Non-oriented electrical steel and method for manufacturing non-oriented electrical steel

Abstract

The present invention relates to a non-oriented electrical steel sheet having a composition comprising the following elements in percentage by weight: 0.0001% < = carbon < = 0.007%, 0.15% < = manganese < = 0.25%, 2.9% < = silicon < = 3.4%, 0.8% < = aluminum < = 1.1%, phosphorus < = 0.15%, sulfur < = 0.006%, nitrogen < = 0.09%, with 3.85% < = Si + Al + Mn < = 5.5%, and the balance being iron and unavoidable impurities. And may include one or more of the following optional elements: 0% < = niobium < = 0.1%, 0% < = titanium < = 0.1%, 0% < = vanadium < = 0.1%, 0% < = chromium < = 1%, 0% < = molybdenum < = 0.5%, 0% < = tungsten < = 0.1%, 0% < = cobalt < = 1%, 0% < = arsenic < = 0.05%, 0.001% < = calcium < = 0.01%, 0% < = copper < = 1%, 0% < = nickel < = 1%, 0% < = boron < = 0.05%, 0% < = lead < = 0.2%, 0% < = tin < = 0.2%, 0% < = antimony < = 0.2%, and the balance being Fe. A steel sheet having a microstructure composed of ferrite and including, in area fraction, 80% to 100% of a recrystallized microstructure having an average crystal grain size of 20 [mu] m to 110 [mu] m, 0% to 20% of a non-recrystallized microstructure having an average crystal grain size of 10 [mu] m to 100 [mu] m, and 0% to 20% of a non-recrystallized microstructure having an average crystal grain size of 10 [mu] m to 100 [mu] m, the balance being iron and unavoidable impurities resulting from processing. And the non-oriented electrical steel sheet has a percentage of eddy current loss in total iron loss measured at 1 T and 400 Hz according to IEC 60404-2 standard, when calculated according to the Bertotti method, of less than 25%, and at the same time has a magnetic polarization (J50) at 5000 A / m of 1.625 T to 1.690 T.

Description

Technical Field

[0001] The present invention relates to a non-oriented electrical steel sheet and a method for manufacturing the same. Specifically, the present invention relates to a non-oriented electrical steel sheet having low iron loss, especially low eddy current loss, and good mechanical properties and a method for manufacturing the same. Background Art

[0002] As a result, due to the global push for energy-saving improvements in electrical equipment, significant research and development efforts are being directed toward achieving the higher performance characteristics required of non-oriented electrical steel sheets used as core materials for electric motors. Recently, in particular, demand has been high for compact, high-power motors for use in electric vehicles and other applications. These electric vehicle motors are designed to achieve high-speed rotation, thereby achieving high torque with minimal losses. This requires lightweight and efficient non-oriented electrical steel, with low losses as its key characteristic. Finding a balance between losses, magnetic permeability, polarization, thermal conductivity, tensile strength, and yield strength is crucial for non-oriented electrical steel.

[0003] The lower the iron losses in a motor, the higher its efficiency. Therefore, to reduce the amount of iron losses in a motor, motor manufacturers have several options. Their primary options are to reduce either hysteresis losses or eddy current losses to improve the efficiency of their motors. Progress is usually achieved through a combination of two approaches. The present invention addresses the second option, namely reducing the motor's eddy current losses. There are two alternative approaches to reducing eddy current losses:

[0004] The first approach consists in reducing the thickness of the steel sheets used in the motor, for example to have a thickness of less than 0.35 mm or even less. Unfortunately, this solution has its limitations due to the reduction in the stacking factor, which reduces the torque achievable for a given machine height and, in turn, significantly reduces the stiffness of certain automotive components and creates acoustic problems that can be unpleasant for passengers.

[0005] The second approach involves optimizing the elemental composition of the steel sheet, for example by increasing the amount of alloying elements to limit eddy current losses. Among these alloying elements, aluminum and manganese have attractive mechanical and magnetic properties, while also significantly reducing eddy current losses. However, the addition of alloying elements can be limited to a certain limit, as above a certain percentage, they influence hysteresis losses and magnetic polarization.

