A method of normalizing non-oriented electrical steel and a method of manufacturing the same

Abstract

The application relates to the technical field of non-oriented silicon steel manufacturing, in particular to a normalizing method of non-oriented electrical steel and a preparation method thereof. The normalizing method comprises the following steps: heating a non-oriented electrical steel hot-rolled plate with a set chemical composition, so that the hot-rolled plate has a target temperature; homogenizing the heated hot-rolled plate under the condition of the target temperature and a first set time; self-homogenizing the homogenized hot-rolled plate under the condition of a second set time, and then cooling to obtain a normalizing base plate; wherein the target temperature, the first set time and the second set time are calculated according to the chemical composition. The application solves the technical problem that the existing non-oriented silicon steel hot-rolled plate is prone to generating oversized grains in the normalizing process, thereby improving the uniformity of the grain size of the normalizing base plate, and reducing the rolling defects or strip breakage caused by the non-uniform grain size.

Description

Technical Field

[0001] This application relates to the field of non-oriented silicon steel manufacturing technology, and in particular to a normalizing method for non-oriented electrical steel and its preparation method. Background Technology

[0002] High-quality non-oriented electrical steel for new energy vehicles is a core material for manufacturing drive motors. Its superior performance and stability are particularly important for the manufacturing and use of drive motors for new energy vehicles.

[0003] The normalizing process of non-oriented silicon steel generally employs a 3-stage or 5-stage normalizing furnace. Hot-rolled steel is typically used as the raw material, with heating in the NOF stage, soaking in the SF stage, and cooling in the tube cooling stage. The aim is to obtain a coarse grain structure, increase recrystallized grains, prevent wedge-like defects, coarsen precipitates, strengthen the {100} and {110} texture components, and weaken the {111} component, resulting in a significant improvement in magnetic properties.

[0004] Currently, most manufacturers employ prolonged normalizing processes to ensure stability and the formation of large grains, thereby guaranteeing the magnetic properties of the finished product. However, after prolonged normalizing, some fully grown grains in non-oriented silicon steel hot-rolled sheets continuously absorb high-temperature energy during the homogenization process. This eventually leads to some grains engulfing surrounding grains, forming enormous grains. These large grains can cause instability and strip breakage in subsequent processes—cold rolling—and the continued presence of large grains within the silicon steel after annealing, resulting in unstable mechanical properties. Stable mechanical properties are one of the primary requirements for non-oriented silicon steel used in new energy vehicles. Summary of the Invention

[0005] This application provides a normalizing method for non-oriented electrical steel and its preparation method, in order to solve the technical problem that existing hot-rolled non-oriented silicon steel plates are prone to producing excessively large grains during the normalizing process.

[0006] In a first aspect, this application provides a normalizing method for non-oriented electrical steel, the method comprising:

[0007] A hot-rolled sheet of non-oriented electrical steel with a set chemical composition is heated to bring the hot-rolled sheet to a target temperature.

[0008] Under the conditions of the target temperature and the first set time, the heated hot-rolled plate is homogenized.

[0009] Under the condition of a second set time, the hot-rolled plate after homogenization is subjected to self-homogenization and then cooled to obtain a normalized substrate; wherein, the target temperature, the first set time, and the second set time are calculated based on the chemical composition.

[0010] Optionally, the target temperature and the chemical composition satisfy the following relationship:

[0011] T1 = 1133 - 66.67*[Si] + 66.67*[Mn] - 33.33*[Al]

[0012] In the formula, T1 represents the target temperature, [Si] represents the weight percentage of Si, [Mn] represents the weight percentage of Mn, and [Al] represents the weight percentage of Al.

[0013] Optionally, the first set time and the chemical composition satisfy the following relationship:

[0014] t1 = -44.18 + 25.45*[Si] + 15.00*[Mn] + 11.36*[Al]

[0015] In the formula, t1 represents the first set time, [Si] represents the weight percentage of Si, [Mn] represents the weight percentage of Mn, and [Al] represents the weight percentage of Al.

[0016] Optionally, the second set time and the chemical composition satisfy the following relationship:

[0017] t2 = 188.18 - 25.45*[Si] - 15.00*[Mn] - 11.36*[Al]

[0018] In the formula, t2 represents the second set time, [Si] represents the weight percentage of Si, [Mn] represents the weight percentage of Mn, and [Al] represents the weight percentage of Al.

