CN111088457B - Non-oriented electrical steel and preparation method thereof - Google Patents

Non-oriented electrical steel and preparation method thereof Download PDF

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CN111088457B
CN111088457B CN201911236377.6A CN201911236377A CN111088457B CN 111088457 B CN111088457 B CN 111088457B CN 201911236377 A CN201911236377 A CN 201911236377A CN 111088457 B CN111088457 B CN 111088457B
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CN111088457A (en
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张利民
朱立光
肖鹏程
张利军
刘增勋
毕燕雷
田鹏
张彩军
张庆军
王博
王雁
周景一
孙立根
王硕明
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North China University of Science and Technology
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/10—Handling in a vacuum
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
    • C21D8/1216—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the working step(s) being of interest
    • C21D8/1222—Hot rolling
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/04—Making ferrous alloys by melting
    • C22C33/06—Making ferrous alloys by melting using master alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/005—Ferrite

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  • Manufacturing Of Steel Electrode Plates (AREA)

Abstract

The invention relates to non-oriented electrical steel and a preparation method thereof. The product comprises the following chemical components in percentage by mass: c: less than or equal to 0.0030 percent, Si: 0.90-1.00%, Mn: 0.2-0.40%, P: 0.015-0.40%, S: less than or equal to 0.004%, Als: 0.025-0.035%, Ti is less than or equal to 0.001%, and the balance is Fe and inevitable impurities. Controlling a converter; LF raises the temperature of molten steel to 1620-1650 ℃, and then high-alumina slag is added; alloying; the temperature of tundish molten steel in the continuous casting process is 1532-1542 ℃; the time of the continuous casting billet in the heating furnace is more than or equal to 120min, the rolling start temperature is 1060-1100 ℃, the finish rolling temperature is 980-1020 ℃, the finish rolling temperature is 840-880 ℃, and the coiling temperature is 680-720 ℃. Through the optimization of components and production process, the non-oriented electrical steel with excellent performance is developed.

Description

Non-oriented electrical steel and preparation method thereof
Technical Field
The invention relates to the technical field of ferrous metallurgy, in particular to the technical field of electrical steel metallurgy.
Background
With the release of the whole text of 'Chinese manufacturing 2025', the transformation of the Chinese industry is synchronously promoted on the wave tip of the tuyere by another secondary station, industrialization, informatization, urbanization and agricultural modernization are synchronously promoted, the potential required in the ultra-large scale is continuously released, a wide space is provided for the development of the manufacturing industry of China, and the development of the manufacturing industry does not leave the great common requirements of innovative development in the fields of electric power materials, intelligent manufacturing, additive manufacturing, new materials and the like. The non-oriented electrical silicon steel occupies an extremely important position in electrification construction, and in a certain sense, the consumption of silicon steel sheets in one country can be used for measuring the electrification degree of the country, so that the electrical steel has great development prospect in the long run. At present, electrical steel is developed towards the direction of replacing heat with cold, and cold rolled silicon steel is developed towards the direction of high grade, low iron loss, low grade and high magnetic induction. Therefore, various large steel mills strive to develop cold-used electrical silicon steel, especially non-oriented electrical silicon steel, to improve the cost performance and market competitiveness of the product.
The main performance requirements of the low-silicon non-oriented electrical steel are low iron loss and high magnetic induction, and the low-silicon non-oriented electrical steel has better physical properties, mechanical properties of materials and other indexes. The low-silicon non-oriented electrical steel produced by the conventional process has high contents of C, Si, S, Al and impurities, is difficult to control, has high iron loss and low magnetic induction, often cannot meet the production requirements of users, and has high cost.
The invention content is as follows:
the invention aims to provide the low-silicon non-oriented electrical steel with low iron loss, high magnetic induction and excellent performances of high tensile strength, high yield strength and the like by optimizing and changing the production process of the product components so as to solve the problems of insufficient performance and high production cost of the low-silicon non-oriented electrical steel produced by the conventional process.
