Smelting production method of rare earth-containing new energy non-oriented silicon steel

Abstract

The invention discloses a rare earth-containing new energy non-oriented silicon steel smelting production method which comprises the following steps: KR desulfurization: slagging-off is carried out twice during desulfurization, the stirring time is 20-25 min each time, and the slagging-off area is greater than 98%; the S content of the treated molten iron is less than or equal to 0.001%; smelting in a converter; performing RH refining; a continuous casting process; and finally, it is guaranteed that recarburization of the tundish is within 5 ppm, aluminum loss ranges from 0.01% to 0.015%, and nitrogen increase is controlled to range from 0.0003% to 0.0005%. The thickness of products which can be stably produced in batches ranges from 0.20 mm to 0.35 mm, various performance indexes of the products meet the requirements of new energy automobile driving motors for materials, and the method can be applied and popularized.

Description

Technical Field

[0001] The invention belongs to the technical field of non-oriented silicon steel, and in particular relates to a smelting production method of non-oriented silicon steel containing rare earth new energy. Background Art

[0002] In order to meet the increasingly stringent requirements of environmental protection regulations and promote the realization of "carbon peak and carbon neutrality", electric vehicles have become the mainstream direction of the current development of the automobile industry. As the heart of electric vehicles, the performance and reliability requirements of the drive motor are more stringent than those of motors for other purposes. Restricted by the space and battery capacity of the entire vehicle, the automotive drive motor is required to have the characteristics of miniaturization, high efficiency, and high power density, while also meeting the complex and harsh service environment conditions and automotive-grade high reliability requirements. These demands have put forward higher requirements on the core functional materials of the drive motor-magnetic conductive materials: high saturation flux density, high magnetic induction intensity, low loss (especially low iron loss under medium frequency conditions of 400-1500Hz), excellent mechanical properties and fatigue resistance, good processing performance and high cost performance.

[0003] Baosteel's steelmaking production line uses poor and mixed mineral resources such as the Bayan Obo Mine and Mongolia to produce molten iron. The Bayan Obo Mine is a large-scale ore deposit with iron, rare earth, niobium and fluorite as the main metals. After smelting, there are still about 0.0020% of rare earths remaining in the steel. Therefore, the rare earth advantages of the Bayan Obo Mine are brought into play. At the same time, the high phosphorus content, large fluctuations in silicon content, and many harmful residual elements in the molten iron (high niobium and high titanium) in the molten iron are targeted, which brings difficulties to the development of high-end products such as rare earth high-strength non-oriented silicon steel, such as production process is not smooth, molten steel castability is poor, molten steel cleanliness is poor, production cost is high, and product quality is poor. The use of the Bayan Obo iron ore to produce new energy non-oriented silicon steel is of great significance, and it has a certain reference value for giving full play to my country's rare earth advantages and developing high-end rare earth high-strength non-oriented silicon steel.

[0004] The patent with application number 201711245381.X provides a method for manufacturing non-oriented silicon steel for rotors, whose chemical composition by weight percentage is: C: 0.001-0.003%, Si: 2.6-3.4%, Mn: 0.20-0.60%, P≤0.005%, S≤0.005%, Al s: 0.75-0.95%, N: 0.002-0.006%, Nb: 0.053-0.20%, and the rest is iron and residual content; the patent strengthens the composition by adding Nb element, which leads to poor magnetic properties.

[0005] The patent with application number 202211561447.7 provides a steelmaking process for non-oriented silicon steel. Non-oriented silicon steel is steelmade by a double-chamber electric heating furnace with a de-impurity chamber and a mixing chamber. It is mainly aimed at the uneven alloy composition of molten steel and heat loss of molten steel of non-oriented silicon steel. It is a technical method for controlling the ironmaking and steelmaking processes.

