Non-oriented silicon steel with excellent comprehensive performance and manufacturing method thereof

Abstract

The invention discloses non-oriented silicon steel with excellent comprehensive performance, which contains Fe and inevitable impurities, and further contains the following chemical elements in percentage by mass: less than or equal to 0.0050% of C, 2.0-4.0% of Si, 0.1-2.0% of Mn, 0.001-2.0% of Al, 0.001-5.0% of Cr, 0.001-5.0% of Ni, 0.001-2.0% of Cu and the balance of Fe. And the mass percentage content of each chemical element also meets the condition that 3 * Si + 0.5 * Al + 0.5 * Mn-5 * Cu-2. 5 * Cr-Ni is greater than or equal to 0 and less than or equal to 13.5%. Correspondingly, the invention further discloses a manufacturing method of the non-oriented silicon steel with the excellent comprehensive performance. By adopting the method, the non-oriented silicon steel plate with excellent comprehensive performance, which integrates heat conduction and electromagnetic performance, can be obtained.

Description

Technical Field

[0001] The present invention relates to a steel plate and a manufacturing method thereof, and in particular to a non-oriented silicon steel plate and a manufacturing method thereof. Background Art

[0002] Non-oriented silicon steel sheets are important soft magnetic metal materials for manufacturing electric motors and generators. In recent years, with the increasing global demand for energy conservation and environmental protection, the new energy vehicle industry has developed rapidly, and at the same time, it has also promoted the development of non-oriented silicon steel materials for drive motors. The operating conditions of new energy vehicle drive motors are worse than those of conventional motors. For example, the operating temperature of the motor is generally 150°C or above. At the same time, the drive motor is restricted by the internal space layout of the car, and its heat dissipation conditions are also worse. Therefore, the temperature rise of the drive motor during operation and the corresponding cooling are a very important topic in the field of drive motor design. In order to reduce the temperature rise of the drive motor, non-oriented silicon steel needs better thermal conductivity.

[0003] In addition, in order to improve the working efficiency and specific power density of the drive motor, the high speed of the motor is an important development trend. When the pole pair number of the motor's rotating magnetic field remains unchanged, the motor speed is proportional to the operating frequency. As the motor design speed increases, the motor operating frequency will also increase accordingly. At present, the operating frequency of the new energy vehicle drive motor has been increased to the medium frequency level of 400-2000Hz. Compared with the 50 and 60Hz power frequency used in ordinary motors, the loss of non-oriented silicon steel under medium frequency conditions is much greater than the loss under power frequency. In order to reduce the iron loss of non-oriented silicon steel, it is necessary to increase the resistivity of non-oriented silicon steel.

[0004] A Chinese patent document with publication number CN104726794A, publication date June 24, 2015, and titled “Non-oriented silicon steel sheet and method for manufacturing the same” discloses a non-oriented silicon steel sheet, which, in terms of weight percent, includes Si: 2.0-3.5%, Mn: 0.5-3.5%, Cr: 0.5-3.5%, Al: greater than 0% and less than 0.8%, C: less than 0.004%, S: less than 0.004%, N: less than 0.004%, Ti: less than 0.004%, and P: less than 0.004%.

[0005] The Chinese patent document with publication number CN104294185A and publication date January 21, 2015, and titled “A non-oriented silicon steel for high-efficiency motors and production method” discloses a non-oriented silicon steel for high-efficiency motors, whose chemical components and weight percentages are: C≤0.0030%, Si: 1.9-2.1%, Mn: 0.28-0.32%, Al: 0.10-0.60%, P: 0.01-0.06%, S≤0.0050%, Cu: 0.10-0.30%, Sb: 0.02-0.05%, N≤0.0030%. This scheme fully exerts the beneficial role of each element in physical metallurgy by controlling the total amount of main alloy elements (Si+Al+Mn) and auxiliary elements (Cu+P+Sb); by studying the combined effect of (Cu+P+Sb) elements on the organizational structure and magnetic properties of silicon steel, it adopts (Cu+P) to replace part of (Si+Al), which can increase the number of rebending times of normalized plates on the one hand; and improve the punching properties of finished plates on the other hand.

