High-performance non-oriented silicon steel and preparation method thereof

Abstract

The application belongs to the technical field of metal materials, and specifically provides a high-performance non-oriented silicon steel, which comprises the following components in percentage by mass: C: 0-0.003%, Si: 1.0-4.5%, Al: 0.022-1.0%, Mn: 0.12-0.93%, N: 0-0.003%, S: 0-0.003%, P: 0-0.005%, and the rest is Fe and inevitable impurities. The high-performance non-oriented silicon steel is a low-iron-loss and high-permeability non-oriented silicon steel, which greatly improves the magnetic properties of medium-silicon-content non-oriented silicon steel, and has a core loss Pt of about 2.81 W / Kg, a magnetic induction intensity B of about 1.71 T at low frequency, a core loss Pt of about 21.82 W / Kg, and a magnetic induction intensity B of about 1.72 T at high frequency. The application also provides a preparation method of the high-performance non-oriented silicon steel, which adopts an annealing process of flash heating and instantaneous holding, and the produced non-oriented silicon has lower iron loss and higher magnetism, better meeting the application requirements of new energy automobile motors, and the great shortening of holding time also accelerates the process flow and improves the production efficiency.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metal materials, and particularly relates to a high-performance non-oriented silicon steel and a preparation method thereof. BACKGROUND

[0002] Electricity is an indispensable energy in modern society, and is the most common and important energy. The production, transmission and use of electric energy cannot be separated from electric machines, power transmission transformers, electric motors and various ballasts, amplifiers, voltage stabilizers, relays, rectifiers and other power and electrical equipment and electrical components. With the principle of electromagnetism, mechanical energy and electric energy conversion, voltage and current conversion or electromechanical device driving can be realized. The key component of these devices and components is an electromagnetic core, and the raw material of the core, electrical steel, has become the cornerstone of the power and electrical industry.

[0003] Silicon steel is the most widely used soft magnetic material in industry, and non-oriented silicon steel is the most widely used electrical steel material, which is widely used in various electric machines. The performance of non-oriented silicon steel sheet is directly related to the loss of electric energy, and determines the performance, volume, weight and cost of electric machines, transformers and other products. Therefore, reducing iron loss and magnetic anisotropy and improving magnetic induction intensity have become the research focus of silicon steel. SUMMARY

[0004] The purpose of the present application is to provide a non-oriented silicon steel with low iron loss and high magnetic permeability.

[0005] To this end, the present application provides a high-performance non-oriented silicon steel, which comprises the following components in mass percentage: C: 0-0.003%, Si: 1.0-4.5%, Al: 0.022-1.0%, Mn: 0.12-0.93%, N: 0-0.003%, S: 0-0.003%, P: 0-0.005%, and the balance of Fe and inevitable impurities.

[0006] The present application also provides a preparation method of the above-mentioned high-performance non-oriented silicon steel, comprising the following steps: smelting molten steel according to the set composition, casting the molten steel into a casting blank, hot rolling, normalizing and pickling the casting blank, cold rolling and annealing to obtain the high-performance non-oriented silicon steel.

[0007] Specifically, the annealing comprises the following steps: (1) heating to the annealing temperature at 200-600℃ / s in an inert atmosphere; (2) cooling after holding at the annealing temperature.

[0008] Specifically, the annealing temperature is 700-1100℃.

[0009] Specifically, the inert atmosphere is a 30-95% nitrogen atmosphere.

[0010] Specifically, the temperature is kept for 0-10s in step (2).

[0011] Specifically, the temperature is kept for 0-10s in step (2).

[0012] Specifically, the cooling rate is 30℃ / s in step (2).

[0013] Specifically, the temperature of the molten steel in the tundish is 1500℃-1580℃, the starting temperature of the hot rolling is 920℃-980℃, the final temperature of the hot rolling is 800℃-860℃, and the soaking temperature of the normalizing and pickling is 900℃-1100℃.

[0014] Specifically, the thickness of the steel strip after cold rolling is 0.15-0.65mm.

[0015] Compared with the prior art, the application has the following advantages and beneficial effects:

[0016] The high-performance non-oriented silicon steel provided by the application is a non-oriented silicon steel with low iron loss and high magnetic permeability, which greatly improves the magnetic properties of medium-silicon-content non-oriented silicon steel, and has an iron core loss Pt of about 2.81W / Kg and a magnetic induction B of about 1.71T at low frequency, and an iron core loss Pt of about 21.82W / Kg and a magnetic induction B of about 1.72T at high frequency.

