Non-grain-oriented electrical steel

Abstract

Non-grain-oriented electrical steel sheet, having a thickness of 0.23 mm to 0.26 mm and having a composition comprising the following elements, expressed as weight percent: 0.0001% ≤ Carbon ≤ 0.007% 0.15% ≤ Manganese ≤ 0.25% 2.9% ≤ Silicon ≤ 3.4% 0.7% ≤ Aluminum ≤ 1.3% 0.05% ≤ Nickel ≤ 1% Phosphorus ≤ 0.15% Sulfur ≤ 0.006% Nitrogen ≤ 0.09% 0.01% 5 Chromium ≤ 1% 0.01% ≤ Copper ≤ 1% 0.1% ≤ Tin ≤ 0.2% with 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% ≤ Molybdenum ≤ 0.5% 0% ≤ Tungsten ≤ 0.1% 0% ≤ Cobalt ≤ 1% 0% ≤ Arsenic ≤ 0.05% 0.001% ≤ Calcium ≤ 0.01% 0% ≤ Boron ≤ 0.05% 0% ≤ Lead ≤ 0.2% 0% ≤ Antimony ≤ 0.2% wherein the remaining composition consists of iron and unavoidable impurities caused by processing, wherein the microstructure of the steel sheet consists of ferrite, comprising 80% to 100% recrystallized microstructure and 0% to 20% non-recrystallized microstructure by area, wherein the average microscale of the recrystallized microstructure is 20 to 110 micrometers, and exhibiting a percentage of eddy current losses of the total iron losses, measured at 1 T and 400 Hz according to standards IEC 60404-2, of less than 35%, calculated according to the Bertotti method.

Description

[0001] The present invention relates to a non-grain-oriented electrical steel sheet. In particular, the present invention relates to a non-grain-oriented electrical steel sheet that exhibits low iron losses, especially low eddy current losses, while simultaneously possessing good mechanical properties.

[0002] Therefore, intensive research and development efforts are being undertaken to equip non-grain-oriented electrical steel sheets, used as the iron core material for electric motors, with higher performance characteristics, as ever greater energy savings in electrical devices are required worldwide. In particular, there has been a high demand recently for compact, high-performance motors that can be used to drive electric vehicles or similar applications. Such an electric motor for vehicles has been designed to enable high rotational speeds and thereby achieve high torque with the lowest possible losses. This requires lightweight and highly efficient non-grain-oriented electrical steels, whose most important property is low losses.The correct balance between losses, permeability, polarization, thermal conductivity, tensile strength and yield strength is crucial for non-grain-oriented electrical steels.

[0003] The lower the iron losses in an electric machine, the higher its efficiency. Manufacturers have several options for reducing iron losses in an electric machine. The most important options are reducing hysteresis losses or eddy current losses to improve the efficiency of their electric machine. Progress is often achieved by combining the two approaches. The present invention relates to the second option, namely the reduction of eddy current losses in an electric machine. There are two approaches to reducing eddy current losses: The first approach is to reduce the thickness of the steel sheets used in the electric motors to less than 0.35 mm or even less. Unfortunately, this solution reaches its limits because it reduces the stacking factor, which in turn lowers the torque achievable for a given motor height, unacceptably reduces the stiffness of certain vehicle components, and causes acoustic problems that create unpleasant conditions for passengers.

[0004] The second approach involves optimizing the elemental composition of the steel sheet, for example, by increasing the proportion of alloying elements to limit eddy current losses. Among these alloying elements, aluminum and manganese, for instance, exhibit attractive mechanical and magnetic properties while simultaneously enabling a significant reduction in eddy current losses. However, adding alloying elements is only possible up to a certain limit, as alloying elements above a certain proportion negatively impact hysteresis losses and magnetic polarization.

[0005] Previous research and development in the field of high-strength non-grain-oriented electrical steel has led to several methods for producing high-strength non-grain-oriented electrical steel, some of which are listed here for the final evaluation of the present invention: US2021 / 371948 is a non-grain-oriented electrical steel sheet with an average magnetostriction λp - p at 400 Hz, 1.0 T of not more than 4.5×10 -6 , a surface area fraction of recrystallized grains in a section in the rolling direction of the steel sheet of 40 to 95% and an average grain size of 10 to 40 micrometers, obtained by subjecting a steel slab containing, in wt% C: not more than 0.005%, 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 fulfilling the conditions Si - 2A1 - Mn≥0, to hot rolling, hot strip annealing, cold rolling and finish annealing under suitable cold rolling and finish annealing conditions, wherein a motor core is produced from such a steel sheet US2021 / 371948 does not show the total strain loss or the eddy current loss.

