includes: MnO 6.0~9.5%, FeO 4.5~8.0%, SiO2 28~33%, CaO 30~35%, Al2O3 4~6%, Na2O 8~9.5%, with the remainder being unavoidable impurities.

2. The mold flux for high-speed continuous casting of electrical steel according to claim 1, characterized in that, The mold flux used for high-speed continuous casting of electrical steel contains MnO and FeO in a mass percentage of 0.8 to 1.5%.

3. The mold flux for high-speed continuous casting of electrical steel according to claim 1, characterized in that, The mold flux used for high-speed continuous casting of electrical steel has a viscosity of 0.15~0.25 Pa·s at 1300℃.

4. The mold flux for high-speed continuous casting of electrical steel according to claim 1, characterized in that, The radiative heat transfer coefficient of the mold flux used for high-speed continuous casting of electrical steel is ≤0.5 W / (m·K).

5. The mold flux for high-speed continuous casting of electrical steel according to claim 1, characterized in that, The melting point of the mold flux used for high-speed continuous casting of electrical steel is 1000~1050℃.

6. The mold flux for high-speed continuous casting of electrical steel according to claim 1, characterized in that, The amount of MnO added is adjusted in real time according to the continuous casting speed; The amount of MnO added is calculated according to the following formula: The amount of MnO added = 0.4 × (V - 5.0); The amount of MnO added is expressed as a percentage of the total mass of the mold flux used for high-speed continuous casting of electrical steel. The unit for the amount of MnO added is %; V is the continuous casting speed, in m / min.

7. The mold flux for high-speed continuous casting of electrical steel according to claim 1, characterized in that, The amount of FeO added is adjusted according to the heat flux density of the meniscus region; When the heat flux density Q in the meniscus region is greater than 35 kW / m 2 At that time, the amount of FeO added is its upper limit. The upper limit is 7-8%.

8. The mold flux for high-speed continuous casting of electrical steel according to claim 1, characterized in that, The mold flux used for high-speed continuous casting of electrical steel is directionally replenished to the curved liquid surface area by aerosol spraying in order to maintain the stability of the thermal resistance layer. The spraying speed of the aerosol spraying method is 0.8~1.2 kg / min; In each ton of high-speed electrical steel casting, the amount of mold flux specifically added for high-speed electrical steel continuous casting is 0.25~0.4 kg.

9. The application of a mold flux as described in any one of claims 1 to 8 for high-speed continuous casting of electrical steel, characterized in that, The mold flux used for high-speed continuous casting of electrical steel is used in continuous casting processes with a casting speed ≥ 5.5 m / min.

10. The application of the mold flux for high-speed continuous casting of electrical steel according to claim 9, characterized in that, The heat flux density fluctuation in the meniscus region is controlled within ±10 kW / m². 2 Within this range, the temperature gradient on the surface of the copper plate in the crystallizer is ≤15℃ / mm.

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