In order to achieve the purpose, the invention adopts the following technical scheme:
a non-oriented electrical steel, characterized in that the electrical steel is obtained by RH vacuum treatment and precise control of the aluminum addition, and the composition of the electrical steel is: by mass percent, C is less than or equal to 0.0020%, and Si: 0.9 to 1.0%, Mn: 0.25-0.35%, P: 0.025-0.035%, S: less than or equal to 0.005 percent, Als: 0.025-0.035%, Ti is less than or equal to 0.001%, and the balance of Fe and inevitable impurities; and controlling rolling and cooling to obtain coarse bulk ferrite with a metallographic structure of the electrical steel, wherein the grain size is uniform, and the average grain size is 7.0-8.0.
A preparation method of non-oriented electrical steel comprises the following steps:
s1, molten iron reserve: the [ S ] in the molten iron is less than or equal to 0.025 percent, and the [ Si ]: 0.30-0.60%, and the temperature of molten iron is more than or equal to 1300 ℃; controlling the raw material [ Ti ] to ensure that the [ Ti ] of the molten steel smelted by the converter is less than or equal to 0.001 percent; molten iron enters a converter after being treated by a desulfurization station: the S is less than or equal to 0.001 percent, and the molten iron is completely slag-off to ensure that the metal liquid level of the ladle is completely exposed;
s2, smelting in a converter: end point C is less than or equal to 0.040%, S is less than or equal to 0.004%, P is less than or equal to 0.030%, [ O ]: 600ppm to 800 ppm; and final slag R: 3.2-3.6, tapping the 'bare steel', 1/5 tapping, and adding 3.3-4.2 kg/t lime;
s3, LF refining: bottom blowing of a steel ladle, namely after the temperature of molten steel is raised to 1620-1650 ℃, adding 100-200 kg/t of high-alumina slag on the slag surface of the steel ladle for top slag modification when [ O ] in the molten steel is higher than 800 ppm;
s4, RH vacuum treatment: RH vacuum treatment is carried out for 30-45 min, the flow of circulating argon is 800-1200 Nl/min, and the vacuum degree is less than or equal to 2 Mbar; controlling the oxygen content of molten steel at the RH decarburization end point to be 300-400 ppm, adding low-carbon low-titanium ferrophosphorus, aluminum, ferromanganese and ultra-low-carbon ferrosilicon in an alloying addition sequence, wherein the low-carbon low-titanium ferrophosphorus is added before decarburization, the aluminum, ferromanganese and ultra-low-carbon ferrosilicon alloy are added according to needs after decarburization is finished, the addition time interval is more than or equal to 3min, high-aluminum slag is added for top slag treatment before leaving the station at 0.5-0.7 kg/t, and the chemical components of the molten steel after RH refining are in percentage by mass: c is less than or equal to 0.0020%, Si: 0.9 to 1.0%, Mn: 0.25-0.35%, P: 0.025-0.035%, S: less than or equal to 0.005 percent, Als: 0.025-0.035%, Ti is less than or equal to 0.001%, and the balance of Fe and inevitable impurities;
s5, continuous casting: the temperature of the tundish molten steel is 1527-1547 ℃, and the casting pulling speed is 0.8-1.2 m/min;
s6, rolling: the furnace time of the continuous casting billet is more than or equal to 120min, the rolling thickness is 2.75mm, the initial rolling temperature is 1060-1100 ℃, the finish rolling temperature is 980-1120 ℃, the final rolling temperature is 840-880 ℃, the coiling temperature is 680-720 ℃, and the continuous casting billet is cooled by adopting a rear-section cooling mode after rolling.
RH vacuum treatment is carried out for 35-43 min, the amount of circulating gas is 1200-1800 Nl/min, and low-carbon low-titanium ferrophosphorus is added: according to the arrival of molten steel [ P ]]Every 0.001% [ P ] increase]Adding low-carbon low-titanium ferrophosphorus 0.04kg/t, blowing oxygen for decarbonization, the decarbonization time is more than or equal to 10min, [ O ]]Residue ofControlling the content at 300-500ppm, adding aluminum: al (1.125X [ O ]]Residue of)/η1+[Als]×t/η2L; wherein: eta1: the absorption rate of aluminum is 45-55%; l: the purity of the aluminum; eta2The absorption rate of the aluminum is 90-95% of a reference value; t: 2.5-3.0 kg/t ferromanganese with the molten steel amount and the content of metal manganese more than or equal to 97 percent, and 12-13 kg/t ultra-low carbon ferrosilicon.