[0006] Early research and development in the field of high strength non-oriented electrical steel has resulted in several methods for producing high strength non-oriented electrical steel, some of which are listed herein for a clear understanding of the present invention:

[0007] US2021 / 371948 is a non-oriented electrical steel sheet having a thickness not greater than 4.5×10-6 The nonoriented electrical steel sheet is obtained by subjecting a steel slab to hot rolling, hot strip annealing, cold rolling under sufficient cold rolling and finish annealing conditions, and finish annealing, wherein the steel slab comprises, in mass %, C: not more than 0.0 05%, Si: 2.8% to 6.5%, Mn: 0.05% to 2.0%, Al: not more than 3.0%, P: not more than 0.20%, S: not more than 0.005%, N: not more than 0.005%, Ti: not more than 0.003%, V: not more than 0.005%, and Nb: not more than 0.005%, and satisfying Si-2Al-Mn ≥ 0, and a motor core is manufactured from such a steel sheet. US2021 / 371948 does not show total elongation and eddy current loss at all. Summary of the Invention

[0008] An object of the present invention is to solve these problems by producing a nonoriented electrical steel sheet having simultaneously, when calculated according to the Bertotti method, a percentage of eddy current loss in the total iron loss of less than 25%, and preferably 18% to 23%, and a magnetic polarization (J50) at 5000 A / m of 1.625 T to 1.690 T, and preferably 1.630 T to 1.680 T.

[0009] In preferred embodiments, the following additional characteristics may also be achieved, alone or in combination:

[0010] - an ultimate tensile strength of 540 MPa or more in both the transverse direction and the rolling direction, and preferably greater than 560 MPa in both the transverse direction and the rolling direction,

[0011] - a yield strength of 430 MPa or more in both the transverse direction and the rolling direction, and preferably 440 MPa or more in both the transverse direction and the rolling direction,

[0012] - a total elongation of 14% or more in both the transverse direction and the rolling direction, and preferably greater than or equal to 16% in both the transverse direction and the rolling direction,

[0013] - When measured at 1T and 400 Hz, the total loss is 11 W / kg to 13 W / kg, and preferably, when measured at 1T and 400 Hz, the total loss is 11 W / kg to 13 W / kg, and more preferably, when measured at 1T and 400 Hz, the total loss is 11 W / kg to 12 W / kg.

[0014] Preferably, such a steel may also have good suitability for rolling and have good stampability and paintability.

[0015] Preferably, the hardness is greater than or equal to 185 HV, and preferably, the hardness is greater than or equal to 195 HV.

[0016] Another object of the invention is also to make available a method for manufacturing these panels that is compatible with conventional industrial applications and at the same time robust to variations in manufacturing parameters.

[0017] The above objects and other advantages of the present invention will become more apparent through detailed description of preferred embodiments of the present invention. DETAILED DESCRIPTION

[0018] The chemical composition of non-oriented electrical steel includes the following elements in weight percentage:

[0019] Carbon is present in the steel of the present invention at 0.0001% to 0.007%. Carbon is a precipitate-forming element and is therefore detrimental to the magnetic properties of the steel of the present invention. Therefore, carbon is present in the steel of the present invention at 0.0001% to 0.007%. Because carbon promotes magnetic aging, the preferred carbon content according to the present invention is 0.002% to 0.007%, and more preferably 0.002% to 0.005%.

[0020] The steel of the present invention has a manganese content of 0.15% to 0.25%. Manganese provides solid solution strengthening and reduces iron loss by increasing specific resistivity. When the amount of manganese added exceeds 0.25%, the magnetic flux density may be significantly reduced, and recrystallization of the steel during annealing will be hindered. The preferred limit of manganese presence is 0.16% to 0.24%, and more preferably 0.17% to 0.22%.

[0021] The steel of the present invention has a silicon content of 2.9% to 3.4%. Silicon contributes to strength through solid solution strengthening and is a key element in reducing eddy current losses, which are iron losses, by increasing the steel's specific electrical resistivity. A minimum silicon content of at least 2.9% is required to achieve these effects. However, exceeding 3.4% makes rolling difficult and significantly reduces the steel's magnetic induction. The preferred limit for silicon is 3% to 3.3%, and more preferably 3.1% to 3.3%.

[0022] The aluminum content is 0.8% to 1.1%. Aluminum increases the resistivity of the material and can effectively reduce the iron loss of steel. When the aluminum content exceeds 1.1%, the magnetic induction of the steel is significantly reduced, which also detrimentally affects the cold rollability of the steel of the present invention. The preferred limit of aluminum is 0.85% to 1.1%, and more preferably 0.9% to 0.98%.

[0023] Sulfur is not an essential element, but may be contained in steel as an impurity. From the perspective of the present invention, the sulfur content is preferably as low as possible. However, from the perspective of manufacturing cost, the sulfur content is 0.006% or less. In addition, if sulfur is present in a high concentration in steel, it will combine to form sulfides, which is detrimental to the magnetic properties of the present invention.

