Non-oriented electrical steel sheet having excellent assembly properties, and method for manufacturing same

Abstract

Disclosed in the present invention is a non-oriented electrical steel sheet having excellent assembly properties. The steel sheet comprises Fe and inevitable impurities, and further comprises the following chemical elements having mass percentage contents as follows: C≤0.0050%, Si: 1.0-4.0%, Mn: 0.10-2.00%, 0<Al≤1.80%, and at least one of Sn and Sb, wherein Sn≤0.50%, and Sb≤0.50%. The mass percentage contents of the chemical elements further satisfy the following formula: 0.6×Si+5×Sn+5×Sb-0.3×Mn-0.5×Al≥0, wherein each chemical element symbol in the formula represents the numerical value preceding the percentage sign of the mass percentage content of the corresponding element. Further disclosed in the present invention is a method for manufacturing the steel sheet, comprising the steps of: smelting and casting; hot rolling; normalizing; cold rolling; and continuous annealing and applying an insulating coating; wherein the temperature of continuous annealing is 700-1,100°C. The non-oriented electrical steel sheet of the present invention has a suitable coefficient of thermal expansion and good electromagnetic properties, so that a non-oriented electrical steel sheet having excellent assembly properties can be obtained.

Description

An excellent assembly performance non-oriented electrical steel sheet and a manufacturing method thereof TECHNICAL FIELD

[0001] The present disclosure relates to a steel sheet and a manufacturing method thereof, and in particular to a non-oriented electrical steel sheet and a manufacturing method thereof. BACKGROUND

[0002] For the stator and rotor of the new energy automobile driving motor, the air gap size is a very important design parameter. The air gap size has a great influence on the performance and operation reliability of the motor. When the air gap is too large, the excitation loss increases, the excitation current also increases, and the power factor of the motor also decreases, thereby degrading the performance of the motor. When the air gap is too small, not only the air gap harmonic magnetic field increases, but also the motor stray loss increases, which affects the performance of the motor. At the same time, too small air gap will affect the assembly accuracy of the motor stator and rotor, and easily cause the rotor to rub against the stator during operation, resulting in "sweeping" phenomenon, causing serious safety hazards and greatly reducing the operation reliability of the driving motor.

[0003] The non-oriented silicon steel sheet is an important metal soft magnetic material for manufacturing motors and generators. Due to the limitation of the space layout inside the automobile, the heat dissipation condition of the driving motor is relatively poor, and the working temperature is much higher than that of the conventional motor. At high temperature, the non-oriented silicon steel material will produce greater thermal expansion after being heated, resulting in a smaller air gap between the stator and the rotor, and affecting the performance of the driving motor stator and rotor. Therefore, it is desirable to obtain a non-oriented silicon steel with excellent thermal expansion performance to obtain good motor assembly accuracy.

[0004] A Chinese patent document with publication number CN111654130A, publication date of September 11, 2020, and title of "A composite rotor structure of energy storage flywheel high-speed permanent magnet synchronous motor" discloses a composite rotor structure of energy storage flywheel high-speed permanent magnet synchronous motor, which mainly includes a rotor shaft, a permanent magnet, a fan-shaped inter-pole filler, a high-temperature alloy fastening sleeve, an annular silicon steel sheet core shielding sleeve, and a carbon fiber fastening sleeve. However, the above patent document uses expensive and not very mature carbon fiber to fix the silicon steel sheet and control the air gap size, and the preparation process is complicated and not suitable for large-scale production. Moreover, the material performance of the non-oriented silicon steel is not involved. SUMMARY

[0005] In view of the above deficiencies in the art, one of the purposes of the present disclosure is to provide a non-oriented electrical steel sheet with excellent assembly performance. The present inventors have found that by optimizing the chemical composition design of the non-oriented electrical steel sheet, the non-oriented electrical steel sheet can obtain a suitable thermal expansion coefficient and a non-oriented silicon steel sheet with excellent assembly performance, and also has good electromagnetic performance.