[0006] It can be seen that the above patent adds as much Si and Al content as possible to the steel to significantly increase the resistivity of the finished steel plate, thereby reducing the iron loss. Adding a certain amount of P and Cr content to the steel can also reduce the iron loss of the finished steel plate, especially the iron loss under high frequency conditions, but these measures will, to a certain extent, limit the increase in normalizing temperature and reduce the manufacturability of cold rolling. Summary of the invention

[0007] One of the purposes of the present invention is to provide a non-oriented silicon steel with excellent comprehensive performance, which optimizes the chemical composition design and process design of the steel, sets a reasonable control range of the thermal conductivity and resistivity of the non-oriented silicon steel, so as to obtain a non-oriented silicon steel sheet with excellent comprehensive performance that takes into account both thermal conductivity and electromagnetic properties.

[0008] In order to achieve the above object, the present invention provides a non-oriented silicon steel with excellent comprehensive performance, which contains Fe and inevitable impurities, and further contains the following chemical elements in mass percentage:

[0009] C≤0.0050%, Si: 2.0~4.0%, Mn: 0.1~2.0%, Al: 0.001~2.0%, Cr: 0.001~5.0%, Ni: 0.001~5.0%, Cu: 0.001~2.0%;

[0010] The mass percentage content of each chemical element also satisfies: 0≤3×Si+0.5×Al+0.5×Mn-5×Cu-2.5×Cr-Ni≤13.5%.

[0011] In the traditional design concept of non-oriented silicon steel products, there is an inherent contradictory relationship between thermal conductivity and resistivity. For example, simply increasing the content of alloys such as Si and Al will lead to a decrease in thermal conductivity and an increase in resistivity. The inventor found through research that the difference in thermal conductivity of non-oriented silicon steel mainly lies in the strength of the metal bond, while the determining factor of the resistivity of non-oriented silicon steel is the level of alloy content. Therefore, the present invention preferably combines the types and contents of chemical elements of non-oriented silicon steel, and balances the relationship between metal bonds and alloy content, and defines the characteristics of the element synergy relationship: 0≤3×Si+0.5×Al+0.5×Mn-5×Cu-2.5×Cr-Ni≤13.5%, so as to effectively control the thermal conductivity and resistivity of non-oriented silicon steel, and achieve the technical effect of thermal conductivity and resistivity of non-oriented silicon steel that takes into account both thermal conductivity and electromagnetic properties.

[0012] Furthermore, the present invention also provides a non-oriented silicon steel with excellent comprehensive performance, wherein the mass percentage of each chemical element is:

[0013] C≤0.0050%, Si: 2.0~4.0%, Mn: 0.1~2.0%, Al: 0.001~2.0%, Cr: 0.001~5.0%, Ni: 0.001~5.0%, Cu: 0.001~2.0%; the balance is Fe and unavoidable impurities.

[0014] In the non-oriented silicon steel sheet of the present invention, the design principles of each chemical element are as follows:

[0015] C: In the non-oriented silicon steel sheet of the present invention, C will strongly hinder the grain growth of the finished strip steel, and easily combine with impurities such as Nb, V, Ti, etc. to form fine precipitates, thereby causing increased losses and producing magnetic aging. Therefore, it must be strictly controlled below 0.0050%.

[0016] Si: In the non-oriented silicon steel sheet described in the present invention, Si is an effective element for increasing resistivity and reducing iron loss. In addition, it has a higher solid solution strengthening ability than other solid solution strengthening elements such as Mn, Al, and Ni. Therefore, Si is the most effective element for balancing high strength and low iron loss. If the Si content is less than 2.0%, the above effect cannot be obtained. Therefore, the Si content is set to be greater than 2.0%. On the other hand, if the Si content is too high, the manufacturability, especially the processability of the silicon steel sheet, will be reduced. In addition, as described later, by properly controlling the grain structure of the silicon steel sheet, the reduction in processability can be suppressed. However, if the Si content exceeds 4.0%, the cold workability will be reduced. Therefore, the present invention controls the Si content to be less than 4.0%. The preferred Si content is 3.6% or less.

[0017] Mn: In the non-oriented silicon steel sheet of the present invention, Mn can improve the resistivity, react with the impurity element S to form MnS, and prevent the hot brittleness caused by the formation of low-melting-point FeS along the grain boundary. Therefore, the addition of Mn of more than 0.1% is necessary, and if it exceeds 2.0%, the grains will not grow fully in the final annealing, which will lead to increased iron loss. Therefore, the present invention controls the Mn content to 0.1-2.00%.