[0017] The preparation method of the high-performance non-oriented silicon steel provided by the application adopts an annealing process of flash heating and instantaneous holding, and compared with the non-oriented silicon steel under low heating rate and long holding time, the produced non-oriented silicon steel has lower iron loss and higher magnetic induction, better meeting the application requirements of new energy automobile motors, and the great shortening of the holding time also speeds up the process flow and improves the production efficiency.

[0018] The application will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 RD direction magnetic property comparison chart under different holding processes: (left) iron loss, (right) magnetic induction.

[0020] Figure 2 TD direction magnetic property comparison chart under different holding processes: (left) iron loss, (right) magnetic induction.

[0021] Figure 3 Metallographic structure photos of the silicon steel prepared under different holding processes: (a) route 1;(b) route 2;(c) route 3;(d) route 4;(e) route 5.

[0022] Figure 4Here are the IPF-Z diagrams and typical texture distribution diagrams: (a,b)route 1; (c,d)route 2; (e,f)route 3; (g,h)route 4; (i,j)route 5.

[0023] Figure 5 For φ2=45°ODF diagram: (a) route 1; (b) route 2; (c) route 3; (d) route 4; (e) route 5. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Although representative embodiments of the present invention have been described in detail, those skilled in the art will understand that various modifications and changes can be made to the present invention without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the embodiments, but should be defined by the appended claims and their equivalents.

[0025] This invention provides a high-performance non-oriented silicon steel, which, by mass percentage, comprises the following components: C: 0-0.003%, Si: 1.0-4.5%, Al: 0.022-1.0%, Mn: 0.12-0.93%, N: 0-0.003%, S: 0-0.003%, P: 0-0.005%, with the remainder being Fe and unavoidable impurities. The microstructure is mainly ferrite.

[0026] Si is an essential element in electrical steel. Adding Si to electrical steel can increase its resistivity, significantly reduce eddy current losses, and also help reduce magnetostriction, thereby reducing noise during core operation. However, as the Si content increases, the saturation magnetic induction intensity of the electrical steel decreases significantly, and the plasticity of the steel plate also decreases markedly, increasing the difficulty of cold working and greatly increasing the risk of breakage and edge cracking. Therefore, the Si content of electrical steel generally does not exceed 3.5%. In this invention, the Si content is controlled between 1.0% and 4.5%.

[0027] Al (Al) plays a similar role to Si (Si) in improving resistivity and stabilizing ferrite in steel, and is therefore a common element in non-oriented electrical steel. Al's increase in resistivity can significantly reduce induced eddy currents, making it a primary means of reducing eddy current losses in electrical steel. However, its drawbacks are similar to Si: it reduces the density and saturation magnetic induction of the electrical steel, affecting the magnetic flux density of the steel plate. In this invention, the Al content is controlled at 0.022-0.32%.

[0028] Mn is an important element to increase resistivity, reduce eddy current loss, promote the formation of favorable surface texture, reduce the occupancy of (111) surface texture, and improve magnetic properties. Meanwhile, Mn is also an indispensable element to prevent hot brittleness, which can form MnS particles with S element to prevent hot brittleness caused by FeS. However, the effect of Mn is also related to the content of S. If the content of S is too high, the amount of MnS precipitates will increase, resulting in an increase in iron loss. In the present application, the content of Mn element is controlled at 0.12-0.93%.

[0029] C and N are both harmful elements in electrical steel, which can cause the precipitation of carbides and nitrides, damage the magnetic properties of the steel plate, and easily cause hot rolling plate cracking. Nitride particles formed by N element can pin the grain boundary migration, form surface fine grain area, and increase iron loss. Therefore, the content of C and N elements in electrical steel should be strictly controlled. In the present application, the content of C and N elements is controlled at 0.003% or less.

[0030] S and P are the most common non-metallic impurity elements in electrical steel. S is considered as an unavoidable impurity element, which can form sulfide particles to hinder magnetic domain movement and is harmful to the magnetic properties of the steel. Therefore, S should be removed as much as possible. P element has obvious solid solution strengthening effect, which can improve the hardness of the steel plate and improve the punching performance of the steel plate. The solid solution P element can also increase the resistivity and reduce the eddy current loss. However, P element has obvious tendency to segregate at dislocations and grain boundaries, which can hinder grain growth, increase magnetic hysteresis loss, and affect the evolution process of texture, thereby affecting the magnetic induction of electrical steel. Therefore, the content of S element in electrical steel should be strictly limited, and the content of P element is influenced by the specific production product and conditions, which generally does not exceed 0.1%. In the present application, the content of S element is controlled at 0.003% or less, and the content of P element is controlled at 0.005% or less.