[0024] The phosphorus content of the steel of the present invention is 0% to 0.15%. Phosphorus reduces hot and cold ductility, particularly due to its tendency to segregate at grain boundaries or co-segregate with manganese. For these reasons, its content is limited to 0.15%, and preferably less than 0.09%.

[0025] Nitrogen is limited to 0.09% to minimize precipitation of aluminum nitrides during solidification, which are detrimental to the magnetic properties of the steel.

[0026] Titanium is an optional element, and when added to the steel of the present invention at 0% to 0.1%, it forms titanium nitrides that appear during solidification of the cast product. Therefore, the amount of titanium is limited to 0.1% to avoid the formation of titanium nitrides that are detrimental to the magnetic properties of the steel of the present invention. Titanium contents below 0.001% have no effect on the steel of the present invention.

[0027] Niobium is present in the steel according to the present invention in amounts of 0% to 0.1% and is suitable for forming carbonitrides to increase the strength of the steel according to the present invention through precipitation hardening. Niobium also influences the size of microstructural components through its precipitation as carbonitrides. However, niobium contents above 0.1% are not economically attractive due to saturation effects.

[0028] Vanadium is present in the steel of the present invention at 0% to 0.1% and effectively enhances the strength of the steel by forming carbides or carbonitrides, and the upper limit is 0.1% from an economical viewpoint.

[0029] Chromium is an optional element of the steel of the present invention, present in an amount of 0% to 1%. Chromium provides strength to the steel through solid solution strengthening, but when used above 1%, it impairs the magnetic properties of the steel. In a preferred embodiment, the chromium content is at least 0.01%.

[0030] Molybdenum is an optional element constituting 0% to 0.5% of the steel of the present invention. Mo has the effect of coarsening carbides and thus reducing iron loss. When it exceeds 0.5%, the effect of improving iron loss is saturated.

[0031] Tungsten is an optional element comprising 0% to 0.1% of the steel of the present invention. Like Mo, tungsten has the effects of coarsening carbides and reducing iron loss. However, when added in an amount less than 0.001% by mass, these effects are not fully achieved, while when added in an amount exceeding 0.1% by mass, the iron loss improvement effect saturates.

[0032] Cobalt is an optional element comprising 0% to 1% of the steel of the present invention. Cobalt increases the magnetic moment of Fe alloys and has the effects of increasing magnetic flux density and reducing iron loss. However, when the addition amount is less than 0.01% by weight, these effects are not fully achieved, while when it exceeds 1% by weight, the raw material cost increases significantly.

[0033] Arsenic is an optional element constituting 0% to 0.05% of the steel of the present invention. As is a grain boundary segregation element and has the effect of improving the structure and thereby reducing iron loss. These effects are achieved by adding not less than 0.001% by weight. However, As is an element that causes grain boundary embrittlement, and this adverse effect becomes particularly pronounced when added in amounts exceeding 0.05% by weight. Therefore, As is preferably added in the range of 0.001% to 0.05% by weight.

[0034] Nickel can be added as an optional element in an amount of 0% to 1% to increase the strength of the steel of the present invention and improve its strength and elongation. However, when its content is above 1%, nickel causes ductility to deteriorate. In a preferred embodiment, the nickel content is kept below 0.04%.

[0035] Copper can be added as an optional element in an amount of 0% to 1% to improve the strength and elongation of the steel of the present invention. However, when its content is higher than 1%, it may deteriorate the surface appearance. In a preferred embodiment, the copper content is at least 0.01%.

[0036] Boron is an optional element of the steel of the present invention and may be present in the range of 0% to 0.05%.Boron forms boron nitrides when added in amounts of at least 0.0001% and imparts additional strength to the steel of the present invention.

[0037] Calcium may optionally be present in the steel of the present invention and may be present in an amount of 0.001% to 0.01%.Calcium aids in the refining of the steel by binding harmful sulphur contents into a globular form, thereby hindering the deleterious effects of sulphur.

[0038] Other elements such as Sn, Pb or Sb may be added individually or in combination in the following proportions: Sn≤0.2%, Pb≤0.2% and Sb≤0.2%. Up to the maximum content levels shown, these elements allow grain refinement during solidification. In a preferred embodiment, the Sn content is less than 0.04%.

[0039] The remainder of the steel's composition consists of iron and unavoidable impurities resulting from processing.

