WO2025056945A1

WO2025056945A1 - A method of manufacturing non-oriented electrical steel

Info

Publication number: WO2025056945A1
Application number: PCT/IB2023/059058
Authority: WO
Inventors: Sébastien CHAMPEMAUD; Elvan EKIZ; Martin LIEBEHERR; Athina PUYPE; Wahib SAIKALY; Lucas SCHIAVONE
Original assignee: ArcelorMittal SA
Current assignee: ArcelorMittal SA
Priority date: 2023-09-13
Filing date: 2023-09-13
Publication date: 2025-03-20
Anticipated expiration: 2026-03-13
Also published as: WO2025057039A1

Abstract

The patent relates to a method of production of a non-oriented electrical steel sheet comprising a step of warm rolling, wherein said warm rolling comprises five to eight rolling passes, wherein - the first rolling pass is performed with an entry temperature of the steel sheet from 70 to 120°C, - the second rolling pass is performed with an entry temperature of the steel sheet from 90 to 175°C and greater than the entry temperature of the first rolling pass, - the remaining rolling passes are performed with an entry temperature of the steel sheet from 190 to 250°C.

Description

A METHOD OF MANUFACTURING NON-ORIENTED ELECTRICAL STEEL The present invention relates to a manufacturing method of a non-oriented electrical steel. Specifically, the present invention relates to a method permitting to manufacture a fully recrystallized ferritic non-oriented electrical steel achieving good magnetic properties, particularly in terms of polarization. American Patent Application US20150213928 A1 discloses a process to manufacture a high-strength electrical steel sheet with excellent magnetic properties, such as a low iron loss. The steel composition comprises, in weight percent, a high content of silicon, from 3.5 to 4.5, a C content of 0.005 % or less, a Mn content from 0.01 % to 0.10 %, an Al content of 0.005 % or less, a Ca content from 0.0010 % to 0.0050 %, a S content 0.0030 % or less, and a N content of 0.0030 % or less, the balance being Fe and incidental impurities. The sheet thickness being 0.40 mm or less and a non-recrystallized deformed microstructure being from 10% to 70%. The manufacturing process comprises a hot band annealing between 900°C and 1000°C and a warm rolling at several hundred °C, so as to reduce sheet breakage. The inventors use a non-recrystallized and recovered microstructure as means for strengthening a steel sheet without using precipitates of carbonitrides or the like. In this patent application, the components other than Si are reduced insofar as possible to decrease the variation of the resulting microstructure and of the tensile strength. However, the method disclosed in this patent is not able to exhibit the influence of the second rolling, e.g. a warm rolling, on the magnetic properties. The goal of the present invention is to improve the polarization of the non-oriented electrical steel via improving the texture which can be obtained by means of the claimed rolling process. The patent relates to a method of production of a non-oriented electrical steel sheet comprising the following steps providing a steel composition comprising the following elements, expressed in percentage by weight: 0.0001% ≤ Carbon ≤ 0.008 % 0.1% ≤ Manganese ≤ 2.0% 2.8% ≤ Silicon ≤ 6.5% 0.1% ≤ Aluminum ≤ 1.2 % 0 % ≤ Phosphorus ≤ 0.15 % 0 % ≤ Sulfur ≤ 0.006 % 0 % ≤ Nitrogen ≤ 0.09% with 3.5% ≤ Si+Al+Mn ≤ 9.5% and can 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% ≤ 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 composition being composed of iron and unavoidable impurities caused by processing, - reheating said semi-finished product to a temperature from 1050°C to 1250°C, - hot rolling the said semi-finished product wherein the hot rolling finishing temperature shall be from 750°C to 950°C to obtain a hot rolled steel sheet, - cooling the hot rolled sheet after the finishing of hot rolling, to a coiling temperature range which is from 450°C to 750°C at a cooling rate of at least 10°C/s - thereafter coiling the hot rolled steel sheet in the coiling temperature range from 450°C to 750°C, - optionally performing scale