[0006] To achieve the above object, the present disclosure provides a non-oriented electrical steel sheet containing Fe and inevitable impurities, further containing the following chemical elements in the mass percentage as follows:

[0007] C≤0.0050%, Si: 1.0-4.0%, Mn: 0.10-2.00%, 0

[0008] The mass percentage of each chemical element also satisfies the following formula: 0.6×Si+5×Sn+5×Sb-0.3×Mn-0.5×Al≥0, for example, 0.6×Si+5×Sn+5×Sb-0.3×Mn-0.5×Al can be 0-5.16, for example, 1.77-5.16, including 1.77-2.65, in which the symbol of each chemical element is substituted into the value before the mass percentage of the corresponding element.

[0009] The inventors found through research that the thermal expansion coefficient of the single-phase uniform solid solution alloy formed by the metal elements and non-metal elements in the non-oriented silicon steel is between the thermal expansion coefficients of each component, while the thermal expansion coefficient of the multi-element alloy depends on the types and contents of the constituent elements, and can be calculated approximately according to the mass percentage of each element using the mixing rule. Therefore, by optimizing the types and contents of the chemical elements in the non-oriented silicon steel and balancing the relationship between the contents of each alloying element, the linear thermal expansion coefficient of the non-oriented silicon steel is effectively controlled, and excellent assembly performance is achieved. Specifically, the inventors limit the synergistic relationship of the elements to satisfy the following formula: 0.6×Si+5×Sn+5×Sb-0.3×Mn-0.5×Al≥0, in which the symbol of each chemical element is substituted into the value before the mass percentage of the corresponding element.

[0010] Preferably, in the non-oriented electrical steel sheet of the present disclosure, the mass percentage of each chemical element is as follows:

[0011] C≤0.0050%, Si: 1.0-4.0%, Mn: 0.10-2.00%, 0

[0012] Preferably, the non-oriented electrical steel sheet of the present disclosure further contains at least one of the following chemical elements in the mass percentage as follows:

[0013] 0

[0014] 0

[0015] 0 < Ca ≤ 0.01%;

[0016] 0 < Mg ≤ 0.01%;

[0017] 0 < REM ≤ 0.01%.

[0018] Preferably, the non-oriented electrical steel sheet of the present disclosure further contains at least one of the following chemical elements in the mass percentage as follows:

[0019] 0 < Cr ≤ 3.0%;

[0020] 0 < Ni ≤ 5.0%;

[0021] 0 < Cu ≤ 2.0%.

[0022] Preferably, in the non-oriented electrical steel sheet of the present disclosure, inevitable impurities include P, S, N and Ti, and the content of each impurity element satisfies at least one of the following: P ≤ 0.15%, S ≤ 0.003%, N ≤ 0.003%, Ti ≤ 0.003%.

[0023] Preferably, the linear thermal expansion coefficient of the non-oriented electrical steel sheet of the present disclosure in the temperature range of 20-200°C is 0 < α < 15 x 10 -6 (1 / K), more preferably 0 < α < 13.5 x 10 -6 (1 / K), and still more preferably 0 < α < 11 x 10 -6 (1 / K).

[0024] The inventors have found through research that when the linear thermal expansion coefficient α is lower than 15 x 10 -6 (1 / K), a better stator and rotor air gap variation rate desired for driving a motor can be obtained. Therefore, in the present disclosure, it is preferred to control the linear thermal expansion coefficient α in the temperature range of 20-200°C to be α < 15 x 10 -6 (1 / K).

[0025] Preferably, the iron loss P 10 / 700 of the non-oriented electrical steel sheet of the present disclosure is ≤ 120 W / kg, more preferably P 10 / 700 ≤ 100 W / kg, and still more preferably P 10 / 700 ≤ 80 W / kg.

[0026] Another object of the present disclosure is to provide a manufacturing method of a non-oriented electrical steel sheet that controls process parameters to obtain a non-oriented silicon steel sheet with excellent assembly performance.

