TWI673370B - Electromagnetic steel sheet, method of forming the same and method of forming ferrite core - Google Patents

Abstract

The invention provides an electromagnetic steel sheet, a manufacturing method thereof, and a manufacturing method of an iron core. In the manufacturing method of the electromagnetic steel sheet, the magnetic characteristics of the electromagnetic steel sheet are improved by adjusting the alloy embryo composition and process parameters, so that the stress relief annealing process can be omitted in the iron core manufacturing process.

Description

Electromagnetic steel sheet, manufacturing method thereof and manufacturing method of iron core law

The invention relates to a method for manufacturing an electromagnetic steel sheet, and in particular to a method for manufacturing a full-process electromagnetic steel sheet, which adjusts process parameters to improve the magnetic characteristics of the electromagnetic steel sheet. When this electromagnetic steel sheet is applied, the stress relief annealing process can be omitted.

Generally speaking, iron cores (such as EI iron cores, rolled iron cores, or other iron cores) are made by using a semi-processed electromagnetic steel sheet, which is laminated after pressing to form an iron core, and then is subjected to stress relief annealing. Afterwards, this iron core is passed into a wire to manufacture a transformer.

The reason why common iron core manufacturing processes require stress relief annealing is mainly because the residual stress generated in the stacking of the punched sheets causes the low magnetic field magnetic flux density (B ₃ ) to decrease and the apparent power to increase. The stress-relief annealing of the iron core can restore the low magnetic field magnetic flux density and reduce the apparent power, which improves the efficiency of the transformer. Therefore, stress relief annealing is a necessary cost in the core manufacturing process.

However, the cost of stress relief annealing is as high as several thousand yuan / ton. As far as the application side of electromagnetic steel sheet is concerned, it is undoubtedly a big burden. Therefore, there is an urgent need to propose a method for manufacturing a full-process electromagnetic steel sheet, which can improve the magnetic characteristics of the electromagnetic steel sheet in advance, so that the magnetic characteristics of the electromagnetic steel sheet are sufficient to compensate the magnetic characteristics caused by residual stress when the iron core is made Degradation. Therefore, the application end of the electromagnetic steel sheet can be omitted from the stress relief annealing process, and the manufacturing cost of the product can be reduced.

Therefore, one aspect of the present invention proposes a method for manufacturing an electromagnetic steel sheet. In some embodiments, the method for manufacturing the electromagnetic steel sheet includes the following steps. First, an alloy embryo is provided, which contains 1.8 weight percent (wt.%) To 2.5 wt.% Silicon, 0.1 wt.% To 1.5 wt.% Aluminum, and a balance of iron. Next, the alloy billet is subjected to a hot rolling process to form a hot rolled material. Then, a first annealing process is performed on the hot-rolled material to form an annealed material. Next, a cold rolling process is performed on the annealed material to form a cold rolled material. After that, a second annealing process is performed on the cold-rolled material to obtain an electromagnetic steel sheet. This second annealing process is performed at 900 ° C. to 1000 ° C. for 50 seconds to 100 seconds, and is cooled at a cooling rate of not more than 10 ° C./second.

According to some embodiments of the present invention, the reheating temperature of the hot rolling process is 1000 ° C to 1200 ° C.

According to some embodiments of the present invention, the first annealing process is performed at 850 ° C to 1150 ° C.

According to some embodiments of the present invention, the first annealing process is performed for 50 seconds to 300 seconds.

According to some embodiments of the present invention, the first annealing process is more inclusive. After the annealing, a pickling step is performed.

According to some embodiments of the present invention, the reduction rate of the cold rolling process is not less than 60%.

According to some embodiments of the present invention, the first annealing process and the cold rolling process are performed once respectively.

According to some embodiments of the present invention, the hot rolling process has a finishing temperature of 800 ° C to 950 ° C.

According to some embodiments of the present invention, after the rolling, the hot rolling process further includes a coiling step, and the temperature of the coiling step is 550 ° C to 750 ° C.

According to another aspect of the present invention, an electromagnetic steel sheet is provided, which is produced by the above-mentioned method for manufacturing an electromagnetic steel sheet. This electromagnetic steel sheet has an iron loss value (W _15/60 ) of not more than 3.85 W / Kg, a low magnetic field magnetic flux density B ₃ of not less than 1.37 T, a high magnetic field magnetic flux density B _{50 of} not less than 1.70 T, and Apparent power greater than 4.7VA / Kg.

