Non-oriented electrical steel and method for manufacturing the same

Abstract

The present invention relates to a non-oriented electrical steel sheet having a composition, expressed in weight percent, of the following elements: 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% (provided that 3.85%≦Si+Al+Mn≦5.5%), and may contain 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%≦thium the remaining composition being iron and unavoidable impurities resulting from processing; the microstructure of the steel sheet is made of ferrite and includes, in area fraction, 80% to 100% of a recrystallized microstructure and 0% to 20% of a non-recrystallized microstructure; the average grain size of the recrystallized microstructure is 20 microns to 110 microns; and We handle non-oriented electrical steel sheets whose eddy current loss ratio in the total iron loss measured at 1 T and 400 Hz in accordance with the 60404-2 standard is less than 25% when calculated according to Bertotti, and whose magnetic polarization at 5000 A / m (J50) is 1.625 T to 1.690 T.

Description

[Technical Field]

[0001] The present invention relates to a non-oriented electrical steel sheet and a manufacturing method thereof, and more particularly to a non-oriented electrical steel sheet having low iron loss, specifically low eddy current loss, while having excellent mechanical properties, and a manufacturing method thereof. [Background technology]

[0002] Therefore, vigorous research and development efforts are being made, and due to the global trend toward achieving energy conservation in electrical appliances, higher performance characteristics are required for non-oriented electrical steel sheets to be used as iron core materials in electric machines. In recent years, there has been an increasing demand for compact, high-power motors, particularly for use in electric vehicles. Such electric vehicle motors are designed to enable high-speed rotation, thereby providing high torque with minimal possible losses. This requires lightweight, highly efficient non-oriented electrical steels with low losses as their primary characteristic. A balance between loss, magnetic permeability, polarization, thermal conductivity, tensile strength, and yield strength is essential for non-oriented electrical steels.

[0003] The lower the iron losses in an electric machine, the more efficient the electric machine will be. Therefore, to reduce the amount of iron loss in an electric machine, electric machine manufacturers have several options, and their primary options are to reduce either hysteresis losses or eddy current losses to improve the efficiency of the electric machine. Progress is often achieved by a combination of these two approaches. This invention relates to the second option, namely, reducing eddy current losses for electric machines. There are two options for reducing eddy current losses:

[0004] The first consists in reducing the thickness of the steel sheets used in the electric machines, such as having a thickness of less than 0.35 mm or even thinner. Unfortunately, this solution has limitations due to the reduction in the lamination ratio, which reduces the torque achievable for a given machine height, and also due to the very large reduction in the stiffness of certain car parts, and the appearance of acoustic problems that cause discomfort to the occupants.

[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 alloys, among others, offer attractive mechanical and magnetic properties while significantly reducing eddy current losses. However, the addition of alloying elements must be limited, since after a certain percentage, the presence of alloying elements affects hysteresis loss and magnetic polarization.

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

[0007] US Patent Application Publication No. 2021 / 371948 discloses a non-oriented electrical steel sheet having a thickness of 4.5 × 10 -6The non-oriented electrical steel sheet has an average magnetostriction λp-p at 400 Hz and 1.0 T of the following value, and an area ratio of recrystallized crystal grains in a cross section in the rolling direction of the steel sheet of 40 to 95%, and contains, by mass%, C: 0.005% or less, Si: 2.8 to 6.5%, Mn: 0.05 to 2.0%, Al: 3.0% or less, P: 0.20% or less, S: 0.005% or less, N: 0.005% or less, Ti: 0.003% or less, V: 0.005% or less, and Nb: 0.005% or less, and the steel slab satisfies the relationship Si-2Al-Mn≧0. By hot rolling, hot band annealing, and subjecting the steel slab to appropriate cold rolling and finish annealing under appropriate conditions, an average grain size of 10 to 40 microns is obtained, and a motor core is produced from such steel sheet. US Patent Application Publication No. 2021 / 371948 does not demonstrate total elongation and eddy current losses at all.

[0008] U.S. Patent Application Publication No. 2020 / 087748 discloses a non-oriented electrical steel sheet and a manufacturing method thereof that significantly improves magnetic permeability at high frequencies by reducing the width of magnetic domains and increasing the speed of magnetic domain wall movement through the use of non-magnetic precipitates such as carbides, nitrides, sulfides, and oxides contained in the electrical steel sheet to increase magnetic permeability at high frequencies.

[0009] EP 4079893 A1 discloses a non-oriented electrical steel sheet and a manufacturing method thereof. Specifically, the invention relates to a non-oriented electrical steel sheet and a manufacturing method thereof in which As and P are appropriately added to improve the texture and magnetic properties.