The LF tapping temperature is 1625-1635 ℃.
The lime used by the converter is lime with CaO more than or equal to 85 percent, S less than or equal to 0.030 percent and activity more than 300 ml.
The preferable continuous casting pouring is 1532-1542 ℃, the drawing speed is 1.0-1.2 m/min, and the required constant speed is more than or equal to 90 percent
The steel ladle adopts carbon-free steel ladle bricks, the slag line adopts low-carbon magnesia carbon bricks with the C less than or equal to 8 percent, the bottom ladle wall of the steel ladle adopts carbon-free alumina-magnesia spinel bricks or carbon-free precast blocks, the drainage sand adopts special drainage sand for silicon steel, the working layer of the tundish adopts carbon-free dry materials, the first layer of covering agent of the tundish adopts wollastonite, and the second layer of the tundish adopts vermiculite as a heat insulating agent.
The average value of the iron loss of the electrical steel is 4.201w/kg, the average value of the magnetic induction is 1.868T, the average value of the tensile strength reaches 482MPa, the average value of the yield strength reaches 365MPa, and the elongation is 36%.
The ultra-low carbon ferrosilicon comprises the following components (wt%): si: 74-80%, Al is less than or equal to 0.5%, Ca is less than or equal to 1.0%, Mn is less than or equal to 0.4%, Cr is less than or equal to 0.2%, P is less than or equal to 0.035%, S is less than or equal to 0.010%, C is less than or equal to 0.02%, and the particle size is as follows: 10-50 mm.
The above Al ═ 1.125 × [ O ]]Residue of)/η1+[Als]×t/η2In L, [ Als ]]Calculated as 0.300%.
The invention has the beneficial effects that:
1. the iron loss mainly depends on the contents of C, Si, S, Al, inclusions and the like in steel and the microstructure, the S content in the molten iron is strictly controlled, and the proper component ratio of C, Si and Al is obtained by strictly controlling the addition amount of Al (1.125 x [ O ] residue)/eta 1+ [ Als ] x t/eta 2 & L and the addition amount of other alloys required by alloying in RH refining.
2. The controlled rolling and controlled cooling technology is adopted, the furnace time is strictly controlled to be more than or equal to 120min, the rolling thickness is 2.75mm, the initial rolling temperature is 1060-1100 ℃, the finish rolling temperature is 980-1120 ℃, the final rolling temperature is 840-880 ℃, the coiling temperature is 680-720 ℃, the plate shape is adjusted, the coarsening of crystal grains is promoted, and the cooling after rolling adopts a back-stage cooling mode so as to ensure that the fine ferrite crystal grains after rolling have enough growth time, thereby obtaining thicker crystal grains in the hot rolling stage, ensuring the uniform size of the crystal grains, reducing the iron loss to the minimum, improving the magnetism of the crystal grains, simultaneously considering that the formed iron scale is easy to acid wash, and providing a good foundation for the quality of subsequent products.
3. Through component optimization and improved production process, the metallographic structure of the obtained electrical steel is coarse bulk ferrite, the grain size is uniform, the average grain size is in the range of 7.0-8.0 grade, and the performance characterization is as follows: the average value of iron loss is reduced from 5.035w/kg to 4.201w/kg, the average value of magnetic induction is improved from 1.313T to 1.868T, the average value of tensile strength reaches 482MPa, the average value of yield strength reaches 365MPa, and the elongation is 36%.
The specific implementation mode is as follows:
the present invention is further illustrated by the following examples, which are not intended to limit the scope of the present invention in any way.
The first embodiment is as follows:
a production process of low-silicon non-oriented electrical steel. The method comprises the following process steps:
s1, adopting a 120-ton converter, and charging molten iron in the converter according to the mass percentage: [ S ]: 0.001 percent; the mass percentage of the smelting end point of the converter is as follows: c: 0.0025%, S: 0.0021%, P: 0.011%, [ O ]: 625 ppm; and final slag R: 3.3, tapping bare steel from the converter, and adding 400kg of lime after tapping 1/5;
s2, the temperature of molten steel is 1629 ℃ after the temperature rise of the molten steel in the LF furnace is finished.