removal process on said hot rolled steel sheet, - hot band annealing is optionally performed on hot rolled steel sheet from 650°C to 1100°C during 10 seconds to 96 hours, - optionally performing scale removal process on said hot rolled steel sheet, - warm rolling said hot rolled steel sheet, wherein said warm rolling comprises five to eight rolling passes, wherein - the first rolling pass is performed with an entry temperature of the steel sheet from 70 to 120°C, - the second rolling pass is performed with an entry temperature of the steel sheet from 90 to 175°C and greater than the entry temperature of the first rolling pass, - the remaining rolling passes are performed with an entry temperature of the steel sheet from 190 to 250°C and - thereafter annealing said warm rolled steel sheet wherein the heating for annealing starts from room temperature to an annealing temperature range T_SOAK which is from 800°C to 1100°C, with a heating rate HR1 of at least 1°C/s, - then perform annealing at annealing temperature during 10 to 5000 seconds, so as to ensure a recrystallisation of 100%, - then cooling the warm rolled steel sheet which starts from the annealing temperature to a temperature T1 from 300°C to 20°C, with a cooling rate CR1 from 1°C/s to 150°C/s - then cooling to room temperature to obtain a non-oriented electrical steel sheet. Chemical composition The of the non-oriented electrical steel comprises the following elements: Carbon content in the steel of present invention is from 0.0001 to 0.008 weight percent. Carbon is a precipitate forming element that is detrimental for the magnetic properties of the present steel. Since the Carbon promotes magnetic aging, the preferred content of Carbon according to the present invention is from 0.0001 to 0.006 weight percent and more preferably from 0.0001 to 0.005 weight percent. Manganese content in the steel of present invention is from 0.1 to 2 weight percent. Manganese provides solid solution strengthening and reduces the iron loss by increasing specific resistance. Preferably, the manganese content in the steel of present invention is from 0.1 to 1.2 weight percent. Even more preferably, the manganese content in the steel of present invention is from 0.1 to 0.5 weight percent. Alternatively, the manganese content in the steel of present invention is from 0.5 to 2.0 weight percent. Silicon content in the steel of present invention is from 2.6 to 6.5 weight percent. Silicon is an element that contributes to increasing the strength by solid solution strengthening and is a key element to reduce eddy current loss of iron loss by increasing specific resistance of steel. The mentioned effects require a minimum Silicon content of at least 2.6 weight percent. However, when silicon content is in an amount exceeding 3.5 weight percent, it causes the rolling to be difficult and the magnetic induction of the steel will be significantly lowered. The preferred limit for the presence of Silicon is from 2.6 to 5.0 weight percent and more preferably from 2.8 to 4.0 weight percent. Aluminium content in the steel of present invention is from 0.1 to 1.2 weight percent. Aluminium increases the electrical resistivity of the material and can effectively reduce the iron loss of steel. When the content of Aluminium is more than 1.2 weight percent, the magnetic induction of the steel will be significantly reduced of the steel of present invention. The preferred limit for the content of Aluminium is from 0.7 to 1.2 weight percent and more preferably from 0.8 to 1.1 weight percent. Alternatively, the preferred limit for the content of Aluminium is from 0.4 to 0.7 weight percent. The non-oriented electrical steel sheet according to the invention mandatorily contains Silicon, Manganese and Aluminum such that the total content is from 3.5 to 9.5 weight percent. When the total content of Si, Mn and Al is less than 3.5 weight percent, it is not possible to achieve the mechanical properties in both transverse and rolling direction along with the magnetic properties. However, when the total content of Si, Mn and Al exceeds 9.5 