[0031] The present application also provides a preparation method of the above high-performance non-oriented silicon steel, which comprises the following steps:

[0032] S1, smelting molten steel according to the set composition, and casting the molten steel into a casting blank; the temperature of the molten steel in the tundish during casting is 1500-1580℃.

[0033] S2, hot rolling the casting blank, and coiling after hot rolling; the opening rolling temperature of the hot rolling is 920-980℃, and the final rolling temperature of the hot rolling is 800-860℃.

[0034] S3, pickling the hot coiled blank after normalizing, the normalizing soaking temperature is 900-1100℃, and then cold rolling to obtain a cold rolled strip with a thickness of 0.15-0.65mm.

[0035] The smelting method of the molten steel includes electric furnace and converter smelting methods, the molten steel forming method includes continuous casting and rolling, ESP, CSP and thin strip continuous casting methods, and the cold rolling includes continuous rolling and single stand reversible rolling.

[0036] S4, the cold-rolled strip adopts an annealing process of flash heating and instantaneous holding

[0037] (1) under an inert atmosphere, preferably 0-100% nitrogen + 100-0% hydrogen atmosphere, the temperature is raised from 30°C to the annealing temperature T at a rate of 200-600°C / s, T is between 700-1100°C;

[0038] (2) under an inert atmosphere, preferably 0-100% nitrogen + 100-0% hydrogen atmosphere, the temperature is held at the annealing temperature T for 0-10s;

[0039] (3) under an inert atmosphere, preferably 0-100% nitrogen + 100-0% hydrogen atmosphere, the temperature is cooled from the annealing temperature T to 30°C at a rate of 30°C / s, to obtain a high-performance non-oriented silicon steel.

[0040] The effect of the high-performance non-oriented silicon steel and the preparation method of the present application is studied through specific examples.

[0041] Example 1:

[0042] The present example provides a high-performance non-oriented silicon steel, which comprises the following components in mass percentage: C: 0.003%; Si: 2.9%; Al: 0.75%; Mn: 0.15%; N: 0.0025%; S: 0.0015%; P: 0.002%, and the rest is Fe and inevitable impurities.

[0043] The above high-performance non-oriented silicon steel is prepared by the following steps.

[0044] S1, smelting molten steel according to the set composition, and casting the molten steel into a casting blank; the molten steel temperature of the casting tundish is 1520°C.

[0045] S2, hot rolling the casting blank, and coiling after hot rolling; the opening rolling temperature of the hot rolling is 950°C, and the final rolling temperature of the hot rolling is 840°C.

[0046] S3, cold rolling after hot coil normalizing and pickling, to obtain a cold-rolled strip with a thickness of 0.35mm.

[0047] S4, the cold-rolled strip is subjected to an annealing process

[0048] (1) under an atmosphere of 75% nitrogen + 25% hydrogen, strictly controlling the air content in the annealing furnace, the temperature is raised from 30°C to 980°C at a rate of 400°C / s;

[0049] (2) under an atmosphere of 75% nitrogen + 25% hydrogen, strictly controlling the air content in the annealing furnace, the temperature is held at the annealing temperature T for 0s;

[0050] (3) in 75% nitrogen + 25% hydrogen atmosphere, strictly control the air content in the annealing furnace, cool from 1050°C to 30°C at a rate of 30°C / s, to obtain high-performance non-oriented silicon steel, marked as route 4.

[0051] Example 2:

[0052] The example provides a high-performance non-oriented silicon steel, which comprises the following components in mass percentage: C: 0.003%; Si: 2.9%; Al: 0.75%; Mn: 0.15%; N: 0.0025%; S: 0.0015%; P: 0.002%, and the rest is Fe and inevitable impurities.

[0053] The high-performance non-oriented silicon steel is prepared by the following steps.

[0054] S1, smelt the molten steel according to the set components, and cast the molten steel into a casting blank; the molten steel temperature of the tundish is 1520°C.

[0055] S2, hot roll the casting blank, and coiling after hot rolling; the opening rolling temperature of the hot rolling is 950°C, and the final rolling temperature of the hot rolling is 840°C.