[0006] The invention relates to a production and manufacturing method of non-oriented silicon steel for a new energy vehicle drive motor. The product has a thickness of 0.20-0.35 mm, good magnetic properties and mechanical properties, and can be promoted and applied in permanent magnet drive motors and asynchronous motors. Summary of the invention

[0007] The purpose of the present invention is to provide a smelting production method of rare earth-containing new energy non-oriented silicon steel, the product has good magnetic properties and mechanical properties, and can be promoted and applied in permanent magnet drive motors and asynchronous motors.

[0008] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0009] The present invention discloses a method for smelting and producing non-oriented silicon steel containing rare earth new energy, comprising:

[0010] KR desulfurization: Desulfurization is carried out twice with slag removal, each stirring time is 20-25min, and the slag removal area is greater than 98%; after treatment, the S content of molten iron is ≤0.001%;

[0011] Converter smelting: The top and bottom combined blowing converter uses argon gas at the bottom of the converter throughout the whole process. The converter tapping temperature is controlled at 1630-1660℃. The harmful element content of converter slag is strictly controlled, especially S and Ti. The converter uses front and rear slag blocks to strictly control the slag to ensure that the ladle slag is less than 70mm. During the converter tapping process, 100-300kg of small-grained lime and Sn and Cr alloys are added. The ladle molten steel composition control requirements are P≤0.020%, S≤0.003%;

[0012] RH refining: After the RH refining ladle is in place, the temperature and oxygen are measured to control the oxygen content to 500-700ppm and the temperature to 1580-1610℃. The ladle is lifted and vacuum treatment is started. During the vacuum treatment, the circulation flow is controlled at 200-260Nm 3 / h, vacuum degree is controlled at 70-90Pa; after decarburization, carbon content is controlled within 0.0010%, deoxidation and alloying are carried out after oxygen determination and temperature measurement, aluminum particles and other alloys are added respectively to ensure that the content of Al s and alloy elements meet the requirements, sampling and testing the composition to meet the requirements, and desulfurization agent is added, and the ratio of desulfurization agent to molten steel is controlled at 5-10kg / t, and the circulation is 5-8min, and temperature measurement and sampling are performed to detect the chemical composition. Whether to add rare earth and the amount of addition are determined according to the requirements of rare earth content in the composition design and the inherited rare earth content. After soft blowing for 4-8min, vacuum is broken and sampling is performed to test the off-site chemical composition;

[0013] Continuous casting process: the tundish, nozzle and covering agent are prepared in accordance with the requirements of ultra-low carbon steel, and special protective slag for non-oriented silicon steel is used; the long nozzle and submerged nozzle are well sealed and the argon gas flow rate is controlled, the tundish covering agent and crystallizer protective slag are evenly covered, and the long nozzle is replaced every 4 furnaces; the casting speed is controlled at 0.90-1.2m / min during the casting process, and the tundish liquid level and stopper rod are stable; finally, the carbon increase of the tundish is guaranteed to be within 5ppm, the aluminum loss is 0.01-0.015%, and the nitrogen increase is controlled at 0.0003-0.0005%.

[0014] Furthermore, the chemical composition of the new energy non-oriented silicon steel by mass percentage is: C 0.0023%, Si3.35%, P 0.011%, S 0.0014%, Als 0.96%, Ti 0.0021%, Nb 0.0024%, As 0.0032%, Cr 0.22%, Sn 0.046%, La+Ce 0.0012%, and the remaining components are Fe and unavoidable impurity elements.

[0015] Furthermore, the chemical composition of the new energy non-oriented silicon steel by mass percentage is: C 0.0022%, Si3.34%, P 0.010%, S 0.0015%, Als 0.94%, Ti 0.0022%, Nb 0.0025%, As 0.0036%, Cr 0.23%, Sn 0.045%, La+Ce 0.0013%, and the remaining components are Fe and unavoidable impurity elements.