weight percent, steel is hardened and the rolling becomes difficult. Even more preferably, the total content of Si, Mn and Al is from 3.5 to 5.5 weight percent. Phosphorus content in the steel of present invention is from 0 to 0.15 weight percent. Phosphorus reduces the hot and cold ductility, particularly due to its tendency to segregate at the grain boundaries or co-segregate with Manganese. For these reasons, its content is limited to 0.15 weight percent and preferably lower than 0.09 weight percent. Sulfur is not an essential element but may be contained as an impurity in steel and from point of view of the present invention the Sulfur content is preferably as low as possible but 0.006 weight percent or less from the viewpoint of manufacturing cost. Further if higher Sulfur is present in steel it combines to form Sulfides which are detrimental for the magnetic properties of the present invention. Nitrogen is not an essential element but may be contained as an impurity in steel. It is limited to 0.09% to minimize the precipitation of Aluminum nitrides during solidification which are detrimental for magnetic properties of the steel. Niobium is an optional element and its content in the steel of present invention is from 0 to 0.1 weight percent. Niobium is suitable for forming carbo-nitrides to increase strength of the Steel of present invention by precipitation hardening. Niobium will also impact the size of microstructural components through its precipitation as carbo-nitrides. However, Niobium content above 0.1 weight percent is not economically interesting as a saturation effect. Titanium is an optional element of the steel composition of the present invention. Titanium content in the steel of present invention is from 0 to 0.1 weight percent. It forms Titanium-nitrides appearing during solidification of the cast product. The amount of Titanium is so limited to 0.1 weight percent to limit the formation of Titanium-nitrides detrimental for magnetic properties of the steel of present invention. Vanadium is an optional element and its content in the steel of present invention is from 0 to 0.1 weight percent. Vanadium is effective in enhancing the strength of steel by forming carbides or carbo-nitrides and the upper limit is 0.1 weight percent from economic points of view. Chromium is an optional element of the steel composition of the present invention. Chromium content in the steel of present invention is from 0 to 1 weight percent. Chromium provide strength to the steel by solid solution strengthening but when used above 1 weight percent impairs surface finish of steel. Molybdenum is an optional element of the steel composition of the present invention. Molybdenum content in the steel of present invention is from 0 to 0.5 weight percent. Molybdenum has apparently an effect of coarsening carbides and thus reducing the iron loss. Without to be bound by theory, when it exceeds 0.5 weight percent, the effect of improving the iron loss is saturated. Tungsten is an optional element of the steel composition of the present invention. Tungsten content in the steel of present invention is from 0 to 0.1 weight percent. Apparently, tungsten has an effect of coarsening carbides and reducing the iron loss, like Mo. Without to be bound by theory, when the addition amount is less than 0.001 weight percent, the above effect cannot be obtained sufficiently, while when it exceeds 0.1 weight percent, the effect of improving the iron loss is saturated. Cobalt is an optional element of the steel composition of the present invention. Cobalt content in the steel of present invention is from 0 to 1 weight percent. Without to be bound by theory, Cobalt is an element increasing the magnetic moment of Fe alloy and has an effect of increasing a magnetic flux density and reducing the iron loss. Without to be bound by theory, when the addition amount is less than 0.01 weight percent, the above effects cannot be obtained sufficiently, while when it exceeds 1 weight percent, the raw material cost is largely increased. Arsenic is an optional element of the steel composition