[0027] To achieve the above object, the present disclosure provides a manufacturing method of a non-oriented electrical steel sheet, comprising the following steps:

[0028] Smelting and casting;

[0029] hot rolling;

[0030] normalizing;

[0031] cold rolling;

[0032] continuous annealing: wherein the continuous annealing temperature is 700-1100°C, and

[0033] coating an insulation coating.

[0034] In the present application, in order to realize the steel sheet microstructure recrystallization, the annealing temperature needs to be greater than the recrystallization temperature. Based on this, in the present application, the continuous annealing temperature is controlled to be 700-1100°C.

[0035] Preferably, in the continuous annealing step of the manufacturing method of the present disclosure, the annealing time is 10-100s.

[0036] Preferably, in the manufacturing method of the present disclosure, the cold rolling step comprises: primary cold rolling, intermediate annealing and secondary cold rolling, wherein the cumulative reduction rate of the secondary cold rolling is 45-75%.

[0037] In some embodiments of the present disclosure, the reduction rate of the secondary cold rolling method has a significant impact on the texture, in order to improve the texture and thus improve the electromagnetic performance, the cumulative reduction rate of the secondary cold rolling can be controlled to be 45-75%.

[0038] The non-oriented electrical steel sheet and the manufacturing method thereof of the present disclosure have the following advantages and beneficial effects:

[0039] The non-oriented electrical steel sheet and the manufacturing method thereof of the present disclosure can make the non-oriented electrical steel sheet obtain a suitable thermal expansion coefficient, while also having good electromagnetic performance, and thus obtain a non-oriented silicon steel sheet with excellent assembly performance, by optimizing the chemical composition design and process flow parameters thereof.

[0040] In some embodiments, the linear thermal expansion coefficient of the non-oriented electrical steel sheet of the present disclosure is α < 15*10 -6 (1 / K) in the temperature range of 20-200°C, the iron loss P 10 / 700 ≤ 120 W / kg.

[0041] The present disclosure also provides an electric motor core, such as a stator core and a rotor core, made of the non-oriented electrical steel sheet of the present disclosure.

[0042] Preferably, the size variation rate of the stator-rotor air gap of the electric motor core of the present disclosure is less than 1%, more preferably less than 0.85%. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 schematically shows the relationship between the linear thermal expansion coefficient a of the non-oriented silicon steel of the present disclosure and the size change rate of the permanent magnet synchronous motor stator-rotor air gap made of the non-oriented silicon steel in the temperature range of 20-200°C. DETAILED DESCRIPTION

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0045] In the present disclosure, the linear thermal expansion coefficient a is determined according to GB / T 4339-2008.

[0046] In the present disclosure, the iron loss P 10 / 700 represents the iron loss value measured at a magnetic polarization strength of 1.0 T and a frequency of 700 Hz, with the unit of W / kg. The iron loss P 10 / 700 is determined according to GB / T 10129-2019.

[0047] In the present disclosure, the stator-rotor air gap size change rate is the ratio of the change amplitude of the air gap size between the stator and the rotor to the original air gap size. The stator-rotor air gap size change rate = air gap size (absolute value) change amount / initial air gap size x 100%. The smaller the stator-rotor air gap size change rate, the better the thermal stability and size stability of the material, and the better the motor operating efficiency and performance.

[0048] In the non-oriented electrical steel sheet of the present disclosure, the design principles of each chemical element are as follows:

[0049] C: In the non-oriented silicon steel sheet of the present disclosure, the C element will strongly hinder the grain growth of the finished steel strip, and the C element is also easy to combine with impurities Nb, V, Ti to form fine precipitates, thereby causing loss increase and magnetic aging. Therefore, in the non-oriented silicon steel sheet of the present disclosure, the mass percentage content of C element is controlled to be below 0.0050%, for example, it can be 0.0009-0.0050%.