S3, RH vacuum treatment is carried out for 36min, the flow of circulating argon is 900Nl/min, and the vacuum degree is 1.8 Mbar; the alloying sequence is low-carbon low-titanium ferro-phosphorus, aluminum, ultra-low-carbon ferrosilicon and manganese metal, and the adding time interval is more than or equal to 3 min;
amount of aluminum added
[O]，ppm 300 400 500 600 700
Aluminum addition amount Kg 495 520 545 570 595
Alloying addition of silicon, manganese and phosphorus
Figure GDA0002740195530000041
60Kg of high-aluminum slag is added before the steel is taken out of the station for top slag treatment, the temperature of RH outgoing molten steel is 1590 ℃, and the chemical components of the molten steel after RH refining are in percentage by mass: c: 0.0016%, Si: 0.92%, Mn: 0.27%, P: 0.029%, S: 0.003%, Als: 0.030%, Ti: 0.0008 percent, and the balance of Fe and inevitable impurities;
s4, the temperature of the continuous casting tundish molten steel is 1534 ℃, the casting drawing speed is 1.0m/min, and the constant speed is 98%;
s5, the time of the continuous casting billet in the heating furnace is 125 min; the rolling thickness is 2.75mm, the initial rolling temperature is 1070 ℃, the finish rolling temperature is 980 ℃, the final rolling temperature is 850 ℃, the coiling temperature is 685 ℃, and the cooling is carried out by adopting a back-end cooling mode after rolling;
s6, the performance of the low-silicon non-oriented electrical steel is detected as follows: iron loss value: 4.111w/kg, magnetic induction value: 1.836T, the tensile strength is 482MPa, the yield strength reaches 360MPa, the elongation is 37 percent, the metallographic structure is coarse block ferrite, the grain size is uniform, the average grain size is in the category of 8.0 grade, and the standard requirement is completely met.
Example two
A production process of low-silicon non-oriented electrical steel. The method comprises the following process steps:
s1, adopting a 120-ton converter, and charging molten iron in the converter according to the mass percentage: [ S ]: 0.0008 percent; the mass percentage of the smelting end point of the converter is as follows: c: 0.0021%, S: 0.0024%, P: 0.012%, [ O ]: 850 ppm; and final slag R: 3.4, tapping bare steel from the converter, and adding 450kg of lime after tapping 1/5;
s2, after the temperature of the molten steel is raised in the LF furnace, the temperature of the molten steel is 1631 ℃, and 100kg of high-alumina slag is added to the slag surface of the steel ladle for top slag modification;
s3, carrying out RH vacuum treatment for 38min, wherein the circulating argon flow is 1000Nl/min, and the vacuum degree is 1.9 Mbar; the alloying sequence is low-carbon low-titanium ferro-phosphorus, aluminum, ultra-low-carbon ferrosilicon and manganese metal, and the adding time interval is more than or equal to 3 min;
amount of aluminum added
[O]，ppm 300 400 500 600 700
Aluminum addition amount Kg 495 520 545 570 595
The alloying addition amount of silicon, manganese and phosphorus is as follows:
Figure GDA0002740195530000051
adding 75Kg of high-aluminum slag for top slag treatment before leaving the station, wherein the temperature of RH leaving molten steel is 1585 ℃, and the chemical components of the molten steel after RH refining are in percentage by mass: c: 0.0017%, Si: 0.94%, Mn: 0.28%, P: 0.030%, S: 0.003%, Als: 0.029%, Ti: 0.0007 percent, and the balance of Fe and inevitable impurities;
s4, the temperature of the molten steel of the continuous casting tundish is 1537 ℃, the casting and drawing speed is 1.1m/min, and the constant speed is 97.5 percent;
s5, the time of the continuous casting slab in the heating furnace is 132 min; the rolling thickness is 2.75mm, the initial rolling temperature is 1080 ℃, the finish rolling temperature is 1000 ℃, the finish rolling temperature is 860 ℃, the coiling temperature is 700 ℃, and the post-rolling cooling mode is adopted for cooling after rolling;
s6, the performance of the low-silicon non-oriented electrical steel is detected as follows: iron loss value: 4.190w/kg, magnetic induction value: 1.872T, tensile strength of 478MPa, yield strength of 356MPa, elongation of 36%, coarse block ferrite as metallographic structure, uniform grain size, average grain size of 7.0 grade, and completely meeting standard requirements.