of the present invention. Arsenic content in the steel of present invention is from 0 to 0.05 weight percent. Without to be bound by theory, Arsenic is a grain boundary segregation element and has an effect of improving the texture and thus reducing the iron loss. The above effect is obtained by the addition of not less than 0.001 weight percent. Without to be bound by theory, Arsenic is an element causing grain boundary embrittlement, and this adverse effect becomes particularly remarkable when it is added by more than 0.05 weight percent. Therefore, As is preferable to be added within the range of 0.001 to 0.05 weight percent. Nickel is an optional element of the steel composition of the present invention. Nickel content in the steel of present invention is from 0 to 1 weight percent. Nickel increases the strength of the steel present invention and to improve its strength and elongation. However, when its content is above 1 weight percent, Nickel causes ductility deterioration. Copper is an optional element of the steel composition of the present invention. Copper content in the steel of present invention is from 0 to 1 weight percent. Copper increases the strength and elongation of the steel of present invention. However, when its content is above 1 weight percent, it can degrade the surface aspects and the magnetic properties, apparently by forming precipitates. Boron is an optional element of the steel composition of the present invention. Boron content in the steel of present invention is from 0 to 0.05 weight percent. Boron forms boro-nitrides and impart additional strength to steel of present invention when added in an amount of at least 0.0001 weight percent. Calcium is an optional element of the steel composition of the present invention. Calcium content in the steel of present invention is from 0 to 0.01 weight percent and preferably from 0.001 to 0.01 weight percent. Apparently, Calcium contributes towards the refining of the steel by binding the detrimental Sulfur content in globular form thereby retarding the harmful effect of Sulfur. Other elements such as Sn, Pb or Sb can be added individually or in combination in the following proportions: Sn ≤ 0.2 weight percent, Pb ≤ 0.2 weight percent and Sb ≤ 0.2 weight percent. Up to the maximum content levels indicated, these elements make it possible to refine the grain during solidification. The remainder of the composition of the steel consists of iron and inevitable impurities resulting from processing. The method according to the invention comprises the provision of a semi-finished casting of steel with a chemical composition of the steel according to the invention. For example, the casting can be done either into ingots or continuously in form of thin slabs or thin strips, i.e. with a thickness ranging from tens of millimetres for thin strip up to approximately 220 mm for slabs. Then the cast is reheated to a temperature from 1050°C to 1250°C. Below 1050°C, hot rolling temperatures become too low which makes rolling difficult and forces on the mill will be too high. Above 1250°C, the steel might become very soft and might show some sagging and thus become difficult to handle. After, the reheated slab is subjected to hot rolling so as to obtain a hot rolled steel sheet. The hot rolling finishing temperature is from 750°C to 950°C. Below 750°C, recrystallization is limited and the microstructure is highly deformed. Above 950°C would mean higher reheating temperatures and thus more impurities in solid solution and possible consequent precipitation and deterioration of magnetic properties as well. The hot rolled steel sheet is then cooled at a cooling rate of at least 10°C.s^-1 to the Coiling Temperature which is from 450°C to 750°C. Preferably, the cooling rate is less than or equal to 200° C.s^-1. Below 450°C, such a coiling temperature would not allow sufficient recovery to take place while this metallurgical step is necessary for magnetic properties. Above 750°C, a thick internal oxidation layer would appear, and would cause difficulties for subsequent processing steps such