Another aspect of the present invention provides a method for manufacturing an iron core. In some embodiments, the method for manufacturing the iron core includes providing the aforementioned electromagnetic steel sheet. Next, a stamping process is performed on the electromagnetic steel sheet to form a plurality of iron chips. Then, these iron chips are stacked to form an iron core. After that, the core is packaged. The manufacturing method of the core eliminates the need for a stress relief annealing process.

100, 200‧‧‧ methods

110‧‧‧ provide alloy embryo

120‧‧‧ hot rolling process of alloy embryo to form hot rolled material

130‧‧‧The first annealing process is performed on the hot rolled material to form an annealed material

140‧‧‧ cold rolling of annealed material to form cold rolled material

150‧‧‧ The second annealing process is performed on the cold-rolled material to produce electromagnetic steel sheets

210‧‧‧ provide electromagnetic steel sheet

220‧‧‧Punching the electromagnetic steel sheet to form a plurality of iron chips

230‧‧‧ stacked iron chips to form an iron core

In order to make the above and other objects, features, advantages, and embodiments of the present invention more comprehensible, the detailed description of the drawings is as follows: 1 is a schematic flowchart of a method for manufacturing an electromagnetic steel sheet according to some embodiments of the present invention.

FIG. 2 is a schematic flowchart of a manufacturing method of an iron core according to some embodiments of the present invention.

Generally speaking, when processing electromagnetic steel sheets to obtain iron cores for transformers, for example, the stamping process and stacking process of the processing process are likely to cause residual stress in the iron core, resulting in a decrease in the low magnetic field magnetic flux density (B ₃ ). And the increase in apparent power. In order to eliminate the residual stress in the iron core, an additional stress-relief annealing process is often required at the application end of the electromagnetic steel sheet, for example, the stress-relief annealing process is performed after the lamination process or between the stamping process or the lamination process. This stress relief annealing process requires the use of high temperature equipment, which results in an increase in process and cost at the application end.

An object of the present invention is to improve the magnetic characteristics of an electromagnetic steel sheet in advance during the manufacturing process of the electromagnetic steel sheet. Therefore, when processing the electromagnetic steel sheet at the application end, the foregoing stress relief annealing process can be omitted, and the iron core made from the electromagnetic steel sheet can still have good magnetic characteristics. The magnetic characteristics achieved by the electromagnetic steel sheet of the present invention can ensure that the iron core can have appropriate iron core iron loss value, exciting current, apparent power, and iron core unit weight iron core when it is subsequently applied to the manufacture of the iron core.

Specifically, if the excitation current and the apparent power are too high under the excitation conditions, the corresponding magnetic field range is 200A / m to 400A / m, so the magnetic characteristics of the electromagnetic steel sheet can be adjusted to adjust the low magnetic field density. B ₃ (ie, the magnetic flux density in a magnetic field of 300 A / m) is the main improvement factor.

In order to achieve the above object, the manufacturing method of the electromagnetic steel sheet of the present invention is adjusted according to the following directions: (1) adjusting the content of silicon and aluminum in the alloy embryo of the electromagnetic steel sheet to increase the low magnetic field magnetic flux density (B ₃ ); 2) Increasing the annealing temperature of the annealing coating line (ACL, for example: the final annealing process), so that the crystal grains are grown and the interfacial area is reduced to increase the low magnetic field magnetic flux density; and (3) after the final annealing process, Slow cooling reduces differential emissions and residual stress. According to this, an electromagnetic steel sheet with good magnetic properties can be prepared, and the stress-relief annealing process can be omitted at the application end of the electromagnetic steel sheet.

The electromagnetic steel sheet application end referred to in the present invention may be, for example, an iron core manufacturer, a transformer manufacturer, or a manufacturer in another similar field.

The magnetic characteristics referred to herein in the present invention can be _evaluated , for example, from an iron loss value (W _15/60 ), a low magnetic field magnetic flux density (B ₃ ), a high magnetic field magnetic flux density (B ₅₀ ), and an apparent power.

The excitation current (I _ex ) referred to here is the minimum current required to establish the core magnetic circuit during the no-load excitation process.

The apparent power (VA / Kg) referred to here is the power required to be input per unit weight in the process of no-load excitation. Furthermore, the apparent power and the aforementioned exciting current substantially represent similar or identical characteristics, and their relationship is shown in the following formula (1): VA / Kg = V _ex × I _ex / Kg (1)

Where V _ex represents the applied voltage, and Kg represents the core weight, both of which are fixed values.

The iron loss (W / Kg) referred to here is during the no-load excitation process. The loss per unit weight of iron core.