[0010] European Patent Application Publication No. 2657357 discloses a non-oriented electrical steel sheet that combines high strength characteristics that can withstand high-speed rotating equipment that is subject to high stress with magnetic characteristics with low iron loss for energy efficiency, and a method for manufacturing the same. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] U.S. Patent Application Publication No. 2021 / 371948 [Patent Document 2] U.S. Patent Application Publication No. 2020 / 087748 [Patent Document 3] European Patent Application Publication No. 4079893 [Patent Document 4] European Patent Application Publication No. 2657357 Summary of the Invention [Problem to be solved by the invention]

[0012] The object of the present invention is to solve these problems by producing a non-oriented electrical steel sheet in which the proportion of eddy current losses in the total iron losses, calculated according to the Bertotti method, is less than 25%, preferably 18% to 23%, and at the same time the magnetic polarization at 5000 A / m (J50) is 1.625 T to 1.690 T, preferably 1.630 T to 1.680 T.

[0013] In preferred embodiments, the following additional properties can also be achieved, either alone or in combination: Ultimate tensile strength of 540 MPa or more in both the transverse and rolling directions, preferably greater than 560 MPa in both the transverse and rolling directions Yield strength of 430 MPa or more in both the transverse and rolling directions, preferably 440 MPa or more in both the transverse and rolling directions Total elongation of 14% or more in both transverse and rolling directions, preferably 16% or more in both transverse and rolling directions A total power dissipation of 11 to 13 W / kg when measured at 1 T and 400 Hz, preferably 11 to 13 W / kg when measured at 1 T and 400 Hz, more preferably 11 to 12 W / kg when measured at 1 T and 400 Hz

[0014] Preferably, such steel has good punchability and coatability and can have good suitability for rolling.

[0015] Preferably the hardness is 185HV or more, preferably 195HV or more.

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

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

[0018] The chemical composition of non-oriented electrical steels includes the following elements in weight percent: The carbon content in the steel of the present invention is between 0.0001% and 0.007%. Carbon is a precipitate-forming element and is therefore detrimental to the magnetic properties of the steel. Therefore, the carbon content in the steel is between 0.0001% and 0.007%. Since carbon promotes magnetic aging, the preferred carbon content according to the present invention is between 0.002% and 0.007%, more preferably between 0.002% and 0.005%.

[0019] The manganese content of the steel of the present invention is 0.15% to 0.25%. Manganese provides solid solution strengthening and reduced core loss by increasing the resistivity. If the manganese content exceeds 0.25%, the magnetic flux density can be significantly reduced and the recrystallization of the steel is inhibited during annealing. The preferred limits for the presence of manganese are 0.16% to 0.24%, more preferably 0.17% to 0.22%.

[0020] The silicon content of the steel of the present invention is 2.9% to 3.4%. Silicon is an element that contributes to increasing strength through solid solution strengthening and is a key element for reducing eddy current core losses by increasing the resistivity of the steel. The above-mentioned effects require a minimum silicon content of at least 2.9%. However, silicon contents in excess of 3.4% make rolling difficult and significantly reduce the magnetic induction of the steel. The preferred limits for the presence of silicon are 3% to 3.3%, more preferably 3.1% to 3.3%.

[0021] The aluminum content is 0.8% to 1.1%. Aluminum increases the electrical resistivity of the material and can effectively reduce the iron loss of the steel. If the aluminum content exceeds 1.1%, the magnetic induction of the steel will be significantly reduced and this will be detrimental to the rollability of the steel in cold rolling. The preferred limit for the presence of aluminum is 0.85% to 1.1%, more preferably 0.9% to 0.98%.

[0022] Although sulfur is not an essential element, it may be contained in the steel as an impurity, and from the viewpoint of the present invention, the sulfur content is preferably as low as possible, but not more than 0.006%, from the viewpoint of production costs. Furthermore, if higher sulfur is present in the steel, the sulfur will combine to form sulfides that are detrimental to the magnetic properties of the present invention.

[0023] The phosphorus content of the steel of the present invention is between 0% and 0.15%, and phosphorus reduces hot and cold ductility due to its tendency to segregate, especially at grain boundaries, or to co-segregate with manganese, and for these reasons its content is limited to 0.15%, preferably less than 0.09%.

[0024] Nitrogen is limited to 0.09% to minimize the precipitation of aluminum nitrides during solidification, which is detrimental to the magnetic properties of the steel.