as warm rolling and/or pickling. The hot rolled steel sheet is optionally subjected to a scale removal step so as to remove, at least partly, the scale formed during the hot rolling. Then the coiled hot rolled steel sheet is optionally subjected to a hot band annealing. The hot band annealing is performed at temperatures from 650°C to 1100°C, for at least 10 seconds and not more than 96 hours. Preferably, it is performed at temperatures from 700°C to 1070°C and more preferably from 720°C to 1050°C. Optionally, a scale removal step of this hot rolled or hot band annealed steel sheet may be performed through, for example, pickling of such sheet. Warm rolling Then the hot rolled steel or hot band annealed sheet is subjected to warm rolling to obtain a warm rolled steel sheet with. For example, the thickness reduction is from 35 to 95%. The warm rolling comprises five to eight rolling passes, wherein - the first rolling pass is performed with an entry temperature of the steel sheet from 70 to 120°C, - the second rolling pass is performed with an entry temperature of the steel sheet from 90 to 175°C and greater than the entry temperature of the first rolling pass, - the remaining rolling passes are performed with an entry temperature of the steel sheet from 190 to 250°C. Preferably, the second rolling pass is performed with an entry temperature of the steel sheet from 90 to 130°C. Alternatively, the second rolling pass is performed with an entry temperature of the steel sheet from 130 to 175°C. Preferably, the remaining rolling passes are performed with an entry temperature of the steel sheet from 200 to 250°C. Annealing Thereafter, the warm rolled steel sheet is then heated wherein the heating starts from room temperature, the warm rolled steel sheet being heated, at a heating rate of at least 1°C.s^-1 to an annealing temperature T_SOAK which is from 800°C to 1100°C. The warm rolled steel sheet is held at the annealing temperature during 10 seconds to 5000 seconds so as to ensure a recrystallisation of 100%. Preferably, the heating rate is of at least 2°C.s^-1 and even more preferably of at least 5°C.s^-1. Preferably, the annealing temperature T_SOAK is from 1000°C to 1100°C and even more preferably is from 1020°C to 1100°C or from 1050 to 1100°C. Preferably, the warm rolled steel sheet is held at the annealing temperature during at least 20 seconds. Even more preferably, the warm rolled steel sheet is held at the annealing temperature during at least 20 seconds. The warm rolled steel sheet is then cooled wherein cooling starts from T_SOAK, the warm rolled steel sheet being cooled down, at a cooling rate CR1 from 1°C/s to 150°C/s, to a temperature T1 which is in a range from 20°C to 300°C. In a preferred embodiment, the cooling rate CR1 is from 3°C/s to 120°C/s. The preferred T1 temperature is from 20°C to 200°C. The cooling of the warm rolled steel sheet can be performed in multiple cooling steps wherein the multiple cooling steps can have different cooling rates. Then, the warm rolled steel sheet is cooled down to room temperature to obtain a non-oriented electrical steel sheet. The non-oriented electrical steel sheet of the present invention may optionally be coated with insulation, organic coating or inorganic coating or combination of them to improve isolation. The invention also relates to a non-oriented electrical steel sheet having a composition comprising of the following elements, expressed in percentage by weight: 0.0001% ≤ Carbon ≤ 0.008 % 0.1% ≤ Manganese ≤ 2.0% 2.8% ≤ Silicon ≤ 6.5% 0.1% ≤ Aluminum ≤ 1.2 % 0 % ≤ Phosphorus ≤ 0.15 % 0 % ≤ Sulfur ≤ 0.006 % 0 % ≤ Nitrogen ≤ 0.09% with 3.5% ≤ Si+Al+Mn ≤ 9.5% and can 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% ≤ 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 composition being composed of iron and unavoidable impurities caused by processing, the microstructure of said steel sheet being made of ferrite and comprising in area fraction 100% recrystallized microstructure wherein the average grain size of recrystallized microstructure is from 15 microns to 250 microns and wherein the following equation is satisfied : ^{^ହ^ ்ಷ} ^_{^భ శ ^^మ శ ^^య} െ ^ 0.015 wherein య _{ௗ ∙ ఘ}