Example three:
a production process of low-silicon non-oriented electrical steel. The method comprises the following process steps:
s1, adopting a 120-ton converter, and charging molten iron in the converter according to the mass percentage: [ S ]: 0.0008 percent; the mass percentage of the smelting end point of the converter is as follows: c: 0.0023%, S: 0.0025%, P: 0.012%, [ O ]: 702 ppm; and final slag R: 3.38, tapping bare steel from the converter, and adding 500kg of lime after tapping 1/5;
s2, after the temperature of molten steel is raised in an LF furnace, the temperature of the molten steel is 1634 ℃;
s3, RH vacuum treatment is carried out for 41min, the flow of circulating argon is 1200Nl/min, and the vacuum degree is 1.96 Mbar; the alloying sequence is low-carbon low-titanium ferro-phosphorus, aluminum, ultra-low-carbon ferrosilicon and manganese metal, and the adding time interval is more than or equal to 3 min;
amount of aluminum added
[O]，ppm 300 400 500 600 700
Aluminum addition amount Kg 495 520 545 570 595
Alloying addition of silicon, manganese and phosphorus
Figure GDA0002740195530000052
Adding 80Kg of high-aluminum slag for top slag treatment before leaving the station, wherein the RH leaving molten steel temperature is 1598 ℃, and the molten steel after RH refining comprises the following chemical components in percentage by mass: c: 0.0019%, Si: 0.98%, Mn: 0.31%, P: 0.032%, S: 0.0035%, Als: 0.032%, Ti: 0.0008 percent, and the balance of Fe and inevitable impurities;
s4, the temperature of the molten steel of the continuous casting tundish is 1540 ℃, the casting pulling speed is 1.2m/min, and the constant speed is 98%;
s5, the time of the continuous casting slab in the heating furnace is 128 min; when the rolling thickness is 2.75mm, the initial rolling temperature is 1100 ℃, the finish rolling temperature is 1020 ℃, the finish rolling temperature is 880 ℃, the coiling temperature is 720 ℃, and the post-rolling cooling mode is adopted for cooling after rolling;
s6, the performance of the low-silicon non-oriented electrical steel is detected as follows: iron loss value: 4.189w/kg, magnetic induction value: 1.852T, 482MPa of tensile strength, 375MPa of yield strength, 36 percent of elongation, coarse block ferrite as a metallographic structure, uniform grain size and 8.0-grade average grain size, and completely meets the standard requirement.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not intended to limit the scope of the present invention, which is defined by the appended claims.

Claims (7)

1. The preparation method of the non-oriented electrical steel is characterized in that the components of the non-oriented electrical steel are obtained by RH vacuum treatment and accurate control of the aluminum addition amount in the alloying stage: by mass percent, C is less than or equal to 0.0020%, and Si: 0.9 to 1.0%, Mn: 0.25-0.35%, P: 0.025-0.035%, S: less than or equal to 0.005 percent, Als: 0.025-0.035%, Ti is less than or equal to 0.001%, and the balance of Fe and inevitable impurities; rolling and cooling are controlled, and the obtained electrical steel has a metallographic structure of coarse block ferrite, uniform crystal grains and an average grain size of 7.0-8.0 grades; the preparation method comprises the following steps:
s1, molten iron reserve: the [ S ] in the molten iron is less than or equal to 0.025 percent, and the [ Si ]: 0.30-0.60%, and the temperature of molten iron is more than or equal to 1300 ℃; controlling the raw material [ Ti ] to ensure that the molten iron [ Ti ] is less than or equal to 0.001 percent after smelting in the converter; molten iron enters a converter after being treated by a desulfurization station: the S is less than or equal to 0.001 percent, and the molten iron is completely slag-off to ensure that the metal liquid level of the ladle is completely exposed;
s2, smelting in a converter: end point C is less than or equal to 0.040%, S is less than or equal to 0.004%, P is less than or equal to 0.030%, [ O ]: 600ppm to 800 ppm; and final slag R: 3.2-3.6, tapping the 'bare steel', 1/5 tapping, and adding 3.3-4.2 kg/t lime;