[0016] Furthermore, the chemical composition of the new energy non-oriented silicon steel by mass percentage is: C 0.0021%, Si3.32%, P 0.010%, S 0.0020%, Als 0.92%, Ti 0.0020%, Nb 0.0024%, As 0.0032%, Cr 0.22%, Sn 0.042%, La+Ce 0.0014%, and the remaining components are Fe and unavoidable impurity elements.

[0017] Furthermore, the chemical composition of the new energy non-oriented silicon steel by mass percentage is: C 0.0020%, Si3.39%, P 0.011%, S 0.0016%, Als 0.94%, Ti 0.0022%, Nb 0.0025%, As 0.0031%, Cr 0.25%, Sn 0.043%, La+Ce 0.0011%, and the remaining components are Fe and unavoidable impurity elements.

[0018] Furthermore, the chemical composition of the new energy non-oriented silicon steel in mass percentage is: C 0.0022%, Si3.38%, P 0.012%, S 0.0017%, Als 0.95%, Ti 0.0021%, Nb 0.0023%, As 0.0030%, Cr 0.24%, Sn 0.05%, La+Ce 0.0010%, and the remaining components are Fe and unavoidable impurity elements.

[0019] Compared with the prior art, the beneficial technical effects of the present invention are:

[0020] The multi-element associated ore of Baotou Steel Bayan Obo is used to develop and produce new energy non-oriented silicon steel products, and a full-process manufacturing method is proposed. The thickness of the products that can be stably produced in batches using the present invention includes 0.20-0.35mm, and the various performance indicators of the products meet the requirements of new energy vehicle drive motors for materials, and can be promoted and applied. DETAILED DESCRIPTION

[0021] The production process of the new energy non-oriented silicon steel product of the present invention is as follows: Bayan Obo mine → ironmaking system → KR desulfurization → converter → RH refining → continuous casting machine → heating furnace → rough rolling → finishing rolling → acid rolling → annealing → reversible rolling mill rolling → annealing coating. The present invention designs the chemical composition and process flow according to the special composition of the Bayan Obo mine, adopts a cold rolling method combining acid rolling and twenty-roll cold rolling, ensures the dimensional tolerance requirements, improves production efficiency, reduces production costs, and improves the magnetic properties of the finished material.

[0022] Ironmaking system: According to the main component system of Bayan Obo ore and the content of associated elements, and combined with the requirements of the design chemical composition, the proportion of different types of ores is formulated. Sintered ore accounts for 65-78%, pelletized ore 22-35%, and the proportion of Bayan Obo ore in blast furnace is controlled at 55%-65%. The composition of molten iron meets the requirements of Si0.3-0.6%, Mn 0.2-0.5%, P0.10-0.20%, S 0.02-0.035%, Ti 0.040-0.065%.

[0023] KR desulfurization: Desulfurization is carried out twice with slag removal, each stirring time is 20-25 minutes, and the slag removal area is greater than 98%; after treatment, the S content of molten iron is ≤ 0.001%.

[0024] Converter smelting: The top and bottom combined converter uses argon gas at the bottom of the converter throughout the whole process. The converter tapping temperature is controlled at 1630-1660℃. The harmful elements in the converter slag are strictly controlled, especially S and Ti. The converter tapping adopts front and rear slag blocking, and the slag is strictly controlled to ensure that the ladle slag is less than 70mm. During the converter tapping process, 100-300kg of small-grained lime and alloys such as Sn and Cr are added. The ladle molten steel composition control requirements are P≤0.020%, S≤0.003%.

[0025] RH refining: After the RH refining ladle is in place, the temperature and oxygen are measured to control the oxygen content to 500-700ppm and the temperature to 1580-1610℃. The ladle is lifted and vacuum treatment is started. During the vacuum treatment, the circulation flow is controlled at 200-260Nm 3 / h, vacuum degree is controlled at 70~90Pa. After decarburization, carbon content is controlled within 0.0010%, deoxidation and alloying are carried out after oxygen determination and temperature measurement, aluminum particles and other alloys are added respectively to ensure that Al s and alloy element content meet the requirements, desulfurizer is added after sampling and inspection of composition meets the requirements, the ratio of desulfurizer to molten steel is controlled at 5~10kg / t, circulation is 5-8min, temperature measurement and sampling are taken to detect chemical composition, whether to add rare earth and the amount of addition are determined according to the requirements of rare earth content in composition design and the inherited rare earth content, vacuum is broken and sampling is taken after soft blowing for 4~8min, and the chemical composition is inspected.