[0025] Titanium is an optional element, and when added to the steel of the present invention, the content is 0% to 0.1%. Titanium forms titanium nitrides that appear during solidification of the casting. For this reason, the amount of titanium is limited to 0.1% to avoid the formation of titanium nitrides, which 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.

[0026] Niobium is present in the steel of the present invention in an amount of 0% to 0.1% and is suitable for forming carbonitrides to increase the strength of the steel of the present invention by precipitation hardening. Niobium also influences the size of microstructural constituents by precipitating as carbonitrides. However, niobium contents above 0.1% are not economically interesting due to saturation effects.

[0027] Vanadium is present in the steel of the present invention in an amount of 0 to 0.1%, and is effective in increasing the strength of the steel by forming carbides or carbonitrides, with the upper limit being 0.1% from an economical viewpoint.

[0028] Chromium is an optional element for the steel of the present invention, and is present in a range of 0% to 1%. Chromium provides strength to the steel through solid solution strengthening, but using more than 1% impairs the magnetic properties of the steel. In a preferred embodiment, the chromium content is at least 0.01%.

[0029] Molybdenum is an optional element that constitutes between 0% and 0.5% of the steel of the present invention.

[0030] Mo has the effect of coarsening carbides, thereby reducing iron loss. If Mo exceeds 0.5%, the effect of improving iron loss saturates.

[0031] Tungsten is an optional element that constitutes 0% to 0.1% of the steel of the present invention. Like Mo, tungsten has the effect of coarsening carbides and reducing iron loss. However, if the amount added is less than 0.001% by mass, this effect cannot be fully achieved, while if the amount added exceeds 0.1% by mass, the effect of improving iron loss saturates.

[0032] Cobalt is an optional element that constitutes 0% to 1% of the steel of the present invention. Cobalt is an element that increases the magnetic moment of the Fe alloy, thereby increasing the magnetic flux density and reducing iron loss. However, if the amount added is less than 0.01 wt%, the above effects cannot be fully achieved, while if the amount added exceeds 1 wt%, the raw material cost increases significantly.

[0033] Arsenic is an optional element that constitutes 0% to 0.05% of the steel of the present invention. As is a grain boundary segregation element and has the effect of improving texture and thereby reducing iron loss. This effect is obtained by adding 0.001% by weight or more. However, As is an element that causes grain boundary embrittlement, and this adverse effect becomes particularly significant when added in excess of 0.05% by weight. Therefore, As is preferably added in the range of 0.001 to 0.05% by weight.

[0034] Nickel may 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 to improve its strength and elongation. However, if its content exceeds 1%, nickel causes a decrease in ductility. In a preferred embodiment, the nickel content is kept below 0.04%.

[0035] Copper may be added as an optional element in an amount of 0% to 1% to increase the strength and elongation of the steel of the present invention. However, if its content exceeds 1%, copper may deteriorate the surface morphology. In a preferred embodiment, the copper content is at least 0.01%.

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

[0037] Calcium may optionally be present in the steel of the present invention in an amount of 0.001% to 0.01%. Calcium contributes to the refining of the steel by binding harmful sulfur inclusions in a spherical form, thereby retarding the harmful effects of sulfur.

[0038] Other elements such as Sn, Pb or Sb can 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 indicated, these elements allow for grain refinement during solidification. In a preferred embodiment, the Sn content is less than 0.04%.

[0039] The remainder of the steel 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 in a total content of 3.85% to 5.5% by weight. If the total content of Si, Mn, and Al is less than 3.85%, the desired mechanical properties, as well as the desired magnetic properties, cannot be achieved. However, if the total content of Si, Mn, and Al exceeds 5.5%, the steel becomes hardened and rolling becomes difficult. The preferred limits for the presence of Si, Mn, and Al are 3.9% to 5.2%, more preferably 4% to 5%.

[0042] The microstructure of non-oriented electrical steels will now be described in detail, with all percentages being area fractions.

[0043] The microstructure is made up of ferrite. The steel of the present invention has an area fraction of 80% to 100% recrystallized microstructure regions with grains having an average grain size of 20 microns to 110 microns. The recrystallized structure with a high degree of recrystallization is due to homogeneous silicon enrichment, which improves the magnetic properties of the steel of the present invention. The controlled grain size ensures mechanical properties both transverse to and in the rolling direction. The preferred degree of recrystallization is 90% to 100%. The preferred average grain size for the present invention is 20 microns to 100 microns, more preferably 20 microns to 90 microns.

[0044] The steel of the present invention may have an area fraction of non-recrystallized microstructure regions of 0% to 20%, with the preferred degree of non-recrystallization being 0% to 10%, more preferably 0% to 5%.