[0006] The purpose of the present invention is to solve these problems by producing non-grain-oriented electrical steel sheets which have a percentage of eddy current losses of less than 35% and preferably less than 30% and more preferably 25% to 30% of the total iron loss when calculated according to the Bertotti method.

[0007] In preferred embodiments, the following additional properties can also be achieved, alone or in combination: a tensile strength of at least 530 MPa in both the transverse and rolling directions, and preferably of more than 550 MPa in both the transverse and rolling directions. - a yield strength of 400 MPa or more in both the transverse and rolling directions, and preferably of 425 MPa or more in both the transverse and rolling directions - a total elongation of 13% or more in both the transverse and rolling directions, and preferably of more than or equal to 15% in both the transverse and rolling directions - a magnetic polarization at 5000 A / m (J50) from 1.61 T to 1.64 T and preferably a magnetic polarization at 5000 A / m (J50) from 1.62 T to 1.64 T, and more preferably a magnetic polarization at 5000 A / m (J50) from 1.625 T to 1.63 T. - a total loss of 11 to 14 W / kg, measured at 1 T and 400 Hz, and preferably of 12 to 13 W / kg, measured at 1 T and 400 Hz.

[0008] Preferably, such a steel can also exhibit good rollability with good stampability and coating properties.

[0009] Preferably with a hardness greater than or equal to 185 HV and preferably with a hardness greater than or equal to 195 HV.

[0010] The aforementioned objective and further advantages of the present invention will be explained in more detail by reference to a detailed description of the preferred embodiment of the present invention.

[0011] The chemical composition of non-grain-oriented electrical steel includes the following elements in weight percent: The carbon content in the steel of the present invention is 0.0001% to 0.007%. Carbon is a precipitation-forming element, which is why it has a detrimental effect on the magnetic properties of the steel. Therefore, the carbon content in the steel is 0.0001% to 0.007%. Since carbon promotes magnetic aging, the preferred carbon content according to the present invention is 0.002% to 0.007%, more preferably 0.003% to 0.006%.

[0012] The manganese content of the steel of the present invention is 0.15% to 0.25%. Manganese promotes solid solution strengthening and reduces iron loss by increasing the resistivity. If the proportion of added manganese exceeds 0.25%, the magnetic flux density can be significantly reduced, and the recrystallization of the steel during annealing is hindered. Preferably, the steel contains a manganese content of 0.16% to 0.24%, and more preferably, 0.18% to 0.20%.

[0013] The silicon content of the steel of the present invention is 2.9% to 3.4%. Silicon is an element that contributes to increased strength through solid solution strengthening and is a key element in reducing eddy current losses from iron by increasing the resistivity of the steel. These effects require a silicon content of at least 2.9%. However, at a silicon content of more than 3.4%, rolling becomes difficult and the magnetic induction of the steel is significantly reduced. Preferably, the steel contains a silicon content of 3% to 3.3%, and more preferably, 3.1% to 3.25%.

[0014] The aluminum content is 0.7% to 1.3%. Aluminum increases the electrical resistance of the material and can effectively reduce iron loss in steel. If the aluminum content exceeds 1.3%, the magnetic induction of the steel is significantly reduced, which also adversely affects the cold rollability of the steel according to the present invention. Preferably, the steel contains an aluminum content of 0.8% to 1.1%, and more preferably, 0.9% to 1%.

[0015] Nickel is an essential element and is present in an amount of 0.05% to 1% to increase the strength of the steel of the present invention and to improve its strength and ductility. However, at a content of more than 1%, nickel causes a deterioration of ductility. The preferred limit for the presence of nickel is 0.05% to 0.9% and more preferably 0.1% to 0.5%.

[0016] Sulfur is not an essential element, but it can be present as an impurity in steel. From the perspective of the present invention, the sulfur content should be as low as possible, and for reasons of production costs, should not exceed 0.006%. If a higher proportion of sulfur is present in the steel, it combines to form sulfides, which adversely affect the magnetic properties of the present invention.