[0026] Continuous casting process: The raw materials for the tundish, nozzle and covering agent shall be prepared according to the requirements of ultra-low carbon steel, and special protective slag for non-oriented silicon steel shall be used. The long nozzle and the submerged nozzle shall be well sealed and the argon gas flow rate shall be controlled. The tundish covering agent and the crystallizer protective slag shall be evenly covered, and the long nozzle shall be replaced every 4 furnaces. The casting speed shall be controlled at 0.90-1.2m / min, and the tundish liquid level and the stopper rod shall be stable. Finally, the carbon increase of the tundish shall be within 5ppm, the aluminum loss shall be 0.01-0.015%, and the nitrogen increase shall be controlled at 0.0003-0.0005%.

[0027] The present invention will be further described in detail below in conjunction with specific embodiments.

[0028] Examples 1 to 5 are specific conditions of producing new energy non-oriented silicon steel using the present invention. The chemical composition of molten iron is shown in Table 1, the chemical composition of converter steel is shown in Table 2, the RH off-site chemical composition is shown in Table 3, the chemical composition of tundish is shown in Table 4, the key process control points of the process are shown in Table 5, and the tensile properties, hardness and magnetic properties of the finished product are shown in Table 6.

[0029] Table 1 Composition of molten iron Unit: %

[0030]

[0031] Table 2 Composition of steel tapped from converter Unit: %

[0032] Example C Si P S Ti Nb As Cr Sn La+Ce 1 0.0025 0.02 0.010 0.0015 0.0003 0.0006 0.0035 0.21 0.045 0.0015 2 0.0019 0.03 0.011 0.0016 0.0004 0.0008 0.0036 0.25 0.040 0.0010 3 0.0022 0.03 0.009 0.0018 0.0003 0.0006 0.0030 0.20 0.038 0.0016 4 0.0018 0.02 0.009 0.0017 0.0002 0.0010 0.0030 0.22 0.046 0.0012 5 0.0026 0.03 0.009 0.0016 0.0003 0.0005 0.0032 0.26 0.040 0.0015

[0033] Table 3 RH off-position component Unit: %

[0034]

[0035] Table 4 Chemical composition Unit: %

[0036]

[0037] Table 5 Finished product performance

[0038]

[0039] The present invention can stably produce new energy non-oriented silicon steel in batches, solve technical difficulties in production, ensure good magnetic and mechanical properties, and has good application prospects.