[0040] 3.85%≤Si+Al+Mn≤5.5%

[0041] The non-oriented electrical steel sheet according to the present invention must contain silicon, manganese, and aluminum so that the total content is 3.85% to 5.5% by weight. When the total content of Si, Mn, and Al is less than 3.85%, it is impossible to achieve the aforementioned mechanical and magnetic properties. However, when the total content of Si, Mn, and Al exceeds 5.5%, the steel hardens and rolling becomes difficult. The preferred limit for the presence of Si, Mn, and Al is 3.9% to 5.2%, and more preferably 4% to 5%.

[0042] The microstructure of the non-oriented electrical steel will now be described in detail, with all percentages being by area fraction.

[0043] The microstructure consists of ferrite. The steel of the present invention has a recrystallized microstructure area of 80% to 100% by area fraction, with the average grain size of the grains ranging from 20 to 110 microns. This recrystallized structure with a high degree of recrystallization is due to uniform silicon enrichment, which improves the magnetic properties of the steel of the present invention. The controlled grain size ensures excellent mechanical properties in both the transverse and rolling directions. The preferred degree of recrystallization is 90% to 100%. The preferred average grain size of the present invention is 20 to 100 microns, and more preferably 20 to 90 microns.

[0044] The steel of the present invention may have a non-recrystallized microstructural region of 0% to 20% by area fraction, with a preferred non-recrystallization degree of 0% to 10%, and more preferably 0% to 5%.

[0045] The microstructure of the non-oriented electrical steel does not contain microstructure components such as martensite, bainite, pearlite and cementite in addition to the above-mentioned microstructure.

[0046] The steel according to the invention can be manufactured by any suitable method. However, as a non-limiting example, it is preferred to use the method according to the invention which will be described in detail.

[0047] Such a preferred method comprises providing a semi-finished casting of steel having the chemical composition of the steel according to the present invention. The casting can be made into an ingot or continuously produced in the form of thin slabs or thin strip (i.e., a thickness range of about 240 mm or less for any form of casting).

[0048] For example, a casting in slab form can be cast using the chemical composition according to the present invention and then reheated at a slab reheating temperature of 1080°C to 1180°C until the temperature is uniform throughout the slab. Below 1100°C, rolling becomes difficult and the forces on the rolling mill will be too high. Above 1180°C, high-silicon steel grades become very soft and may exhibit some sagging, making them difficult to handle. Preferred slab reheating temperatures are 1090°C to 1170°C, and more preferably 1100°C to 1160°C.

[0049] The reheated slab is then subjected to hot rolling, where the hot finishing temperature influences the final hot-rolled microstructure and occurs between 840°C and 900°C. When the finishing temperature is below 840°C, recrystallization is limited and the microstructure is highly deformed. Temperatures above 900°C result in greater impurities in the solid solution, potentially leading to precipitation and deterioration of magnetic properties. The preferred hot finishing temperature is between 850°C and 890°C, and more preferably between 850°C and 880°C.

[0050] The hot-rolled steel sheet obtained in this manner is then immediately cooled to the coiling temperature of the hot-rolled steel sheet, which also applies to the hot-rolled steel sheet; this occurs at 540°C to 640°C. Coiling at temperatures below 540°C will not result in the appropriate distribution and size of the precipitates of the steel according to the invention. Above 640°C, a thick oxide layer will form, which will make subsequent processing steps (such as cold rolling and / or pickling) difficult. Preferably, the cooling rate will be less than or equal to 200°C / second, and more preferably, the cooling rate will be between 12°C / second and 75°C / second. The preferred coiling temperature is 540°C to 590°C.

[0051] The coiled hot rolled steel sheet is then cooled to room temperature and then subjected to optional hot strip annealing.

[0052] The hot rolled steel sheet may be subjected to an optional descaling step to remove the scale formed during hot rolling prior to the optional hot strip annealing. The hot rolled sheet is then subjected to an optional hot strip annealing, such hot strip annealing being conducted at a temperature of 900°C to 1000°C, preferably for at least 10 seconds and for no more than 96 hours, with the temperature preferably being maintained at 910°C to 990°C, and more preferably at 940°C to 980°C. Thereafter, the optional descaling step of the hot rolled steel sheet may be performed, for example, by pickling the sheet. The preferred duration of the hot strip annealing is 10 to 500 seconds, and more preferably 20 to 120 seconds.

[0053] Therefore, the obtained hot-rolled steel sheet may optionally have a thickness of 0.8 mm to 3.5 mm, and preferably 0.9 mm to 3 mm, and more preferably 1 mm to 2.8 mm.