[0019] Optionally, the set chemical composition includes:

[0020] C, Si, Mn, Al, S, Ti, Nb, and Fe; wherein,

[0021] The content of C is ≤0.004%, the content of Si is 2.2%-4.0% by weight, the content of Mn is 0.1%-1.2% by weight, the content of Al is 0.1%-1.2% by weight, the content of S is ≤0.01% by weight, the content of Ti is ≤0.005% by weight, and the content of Nb is ≤0.005% by weight.

[0022] Optionally, the heating rate in the heating is >12.5°C / s.

[0023] Optionally, the hot-rolled plate after the homogenization is self-homogenized under the condition of the second set time, and then cooled to obtain a normalized base plate, including:

[0024] Under the condition of a second set time, the hot-rolled plate after homogenization is subjected to self-homogenization.

[0025] Under a set cooling rate, the hot-rolled plate after self-heating is subjected to radiation cooling, followed by air cooling and water cooling to obtain a normalized substrate.

[0026] Optionally, the set cooling rate is >5℃ / s.

[0027] Optionally, the endpoint temperature of the radiative cooling is <650°C.

[0028] Secondly, this application provides a method for preparing non-oriented electrical steel, the method comprising the method described in any embodiment of the first aspect.

[0029] The technical solutions provided in this application have the following advantages compared with the prior art:

[0030] The normalizing method for non-oriented electrical steel provided in this application proposes a self-homing process concept. This allows for improved uniformity of grain size in the normalized substrate while effectively reducing energy consumption during actual production, thereby reducing rolling defects or strip breakage caused by grain size inhomogeneity. Furthermore, by calculating the homogenization temperature, homogenization time, and self-homing time based on the chemical composition of the electrical steel, the uniformity of grain size in the normalized substrate is ensured, while simultaneously improving the elongation of the finished electrical steel product. In addition, the normalized substrate for non-oriented silicon steel for new energy vehicles produced using this method can achieve a relatively uniform grain size. Using this normalized substrate as raw material, it effectively reduces rolling defects or strip breakage caused by grain size inhomogeneity during rolling. Using this normalized substrate as raw material, it yields finished non-oriented silicon steel products for new energy vehicles with stable elongation. This method, by controlling the conventional homogenization time and innovatively using self-homing, effectively reduces the energy consumption level of the normalizing process for non-oriented silicon steel. Attached Figure Description

[0031] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0032] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1A schematic flowchart illustrating a normalization method for non-oriented electrical steel provided in this application embodiment;

[0034] Figure 2 A schematic diagram of the grain structure of a non-oriented electrical steel provided in an embodiment of this application;

[0035] Figure 3 A schematic diagram of the grain structure of a non-oriented electrical steel provided as a comparative example of this application;

[0036] Figure 4 This is a schematic diagram illustrating the division of the furnace sections in the 3-section and 5-section normalizing furnaces provided in this application. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0038] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0039] In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. Furthermore, in the description of this application, terms such as "comprising" and "including" mean "including but not limited to." In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this document, "and / or" describes the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone. A and B can be singular or plural. In this document, "at least one" means one or more, and "more than one" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c" or "at least one of a, b, and c" can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be a single or multiple.

[0040] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0041] Firstly, this application provides a normalizing method for non-oriented electrical steel; please refer to [link to relevant documentation]. Figure 1 The method includes:

[0042] S1. Heating a hot-rolled non-oriented electrical steel sheet with a set chemical composition to bring the hot-rolled sheet to a target temperature;

[0043] S2. Under the conditions of the target temperature and the first set time, the heated hot-rolled plate is homogenized.

[0044] S3. Under the condition of the second set time, the hot-rolled plate after homogenization is subjected to self-homogenization and then cooled to obtain a normalized substrate; wherein, the target temperature, the first set time and the second set time are calculated based on the chemical composition.

[0045] Currently, the normalizing process of non-oriented silicon steel generally employs a 3-stage or 5-stage normalizing furnace. Hot-rolled steel is typically used as the raw material, with heating in the NOF stage, soaking in the SF stage, and cooling in the tube cooling stage. The aim is to obtain a coarse grain structure, increase recrystallized grains, prevent the formation of wedge-like defects, coarsen precipitates, strengthen the {100} and {110} texture components, and weaken the {111} component, thereby significantly improving magnetic properties.