Please refer to FIG. 1, which is a schematic flowchart of a method for manufacturing an electromagnetic steel sheet according to some embodiments of the present invention. In the method 100 of FIG. 1, step 100 first provides an alloy embryo. In some embodiments, this alloy blank comprises 1.8 weight percent (wt.%) To 2.5 wt.% Silicon, 0.1 wt.% To 1.5 wt.% Aluminum, and the balance of iron. In some embodiments, the alloy embryo may further contain trace elements of not more than 0.5 wt.%.

This alloy embryo uses a specific content of silicon and aluminum to reduce the iron loss value of the electromagnetic steel sheet and increase the magnetic flux density, especially the high magnetic field magnetic flux density (B ₅₀ ). Therefore, if the silicon content of the alloy embryo is less than 1.8 wt.% Or the aluminum content is less than 0.1 wt.%, The iron loss value of the electromagnetic steel sheet is too high. On the other hand, if the silicon content of the alloy embryo is greater than 2.5 wt.% Or the aluminum content is greater than 1.5 wt.%, The magnetic flux density (B ₃ and B ₅₀ ) of the electromagnetic steel sheet is not good.

In some embodiments, trace elements may include unavoidable carbon, manganese, phosphorus, sulfur, and the like. Preferably, the carbon content may be, for example, not more than 0.005 wt.% (About 30 ppm), the manganese content may be, for example, not more than 0.3 wt.%, The phosphorus content may be, for example, not more than 0.02 wt.%, And the sulfur content may be, for example, not more than 0.005 wt. .%.

Next, as shown in step 120, a hot rolling process is performed on the alloy blank to form a hot rolled material. In some embodiments, this hot rolling process may, for example, heat the alloy billet to a reheating temperature of 1000 ° C to 1200 ° C. After hot rolling, the finish rolling temperature may be, for example, about 800 ° C to 950 ° C. When the reheating temperature is lower than 1000 ° C, the hot rolling process cannot be performed. On the other hand, when the reheating temperature is higher than 1200 ° C, the precipitates in the alloy embryo may be dissolved and the grains may be excessively formed. Long, thus deteriorating the iron loss value. In addition, if the above-mentioned finish rolling temperature is too low, it means that the reheat temperature is insufficient, and the predetermined reduction rate cannot be achieved. If the above-mentioned finish rolling temperature is too high, it means that the reheating temperature is too high, and the practical feasibility is not high. In some examples, the reduction rate of this hot rolling process may be, for example, greater than 99%. In still other examples, the thickness of the hot-rolled material may be, for example, 1.8 mm to 2.5 mm. In some embodiments, the hot rolling process may further include a coiling step after the rolling, and cooling to room temperature. The coiling temperature in this coiling step may be, for example, 550 ° C to 750 ° C.

Next, as shown in step 130, a first annealing process is performed on the hot-rolled material to form an annealed material. In some embodiments, the first annealing process may be performed at, for example, 850 ° C to 1150 ° C for 50 seconds to 300 seconds. If the temperature of the first annealing process is less than 850 ° C or the time is less than 50 seconds, the grains in the hot-rolled material are too small, which is likely to cause defects in the grain boundaries, resulting in a high magnetic field flux density (B ₅₀ ) that is highly related to the texture of the structure. Degradation. On the other hand, due to process limitations, the temperature of the first annealing process should not be higher than 1150 ° C or the time should not be longer than 300 seconds.

In some embodiments, before the annealing, the first annealing process further includes steps such as unwinding and heating. In other embodiments, after the annealing, the first annealing process further includes steps such as cooling and pickling. The pickling here can remove the rust generated on the surface of the steel sheet due to the aforementioned hot rolling process, which is beneficial to the subsequent cold rolling process. In some specific examples, this first annealing process may be performed by, for example, a continuous annealing pickling line (Annealing & Pickling Line; APL).

Next, as shown in step 140, a cold rolling process is performed on the annealed material to form a cold rolled material. In some embodiments, the reduction rate of the cold rolling process may be, for example, not less than 60%. In some examples, the thickness of the cold-rolled material may be, for example, 0.1 mm to 0.5 mm. Generally speaking, this cold rolling process can store strain energy in the cold rolled material to facilitate the grain growth during the subsequent annealing process. Therefore, if the reduction rate of the cold rolling process is less than 60%, sufficient cold energy cannot be obtained for the cold rolled material, which will result in poor annealing and recrystallization effect and low magnetic field density (B ₃ ). In some embodiments, the method 100 performs the first annealing process and the cold rolling process only once.