[0018] Al: In the non-oriented silicon steel sheet of the present invention, Al is an element that increases resistivity and can effectively reduce the iron loss of steel. However, when the Al content is higher than 2.0%, the magnetic induction of the steel will be significantly reduced, and the cold rolling performance will be significantly reduced; while when the Al content is lower than 0.001%, fine nitrides will be precipitated in the steel, which will hinder the grain growth during the hot-rolled sheet annealing and finished product annealing, resulting in the deterioration of magnetic properties.

[0019] Cr: In the non-oriented silicon steel sheet described in the present invention, Cr can improve thermal conductivity, increase resistivity, reduce eddy current loss, and reduce high-frequency iron loss. However, when the Cr content exceeds 5.0%, the magnetic flux density decreases and the cost increases. Therefore, the present invention controls the Cr content to 0.001-5.0%.

[0020] Ni: In the non-oriented silicon steel sheet of the present invention, Ni can improve thermal conductivity, solid solution strengthen silicon steel, and increase the resistance of silicon steel to reduce iron loss without reducing saturation flux density. However, if the Ni content exceeds 5.0%, the cost becomes significantly higher. Therefore, the present invention controls the Ni content to 0.001-5.0%.

[0021] Cu: In the non-oriented silicon steel sheet of the present invention, Cu can increase the resistivity and improve the thermal conductivity. However, when the Cu content exceeds 2.0%, the magnetic flux density decreases and the cost increases. Therefore, the present invention controls the Cu content to 0.001-2.0%.

[0022] Furthermore, in the non-oriented silicon steel of the present invention, it also contains 0≤Sn≤0.5wt% and / or 0≤Sb≤0.5wt%.

[0023] In a preferred embodiment of the present invention, at least one of Sn and Sb may also be contained. Sn and Sb are elements that are beneficial to ensuring low iron loss by suppressing oxidation and nitridation during annealing through surface segregation. In addition, it also has the effect of improving the texture and increasing the magnetic flux density by segregating at the grain boundaries. However, if the content of Sn and Sb is excessive, the toughness of the steel will be reduced, and there is a possibility that cold rolling will be difficult. Therefore, the content of Sn and Sb should be less than 0.05%, respectively.

[0024] Furthermore, the non-oriented silicon steel of the present invention further contains at least one of the following chemical elements:

[0025] 0≤Ca≤0.02wt%;

[0026] 0≤Mg≤0.02wt%;

[0027] 0≤REM≤0.02wt%.

[0028] In a preferred embodiment of the present invention, at least one of Ca, Mg, and REM may be contained. Ca, Mg, and REM are elements that fix the impurity S as sulfide or sulfur oxide, inhibit the fine precipitation of MnS, etc., and promote recrystallization and grain growth during final annealing. However, when Ca, Mg, and REM are higher than 0.02%, sulfide or sulfur oxide will be excessively generated, hindering recrystallization and grain growth during final annealing. Therefore, the present invention controls any one of Ca, Mg, and REM to less than 0.02%.

[0029] Furthermore, among the inevitable impurities in the non-oriented silicon steel described in the present invention, the mass percentage of each impurity element satisfies at least one of the following items: P≤0.2%, S≤0.005%, N≤0.005%, Nb≤0.005%, V≤0.005%, Ti≤0.005%.

[0030] In the present invention, P, S, N, Nb, V, and Ti are all impurity elements, and their contents are preferably as low as possible when process conditions permit.

[0031] P will segregate along the grain boundaries, and a content exceeding 0.20% will aggravate the brittleness of the silicon steel sheet. Therefore, in some embodiments, the P content is controlled to be less than 0.2%.

[0032] S is an element harmful to the magnetism of silicon steel. When the S content exceeds 0.005%, the number of harmful inclusions such as MnS and Cu2S will increase greatly, which will strongly hinder the growth of grains and deteriorate the magnetism of steel. Therefore, in some embodiments, the S content is controlled to be below 0.005%.

[0033] When the N content exceeds 0.005%, the precipitates of Nb, V, Ti, Al, etc. will increase greatly, strongly hindering the grain growth and deteriorating the magnetic properties of the steel. Therefore, in some embodiments, the N content is controlled to be less than 0.005%.