[0040] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for smelting and producing non-oriented silicon steel containing rare earth new energy, characterized in that: include: KR desulfurization: Desulfurization is carried out twice with slag removal, each stirring time is 20-25min, and the slag removal area is greater than 98%; after treatment, the S content of molten iron is ≤0.001%; Converter smelting: The top and bottom combined blowing converter uses argon gas at the bottom of the converter throughout the whole process. The converter tapping temperature is controlled at 1630-1660℃. The harmful element content of converter slag is strictly controlled, especially S and Ti. The converter tapping adopts front and rear slag blocking, and the slag is strictly controlled to ensure that the ladle slag is less than 70mm. During the converter tapping process, 100-300kg of small-grained lime and Sn and Cr alloys are added; the ladle molten steel composition control requirements are P≤0.020%, S≤0.003%; RH refining: After the RH refining ladle is in place, the temperature and oxygen are measured to control the oxygen content to 500-700ppm and the temperature to 1580-1610℃. The ladle is lifted and vacuum treatment is started. During the vacuum treatment, the circulation flow is controlled at 200-260Nm 3 / h, vacuum degree is controlled at 70-90Pa; after decarburization, carbon content is controlled within 0.0010%, deoxidation and alloying are carried out after oxygen determination and temperature measurement, aluminum particles and other alloys are added respectively to ensure that the content of Als and alloy elements meet the requirements, sampling and inspection of the composition meet the requirements and then add desulfurizer, the ratio of desulfurizer to molten steel is controlled at 5-10kg / t, circulation 5-8min, temperature measurement and sampling to detect chemical composition, whether to add rare earth and the amount of addition are determined according to the requirements of rare earth content in the composition design and the inherited rare earth content, soft blowing for 4-8min and vacuum breaking sampling to inspect the off-site chemical composition; Continuous casting process: the tundish, nozzle and covering agent are prepared in accordance with the requirements of ultra-low carbon steel, and special protective slag for non-oriented silicon steel is used; the long nozzle and submerged nozzle are well sealed and the argon gas flow rate is controlled, the tundish covering agent and crystallizer protective slag are evenly covered, and the long nozzle is replaced every 4 furnaces; the casting speed is controlled at 0.90-1.2m / min during the casting process, and the tundish liquid level and stopper rod are stable; finally, the carbon increase of the tundish is guaranteed to be within 5ppm, the aluminum loss is 0.01-0.015%, and the nitrogen increase is controlled at 0.0003-0.0005%.

2. The method for smelting and producing rare earth-containing new energy non-oriented silicon steel according to claim 1, characterized in that: The chemical composition of the new energy non-oriented silicon steel in mass percentage is: C 0.0023%, Si 3.35%, P 0.011%, S0.0014%, Als 0.96%, Ti 0.0021%, Nb 0.0024%, As 0.0032%, Cr 0.22%, Sn 0.046%, La+Ce 0.0012%, and the remaining components are Fe and unavoidable impurity elements.

3. The method for smelting and producing rare earth-containing new energy non-oriented silicon steel according to claim 1, characterized in that: The chemical composition of the new energy non-oriented silicon steel in mass percentage is: C 0.0022%, Si 3.34%, P 0.010%, S0.0015%, Als 0.94%, Ti 0.0022%, Nb 0.0025%, As 0.0036%, Cr 0.23%, Sn 0.045%, La+Ce 0.0013%, and the remaining components are Fe and unavoidable impurity elements.

4. The method for smelting and producing rare earth-containing new energy non-oriented silicon steel according to claim 1, characterized in that: The chemical composition of the new energy non-oriented silicon steel in mass percentage is: C 0.0021%, Si 3.32%, P 0.010%, S0.0020%, Als 0.92%, Ti 0.0020%, Nb 0.0024%, As 0.0032%, Cr 0.22%, Sn 0.042%, La+Ce 0.0014%, and the remaining components are Fe and unavoidable impurity elements.

5. The method for smelting and producing rare earth-containing new energy non-oriented silicon steel according to claim 1, characterized in that: The chemical composition of the new energy non-oriented silicon steel by mass percentage is: C 0.0020%, Si 3.39%, P 0.011%, S0.0016%, Als 0.94%, Ti 0.0022%, Nb 0.0025%, As 0.0031%, Cr 0.25%, Sn 0.043%, La+Ce 0.0011%, and the remaining components are Fe and unavoidable impurity elements.

6. The method for smelting and producing rare earth-containing new energy non-oriented silicon steel according to claim 1, characterized in that: The chemical composition of the new energy non-oriented silicon steel by mass percentage is: C 0.0022%, Si 3.38%, P 0.012%, S0.0017%, Als 0.95%, Ti 0.0021%, Nb 0.0023%, As 0.0030%, Cr 0.24%, Sn 0.05%, La+Ce 0.0010%, and the remaining components are Fe and unavoidable impurity elements.

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