[0046] However, after long-term normalization, some fully grown grains of non-oriented silicon steel hot-rolled sheets continuously absorb high-temperature energy during the homogenization process, eventually causing some grains to devour surrounding grains and form huge grains. These huge grains will lead to instability in the subsequent process—cold rolling, i.e., strip breakage, and the presence of huge grains in the silicon steel after annealing, resulting in unstable mechanical properties of the finished product.

[0047] This application provides a normalizing method for non-oriented electrical steel to obtain a normalized substrate of non-oriented silicon steel with relatively uniform grain size, for the production of high-quality non-oriented silicon steel products for new energy applications. In this application, "target temperature" represents the homogenization temperature, "first set time" represents the homogenization time, and "second set time" represents the self-homogenization time. This method utilizes a three-stage normalizing furnace (including a non-oxidizing furnace, a homogenizing furnace, a radiant tube cooling furnace, and external air jet cooling and water spray cooling equipment), or a five-stage normalizing furnace, specifically comprising: a non-oxidizing furnace, a radiant tube heating furnace, a radiant tube cooling and heating mixing furnace 1, a homogenizing furnace, and a radiant tube cooling and heating mixing furnace 2. See [link to relevant documentation]. Figure 4 The oxidation-free furnace uses open flame heating, with flue gas flowing in the opposite direction to the strip's movement, forming convective heat exchange with the strip. The soaking furnace uses dielectric radiation such as resistance bands or resistance rods for heating, while being protected with pure nitrogen. The radiant tube cooling furnace uses radiant tubes for radiant cooling. Production is carried out using 3- or 5-stage normalizing furnaces. By differentiating steel grades according to their composition and different process temperatures, the soaking time and heating / cooling rates of the normalizing process are standardized. Simultaneously, the advantages of the soaking furnace's heat preservation and the residual heat of the strip are utilized to provide the strip with time for self-soaking, achieving the purpose of homogenization simultaneously.

[0048] "Homothering time" refers to the time during which the heated non-oriented strip steel is kept at a constant temperature in a homogenizing furnace by radiant heating from resistance bands or bars. To ensure uniform grain coarsening and minimize the problem of grains engulfing each other and growing into giant grains, the concept of self-homothering time has been introduced. "Self-homothering time" refers to the time during which the heated strip steel, with all heating and cooling equipment and facilities shut off, remains unaffected by these systems, utilizing only its own temperature and energy to pass through the homogenizing furnace at an extremely low temperature drop rate (less than 0.2℃ / second). "Self-homothering" effectively avoids the need for external energy sources, preventing some grains from gaining energy and engulfing surrounding grains to grow into giant grains. Furthermore, using self-homothering technology reduces the electrical energy used by the homogenizing furnace, resulting in energy savings and reduced consumption for production enterprises. Please refer to [link to relevant documentation]. Figure 2 and Figure 3 .

[0049] In some embodiments, the target temperature and the chemical composition satisfy the following relationship:

[0050] T1=1133-66.67*[Si]+66.67*[Mn]-33.33*[Al]

[0051] In the formula, T1 represents the target temperature, [Si] represents the weight percentage of Si, [Mn] represents the weight percentage of Mn, and [Al] represents the weight percentage of Al.

[0052] In this embodiment, the homogenization temperature is calculated using the expression relating the homogenization temperature to the chemical composition of the electrical steel. This homogenization temperature simultaneously satisfies 830℃ < T1 < 1070℃. During heat treatment, homogenization temperature and homogenization time are two crucial factors. The method provided in this application, through practical application, establishes the relationship between hot-rolled steel substrates with different compositions and homogenization temperatures, times, and self-homogenization times. By detecting the grain size and corresponding elongation levels of the actual normalized steel plates, a fitting model is established to ultimately derive the optimal solution relationship between the homogenization temperature and composition, which has been verified in practice.

[0053] In some embodiments, the first set time and the chemical composition satisfy the following relationship:

[0054] t1=-44.18+25.45*[Si]+15.00*[Mn]+11.36*[Al]

[0055] In the formula, t1 represents the first set time, [Si] represents the weight percentage of Si, [Mn] represents the weight percentage of Mn, and [Al] represents the weight percentage of Al.