[0034] Nb, V, and Ti may combine with carbon or nitrogen to form precipitates (carbides or nitrides). These precipitates may deteriorate the magnetic properties, hinder the grain growth during annealing, and deteriorate the magnetic properties. Therefore, in some embodiments, the contents of Nb, V, and Ti should be controlled below 0.005%.

[0035] Furthermore, in the non-oriented silicon steel of the present invention, the mass percentage of Si further satisfies: Si: 2.0-3.6%.

[0036] Furthermore, in the non-oriented silicon steel described in the present invention, the number of grains with a grain size of more than 10 μm accounts for more than 10%.

[0037] Furthermore, the number of grains with a grain size of more than 10 μm accounts for more than 50%.

[0038] Furthermore, in the non-oriented silicon steel of the present invention, the thermal conductivity λ of the non-oriented silicon steel at 150°C is 150 The resistivity at room temperature is 40 to 90 μΩ·cm and meets the following conditions: 1000 ≤ λ 150 ×ρ≤2000.

[0039] In order to better describe the actual working conditions of the motor, the thermal conductivity of the present invention is expressed as the thermal conductivity λ at 150°C. 150 The inventors found through research that for permanent magnet synchronous motors, when the value exceeds 1000≤λ 150 When ×ρ≤2000, the expected temperature rise performance of the permanent magnet synchronous motor cannot be obtained.

[0040] Furthermore, the temperature rise of the permanent magnet synchronous motor manufactured by using the non-oriented silicon steel during operation is lower than 125°C.

[0041] Furthermore, in the non-oriented silicon steel of the present invention, the iron loss P 10 / 700 ≤50W / kg.

[0042] Another object of the present invention is to provide a method for manufacturing non-oriented silicon steel with excellent comprehensive performance, which controls the process parameters and adapts the composition ratio of the non-oriented silicon steel to obtain a non-oriented silicon steel plate with excellent comprehensive performance that takes into account both thermal conductivity and electromagnetic properties.

[0043] In order to achieve the above object, the present invention provides a method for manufacturing non-oriented silicon steel with excellent comprehensive performance, which comprises the steps of:

[0044] smelting and casting;

[0045] Hot rolling;

[0046] Normalization;

[0047] Cold rolling;

[0048] Continuous annealing and insulating coating: The continuous annealing temperature is 700-1100°C.

[0049] In the present invention, the continuous annealing temperature is controlled to be 700-1100°C because: in order to achieve recrystallization of the steel plate structure, the annealing temperature needs to be greater than the recrystallization temperature. Based on this, the present invention needs to control the lower limit of the continuous annealing temperature to 700°C.

[0050] In some embodiments of the present invention, in the cold rolling step, a single cold rolling process may be used to directly roll the steel sheet to the finished product thickness.

[0051] In another embodiment of the present invention, the cold rolling step may adopt a process of primary cold rolling, intermediate annealing and secondary cold rolling, wherein the cumulative reduction ratio of the secondary cold rolling is 45-75%.

[0052] In this embodiment, the cumulative reduction rate of the secondary cold rolling is controlled to be 45-75% because the reduction rate of the secondary cold rolling method has a significant effect on the texture. In order to improve the texture and thus improve the electromagnetic properties, the present invention controls the reduction rate to be 45-75%.

[0053] The non-oriented silicon steel with excellent comprehensive performance described in the present invention has the following advantages and beneficial effects:

[0054] The present invention is based on the research findings that the difference in thermal conductivity of non-oriented silicon steel mainly lies in the strength of metal bonds, and the determining factor of resistivity of non-oriented silicon steel is the level of alloy content. The present invention preferably combines the types and contents of chemical elements in non-oriented silicon steel, balances the relationship between metal bonds and alloy content, thereby effectively controlling the thermal conductivity and resistivity of non-oriented silicon steel, and with the assistance of appropriate manufacturing process, controls the thermal conductivity λ of non-oriented silicon steel at 150°C. 150 The resistivity at room temperature is 40 to 90 μΩ·cm and meets the following conditions: 1000 ≤ λ 150 ×ρ≤2000, and finally a non-oriented silicon steel sheet with excellent comprehensive performance taking into account both thermal conductivity and electromagnetic properties is obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 It shows the λ of the non-oriented silicon steel of the present invention. 150 ×ρ and the temperature rise of the permanent magnet synchronous motor made of the non-oriented silicon steel.