[0054] The hot rolled steel sheet is then subjected to cold rolling at a thickness reduction ratio of 50% to 95% to obtain a cold rolled steel sheet. Preferably, the thickness reduction ratio is 60% to 95%, and more preferably 75% to 95%.

[0055] The cold rolled steel sheet is then subjected to a heat treatment which imparts the necessary mechanical properties and microstructure to the steel of the present invention.

[0056] The cold rolled steel sheet is then heated, wherein the heating starts from room temperature and is heated to an annealing temperature T of 890°C to 960°C at a heating rate HR1 of at least 1°C / second. 均热 In a preferred embodiment, the heating rate HR1 for heating is at least 2°C / second, and more preferably at least 5°C / second. 均热 The temperature is 890°C to 950°C.

[0057] Cold rolled steel sheet in T 均热 The holding time is 10 seconds to 5000 seconds to ensure 80% to 100% recrystallization.

[0058] The cold rolled steel sheet is then cooled, wherein the cooling is carried out from T 均热 Initially, the cold-rolled steel sheet is cooled to a temperature T1 in the range of 20°C to 300°C at a cooling rate CR1 of 1°C / s to 150°C / s. In a preferred embodiment, the cooling rate CR1 is 3°C / s to 120°C / s. The preferred T1 temperature is 20°C to 200°C.

[0059] The cold-rolled steel sheet thus obtained must have a thickness of 0.15 mm to 0.22 mm, and more preferably 0.16 mm to 0.21 mm, even more preferably 0.18 mm to 0.21 mm.

[0060] Then, the cold rolled steel sheet is cooled to room temperature to obtain a non-oriented electrical steel sheet.

[0061] The nonoriented electrical steel sheet of the present invention may be optionally coated with an insulating organic coating or an inorganic coating or a combination thereof to improve insulation properties.

[0062] Example

[0063] The following tests, examples, graphical illustrations and tables presented herein are non-limiting in nature and must be considered for purposes of illustration only and will demonstrate the advantageous features of the present invention.

[0064] Steel plates made of steel having different compositions are summarized in Table 1, wherein the steel plates were respectively produced according to the process parameters specified in Table 2. Thereafter, Table 3 summarizes the evaluation results of the obtained characteristics.

[0065] All steels in Table 1 have nitrogen contents below 0.09%.

[0066] Table 2 summarizes the hot rolling and annealing process parameters applied to the cold-rolled steel sheets to impart the mechanical and magnetic properties required for the steels in Table 1 to be non-oriented electrical steels. All of the inventive steels I1 to I4 were cooled at a cooling rate of 15°C / second after hot rolling. Furthermore, for the inventive examples, the heating rate HR1 to the annealing soaking temperature was 5°C / second. For all inventive examples, the T1 temperature was 25°C, and the cooling rate CR1 was 5°C / second.

[0067] All steels produced according to the parameters of Table 2 showed a microstructure with greater than 95% recrystallization and with a grain size ranging from 20 μm to 110 μm.

[0068]

[0069] Table 3

[0070] The results of various mechanical tests performed in accordance with the standards are summarized. The ultimate tensile strength, total elongation and yield strength were measured according to the NF EN ISO 6892-1 standard, and the J50 magnetic properties and the total iron loss at 1T and 400Hz were measured according to the IEC 60404-2 standard. The eddy current losses were calculated according to the Bertotti method published by Giorgio Berttoti in the paper entitled "General Properties of Power Losses in Soft Ferromagnetic Materials" published in IEEE TRANSACTIONS ON MAGNETICS, Vol. 24, No. 1, January 1988. Equation 2 determines the value of the power loss given by (P 经典 ) are classical losses represented by , which for the purposes of this invention are called eddy current losses.

[0071] The average grain size of the recrystallized microstructure was measured using the linear intercept method according to ASTM E112 96(02).