s3, LF refining: bottom blowing of a steel ladle, namely after the temperature of molten steel is raised to 1620-1650 ℃, adding 100-200 kg/t of high-alumina slag on the slag surface of the steel ladle for top slag modification when [ O ] in the molten steel is higher than 800 ppm;
s4, RH vacuum treatment: RH vacuum treatment is carried out for 30-45 min, the flow of circulating argon is 800-1200 Nl/min, and the vacuum degree is less than or equal to 2 Mbar; controlling the oxygen content of molten steel at the RH decarburization end point to be 300-400 ppm, adding low-carbon low-titanium ferrophosphorus, aluminum, ferromanganese and ultra-low-carbon ferrosilicon in sequence by alloying, wherein the low-carbon low-titanium ferrophosphorus is added before decarburization, the aluminum, ferromanganese and ultra-low-carbon ferrosilicon are added according to needs after decarburization is finished, the adding time interval is more than or equal to 3min, adding 0.5-0.7 kg/t of high-aluminum slag before leaving a station for top slag treatment, and refining the molten steel according to the mass percent of chemical components: c is less than or equal to 0.0020%, Si: 0.9 to 1.0%, Mn: 0.25-0.35%, P: 0.025-0.035%, S: less than or equal to 0.005 percent, Als: 0.025-0.035%, Ti is less than or equal to 0.001%, and the balance of Fe and inevitable impurities;
s5, continuous casting;
s6, rolling: the furnace time of the continuous casting billet is more than or equal to 120min, the rolling thickness is 2.75mm, the initial rolling temperature is 1060-1100 ℃, the finish rolling temperature is 980-1120 ℃, the final rolling temperature is 840-880 ℃, the coiling temperature is 680-720 ℃, and the continuous casting billet is cooled by adopting a rear-section cooling mode after rolling.
2. The method for preparing non-oriented electrical steel according to claim 1, wherein RH vacuum treatment is carried out for 35-43 min, the flow of circulating argon is 900-1200 Nl/min, and low-carbon low-titanium ferrophosphorus is added: according to the arrival of molten steel [ P ]]Every 0.001% [ P ] increase]Adding low-carbon low-titanium ferrophosphorus 0.04kg/t, blowing oxygen for decarbonization, the decarbonization time is more than or equal to 10min, [ O ]]Residue ofControlling the content at 300-500ppm, adding aluminum: al (1.125X [ O ]]Residue of)/η1+[Als]×t/η2L; wherein: eta1: the absorption rate of aluminum is 45-55%; l: the purity of the aluminum; eta2The absorption rate of the aluminum is 90-95% of a reference value; t: 2.5-3.0 kg/t ferromanganese with the molten steel amount and the content of metal manganese more than or equal to 97 percent, and 12-13 kg/t ultra-low carbon ferrosilicon.
3. The method of making a non-oriented electrical steel according to claim 1 or 2, having an LF tapping temperature of 1625-1635 ℃.
4. The method of producing a nonoriented electrical steel according to claim 1 or 2, wherein the lime used in the converter is lime having CaO of not less than 85%, S of not more than 0.030%, and activity of more than 300 ml.
5. The method for producing a nonoriented electrical steel according to claim 1 or 2, wherein the temperature of the continuous casting tundish molten steel is 1527 to 1547 ℃ and the casting drawing speed is 0.8 to 1.2 m/min.
6. The method for preparing non-oriented electrical steel according to claim 1 or 2, wherein the ladle adopts carbon-free ladle bricks, the slag line adopts low-carbon magnesia carbon bricks with the C less than or equal to 8%, the ladle bottom wall adopts carbon-free alumina-magnesia spinel bricks or carbon-free precast blocks, the drainage sand adopts drainage sand special for silicon steel, the working layer of the tundish adopts carbon-free dry materials, the first layer of covering agent of the tundish adopts wollastonite, and the second layer of the tundish adopts vermiculite as a heat preservation agent.
7. The method of producing a non-oriented electrical steel according to claim 1 or 2, the ultra-low-carbon ferrosilicon composition (wt%): si: 74-80%, Al is less than or equal to 0.5%, Ca is less than or equal to 1.0%, Mn is less than or equal to 0.4%, Cr is less than or equal to 0.2%, P is less than or equal to 0.035%, S is less than or equal to 0.010%, C is less than or equal to 0.02%, and the particle size is as follows: 10-50 mm.
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