[0017] The phosphorus content of the steel of the present invention is 0% to 0.15%. Phosphorus reduces hot and cold formability, particularly due to its tendency to segregate at the grain boundaries or to co-segregate with manganese. For these reasons, its content is limited to 0.15% and is preferably below 0.09%.

[0018] The nitrogen content is limited to 0.09% to minimize the precipitation of aluminium nitrides during solidification, which would adversely affect the magnetic properties of the steel.

[0019] Titanium is an optional element, and its content when added to the steel of the present invention is 0% to 0.1%. It forms titanium nitrides, which occur during the solidification of the casting. The titanium content is limited to 0.1% to avoid the formation of titanium nitrides, which would impair the magnetic properties of the steel of the present invention. A titanium content of less than 0.001% has no effect on the steel of the present invention.

[0020] Niobium is present in the steel of the present invention in an amount of 0% to 0.1% and is suitable for the formation of carbonitrides in order to increase the strength of the steel of the present invention by precipitation hardening. Niobium also influences the size of the microstructural components through the formation of carbonitrides. However, a niobium content above 0.1% is not economically viable due to the saturation effect.

[0021] Vanadium is present in the steel of the present invention in an amount of 0% to 0.1% and is effective in improving the strength of the steel by forming carbides or carbonitrides, the upper limit being 0.1% for economic reasons.

[0022] Chromium is an optional element for the steel of the present invention, and the chromium content is 0% to 1%. Chromium imparts strength to the steel through solid solution strengthening, but at a content above 1%, it impairs the magnetic properties of the steel. In a preferred embodiment, the chromium content is at least 0.01%.

[0023] Molybdenum is an optional element that constitutes 0% to 0.5% of the steel of the present invention.

[0024] Mo causes a coarsening of the carbides and thus reduces iron loss. At a value above 0.5%, the effect of improving iron loss is saturated.

[0025] Tungsten is an optional element comprising 0 to 0.1% of the steel of the present invention. Tungsten coarsens the carbides and reduces iron loss, similar to molybdenum. However, with an added amount of less than 0.001% by weight, the effect described above cannot be sufficiently achieved, while with an added amount of more than 0.1% by weight, the effect of improving iron loss is saturated.

[0026] Cobalt is an optional element comprising 0 to 1% of the steel of the present invention. Cobalt is an element that increases the magnetic moment of iron alloys, resulting in an increase in magnetic flux density and a reduction in iron loss. However, if the added amount is less than 0.01% by weight, the aforementioned effects cannot be sufficiently achieved, while if the added amount exceeds 1%, the raw material costs increase considerably.

[0027] Arsenic is an optional element comprising 0% to 0.05% of the steel of the present invention. As is a grain boundary segregation element and improves the texture, thus reducing iron loss. The effect described above is achieved by adding at least 0.001% by weight. However, since arsenic is an element that causes grain boundary embrittlement, and this adverse effect becomes particularly pronounced when added in amounts greater than 0.05%, As should preferably be added in the range of 0.001% to 0.05%.

[0028] Copper can be added as an optional element in an amount of 0% to 1% to increase the strength and ductility of the steel of the present invention. However, if its content exceeds 1%, it can impair the surface quality. In a preferred embodiment, the copper content is at least 0.01%.

[0029] Boron is an optional element for the steel of the present invention and may be present in an amount of 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%.

[0030] Calcium can optionally be included in the steel of the present invention in amounts from 0.001% to 0.01%. Calcium contributes to the refinement of the steel by binding the harmful sulfur content in globular form and thus delaying the harmful effects of sulfur.

[0031] Other elements such as Sn, Pb, or Sb can be added individually or in combination with the following levels: Sn ≤ 0.2%, Pb ≤ 0.2%, and Sb ≤ 0.2%. Up to the specified maximum levels, these elements enable grain refinement during solidification. In a preferred embodiment, the Sn content is below 0.04%. In another preferred embodiment, the Sn content is preferably above 0.01%, and even better, 0.01% to 0.04%.

[0032] The rest of the steel's composition consists of iron and unavoidable impurities that arise during processing. 3.85%≤Si+Al+Mn≤5.5%

[0033] The non-grain-oriented electrical steel sheet according to the invention necessarily contains silicon, manganese, and aluminum, such that the total content is 3.85% to 5.5% by weight. If the total content of Si, Mn, and Al is less than 3.85%, the desired mechanical and magnetic properties cannot be achieved. However, if the total content of Si, Mn, and Al exceeds 5.5%, the steel becomes hard and difficult to roll. The preferred limit for the content of Si, Mn, and Al is 3.9% to 5.2%, and more preferably 4% to 5%.