[0050] Si: In the non-oriented silicon steel sheet of the present disclosure, when the mass percentage content of Si element is too low, the steel sheet cannot obtain excellent thermal expansion performance and electromagnetic performance; when the mass percentage content of Si element is too high, the cold workability of the steel sheet will be reduced. Therefore, in the non-oriented silicon steel sheet of the present disclosure, the mass percentage content of Si element is controlled to be between 1.0-4.0%. In some embodiments, the mass percentage content of Si element can be preferably controlled to be between 1.0-3.9%, and more preferably controlled to be between 2.6-3.9%.

[0051] Mn: In the non-oriented silicon steel sheet of the present disclosure, the Mn element can react with the impurity element S element to form MnS, which can prevent the hot brittleness phenomenon caused by the formation of low-melting-point FeS along the grain boundaries. Since Mn is a high-thermal-expansion-coefficient metal element, when the mass percentage content of the Mn element is too high, it will cause the thermal expansion coefficient of the silicon steel to be too large. Therefore, in the non-oriented silicon steel sheet of the present disclosure, the mass percentage content of the Mn element is controlled to be between 0.10-2.00%, preferably 0.35-1.50%.

[0052] Al: In the non-oriented silicon steel sheet of the present disclosure, since Al element is a high-thermal-expansion-coefficient metal element, when the mass percentage content of the Al element is too high, it will cause the thermal expansion coefficient of the silicon steel to be too large. Therefore, in the non-oriented silicon steel sheet of the present disclosure, the mass percentage content of the Al element is controlled to be between 0

[0053] Sn and Sb: In the non-oriented silicon steel sheet of the present disclosure, Sn element and Sb element can promote the growth of beneficial crystal texture, promote the increase of magnetic induction and the decrease of iron loss. When the mass percentage content of Sn element and Sb element is too high, it will cause grain refinement and abnormal segregation. Therefore, in the non-oriented silicon steel sheet of the present disclosure, the mass percentage content of Sn element is controlled to be Sn≤0.50%, for example, it can be 0.10-0.50%, and the mass percentage content of Sb element is controlled to be Sb≤0.50%, for example, it can be 0.03-0.50%.

[0054] The non-oriented silicon steel sheet of the present disclosure also preferably contains one or more of Ge, Bi, Ca, Mg, REM, Cr, Ni, Cu.

[0055] Ge: In the non-oriented silicon steel sheet of the present disclosure, Ge element can significantly increase the proportion of beneficial crystal texture. When the mass percentage content of Ge element is too high, it will greatly increase the manufacturing cost of the steel sheet. Therefore, in the non-oriented silicon steel sheet of the present disclosure, the mass percentage content of Ge element can be controlled to be 0

[0056] Bi: In the non-oriented silicon steel sheet of the present disclosure, Bi element can significantly increase the proportion of beneficial crystal texture. When the mass percentage content of Bi element is too high, it will cause the grain size to be severely refined. Therefore, in the non-oriented silicon steel sheet of the present disclosure, the mass percentage content of Bi element can be controlled to be 0

[0057] Ca: In the non-oriented silicon steel sheet of the present disclosure, Ca element can improve the cleanliness of the steel and promote the grain size growth. When the mass percentage content of Ca element is too high, it will cause the manufacturing cost to increase greatly. Therefore, in the non-oriented silicon steel sheet of the present disclosure, the mass percentage content of Ca element can be controlled to be 0

[0058] Mg: In the non-oriented silicon steel sheet of the present disclosure, the Mg element can improve the cleanliness of the steel and promote the grain size growth. When the mass percentage content of the Mg element is too high, it will cause grain refinement and deterioration of iron loss. Therefore, in the non-oriented silicon steel sheet of the present disclosure, the mass percentage content of the Mg element can be controlled as 0 < Mg < 0.01%.

[0059] REM: In the non-oriented silicon steel sheet of the present disclosure, REM can improve the cleanliness of the steel and promote the grain size growth. When the mass percentage content of REM is too high, it will cause a substantial increase in manufacturing cost. Therefore, in the non-oriented silicon steel sheet of the present disclosure, the mass percentage content of REM can be controlled as 0 < REM < 0.01%.