[0045] In addition to the above microstructure, the microstructure of non-oriented electrical steels does not include microstructural constituents such as martensite, bainite, pearlite and cementite.

[0046] The steel according to the invention can be produced by any suitable method, however, it is preferred to use the method according to the invention detailed below, by way of non-limiting example.

[0047] Such a preferred method consists in providing a semi-finished casting of steel having the chemical composition of the steel according to the invention. The casting can be ingot or continuously in the form of thin slab or thin strip, i.e. thicknesses in the range of less than about 240 mm for any form of casting.

[0048] For example, castings in the form of slabs are cast with the chemical composition according to the present invention and then reheated, with the slab reheating temperature being between 1080°C and 1180°C until the temperature is uniform throughout the slab. Below 1100°C, rolling becomes difficult and the force on the mill becomes too high. Above 1180°C, high silicon grades become very soft and may exhibit some deflection, making them difficult to handle. A preferred slab reheating temperature is between 1090°C and 1170°C, more preferably between 1100°C and 1160°C.

[0049] The reheated slab is subjected to hot rolling at 840°C to 900°C, where the hot rolling finish temperature plays a role in the final hot rolled microstructure. A finish rolling temperature below 840°C limits recrystallization and results in a highly distorted microstructure. A temperature above 900°C means more impurities in solid solution, which can result in precipitation and deterioration of magnetic properties. The preferred hot rolling finish temperature is 850°C to 890°C, more preferably 850°C to 880°C.

[0050] The hot-rolled steel sheet thus obtained is then immediately cooled to the coiling temperature of the hot-rolled steel sheet, which also serves the same purpose for the hot-rolled steel sheet, at a cooling rate of at least 10°C / s, and the cooling is carried out at 540°C to 640°C. Coiling at temperatures below 540°C results in the precipitates of the steel of the present invention not having the appropriate distribution and size. Above 640°C, a thick oxide layer appears, causing difficulties for subsequent processing steps such as cold rolling and / or pickling. Preferably, the cooling rate is 200°C / s or less, more preferably 12°C / s to 75°C / s. 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 an optional hot band anneal.

[0052] The hot-rolled steel sheet may be subjected to an optional descaling step prior to the optional hot band annealing to remove scale formed during hot rolling. The hot-rolled sheet is then subjected to the optional hot band annealing, which is preferably carried out at a temperature of 900°C to 1000°C for at least 10 seconds and up to 96 hours, with the temperature preferably being maintained at 910°C to 990°C, more preferably 940°C to 980°C. The optional descaling step of the hot-rolled steel sheet may then be carried out, for example, by pickling the sheet. The preferred time for the hot band annealing is 10 seconds to 500 seconds, more preferably 20 seconds to 120 seconds.

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

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

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

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

[0057] The cold rolled steel sheet is maintained at Tsoak for 10 seconds to 5000 seconds to ensure 80% to 100% recrystallization.

[0058] The cold-rolled steel sheet is then cooled, starting from Tsoak, at a cooling rate CR1 of 1°C / s to 150°C / s to a temperature T1 in the range of 20°C to 300°C. 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, more preferably 0.16 mm to 0.21 mm, and even more preferably 0.18 mm to 0.21 mm.

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

[0061] The non-oriented electrical steel sheets of the present invention may be optionally coated with an insulating, organic or inorganic coating, or a combination thereof, to improve dielectric isolation. [Example]

[0062] The following tests, examples, figurative illustrations and tables presented herein are non-limiting in nature and should be considered for illustrative purposes only, illustrating advantageous features of the present invention.

[0063] Steel sheets made from steels with different compositions are summarized in Table 1, and the steel sheets are manufactured according to the process parameters specified in Table 2. Subsequently, Table 3 summarizes the results of the evaluation of the obtained properties.

[0064] All steels in Table 1 had a nitrogen content of less than 0.09%.

[0065] Table 2 summarizes the hot rolling and annealing process parameters performed on the cold rolled steel sheets to impart the necessary mechanical and magnetic properties to the steels of Table 1 to become non-oriented electrical steels. All inventive steels I1 to I4 are cooled at a cooling rate of 15°C / s after hot rolling. Furthermore, in the inventive examples, the heating rate HR1 to the annealing soak temperature is 5°C / s. The T1 temperature for all inventive examples is 25°C, while the cooling rate CR1 is 5°C / s.

[0066] All steels produced according to the parameters in Table 2 exhibited microstructures with greater than 95% recrystallization and grain sizes between 20 and 110 μm.