[0056] Figure 2 The microstructure metallographic diagram of the non-oriented silicon steel of Example 5 of the present invention is shown. DETAILED DESCRIPTION

[0057] The inventors found through research that the difference in thermal conductivity of non-oriented silicon steel mainly lies in the strength of the metal bond, while the determining factor of the resistivity of non-oriented silicon steel is the alloy content. Therefore, if the types and contents of chemical elements in non-oriented silicon steel are optimally combined and the relationship between metal bonds and alloy content is well balanced, the thermal conductivity and resistivity of non-oriented silicon steel can be effectively controlled. In order to better describe the actual working conditions of the motor, the thermal conductivity is expressed as the thermal conductivity λ at 150°C. 150 Representation.

[0058] In the present invention, steel plates with different thermal conductivity and resistivity are used to trial-produce permanent magnet synchronous motors. The main parameters of the motors are: outer diameter 220 mm, stack thickness 150 mm, rated power 150 KW, and maximum torque 350 Nm. The temperature rise of the trial-produced permanent magnet synchronous motor under working conditions is measured, and λ is obtained. 150 The correlation diagram between ×ρ and the temperature rise of permanent magnet synchronous motor is as follows Figure 1 shown.

[0059] from Figure 1 It can be seen that when it exceeds 1000≤λ 150 In the range of ×ρ≤2000, the desired temperature rise performance cannot be obtained.

[0060] The non-oriented silicon steel with excellent comprehensive performance and the manufacturing method thereof described in the present invention will be further explained and illustrated below in combination with specific embodiments and the accompanying drawings of the specification. However, such explanation and illustration do not constitute an improper limitation on the technical solution of the present invention.

[0061] Examples 1-9 and Comparative Examples 1-6

[0062] Table 1-1 and Table 1-2 list the mass percentage of each chemical element in the non-oriented silicon steel sheets of Examples 1-9 and the comparative steel sheets of Comparative Examples 1-6.

[0063] Table 1-1. (wt%, the balance is Fe and other inevitable impurities except P, S, N, Nb, V, Ti)

[0064]

[0065] Table 1-2. (wt%, the balance is Fe and other inevitable impurities except P, S, N, Nb, V, Ti)

[0066] No. Sn Sb Ca Mg REM P S N Nb V Ti Example 1 0.45 0.21 0.002 / / 0.19 0.0047 0.0012 0.0047 0.0037 0.0007 Example 2 / 0.47 / 0.002 / 0.01 0.0024 0.0012 0.0011 0.0011 0.0049 Example 3 0.17 0.15 / / 0.002 0.07 0.0022 0.0016 0.0035 0.0024 0.0015 Example 4 0.05 0.19 0.018 0.018 / 0.05 0.0011 0.0048 0.0019 0.0013 0.0012 Example 5 / / / / / 0.06 0.0028 0.0011 0.0024 0.0019 0.0019 Example 6 0.03 0.02 / / 0.017 0.04 0.0021 0.0009 0.0021 0.0041 0.0022 Example 7 0.32 0.05 0.0009 / / 0.02 0.0005 0.0016 0.0011 0.0017 0.0011 Example 8 0.04 0.35 / 0.0009 / 0.06 0.0018 0.0012 0.0022 0.0023 0.0028 Example 9 0.03 0.04 / / 0.0008 0.04 0.0014 0.0019 0.0029 0.0037 0.0021 Comparative Example 1 0.004 0.02 / / / 0.03 0.0022 0.0008 0.0051 0.0018 0.0024 Comparative Example 2 / / / / / 0.03 0.0011 0.0005 0.0028 0.0051 0.0023 Comparative Example 3 0.002 0.003 / / / 0.04 0.0025 0.0011 0.0021 0.0009 0.0051 Comparative Example 4 / 0.005 / / / 0.07 0.0028 0.0015 0.0005 0.0016 0.0011 Comparative Example 5 0.005 / / / / 0.02 0.0022 0.0051 0.0018 0.0012 0.0032 Comparative Example 6 0.008 0.001 / / / 0.03 0.0058 0.0008 0.0014 0.0019 0.0018

[0067] The non-oriented silicon steel sheets of Examples 1-9 described in the present invention are all prepared by the following steps:

[0068] (1) After blast furnace molten iron is subjected to molten iron pretreatment, converter smelting, RH refining and continuous casting, a continuous casting billet with a target nominal thickness of 300 mm is obtained. The chemical element composition of the continuous casting billet in each embodiment is shown in Table 1-1 and Table 1-2.