- J50 is the magnetic polarisation in Tesla, - T_R1 is the warm rolling temperature at the entry of the first pass, - T_R2 is the warm rolling temperature at the entry of the second pass, - T_R3 is the warm rolling temperature at the entry of the third pass, - T_f is the texture factor, - d is the average grain size in µm, - ρ is the resistivity in µΩ.cm. The area fraction and the grain size are measured per the ASTM E112 standards with linear intercept method. The texture factor is defined as the ratio of {100}〈uvw〉; cube fiber and {111}〈uvw〉; gamma fiber. The cube and gamma fibers can be measured by XRD. For example, a diffraction goniometer is operated at 35 kV and 45 mA. The average grain size is measured as per the ASTM E112 (2013) standards with linear intercept method. The resistivity is measured per the ASTM A712 – 14 standard. Preferably, said composition comprises from 2.8 to 3.3 weight percent of Silicon. Preferably, said composition comprises from 0.1 to 1.2 weight percent of Manganese. Alternatively, said composition can comprise from 0.5 to 2.0 weight percent of Manganese. The steel of the present invention has a microstructure made of ferrite. The microstructure of the non-oriented electrical steel is free from microstructural components such as martensite, bainite, pearlite and cementite. The steel of the present invention has a recrystallised microstructural region of 100% in area fraction. The steel of the present invention has grains having an average grain size from 15 microns to 250 microns. The average grain size is measured as per the ASTM E112 (2013) standards with linear intercept method. Preferably, the average grain size is from 15 microns to 35 microns. Apparently, this grain size range is preferred for the domain of high-speed rotors. Preferably, the average grain size is from 35 microns to 80 microns. Apparently, this grain size range is preferred for the domain of stators of high frequency machines and high-speed rotors. Preferably, the average grain size is from 80 microns to 120 microns. Apparently, this grain size range is preferred for the domain of stators using torque. Preferably, the average grain size is from 120 microns to 250 microns. Apparently, this grain size range is preferred for the domains of industrial generators and traction or propulsion motors. Preferably, the steel satisfies following equation: ^{^ହ^ ்ಷ} ^_{^భ శ ^^మ శ ^^య} െ ^ 0.013. య _{ௗ ∙ ఘ}

The invention also relates to the use of a steel sheet as previously described or of a steel sheet produced as previously described, for the manufacture of parts of electrical vehicle or electrical machines The invention also relates to a vehicle or electrical machine comprising a part obtained as previously described. EXEMPLES The following tests, examples, figurative exemplification and tables which are presented herein are non-restricting in nature and must be considered for purposes of illustration only and will display the advantageous features of the present invention. Steel sheets made of steels with different compositions are gathered in Table 1. The steel sheets are produced according to process parameters as stipulated in Tables 2 and 3, respectively. Table 2 gathers the process parameters of the reheating, the hot rolling, the coiling and the hot band annealing. Table 3 gathers the process parameters of the second rolling, i.e. cold or warm rolling, and of the final annealing. Table 4 exemplifies the result of the tests conducted on both the inventive and reference steels. The inventive and references steels should be compared in pairs. For example, Reference 13 and Invention 20 permits to assess the impact of the claimed warm rolling on the texture and on the magnetic polarization. Indeed, the other process parameters are the same, i.e. hot rolling, coiling, hot band annealing, final annealing. The steel “Invention 20” according to the invention has a better Texture Factor than the “Reference 13” which permits to get a better