[0034] The microstructure of the non-grain-oriented electrical steel is now described in detail, with all percentages given in area fractions.

[0035] The microstructure consists of ferrite. The steel of the present invention has a recrystallized microstructure with a surface area of ​​80% to 100% and grains with an average grain size of 20 to 110 micrometers. The recrystallized structure with a high degree of recrystallization is due to the homogeneous silicon enrichment, which improves the magnetic properties of the steel of the present invention. A controlled grain size ensures the mechanical properties in both the transverse and rolling directions. The preferred degree of recrystallization is 90% to 100%. The preferred average grain size for the present invention is 20 to 100 micrometers, and more preferably 20 to 90 micrometers.

[0036] The steel of the present invention can have a non-recrystallized microstructure area with a surface area fraction of 0% to 20%, wherein the preferred degree of non-recrystallization is 0% to 10% and more preferably 0% to 5%.

[0037] In addition to the aforementioned microstructure, the microstructure of non-grain-oriented electrical steel is free of microstructural components such as martensite, bainite, pearlite and cementite.

[0038] The steel according to the invention can be produced by any suitable method. However, the use of the method according to the invention, which is explained in more detail as a non-limiting example, is preferred.

[0039] This preferred method consists of providing a semi-finished steel casting with a steel chemical composition according to the invention. The casting can be carried out either in the form of ingots or continuously in the form of thin slabs or thin strips, i.e., with a thickness of about 240 mm or less for each mold.

[0040] For example, the casting is produced in the form of a slab with the chemical composition of the invention and then reheated, with the slab reheating temperature being between 1100 °C and 1250 °C until the temperature is homogeneous throughout the slab. Below 1100 °C, rolling becomes difficult and the forces on the rolling mill become too high. Above 1250 °C, the high-silicon grades become very soft and can exhibit some deflection, making them difficult to handle. The preferred slab reheating temperature is between 1080 °C and 1200 °C, and more preferably between 1120 °C and 1190 °C.

[0041] The reheated slab is subjected to a hot rolling process, where the finish rolling temperature (FRT) plays a role in the final hot-rolled microstructure and is between 840 °C and 920 °C. If the finish rolling temperature is below 840 °C, recrystallization is limited and the microstructure is severely deformed. Temperatures above 920 °C would lead to increased impurities in the solid solution and potentially result in precipitates and a deterioration of the magnetic properties. Preferably, the finish rolling temperature is between 840 °C and 900 °C, and more preferably between 850 °C and 880 °C.

[0042] The resulting hot-rolled steel sheet is then immediately cooled at a rate of at least 10 °C / s to the winding temperature of the hot-rolled steel sheet, which also plays a role in the hot rolling of the steel sheet; this temperature is 550 °C to 650 °C. At temperatures below 550 °C, a suitable distribution and size of precipitates for the steel of the present invention is not achieved during winding. Above 650 °C, a thick oxide layer would form, which causes difficulties in subsequent processing steps, such as cold rolling and / or pickling. Preferably, the cooling rate is less than or equal to 200 °C / s, and more preferably, the cooling rate is 12 °C / s to 75 °C / s. Preferably, the winding temperature is 550 °C to 600 °C, and more preferably, 560 °C to 590 °C.

[0043] The wound hot-rolled steel sheet is then cooled to room temperature before optionally undergoing hot strip annealing.

[0044] The hot-rolled steel sheet can optionally undergo a scale removal step to remove the scale formed during hot rolling before optional hot strip annealing. The hot-rolled sheet is then subjected to optional hot strip annealing at temperatures of 900 °C to 1080 °C, preferably for at least 10 seconds and not more than 96 hours, with the temperature preferably remaining between 900 °C and 1050 °C and more preferably between 925 °C and 1010 °C. An optional step to remove scale from this hot-rolled steel sheet can then be carried out, for example, by pickling the sheet.

[0045] The hot-rolled steel sheet thus obtained can optionally have a thickness of 0.8 mm to 3.5 mm, preferably of 0.9 mm to 3 mm and even more preferably of 1 mm to 2.8 mm.

[0046] This hot-rolled steel sheet is subsequently cold-rolled to obtain a cold-rolled steel sheet with a thickness reduction of 50 to 95%. Preferably, the thickness reduction is 60% to 95%, and more preferably 75% to 95%.