[0072]

Claims

1. A non-oriented electrical steel sheet having a composition comprising the following elements: expressed in weight percentage, 0.0001%≤Carbon≤0.007% 0.15%≤Manganese≤0.25% 2.9%≤Silicon≤3.4% 0.8%≤Aluminum≤1.1% Phosphorus ≤ 0.15% Sulfur ≤ 0.006% Nitrogen ≤ 0.09% Of which 3.85%≤Si+Al+Mn≤5.5% and can include one or more of the following optional elements: 0%≤Niobium≤0.1% 0%≤Titanium≤0.1% 0%≤Vanadium≤0.1% 0%≤Cr≤1% 0%≤Molybdenum≤0.5% 0%≤Tungsten≤0.1% 0%≤Cobalt≤1% 0%≤Arsenic≤0.05% 0.001%≤Calcium≤0.01% 0%≤Copper≤1% 0%≤Nickel≤1% 0%≤boron≤0.05% 0%≤Lead≤0.2% 0%≤Tin≤0.2% 0%≤Antimony≤0.2% The balance of the composition is composed of iron and inevitable impurities caused by processing, the microstructure of the steel sheet is composed of ferrite and contains, by area fraction, 80% to 100% of a recrystallized microstructure and 0% to 20% of a non-recrystallized microstructure, wherein the average grain size of the recrystallized microstructure is 20 μm to 110 μm, and the non-oriented electrical steel sheet has an eddy current loss as measured at 1 T and 400 Hz according to IEC 60404-2 standard of less than 25% in the total iron loss when calculated according to the Bertotti method, and simultaneously has a magnetic polarization (J50) at 5000 A / m of 1.625 T to 1.690 T. 2 . The non-oriented electrical steel sheet according to claim 1 , wherein the composition comprises 3.1% to 3.3% of silicon. 3 . The non-oriented electrical steel sheet according to claim 1 , wherein the composition comprises 0.002% to 0.007% of carbon. 4 . The non-oriented electrical steel sheet according to claim 1 , wherein the composition comprises 0.85% to 1.1% of aluminum. 5 . The non-oriented electrical steel sheet according to claim 1 , wherein the composition comprises 0.16% to 0.24% of manganese.

6. The non-oriented electrical steel sheet according to any one of claims 1 to 5, wherein the amount of non-recrystallized microstructure is 0% to 10%.

7. The nonoriented electrical steel sheet according to any one of claims 1 to 6, wherein the amount of recrystallized microstructure is 90% to 100%.

8. The nonoriented electrical steel sheet according to any one of claims 1 to 7, wherein the steel sheet has an ultimate tensile strength of at least 540 MPa in both the transverse direction and the rolling direction. 9 . The nonoriented electrical steel sheet according to claim 1 , which has a yield strength of 430 MPa or more in both the transverse direction and the rolling direction.

10. The non-oriented electrical steel sheet according to any one of claims 1 to 9, wherein the total elongation of the steel sheet in both the transverse direction and the rolling direction is at least 14%.

11. A method for producing a non-oriented electrical steel sheet according to any one of claims 1 to 10, comprising the following steps in sequence: - providing a steel composition according to any one of claims 1 to 5; - reheating the semi-finished product to a temperature of 1100° C. to 1250° C.; - rolling the semi-finished product to obtain hot-rolled steel sheets, wherein the hot rolling finishing temperature should be 840° C. to 900° C.; - cooling the hot rolled steel sheet immediately after hot rolling; - then cooling the hot rolled steel sheet from the end of hot rolling to a coiling temperature in the range of 540°C to 640°C at a cooling rate of at least 10°C / second; - thereafter coiling the hot rolled steel sheet at a coiling temperature ranging from 540° C. to 640° C.; - optionally subjecting the hot rolled steel sheet to a descaling process; - optionally subjecting the hot rolled steel sheet to a hot strip annealing at 650° C. to 1100° C. for a period of 10 seconds to 96 hours; - optionally subjecting the hot rolled steel sheet to a descaling process; - cold rolling the hot-rolled steel sheet at a reduction ratio of 50% to 95% to obtain a cold-rolled steel sheet; - Thereafter, the cold rolled steel sheet is annealed, wherein the heating for annealing is started from room temperature to an annealing temperature range T of 900° C. to 1000° C. 均热 , wherein the heating rate HR1 is at least 1° C. / second; - then annealing at the annealing temperature for a period of 10 seconds to 5000 seconds; - then cooling the cold rolled steel sheet, the cooling starting from the annealing temperature to a temperature T1 of 300° C. to 20° C., wherein the cooling rate CR1 is 1° C. / s to 150° C. / s; -Then cooled to room temperature to obtain a non-oriented electrical steel sheet.

12. The method according to claim 11, wherein the T used for annealing is 均热 The temperature is 900°C to 980°C.

13. The method according to any one of claims 11 or 12, wherein the temperature T1 is from 200°C to 20°C. 14 . The method according to claim 11 , wherein the cooling rate CR1 is 3° C. / sec to 120° C. / sec.

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