magnetic polarization then the “Reference 13”. The same reasoning and conclusion can be made with the following pairs : “Reference 14” and “Invention 21”, “Reference 15” and “Invention 22”, “Reference 23” and “Invention 32”, “Reference 24” and “Invention 33”, “Reference 25” and “Invention 34”. Consequently, it is clear that the present process permits to improve the polarization and texture of non-oriented electrical steel. Steel C Mn Si Cr Al Sn Ti S P N Ni Steel A 0.0046 0.96 2.93 0.0376 0.93 0.001 0.0038 0.0007 0.0100 0.0011 0.0124 Steel B 0.0040 0.95 3.30 0.0332 0.90 0.001 0.0038 0.0007 0.0152 0.0014 0.0131 Table 1: Composition in weight percent of the steel Hot rolling Coiling Hot band annealing Reheating FRT Hot rolled Average cooling rate to Coiling soaking Annealing Sample Steel T (°C) (°C) thickness [mm] coiling (°C/s) Temperature T [°C] time [hours] (°C) Reference 13 1150 851 2 20 640 815 24 Invention 20 1150 851 2 20 640 815 24 Reference 14 1150 851 2 20 640 815 24 Steel A Invention 22 1150 851 2 20 640 815 24 Reference 15 1150 851 2 20 640 815 24 Invention 21 1150 851 2 20 640 815 24 Reference 23 1150 851 2 20 640 815 24 Invention 32 1150 851 2 20 640 815 24 Reference 24 1150 851 2 20 640 815 24 Steel B Invention 33 1150 851 2 20 640 815 24 Reference 25 1150 851 2 20 640 815 24 Invention 34 1150 851 2 20 640 815 24 Table 2: Process parameters of the reheating, hot rolling, coiling and HBA steps Second rolling Final Annealing rolling soaking Sample Steel 1^st 2^nd 3^rd 4^th 5^th 6^th 7^th 8^th thickness Soaking T [°C] time [mm] [seconds] Reference 13 25 107173 25 25 25 25 25 0,35 1000 40 Invention 20 91 154212 220 220 220 220 220 0,35 1000 40 Reference 14 Steel 25 107173 25 25 25 25 25 0,35 1020 40 Invention 22 A 91 154212 220 220 220 220 220 0,35 1020 40 Reference 15 25 107173 25 25 25 25 25 0,35 1070 40 Invention 21 91 154212 220 220 220 220 220 0,35 1070 40 Reference 23 25 107173 25 25 25 25 25 0,35 1000 40 Invention 32 90 108232 220 220 220 220 220 0,35 1000 40 Reference 24 Steel 25 107173 25 25 25 25 25 0,35 1020 40 Invention 33 B 90 108232 220 220 220 220 220 0,35 1020 40 Reference 25 25 107173 25 25 25 25 25 0,35 1070 40 Invention 34 90 108232 220 220 220 220 220 0,35 1070 40 Table 3: Process parameters of the warm rolling and rolling according to the state of the art Recrystallised Grain size Average Texture J50 ^{^^50} Steel ρ _{TR1 ^ TR2 ^ TR3} ₃ [%] [μm] A Factor [T] െ ^{^^} ^_{^ ∙ ^^} Reference 13 100 74 32,54 0,80 1,651 56.87 0.016 Invention 20 100 90 31,56 1,33 1,655 56.87 0.011 Reference 14 100 93 32,09 1,11 1,645 56.87 0.016 Steel A Invention 22 100 105 31,23 1,17 1,656 56.87 0.011 Reference 15 100 146 31,89 1,19 1,640 56.87 0.016 Invention 21 100 134 31,03 1,53 1,645 56.87 0.011 Reference 23 100 129 32,11 0,78 1,634 60.71 0.016 Invention 32 100 97 31,06 1,58 1,650 60.71 0.011 Reference 24 100 134 31,45 1,06 1,641 60.71 0.016 Steel B Invention 33 100 140 30,60 1,45 1,655 60.71 0.011 Reference 25 100 156 31,60 1,13 1,623 60.71 0.016 Invention 34 100 165 31,30 1,49 1,641 60.71 0.011 Table 4: Microstructural and Magnetic properties

Claims

CLAIMS 1. A method of production of a non-oriented electrical steel sheet comprising the following steps providing a steel composition comprising the following elements, expressed in percentage by weight: 0.0001% ≤ Carbon ≤ 0.008 % 0.1% ≤ Manganese ≤ 2.0% 2.8% ≤ Silicon ≤ 6.5% 0.1% ≤ Aluminum ≤ 1.2 % 0 % ≤ Phosphorus ≤ 0.15 % 0 % ≤ Sulfur ≤ 0.006 % 0 % ≤ Nitrogen ≤ 0.09% with 3.5% ≤ Si+Al+Mn ≤ 9.5% and can 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% ≤ 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 composition being composed of iron and unavoidable impurities caused by processing, - reheating said semi-finished product to a temperature from 1050°C to 1250°C, - hot rolling the said semi-finished product wherein the hot rolling finishing temperature shall be from 750°C to 950°C to obtain a hot rolled steel sheet, - cooling the hot rolled sheet after the finishing of hot rolling, to a coiling temperature range which is from 450°C to 750°C at a cooling rate of at least 