[0047] The cold-rolled steel sheet is then subjected to a heat treatment which gives the steel of the present invention the required mechanical properties and microstructure.

[0048] The cold-rolled steel sheet is then heated, starting at room temperature and being heated to an annealing temperature (Tsoak) of 900 °C to 1050 °C, preferably 910 °C to 1020 °C and more preferably 925 °C to 985 °C, at a heating rate HR1 of at least 1 °C / s. In a preferred embodiment, the heating rate HR1 is at least 2 °C / s and more preferably at least 5 °C / s.

[0049] The cold-rolled steel sheet is held at a temperature of Tsoak for 10 to 5000 seconds to ensure recrystallization of 80 to 100%.

[0050] The cold-rolled steel sheet is then cooled, with the cooling process starting at Tsoak and the cold-rolled steel sheet being cooled 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 temperature T1 is 20 °C to 200 °C.

[0051] The resulting cold-rolled steel sheet preferably has a thickness of 0.23 mm to 0.26 mm, more preferably of 0.23 mm to 0.25 mm, and even more preferably of 0.24 mm to 0.25 mm.

[0052] The cold-rolled steel sheet is then cooled to room temperature to obtain a non-grain-oriented electrical steel sheet.

[0053] The non-grain-oriented electrical steel sheet of the present invention can optionally be coated with insulation, an organic coating or an inorganic coating or a combination thereof to improve the insulation. EXAMPLES

[0054] The following tests, examples, illustrations and tables presented herein are not limiting and serve only to illustrate the advantageous features of the present invention.

[0055] Steel sheets made from steels with different compositions are summarized in Table 1, with each sheet being produced according to the process parameters specified in Table 2. The results of the evaluations of the obtained properties are then listed in Table 3.

[0056] All steels in Table 1 had a nitrogen content of less than 0.09%.

[0057] Table 2 lists the process parameters for hot rolling and annealing applied to cold-rolled steel sheets to impart the required mechanical and magnetic properties to the steels from Table 1, transforming them into non-grain-oriented electrical steel. All steels according to the invention, I1 to I6, are cooled after hot rolling at a cooling rate of 15 °C / s. Furthermore, in the examples according to the invention, the heating rate HR1 to the annealing temperature is 5 °C / s. The temperature T1 is 25 °C in all examples according to the invention, while the cooling rate CR1 is 5 °C / s.

[0058] All steels produced according to the parameters in Table 2 exhibited a microstructure with more than 95% recrystallization and a grain size of 20 to 110 µm. Table 1: Steel C Mn Si Al Ni Cr Cu P S Sn I1 0,0034 0,1987 3,1494 0,9491 0,124 0,0236 0,016 0,0119 0,0013 0,0124 I2 0,0034 0,1987 3,1494 0,9491 0,124 0,0236 0,016 0,0119 0,0013 0,0124 I3 0,0034 0,1987 3,1494 0,9491 0,124 0,0236 0,016 0,0119 0,0013 0,0124 I4 0,0034 0,1987 3,1494 0,9491 0,124 0,0236 0,016 0,0119 0,0013 0,0124 I5 0,0034 0,1987 3,1494 0,9491 0,124 0,0236 0,016 0,0119 0,0013 0,0124 I6 0,0034 0,1987 3,1494 0,9491 0,124 0,0236 0,016 0,0119 0,0013 0,0124 Table 2: Try Reheating (°C) FRT(°C) Wrapping (°C) Hot strip annealing (°C) Hot strip annealing time (sec.) Thickness reduction (%) Tsoak (°C) Glow time (seconds) Thickness, cold-rolled (mm) I1 1126 850 570 1000 20 88 970 40 0,242 I2 1126 850 570 1000 20 88 970 40 0,242 I3 1131 852 567 930 20 88 960 40 0,243 I4 1131 852 567 930 20 88 980 40 0,244 I5 1130 854 567 930 20 88 950 40 0,245 I6 1130 854 567 930 20 88 940 40 0,246 Table 3

[0059] The results of the various mechanical tests, performed according to the standards, are compiled. Tensile strength, total elongation, and yield strength are measured according to standard NF EN ISO 6892-1, and the magnetic properties J50 and total power loss at 1 T and 400 Hz are measured according to standard IEC 60404-2. Eddy current losses are calculated using the Bertotti method, published in the article "General Properties of Power Losses in Soft Ferromagnetic Materials" by Giorgio Bertotti in IEEE TRANSACTIONS ON MAGNETICS, Vol. 24, No. 1, January 1988. Equation 2 is used to determine the classical losses, which are calculated using (P Klasse ) which are referred to as eddy current losses for the purposes of this invention.