[0056] In this embodiment, the soaking time is calculated using the expression relating the soaking time to the chemical composition of the electrical steel, and this soaking time simultaneously satisfies 15s < t1 < 90s. During heat treatment, soaking temperature and soaking time are two crucial factors. This patent, through practical application, establishes a model relating hot-rolled steel substrates with different compositions to soaking temperature, soaking time, and self-soaking time. By detecting the grain size of actual normalized steel plates and the corresponding elongation levels of finished products, a fitting model is established to ultimately derive the optimal solution relationship between the soaking time and composition, which has been verified in practice.

[0057] In some embodiments, the second set time and the chemical composition satisfy the following relationship:

[0058] t2=188.18-25.45*[Si]-15.00*[Mn]-11.36*[Al]

[0059] In the formula, t2 represents the second set time, [Si] represents the weight percentage of Si, [Mn] represents the weight percentage of Mn, and [Al] represents the weight percentage of Al.

[0060] In this embodiment, the self-basing time is calculated using the expression relating the self-basing time to the chemical composition of the electrical steel. This self-basing time simultaneously satisfies 130s > t2 > 30s. During heat treatment, the basing temperature and basing time are two crucial factors. This patent, through practical application, establishes a model relating hot-rolled steel substrates with different compositions to basing temperature, basing time, and self-basing time. By detecting the grain size of the actual normalized steel plate and the corresponding elongation level of the finished product, a fitting model is established to ultimately derive the optimal solution relationship between the self-basing time and composition, which has been verified in practice.

[0061] In some embodiments, the specified chemical composition includes: C, Si, Mn, Al, S, Ti, Nb, and Fe; wherein,

[0062] The content of C is ≤0.004 wt%, the content of Si is 2.2 wt%-4.0 wt%, the content of Mn is 0.1 wt%-1.2 wt%, the content of Al is 0.1 wt%-1.2 wt%, the content of S is ≤0.01 wt%, the content of Ti is ≤0.005 wt%, and the content of Nb is ≤0.005 wt%.

[0063] The positive effects of controlling the carbon content to ≤0.004 wt%: Carbon is a harmful element in non-oriented silicon steel. An increase in carbon content can deteriorate magnetic properties to some extent and cause magnetic aging. Therefore, the carbon content is generally required to be ≤0.004% to reduce the impact of carbon on the finished product's performance. Specifically, the carbon content can be 0.004 wt%, 0.0035 wt%, 0.003 wt%, etc.

[0064] The positive effects of controlling the Si content to 2.2 wt%-4.0 wt%: Silicon, as the core element in non-oriented silicon steel, mainly functions to increase resistivity, thereby reducing iron loss in the finished product. Excessive Si content will reduce iron loss to some extent, but will increase the manufacturing difficulty of non-oriented electrical steel, resulting in reduced rollability; conversely, insufficient Si content will reduce resistivity to some extent, leading to a product with insufficient magnetic properties. Specifically, the Si content can be 2.2, 2.6, 3.0, 3.4 wt%, 3.8 wt%, 4.0 wt%, etc.

[0065] The positive effects of controlling the Mn content to 0.1 wt%-1.2 wt%: Manganese is also one of the core components in non-oriented electrical steel. It can improve resistivity to a certain extent and can form manganese sulfide with trace amounts of sulfur in electrical steel, which can prevent hot brittleness caused by the formation of low-melting-point iron sulfide along grain boundaries. Increasing the manganese content to a certain extent can coarsen the manganese sulfide, which is beneficial to grain growth. If the content is too high, it will increase the cost and manufacturing difficulty to some extent; if the content is too low, it will increase hot brittleness to some extent, and if it is too low, the manganese sulfide will not be able to coarsen, which will inhibit grain growth. Specifically, the Mn content can be 0.1 wt%, 0.5 wt%, 1.0 wt%, 1.2 wt%, etc.

[0066] The positive effects of controlling the Al content to 0.1%-1.2% by weight: Aluminum, like silicon, can increase resistivity and reduce iron loss in the finished product. Excessive Al content will increase manufacturing difficulty and reduce rollability; insufficient Al content will fail to optimize magnetic properties and may even lead to the formation of aluminum nitride, worsening the magnetic properties of the finished product. Specifically, the Al content can be 0.1% by weight, 0.5% by weight, 1.0% by weight, 1.2% by weight, etc.

[0067] The positive effects of controlling the sulfur content to ≤0.01% by weight: Sulfur is a harmful element in silicon steel. Reducing the sulfur content can effectively reduce the formation of manganese sulfide, thus improving the magnetic properties of the finished product. Specifically, the sulfur content can be 0.01% by weight, 0.005% by weight, etc.