10°C/s - thereafter coiling the hot rolled steel sheet in the coiling temperature range from 450°C to 750°C, - optionally performing scale removal process on said hot rolled steel sheet, - hot band annealing is optionally performed on hot rolled steel sheet from 650°C to 1100°C during 10 seconds to 96 hours, - optionally performing scale removal process on said hot rolled steel sheet, - warm rolling said hot rolled steel sheet, wherein said warm rolling comprises five to eight rolling passes, wherein - the first rolling pass is performed with an entry temperature of the steel sheet from 70 to 120°C, - the second rolling pass is performed with an entry temperature of the steel sheet from 90 to 175°C and greater than the entry temperature of the first rolling pass, - the remaining rolling passes are performed with an entry temperature of the steel sheet from 190 to 250°C and - thereafter annealing said warm rolled steel sheet wherein the heating for annealing starts from room temperature to an annealing temperature range Tsoak which is from 800°C to 1100°C, with a heating rate HR1 of at least 1°C/s, - then perform annealing at annealing temperature during 10 to 5000 seconds, so as to ensure a recrystallisation of 100%, - then cooling the warm rolled steel sheet which starts from the annealing temperature to a temperature T1 from 300°C to room temperature, with a cooling rate CR1 from 1°C/s to 150°C/s to obtain a non-oriented electrical steel sheet. 2. A method according to claim 1, wherein the second rolling pass is performed with an entry temperature of the steel sheet from 90 to 130°C. 3. A method according to claim 1, wherein the second rolling pass is performed with an entry temperature of the steel sheet from 130 to 175°C. 4. A method according to any one of the claims 1 to 3, wherein the remaining rolling passes are performed with an entry temperature of the steel sheet from 200 to 250°C. 5. A method according to any one of the claims 1 to 4, wherein the annealing temperature range Tsoak which is from 1000°C to 1100°C. 6. A method according to claim 5, wherein the annealing temperature range Tsoak which is from 1020°C to 1100°C. 7. A non-oriented electrical steel sheet having a composition comprising of the following elements, expressed in percentage by weight: 0.0001% ≤ Carbon ≤ 0.008 % 0.1% ≤ Manganese ≤ 2.0% 2.6% ≤ Silicon ≤ 6.5% 0.1% ≤ Aluminum ≤ 1.2 % 0 % ≤ Phosphorus ≤ 0.15 % 0 % ≤ Sulfur ≤ 0.006 % 0 % ≤ Nitrogen ≤ 0.09% with 3.5% ≤ Si+Al+Mn ≤ 9.5% and can 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% ≤ 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 composition being composed of iron and unavoidable impurities caused by processing, the microstructure of said steel sheet being made of ferrite and comprising in area fraction 100% recrystallized microstructure wherein the average grain size of recrystallized microstructure is from 15 microns to 250 microns and wherein the following equation is satisfied : ^{^ହ^ ்ಷ} ^_{^భ శ ^^మ శ ^^య} െ_{ௗ ∙ ఘ} ^ 0.015 wherein య - J50 is the magnetic

in Tesla - T_R1 is the warm rolling temperature at the entry of the first pass, - T_R2 is the warm rolling temperature at the entry of the second pass, - T_R3 is the warm rolling temperature at the entry of the third pass, - T_f is the texture factor, - d is the average grain size in µm and - ρ is the resistivity in µΩ.cm. 8. A non-oriented electrical steel sheet according to claim 7, wherein said composition comprises from 2.6 to 5.0 weight percent of Silicon. 9. A non-oriented electrical steel sheet according to claim 7 or 8, wherein said composition comprises from 0.1 to 1.2 weight percent of Manganese. 10. A non-oriented electrical steel sheet according to claim 7 or 8, wherein said composition comprises from 0.5 to 2.0 weight percent of Manganese. 11. Use of a steel sheet according to anyone of claims 7 to 10 or of a steel sheet produced according to the method of claims 1 to 8, for the manufacture of parts of electrical vehicle or electrical machines 12. Vehicle or Electrical machine comprising a part obtained according to claim 11.