[0060] The average grain size of the recrystallized microstructure is measured according to the standard ASTM E112 96(02) using the linear intercept method. Try Tensile strength (MPa) Yield strength (MPa) Total elongation (%) J50(T) P1T / 400 Hz(W / kg) % of eddy current losses WR QR WR QR WR QR I1 556 581 432 455 17,3 21,1 1,627 12,540 27,5 I2 566 586 444 459 23,2 23,2 1,626 12,710 27,1 I3 561 573 433 445 17 20 1,630 12,650 27,5 I4 553 588 427 457 12,6 20,1 1,626 12,420 28,2 I5 554 576 426 446 19,5 16,8 1,629 12,650 27,9 I6 561 582 431 452 15,8 18,6 1,627 12,760 27,9 QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] US 2021 / 371948

[0005] Cited non-patent literature

[0000] “General Properties of Power Losses in Soft Ferromagnetic Materials” by Giorgio Berttoti in IEEE TRANSACTIONS ON MAGNETICS, Vol. 24, No.1, January 1988

[0059]

Claims

[1] Non-grain-oriented electrical steel sheet having a thickness of 0.23 mm to 0.26 mm and having a composition comprising the following elements, expressed as weight percent: 0.0001% ≤ Carbon ≤ 0.007% 0.15% ≤ Manganese ≤ 0.25% 2.9% ≤ Silicon ≤ 3.4% 0.7% ≤ Aluminum ≤ 1.3% 0.05% ≤ Nickel ≤ 1% Phosphorus ≤ 0.15% Sulfur ≤ 0.006% Nitrogen ≤ 0.09% 0.01% 5 Chromium ≤ 1% 0.01% ≤ Copper ≤ 1% 0.1% ≤ Tin ≤ 0.2% with 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% ≤ Molybdenum ≤ 0.5% 0% ≤ Tungsten ≤ 0.1% 0% ≤ Cobalt ≤ 1% 0% ≤ Arsenic ≤ 0.05% 0.001% ≤ Calcium ≤ 0.01% 0% ≤ Boron ≤ 0.05% 0% ≤ Lead ≤ 0.2% 0% ≤ Antimony ≤ 0.2% wherein the remaining composition consists of iron and unavoidable impurities caused by processing, wherein the microstructure of the steel sheet consists of ferrite, comprising 80% to 100% recrystallized microstructure and 0% to 20% non-recrystallized microstructure by area, wherein the average microscale of the recrystallized microstructure is 20 to 110 micrometers, and exhibiting a percentage of eddy current losses of the total iron losses, measured at 1 T and 400 Hz according to standards IEC 60404-2, of less than 35%, calculated according to the Bertotti method. [2] Non-grain-oriented electrical steel sheet according to claim 1, wherein the composition includes 3% to 3.3% silicon. [3] Non-grain-oriented electrical steel sheet according to one of claims 1 or 2, wherein the composition includes 0.002% to 0.007% carbon. [4] Non-grain-oriented electrical steel sheet according to any one of claims 1 to 3, wherein the composition includes 0.8% to 1.1% aluminium. [5] Non-grain-oriented electrical steel sheet according to any one of claims 1 to 4, wherein the composition includes 0.16% to 0.24% manganese. [6] Non-grain-oriented electrical steel sheet according to any one of claims 1 to 5, wherein the proportion of non-recrystallized structure is 0% to 10%. [7] Non-grain-oriented electrical steel sheet according to any one of claims 1 to 6, wherein the proportion of recrystallized structure is 90% to 100%. [8] Non-grain-oriented electrical steel sheet according to any one of claims 1 to 7, wherein the steel sheet has a tensile strength of at least 530 MPa in both the transverse and rolling directions. [9] Double cold-rolled non-grain-oriented electrical steel sheet according to any one of claims 1 to 8, having a yield strength of 400 MPa or more in both the transverse and rolling directions. [10] Non-grain-oriented electrical steel sheet according to any one of claims 1 to 9, wherein the steel sheet has a total elongation of at least 13% in both the transverse and rolling directions.