[0060] Cr: In the non-oriented silicon steel sheet of the present disclosure, the Cr element can increase the resistivity, and also reduce the eddy current loss and high-frequency iron loss. However, when the mass percentage content of the Cr element is too high, it will reduce the magnetic flux density of the steel sheet and increase the cost. Therefore, in the non-oriented silicon steel sheet of the present disclosure, the mass percentage content of the Cr element can be controlled as 0 < Cr < 3.0%.

[0061] Ni: In the non-oriented silicon steel sheet of the present disclosure, the Ni element can increase the resistance of the silicon steel, thereby reducing the iron loss without reducing the saturation magnetic flux density. However, when the mass percentage content of the Ni element is too high, the cost of the steel sheet will be significantly increased. Therefore, in the non-oriented silicon steel sheet of the present disclosure, the mass percentage content of the Ni element can be controlled as 0 < Ni < 5.0%.

[0062] Cu: In the non-oriented silicon steel sheet of the present disclosure, Cu can increase the resistivity. However, when the mass percentage content of the Cu element is too high, it will reduce the magnetic flux density and increase the cost. Therefore, in the non-oriented silicon steel sheet of the present disclosure, the mass percentage content of the Cu element can be controlled as 0 < Cu < 2.0%.

[0063] In the non-oriented silicon steel sheet of the present disclosure, P, S, N and Ti are all impurity elements in the steel. In the case where the technical conditions permit, the content of the impurity elements in the steel should be reduced as much as possible in order to obtain a steel material with better performance and higher quality, wherein:

[0064] P: In the non-oriented silicon steel sheet of the present disclosure, when the mass percentage content of the P element is too high, it will reduce the cold rolling stability of the steel sheet. Therefore, in the non-oriented silicon steel sheet of the present disclosure, the mass percentage content of the P element can be controlled as P < 0.15%.

[0065] S: In the non-oriented silicon steel sheet of the present disclosure, when the mass percentage content of S element is too high, sulfide inclusions will be significantly increased, and the grain size growth will be inhibited. Therefore, in the non-oriented silicon steel sheet of the present disclosure, the mass percentage content of S element can be controlled as S≤0.003%.

[0066] N: In the non-oriented silicon steel sheet of the present disclosure, when the mass percentage content of N element is too high, nitride inclusions will be significantly increased, and the grain size growth will be inhibited. Therefore, in the non-oriented silicon steel sheet of the present disclosure, the mass percentage content of N element can be controlled as N≤0.003%.

[0067] Ti: In the non-oriented silicon steel sheet of the present disclosure, when the mass percentage content of Ti element is too high, nitride inclusions will be significantly increased, and the grain size growth will be inhibited. Therefore, in the non-oriented silicon steel sheet of the present disclosure, the mass percentage content of Ti element can be controlled as Ti≤0.003%.

[0068] The non-oriented electrical steel sheet with excellent assembly performance and the manufacturing method thereof of the present disclosure will be further explained and described below in combination with the drawings of the specification and specific examples, however the explanation and description do not constitute undue limitation on the technical solutions of the present disclosure.

[0069] Examples 1-7 and Comparative Examples 1-3

[0070] The non-oriented electrical steel sheets of Examples 1-7 are all prepared by the following steps:

[0071] (1) Smelting and casting: after the high furnace molten iron is sequentially subjected to molten iron pretreatment, converter smelting, RH refining and continuous casting, a continuous casting billet with a thickness of 300 mm is obtained.

[0072] (2) Hot rolling: the heating temperature is 1080℃, and the holding time is 2 hours.

[0073] (3) Normalization: the finish rolling temperature of the steel coil is 820℃, and the coiling temperature is 600℃, obtaining a hot-rolled plate with a thickness between 1.5-2.5 mm.

[0074] (4) Cold rolling: Examples 1-4 adopt a two-stage cold rolling process, after the first cold rolling, intermediate annealing and second cold rolling are carried out, and the cumulative reduction rate of the second cold rolling is 45-75%; Examples 5-7 adopt a one-stage cold rolling process, and are directly rolled to the finished thickness.