[0069] (2) Heating: The heating temperature can be 1050°C and the holding time can be 1.5 hours;

[0070] (3) Finish rolling and coiling: The final rolling temperature of the steel coil can be 800°C, and the coiling temperature can be 625°C, to obtain a hot-rolled plate with a thickness of 1.5-2.5 mm;

[0071] (4) Normalizing annealing: the annealing temperature can be 950°C;

[0072] (5) cold rolling after pickling;

[0073] (6) Continuous annealing and insulating coating; wherein the continuous annealing temperature is 700-1100°C.

[0074] In each embodiment, Examples 6-9 and Comparative Examples 4-6 adopt a single cold rolling process; Examples 1-5 adopt a single cold rolling + intermediate annealing + secondary cold rolling process, and the cumulative reduction rate of the secondary cold rolling is controlled to be 45-75%. The other steps of Comparative Examples 1-6 are basically the same as those of the embodiments of the present invention.

[0075] Table 2 lists the specific process parameters of the manufacturing method of the non-oriented silicon steel sheets of Examples 1-9 and the comparative steel sheets of Comparative Examples 1-6. Table 2.

[0076]

[0077]

[0078] In addition, the present invention also samples the non-oriented silicon steel sheets of Examples 1-9 and the comparative steel sheets of Comparative Examples 1-6, and tests the relevant properties of the steel sheets of each embodiment and comparative example. The results of the observation and relevant performance tests are listed in Table 3. The specific testing methods of the relevant performances are as follows:

[0079] Microstructure detection: The grain size statistics adopt the area method of "GB / T6394-2017 Method for Determination of Average Grain Size of Metals".

[0080] Iron loss performance test: Based on the national standard "GB / T10129-2019 Measurement method of medium frequency magnetic properties of electrical steel strip (sheet)", the Epstein square circle method is used for iron loss performance test. The test temperature is 20℃ constant temperature test, the sample size is 30mm×300mm, the target mass is 0.25kg, and the test parameters are P 10 / 700 .

[0081] Thermal conductivity test: The transient plane heat source method was used for testing in accordance with the national standard GB / T 32064-2015. The testing equipment can adopt Hot Disk TPS2500S.

[0082] Room temperature resistivity test: Detection was carried out with reference to GB / T 351.

[0083] Table 3 lists the relevant performance test results of the non-oriented silicon steel sheets of Examples 1-9 and the comparative steel sheets of Comparative Examples 1-6.

[0084] Table 3.

[0085]

[0086]

[0087] Note: The "temperature rise" in Table 3 is the temperature rise data of the permanent magnet synchronous motors trial-produced using the corresponding examples and comparative examples.

[0088] Figure 2 Shows the microstructure metallographic diagram of Example 5 of the non-oriented silicon steel of the present invention. As Figure 2 shown, the proportion of the number of grains with a grain size of more than 10 μm exceeds 50%. Figure 2 The "祄" in it represents "μm".

[0089] Combining Table 1, Table 2 and Table 3, it can be seen that in Examples 1-9 that meet the design requirements of the present invention, due to the unique composition design and process design of the present invention, the finally obtained finished non-oriented silicon steel sheet has a thermal conductivity λ 150 of 10-35 W / mK at 150 °C, a resistivity ρ of 40-90 μΩ·cm at room temperature, and satisfies: 1000 ≤ λ 150 × ρ ≤ 2000, and at the same time also has good electromagnetic properties. The iron loss P 10 / 700 of the finished steel sheet ≤ 50 W / kg. The temperature rise of the permanent magnet synchronous motors manufactured using these examples is lower than the target value of 125 °C.