[0068] The positive effects of controlling the Ti content to ≤0.005 wt%: Titanium is a harmful element in non-oriented silicon steel. Reducing the titanium content can effectively reduce the precipitation of titanium pinning grain boundaries, which has a beneficial effect on the magnetic properties of the finished product. Specifically, the Ti content can be 0.005 wt%, 0.004 wt%, etc.

[0069] The positive effects of controlling the Nb content to ≤0.005% by weight: Niobium can form fine precipitates with carbon, inhibiting recrystallization and deteriorating the magnetic properties of the finished product. Reducing the niobium content can optimize the magnetic properties of the finished product. Specifically, the Nb content can be 0.005% by weight, 0.004% by weight, etc.

[0070] In some embodiments, the heating rate is >12.5°C / s.

[0071] The positive effects of controlling the heating rate to >12.5℃ / s include: effectively optimizing the texture of the finished product and improving its magnetic properties. Specifically, this heating rate can be 13℃ / s, 14℃ / s, 15℃ / s, etc.

[0072] In some embodiments, the step of subjecting the homogenized hot-rolled plate to self-homogenization and then cooling under a second predetermined time condition to obtain a normalized substrate includes:

[0073] Under the condition of a second set time, the hot-rolled plate after homogenization is subjected to self-homogenization.

[0074] Under a set cooling rate, the hot-rolled plate after self-heating is subjected to radiation cooling, followed by air cooling and water cooling to obtain a normalized substrate.

[0075] The positive effects of radiation cooling followed by air cooling and water cooling on the hot-rolled plate are: ensuring uniform cooling.

[0076] In some implementations, the set cooling rate is >5°C / s.

[0077] The positive effects of controlling the radiation cooling rate to >5℃ / s include: preventing excessive grain growth and increasing the difficulty of rolling and manufacturing. Specifically, this radiation cooling rate can be 6℃ / s, 7℃ / s, 8℃ / s, etc.

[0078] In some embodiments, the endpoint temperature of the radiative cooling is <650°C.

[0079] The positive effects of controlling the endpoint temperature of radiation cooling to <650℃ include: preventing excessive oxidation of the strip steel, reducing the difficulty of subsequent pickling, and improving surface quality. Specifically, the endpoint temperature of radiation cooling can be 640℃, 635℃, 630℃, 625℃, etc.

[0080] Secondly, based on the same inventive concept, this application provides a method for preparing non-oriented electrical steel, the method comprising the method described in any embodiment of the first aspect.

[0081] The above preparation method includes the following steps: steelmaking, hot rolling, normalizing pickling, cold rolling, annealing, and coating; wherein,

[0082] Steelmaking process: includes converter blowing, RH refining and continuous casting. Through these three processes, the composition, inclusions and microstructure of slab products can be strictly controlled; and unavoidable impurities and residual elements in steel can be controlled at a low level.

[0083] Hot rolling process: includes heating in a heating furnace, rough descaling, rough rolling, fine descaling, fine rolling laminar flow cooling and coiling; through the above process, the size, inclusions, microstructure stability of hot-rolled plates, and the easy removal of surface iron oxide in non-oriented silicon steel hot-rolled coils can be strictly controlled.

[0084] The preparation method of this non-oriented electrical steel is based on the normalization method of the above-mentioned non-oriented electrical steel. The specific steps of the normalization method of the non-oriented electrical steel can be referred to the above embodiments. Since the preparation method of this non-oriented electrical steel adopts some or all of the technical solutions of the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be repeated here.

[0085] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If there is no corresponding national standard, then general international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0086] The production method of non-oriented silicon steel hot-rolled plate includes steelmaking and hot rolling steps, as detailed below:

[0087] Steelmaking process: includes converter blowing, RH refining and continuous casting. Through these three processes, the composition, inclusions and microstructure of slab products can be strictly controlled; and unavoidable impurities and residual elements in steel can be controlled at a low level.

[0088] Hot rolling process: includes heating in a heating furnace, rough descaling, rough rolling, fine descaling, fine rolling laminar flow cooling and coiling; through the above process, the size, inclusions, microstructure stability of hot-rolled plates, and the easy removal of surface iron oxide in non-oriented silicon steel hot-rolled coils can be strictly controlled.