[0075] (5) Continuous annealing: the continuous annealing temperature is 700-1100℃, and the annealing time is 10-100s.

[0076] (6) Coating with insulating coating.

[0077] The comparative steels of Comparative Examples 1-3 are also prepared by the above steps, but the chemical compositions and process parameters thereof do not meet the design requirements of the present application.

[0078] Table 1-1, Table 1-2 and Table 1-3 list the mass percentage of each chemical element in the non-oriented electrical steel sheets of Examples 1-7 and the comparative steels of Comparative Examples 1-3.

[0079] Table 1-1. (wt%, the balance being Fe and inevitable impurities other than P, S, N and Ti)

[0080] Table 1-2. (wt%, the balance being Fe and inevitable impurities other than P, S, N and Ti)

[0081] Table 1-3. (wt%, the balance being Fe and inevitable impurities other than P, S, N and Ti)

[0082] Table 2 lists the specific process parameters of the non-oriented electrical steel sheets of Examples 1-7 and the comparative steels of Comparative Examples 1-3.

[0083] Table 2.

[0084] Note: " / " in the table indicates that one cold rolling process is adopted to directly roll to the finished thickness.

[0085] The non-oriented electrical steel sheets of Examples 1-7 and the comparative steels of Comparative Examples 1-3 prepared are sampled and tested for relevant properties, and the results obtained by the relevant property tests are listed in Table 3, and the specific testing methods of the relevant properties are described as follows:

[0086] Iron loss performance test: Based on the national standard "GB / T 10129-2019 Method for Measuring Medium Frequency Magnetic Properties of Electrical Steel Strip (Sheet)", the iron loss performance test is carried out by using the Epstein square method, the test temperature is 20°C constant temperature test, the sample size is 30mm x 300mm, the target mass is 0.25kg, and the test parameters are P 10 / 700 .

[0087] Linear thermal expansion coefficient test: The push rod method is used to test the linear thermal expansion coefficient of the steel sheet in the temperature range of 20-200°C according to the national standard GB / T 4339-2008, and the test equipment adopts Linseis L75 VS1400C / 500LT thermal dilatometer.

[0088] Stator-rotor air gap size change rate test: using a plug gauge to measure. The plug gauge is inserted between the stator and rotor core, and the air gap size is measured by adjusting the tightness of the plug gauge. Usually, measurements are taken at the upper and lower left and right points of the stator and rotor, and at least three points are measured to ensure the accuracy of the data.

[0089] Table 3 lists the test results of the relevant properties of the non-oriented electrical steel sheets of Examples 1-7 and the comparative steels of Comparative Examples 1-3.

[0090] Table 3.

[0091] As can be seen from Table 3 above, the linear thermal expansion coefficients a of the non-oriented electrical steel sheets of Examples 1-7 are all less than 15 x 10 -6 (1 / K) in the temperature range of 20-200°C, and the iron losses P 10 / 700 of the same are all less than 120 W / kg, having good electromagnetic properties and excellent assembly properties.

[0092] In addition, as can be seen from Table 3, the stator-rotor air gap size change rates of the permanent magnet synchronous motors made of the non-oriented silicon steel of Examples 1-7 are all less than 1%.

[0093] In addition, the inventors have determined the correlation between the size change rate of the stator-rotor air gap of the trial permanent magnet synchronous motor and the linear thermal expansion coefficient a of the non-oriented silicon steel in the temperature range of 20-200°C through experiments. The parameters of the trial permanent magnet synchronous motor are as follows: outer diameter 200 mm, inner diameter 170 mm, stack thickness 120 mm, rated power 160 KW, and maximum torque 300 Nm.

[0094] FIG. 1 schematically shows the relationship between the linear thermal expansion coefficient a of the non-oriented silicon steel of the present disclosure and the size change rate of the stator-rotor air gap of the permanent magnet synchronous motor made of the same in the temperature range of 20-200°C.