[0090] However, for the comparative steel sheets of Comparative Examples 1-6, due to the composition, secondary cold rolling process and continuous annealing process not meeting the requirements of the present invention, their thermal conductivity and resistivity do not meet the requirements of the present invention. Therefore, the temperature rise of the permanent magnet synchronous motors manufactured using these comparative examples is higher than the target value of 125 °C. This is because there are heat generation and heat dissipation phenomena when the motor is working. Heat generation is closely related to the resistivity of the silicon steel sheet, while heat dissipation is related to the thermal conductivity of the silicon steel sheet. When these two properties of the silicon steel sheet cannot meet the requirements, the heat generated by the silicon steel sheet cannot be conducted out in time, resulting in an increase in the motor temperature. Too high a temperature rise will seriously affect the motor performance and operation safety and must be controlled within a certain range.

[0091] It should be noted that the combination of the various technical features in this case is not limited to the combination described in the claims of this case or the combination described in the specific embodiments. All technical features recorded in this case can be freely combined or combined in any way unless there is a contradiction between them.

[0092] It should also be noted that the above-listed embodiments are only specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and similar changes or modifications made therewith can be directly derived or easily associated with the contents disclosed by those skilled in the art from the present invention, and all should belong to the protection scope of the present invention.

Claims

1. A non-oriented silicon steel with excellent comprehensive performance, containing Fe and inevitable impurities, characterized in that: It also contains the following chemical elements in percentage by mass: C≤0.0050%, Si: 2.0~4.0%, Mn: 0.1~2.0%, Al: 0.001~2.0%, Cr: 0.001~5.0%, Ni: 0.001~5.0%, Cu: 0.001~2.0%; The mass percentage content of each chemical element also satisfies: 0≤3×Si+0.5×Al+0.5×Mn-5×Cu-2.5×Cr-Ni≤13.5%.

2. The non-oriented silicon steel according to claim 1, characterized in that: The mass percentage of each chemical element is: C≤0.0050%, Si: 2.0~4.0%, Mn: 0.1~2.0%, Al: 0.001~2.0%, Cr: 0.001~5.0%, Ni: 0.001~5.0%, Cu: 0.001~2.0%; the balance is Fe and other inevitable impurities.

3. The non-oriented silicon steel according to claim 1 or 2, characterized in that: It also contains 0≤Sn≤0.5wt% and / or 0≤Sb≤0.5wt%.

4. The non-oriented silicon steel according to claim 1 or 2, characterized in that: It also contains at least one of the following chemical elements: 0≤Ca≤0.02wt%; 0≤Mg≤0.02wt%; 0≤REM≤0.02wt%.

5. The non-oriented silicon steel according to claim 1, characterized in that: Among the inevitable impurities, the mass percentage of each impurity element satisfies at least one of the following items: P≤0.2%, S≤0.005%, N≤0.005%, Nb≤0.005%, V≤0.005%, Ti≤0.005%.

6. The non-oriented silicon steel according to claim 1 or 2, characterized in that: The Si mass percentage content further satisfies: Si: 2.0-3.6%.

7. The non-oriented silicon steel according to claim 1 or 2, characterized in that: The number of grains with a grain size of more than 10μm accounts for more than 10%.

8. The non-oriented silicon steel according to claim 7, characterized in that: The number of grains with a grain size of more than 10μm accounts for more than 50%.

9. The non-oriented silicon steel according to claim 1 or 2, characterized in that: The thermal conductivity λ of the non-oriented silicon steel at 150°C 150 The resistivity at room temperature is 40 to 90 μΩ·cm and meets the following conditions: 1000 ≤ λ 150 ×ρ≤2000.

10. The non-oriented silicon steel according to claim 1 or 2, characterized in that: Its iron loss P 10 / 700 ≤50W / kg.

11. The non-oriented silicon steel according to claim 1 or 2, characterized in that: The temperature rise of the permanent magnet synchronous motor manufactured by the non-oriented silicon steel is lower than 125° C. during operation.

12. A method for manufacturing non-oriented silicon steel according to any one of claims 1 to 11, characterized in that: Includes steps: smelting and casting; Hot rolling; Normalization; Cold rolling; Continuous annealing and insulating coating: The continuous annealing temperature is 700-1100°C.

13. The manufacturing method according to claim 12, characterized in that: In the cold rolling step, a primary cold rolling process is adopted.

14. The manufacturing method according to claim 12, characterized in that: In the cold rolling step, a process of primary cold rolling, intermediate annealing and secondary cold rolling is adopted, wherein the cumulative reduction rate of the secondary cold rolling is 45-75%.

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