[0089] The raw material composition range for non-oriented silicon steel hot-rolled sheet is as follows: C content ≤0.004 wt%, Si content 2.2 wt%-4.0 wt%, Mn content 0.1 wt%-1.2 wt%, Al content 0.1 wt%-1.2 wt%, S content ≤0.01 wt%, Ti content ≤0.005 wt%, Nb content ≤0.005 wt%; the balance is Fe and other unavoidable impurities.

[0090] Example 1 and Comparative Example 1

[0091] Table 1. Main component parameters (wt%) of Example 1 and Comparative Example 1 of this application

[0092]

[0093]

[0094] The main parameters of the normalization process are calculated as follows:

[0095] Table 2 Main process parameters of Example 1 and Comparative Example 1 of this application

[0096]

[0097] Comparing the grain size of the normalized non-oriented silicon steel plates produced using Example 1 and Comparative Example 1:

[0098] Comparative Example 1: The average grain size of the normalized plate was 198.7 μm, the standard deviation was 131.7 μm, and the data volume was 306.

[0099] Example 1: The average grain size of the normalized plate was 198.7 μm, the standard deviation was 85.59 μm, and the data volume was 306.

[0100] Using the process of Example 1, while keeping the average grain size of the non-oriented normalized plate unchanged, Example 1 reduces the standard deviation of grain size by 46.11 μm compared to Comparative Example 1, and the grain size of Example 1 is significantly more uniform than that of Comparative Example 1.

[0101] The elongation of the finished products produced in Comparative Example 1 and Comparative Group 1 are as follows:

[0102] Comparative Example 1: Mean elongation of finished board: 34.65%, standard deviation: 8.187%, data volume: 97;

[0103] Example 1: The average elongation of the finished board was 34.64%, the standard deviation was 2.504%, and the data volume was 97.

[0104] Using the process of Example 1 of this application, the standard deviation can be reduced from 8.187 to 2.504 while maintaining the mean elongation unchanged, representing a reduction of 69.41%. The elongation of Example 1 is more stable and uniform than that of the finished product in Comparative Example 1.

[0105] Example 2 and Comparative Example 2

[0106] The steel plate compositions of Example 2 and Comparative Example 2 are shown below:

[0107] Table 3. Main component parameters (wt%) of Example 2 and Comparative Example 2 of this application

[0108] Ingredients Si Mn Al Example 2 4 1.2 1.2 Comparative Example 2 4 1.2 1.2

[0109] The main parameters of the normalization process are calculated as follows:

[0110] Table 4. Main process parameters of Example 2 and Comparative Example 2 of this application

[0111]

[0112]

[0113] Comparing the grain size of the normalized non-oriented silicon steel plates produced using Example 2 and Comparative Example 2:

[0114] Comparative Example 2: The average grain size of the normalized plate was 66.94 μm, the standard deviation was 61.96 μm, and the data volume was 211.

[0115] Example 2: The average grain size of the normalized plate was 66.73 μm, the standard deviation was 31.31 μm, and the data volume was 211.

[0116] Using the process of Example 2, while keeping the average grain size of the non-oriented normalized plate unchanged, Example 2 reduces the standard deviation of grain size by 30.65 μm compared to Comparative Example 2, and the grain size of Example 2 is significantly more uniform than that of Comparative Example 2.

[0117] The elongation of the finished products produced in Comparative Example 2 and Comparative Group 2 are as follows:

[0118] Comparative Example 2: Mean elongation of finished board 11.73%, standard deviation 3.895%, data volume 100;

[0119] Example 2: The average elongation of the finished board was 11.72%, the standard deviation was 1.787%, and the data volume was 100.

[0120] Using Example 2 in production, the standard deviation decreased from 3.895 to 1.787 while maintaining the mean elongation unchanged, representing a reduction of 54.12%. The elongation of Example 2 is more stable and uniform than that of Comparative Example 2.

[0121] Example 3 and Comparative Example 3

[0122] The steel plate compositions of Example 3 and Comparative Example 3 are shown below:

[0123] Table 5. Main component parameters (wt%) of Example 3 and Comparative Example 3 of this application

[0124] Ingredients Si Mn Al Example 3 3 0.6 0.6 Comparative Example 3 3 0.6 0.6

[0125] The main parameters of the normalization process are calculated as follows:

[0126] Table 6. Main process parameters of Example 3 and Comparative Example 3 of this application

[0127]

[0128] Comparing the grain size of the normalized non-oriented silicon steel plates produced using Example 3 and Comparative Example 3:

[0129] Comparative Example 3: The average grain size of the normalized plate was 140.6 μm, the standard deviation was 131.6 μm, and the data volume was 306.