[0056] S3, cold roll after hot coiling normalizing and pickling, to obtain a cold rolling strip with a thickness of 0.35 mm.

[0057] S4, the cold rolling strip is subjected to an annealing process.

[0058] (1) in 75% nitrogen + 25% hydrogen atmosphere, strictly control the air content in the annealing furnace, heat from 30°C to 1050°C at a rate of 400°C / s;

[0059] (2) in 75% nitrogen + 25% hydrogen atmosphere, strictly control the air content in the annealing furnace, keep the annealing temperature T for 0s;

[0060] (3) in 75% nitrogen + 25% hydrogen atmosphere, strictly control the air content in the annealing furnace, cool from 1050°C to 30°C at a rate of 30°C / s, to obtain high-performance non-oriented silicon steel, marked as route 4.

[0061] Example 3:

[0062] The example provides a high-performance non-oriented silicon steel, which comprises the following components in mass percentage: C: 0.003%; Si: 2.9%; Al: 0.75%; Mn: 0.15%; N: 0.0025%; S: 0.0015%; P: 0.002%, and the rest is Fe and inevitable impurities.

[0063] The high-performance non-oriented silicon steel is prepared by the following steps.

[0064] S1, smelting molten steel according to the set composition, and casting the molten steel into a casting blank; the casting tundish molten steel temperature is 1520°C.

[0065] S2, hot rolling the casting blank, and coiling after hot rolling; the hot rolling roughing temperature is 950°C, and the hot rolling finishing temperature is 840°C.

[0066] S3, cold rolling after hot coil normalizing and pickling, and obtaining a 0.35 mm thick cold-rolled strip.

[0067] S4, annealing process is performed on the cold-rolled strip.

[0068] (1) in a 75% nitrogen + 25% hydrogen atmosphere, strictly controlling the air content in the annealing furnace, and heating from 30°C to 1050°C at a rate of 400°C / s;

[0069] (2) in a 75% nitrogen + 25% hydrogen atmosphere, strictly controlling the air content in the annealing furnace, and annealing at the annealing temperature T for 10s;

[0070] (3) in a 75% nitrogen + 25% hydrogen atmosphere, strictly controlling the air content in the annealing furnace, and cooling from 980°C to 30°C at a rate of 30°C / s, to obtain the high-performance non-oriented silicon steel, marked as route 5.

[0071] Comparative Example 1:

[0072] The comparative example provides a non-oriented silicon steel, the high-performance non-oriented silicon steel includes the following components in mass percentage: C: 0.003%; Si: 2.9%; Al: 0.75%; Mn: 0.15%; N: 0.0025%; S: 0.0015%; P: 0.002%, and the rest is Fe and inevitable impurities.

[0073] The non-oriented silicon steel is prepared by the following steps.

[0074] S1, smelting molten steel according to the set composition, and casting the molten steel into a casting blank; the casting tundish molten steel temperature is 1520°C.

[0075] S2, hot rolling the casting blank, and coiling after hot rolling; the hot rolling roughing temperature is 950°C, and the hot rolling finishing temperature is 840°C.

[0076] S3, cold rolling after hot coil normalizing and pickling, and obtaining a 0.35 mm thick cold-rolled strip.

[0077] S4, annealing process is performed on the cold-rolled strip.

[0078] (1) in 75% nitrogen + 25% hydrogen atmosphere, strictly control the air content in the annealing furnace, heat from 30°C to 980°C at a rate of 100°C / s;

[0079] (2) in 75% nitrogen + 25% hydrogen atmosphere, strictly control the air content in the annealing furnace, keep at the annealing temperature T for 0s;

[0080] (3) in 75% nitrogen + 25% hydrogen atmosphere, strictly control the air content in the annealing furnace, cool from 980°C to 30°C at a rate of 30°C / s, get non-oriented silicon steel, marked as route 1.

[0081] Comparative Example 2:

[0082] The present comparative example provides a non-oriented silicon steel, the high-performance non-oriented silicon steel comprises the following components in mass percentage: C: 0.003%; Si: 2.9%; Al: 0.75%; Mn: 0.15%; N: 0.0025%; S: 0.0015%; P: 0.002%, and the rest is Fe and inevitable impurities.

[0083] The above non-oriented silicon steel is prepared by the following steps.