[0095] As can be seen from FIG. 1, when the linear thermal expansion coefficient a in the temperature range of 20-200°C is greater than 15 x 10 -6 (1 / K), the stator-rotor air gap size change rate of the permanent magnet synchronous motor is greater than 1%.

[0096] It should be noted that the combination of the technical features in the present case is not limited to the combination manner described in the claims of the present case or the combination manner described in the specific embodiments, and all the technical features described in the present case can be freely combined or combined in any manner, unless contradictory to each other.

[0097] It should also be noted that the above-mentioned embodiments are only specific embodiments of the present application. Obviously, the present application is not limited to the above-mentioned embodiments, and similar changes or modifications made in accordance with the disclosure of the present application are directly derived or easily thought of by those skilled in the art, and should all belong to the protection scope of the present application.

Claims

1. A non-oriented electrical steel sheet containing Fe and unavoidable impurities, characterized in that, The non-oriented electrical steel sheet further contains at least one of the following chemical elements with the mass percentage as follows: C≤0.0050%, Si: 1.0-4.0%, Mn: 0.10-2.00%, 0 The mass percentage of each chemical element also satisfies the following formula: 0.6×Si+5×Sn+5×Sb-0.3×Mn-0.5×Al≥0, wherein the chemical element symbols are respectively substituted into the mass percentage before the corresponding element's mass percentage.

2. The non-oriented electrical steel sheet according to claim 1, characterized in that, The mass percentage of each chemical element of the non-oriented electrical steel sheet is as follows: C≤0.0050%, Si: 1.0-4.0%, Mn: 0.10-2.00%, 0 3. The non-oriented electrical steel sheet according to claim 1 or 2, characterized in that, The non-oriented electrical steel sheet further contains at least one of the following chemical elements with the mass percentage as follows: 0 0 0 0 0 4. The non-oriented electrical steel sheet according to claim 1 or 2, characterized in that, 0 0＜Cr≤3.0％； 0 The non-oriented electrical steel sheet further contains at least one of the following chemical elements with the mass percentage as follows:

5. The non-oriented electrical steel sheet according to claim 1 or 2, characterized in that, 0 6. The non-oriented electrical steel sheet according to claim 1 or 2, characterized in that, The non-oriented electrical steel sheet has a linear thermal expansion coefficient a < 15 x 10 -6 (1 / K) in the temperature range of 20 to 200 °C, more preferably 0 < a < 13.5 x 10 -6 (1 / K).

7. The non-oriented electrical steel sheet according to claim 1 or 2, characterized in that, The iron loss P of the non-oriented electrical steel sheet 10 / 700 ≤ 120 W / kg, more preferably P 10 / 700 ≤ 100 W / kg, still more preferably P 10 / 700 ≤ 80 W / kg.

8. A method of manufacturing the non-oriented electrical steel sheet according to any one of claims 1 to 7, characterized in that, 0 The inevitable impurities include P, S, N and Ti, and the content of each impurity element satisfies at least one of the following: P≤0.15%, S≤0.003%, N≤0.003%, Ti≤0.003%. The method comprises the following steps: Smelting and casting; Hot rolling; Normalizing; Cold rolling; 9. The method of claim 8, wherein, Continuous annealing: wherein the continuous annealing temperature is 700-1100°C, and 10. The method of claim 8, wherein, Coating an insulation coating. In the continuous annealing step, the annealing time is 10-100s.

12. The motor core of claim 11, wherein, The cold rolling step comprises: primary cold rolling, intermediate annealing and secondary cold rolling, wherein the cumulative reduction of the secondary cold rolling is 45-75%.

11. An electric motor core made of the non-oriented electrical steel sheet of any one of claims 1-7, comprising a stator core and / or a rotor core. The stator-rotor air gap size variation rate of an electric motor assembled from the electric motor core is less than 1%, preferably less than 0.85%. The stator-rotor air gap size variation rate of an electric motor assembled from the electric motor core is less than 1%, preferably less than 0.85%.

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