[0067] Table 1:

[0068] [Table 1]

[0069] Table 2:

[0070] [Table 2]

[0071] Table 3 The results of various mechanical tests performed in accordance with the standards are summarized. Ultimate tensile strength, total elongation, and yield strength were measured in accordance with the NF EN ISO 6892-1 standard, and J50 magnetic properties and total core loss at 1 T and 400 Hz were measured in accordance with the IEC 60404-2 standard. Eddy current loss is calculated according to the Bertotti method published in the paper "General Properties of Power Losses in Soft Ferromagnetic Materials" by Giorgio Berttoti, published in IEEE TRANSACTIONS ON MAGNETICS, Vol. 24, No. 1, January 1988. Equation 2 is the eddy current loss (P), which is referred to in the present invention as class ) to identify the classical loss.

[0072] The average grain size of the recrystallized microstructure is measured by the linear intercept method according to the ASTM E112 96(02) standard.

[0073] [Table 3]

Claims

1. 1. A non-oriented electrical steel sheet having a composition, expressed in weight percent, comprising the following elements: 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% (However, 3.85%≦Si+Al+Mn≦5.5%) and may contain 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% The remainder of the composition is composed of iron and unavoidable impurities resulting from processing, the microstructure of the steel sheet is made of ferrite, and includes, by area fraction, 80% to 100% of a recrystallized microstructure and 0% to 20% of a non-recrystallized microstructure, the average grain size of the recrystallized microstructure being 20 microns to 110 microns, and the proportion of eddy current loss in the total iron loss measured at 1 T and 400 Hz in accordance with the IEC 60404-2 standard is less than 25% when calculated according to the Bertotti method, while the magnetic polarization at 5000 A / m (J50) is 1.625 T to 1.690 T.

2. 2. The non-oriented electrical steel sheet according to claim 1, wherein the composition comprises 3.1% to 3.3% silicon.

3. 3. The non-oriented electrical steel sheet according to claim 1, wherein the composition contains 0.002% to 0.007% carbon.

4. The non-oriented electrical steel sheet according to any one of claims 1 to 3, wherein the composition comprises 0.85% to 1.1% aluminum.

5. The non-oriented electrical steel sheet according to any one of claims 1 to 4, wherein the composition comprises 0.16% to 0.24% 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 non-oriented electrical steel sheet according to any one of claims 1 to 6, wherein the amount of recrystallized microstructure is 90% to 100%.

8. 8. The non-oriented electrical steel sheet according to claim 1, wherein the steel sheet has a tensile strength of at least 540 MPa in both the transverse and rolling directions.

9. The non-oriented electrical steel sheet according to any one of claims 1 to 8, having a yield strength of 430 MPa or more in both the transverse direction and the rolling direction.

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

11. The following successive steps: 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; A step of rolling the semi-finished product at a hot rolling finishing temperature of 840°C to 900°C to obtain a hot-rolled steel plate; - A process of cooling the hot-rolled sheet immediately after finishing the hot rolling. Then, cooling the hot-rolled steel sheet from the finish of hot rolling to a coiling temperature range of 540°C to 640°C at a cooling rate of at least 10°C / s. - Then, the hot-rolled steel sheet is coiled at a coiling temperature range of 540°C to 640°C. Optionally, performing a descaling treatment on the hot rolled steel sheet; Optionally, performing a hot band anneal on the hot rolled steel sheet at 650°C to 1100°C for a time period of 10 seconds to 96 hours; Optionally, performing a descaling treatment on the hot rolled steel sheet; - A step of cold rolling the hot-rolled steel sheet at a reduction ratio of 50% to 95% to obtain a cold-rolled steel sheet; subsequent annealing of the cold-rolled steel sheet, starting from room temperature, to an annealing temperature range Tsoak, between 900°C and 1000°C, at a heating rate HR1 of at least 1°C / s; then carrying out annealing at the annealing temperature for a period of 10 to 5000 seconds; then cooling the cold-rolled steel sheet starting from the annealing temperature to a temperature T1 between 300°C and 20°C at a cooling rate CR1 between 1°C / s and 150°C / s; - Next, a step of cooling to room temperature to obtain a non-oriented electrical steel sheet The method for producing a non-oriented electrical steel sheet according to any one of claims 1 to 10, comprising:

12. 12. The method of claim 11, wherein the Tsoak temperature for annealing is between 900°C and 980°C.

13. 13. The method according to claim 11, wherein the temperature T1 is between 200°C and 20°C.

14. The method according to any one of claims 11 to 13, wherein the cooling rate CR1 is from 3°C / s to 120°C / s.

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