[0084] S1, smelt the molten steel according to the set components, and cast the molten steel into a casting blank; the molten steel temperature of the casting tundish is 1520°C.

[0085] S2, hot roll the casting blank, and coiling after hot rolling; the opening rolling temperature of the hot rolling is 950°C, and the final rolling temperature of the hot rolling is 840°C.

[0086] S3, after hot coiling normalizing and pickling, cold roll to obtain a cold-rolled strip with a thickness of 0.35mm.

[0087] S4, the cold-rolled strip is subjected to annealing process

[0088] (1) in 75% nitrogen + 25% hydrogen atmosphere, strictly control the air content in the annealing furnace, heat from 30°C to 980°C at a rate of 400°C / s;

[0089] (2) in 75% nitrogen + 25% hydrogen atmosphere, strictly control the air content in the annealing furnace, keep at the annealing temperature T for 15s;

[0090] (3) in 75% nitrogen + 25% hydrogen atmosphere, strictly control the air content in the annealing furnace, cool from 980°C to 30°C at a rate of 30°C / s, get non-oriented silicon steel, marked as route 2.

[0091] Example 4:

[0092] The magnetic properties of the non-oriented silicon steel RD and TD directions prepared by examples 1-3 and comparative examples 1-2 were studied, and the results are shown in Table 1. Figures 1-2

[0093] Route 1 P 15 / 50 about 3.41 W / Kg, B 50 about 1.70 T, P 10 / 400 about 24.12 W / Kg, B 50 about 1.71 T.

[0094] Route 2 P 15 / 50 about 3.27 W / Kg, B 50 about 1.69 T, P 10 / 400 about 23.30 W / Kg, B 50 about 1.70 T.

[0095] Route 3 P 15 / 50 about 2.81 W / Kg, B 50 about 1.71 T, P 10 / 400 about 21.82 W / Kg, B 50 about 1.72 T.

[0096] Route 4 P 15 / 50 about 2.69 W / Kg, B 50 about 1.70 T, P 10 / 400 about 21.54 W / Kg, B 50 about 1.71 T.

[0097] Route 5 P 15 / 50 about 2.76 W / Kg, B 50 about 1.70 T, P 10 / 400 about 21.50 W / Kg, B 50 about 1.70 T.

[0098] As can be seen from the above, the core loss of route 3 under the instantaneous heat preservation process is lower, and there is no big difference between route 3, route 4 and route 5, but the heat preservation temperature of route 3 is lower, the process is easier to realize, and the magnetic induction intensity is not reduced compared with other groups, and even has improved, so the magnetic property of route 3 is the best.

[0099] The above examples are only illustrative of the present application, and do not constitute a limitation on the scope of protection of the present application, any design identical or similar to the present application falls within the scope of protection of the present application.​

Claims

1. A method for producing a high-performance non-oriented silicon steel, characterized by, The method comprises the following steps: melting molten steel with set components, casting the molten steel into a casting blank, hot rolling, normalizing and pickling, cold rolling and annealing the casting blank to obtain high-performance non-oriented silicon steel; the high-performance non-oriented silicon steel comprises the following components in percentage by mass: C: 0-0.003%, Si: 1.0-4.5%, Al: 0.022-1.0%, Mn: 0.12-0.93%, N: 0-0.003%, S: 0-0.003%, P: 0.002-0.005%, and the rest is Fe and inevitable impurities; the annealing comprises the following steps: (1) heating to an annealing temperature at a rate of 400-600 ℃ / s under an inert atmosphere; the annealing temperature is 980-1100 ℃; (2) cooling at a rate of 30-40 ℃ / s after holding at the annealing temperature for 0 s.

2. The method of producing high performance non-oriented silicon steel according to claim 1, characterized by: The inert atmosphere is 30-95% nitrogen atmosphere.

3. The method of producing high performance non-oriented silicon steel according to claim 1, characterized in that: The step (2) is holding under 30-95% nitrogen atmosphere.

4. The method of producing high performance non-oriented silicon steel according to claim 1, characterized in that: The molten steel temperature of the casting tundish is 1500-1580 ℃; the open rolling temperature of the hot rolling is 920-980 ℃, and the final rolling temperature of the hot rolling is 800-860 ℃; the normalizing soaking temperature of the normalizing and pickling is 900-1100 ℃.

5. The method of producing high performance non-oriented silicon steel according to claim 1, wherein: The thickness of the steel strip after cold rolling is 0.15-0.65 mm.

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