[0130] Example 3: The average grain size of the normalized plate was 140.5 μm, the standard deviation was 85.84 μm, and the data volume was 306.

[0131] Using the process of Example 3, while keeping the average grain size of the non-oriented normalized plate unchanged, Example 3 reduced the standard deviation of the grain size by 45.76 μm compared to Comparative Example 3, and the grain size of Example 3 was significantly more uniform than that of Comparative Example 3.

[0132] The elongation of the finished products produced in Comparative Example 3 and Comparative Group 3 are as follows:

[0133] Comparative Example 3: Mean elongation of finished board 20.51%, standard deviation 4.583%, data volume 100;

[0134] Example 3: The average elongation of the finished board was 20.52%, the standard deviation was 1.809%, and the data volume was 100.

[0135] Using the process of Example 3 in the application, the standard deviation can be reduced from 4.583 to 1.809 while maintaining the same mean elongation, representing a reduction of 60.53%. The elongation of Example 3 is more stable and uniform than that of Comparative Example 3.

[0136] As can be seen from Examples 1-3 and Comparative Examples 1-3, the normalized substrate for high-quality non-oriented silicon steel used in new energy vehicles produced by the method of this application has a more uniform and stable grain size. The elongation after fracture of non-oriented silicon steel produced using this normalized substrate can have a smaller standard deviation while ensuring the mean value, and the stability is better. In contrast, the normalized substrate for non-oriented silicon steel in the comparative examples produced by conventional processes has poor stability in terms of grain size and elongation after fracture.

[0137] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A normalizing method for non-oriented electrical steel, characterized in that, The method includes: A hot-rolled sheet of non-oriented electrical steel with a set chemical composition is heated to bring the hot-rolled sheet to a target temperature. Under the conditions of the target temperature and the first set time, the heated hot-rolled plate is homogenized. Under the condition of a second set time, the hot-rolled plate after homogenization is subjected to self-homogenization and then cooled to obtain a normalized substrate; wherein, the target temperature, the first set time, and the second set time are calculated based on the chemical composition; The target temperature and the chemical composition satisfy the following relationship: T1=1133-66.67*[Si] +66.67*[Mn]-33.33*[Al]; The first set time and the chemical composition satisfy the following relationship: t1=-44.18+25.45*[Si]+15.00* [Mn] +11.36* [Al]; The second set time and the chemical composition satisfy the following relationship: t2=188.18-25.45*[Si]-15.00* [Mn]-11.36* [Al]; In the formula, T1 represents the target temperature, t1 represents the first set time, t2 represents the second set time, [Si] represents the weight percentage of Si, [Mn] represents the weight percentage of Mn, and [Al] represents the weight percentage of Al.

2. The method according to claim 1, characterized in that, The specified chemical components include: C, Si, Mn, Al, S, Ti, Nb, and Fe; among which, The C content is ≤0.004%, the Si content is 2.2 wt% - 4.0 wt%, the Mn content is 0.1 wt% - 1.2 wt%, the Al content is 0.1 wt% - 1.2 wt%, the S content is ≤0.01 wt%, the Ti content is ≤0.005 wt%, and the Nb content is ≤0.005 wt%.

3. The method according to claim 1, characterized in that, The heating rate is >12.5℃ / s.

4. The method according to claim 1, characterized in that, Under the condition of a second set time, the hot-rolled plate after homogenization is subjected to self-homogenization and then cooled to obtain a normalized substrate, comprising: Under the condition of a second set time, the hot-rolled plate after homogenization is subjected to self-homogenization. Under a set cooling rate, the hot-rolled plate after self-heating is subjected to radiation cooling, followed by air cooling and water cooling to obtain a normalized substrate.

5. The method according to claim 4, characterized in that, The set cooling rate is >5℃ / s.

6. The method according to claim 4 or 5, characterized in that, The endpoint temperature of the radiation cooling is <650℃.

7. A method for preparing non-oriented electrical steel, characterized in that, The method includes the method described in any one of claims 1-6.

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