Then, as shown in step 150, a second annealing process is performed on the cold-rolled material to obtain an electromagnetic steel sheet. In some embodiments, the temperature of the second annealing process may be 900 ° C to 1000 ° C. In some other embodiments, the second annealing process may be performed, for example, for 50 seconds to 100 seconds. If the temperature of the second annealing process is lower than 900 ° C. or the time is shorter than 50 seconds, the grain growth is insufficient (that is, the size is not large enough), resulting in poor low magnetic field magnetic flux density (B ₃ ). On the other hand, if the temperature of the second annealing process is higher than 1000 ° C. or the time is longer than 100 seconds, although the crystal grains can grow significantly, excessively large crystal grains will cause high magnetic field magnetic flux (B ₅₀ ) to deteriorate. In other words, in the manufacturing method of the present invention, the low magnetic field magnetic flux density B ₃ and the high magnetic field magnetic flux density B ₅₀ are two characteristics that are balanced with each other. The appropriate process parameters need to be adjusted to make the electromagnetic steel sheet both good These two properties.

In some embodiments, the second annealing process further includes a slow cooling electromagnetic steel sheet. In some examples, the electromagnetic steel sheet may be cooled, for example, at a cooling rate of not more than 10 ° C / second. In still other examples, the electromagnetic steel sheet may be cooled, for example, at a cooling rate of 3 ° C / second to 10 ° C / second. The slower the cooling rate, the larger the grains can grow, and the fewer impurities and defects in the electromagnetic steel sheet. Therefore, the slower the cooling rate, the lower the iron loss value and the low magnetic field flux density B ₃ can be obtained.

In some embodiments, the electromagnetic steel sheet produced by the method 100 may have, for example, an iron loss value (W _15/60 ) of not more than 3.85 W / Kg, a low magnetic field magnetic flux density B ₃ of not less than 1.37 T, and not less than High magnetic field density B _{50 of} 1.70T, and apparent power of not more than 4.7VA / Kg. When the electromagnetic steel sheet has the above-mentioned properties, when the electromagnetic steel sheet is further punched and stacked into an iron core, it can meet the required properties of the iron core.

Some aspects of the present invention further provide a method for manufacturing an iron core. Please refer to FIG. 2, which is a schematic flowchart of a manufacturing method of an iron core according to some embodiments of the present invention. As shown in step 210 of method 200, first, an electromagnetic steel sheet prepared by the foregoing method is provided.

Next, as shown in step 220, a stamping process (for example, punching) is performed on the electromagnetic steel sheet to form a plurality of iron chips. Then, as shown in step 230, these iron chips are stacked to form an iron core.

In some embodiments, the core may include, but is not limited to, an EI core, a rolled core, a toroidal core, a C-type core, or a can-type core. This iron core can be used in transformers, for example.

In some embodiments, the method 200 does not include a stress relief annealing process. In other words, when the electromagnetic steel sheet produced by the manufacturing method of the present invention is used as an iron core, the process of the stress relief annealing process can be omitted, and the cost of applying the electromagnetic steel sheet can be greatly reduced.

In some embodiments, for example, an electromagnetic steel sheet is made as an EI core. When the size of the center leg of the EI core is 1.5 inches, the EI core can have an iron core loss of not more than 8W, an exciting current of not more than 0.2 Arms, and an apparent power of not more than 8.2VA / Kg. And iron no more than 2.8W / Kg Core iron loss per unit weight.

In other embodiments, when the center leg size of the EI core is 1.75 inches, the EI core may have an iron core loss of not more than 18W, an exciting current of not more than 0.6 Arms, and not more than 11.2VA / The apparent power of Kg, and the iron loss per unit weight of the core of not more than 2.8W / Kg.

Hereinafter, specific examples of the manufacturing method of the electromagnetic steel sheet of the present invention and the evaluation results thereof will be described with examples and comparative examples.

Manufacture of electromagnetic steel sheet

Example 1

An alloy blank (thickness: 450 mm) with a composition of 2.5 wt.% Silicon, 0.1 wt.% Aluminum, and the balance of iron was heated to 1000 ° C, and then hot-rolled to a hot-rolled material having a thickness of 2.5 mm. 800 ° C. Next, continuous annealing was performed at 1000 ° C. for 60 seconds, and pickling was performed to form an annealed material. Then, the annealed material was cold rolled to a thickness of 0.5 mm to form a cold rolled material. Thereafter, the cold-rolled material was subjected to a final annealing process at 980 ° C. for 60 seconds (corresponding to a line speed of 100 mpm), and then cooled at a cooling rate of 8 ° C./sec to obtain a full-process electromagnetic steel sheet of Example 1.

Example 2

An alloy blank (thickness: 450 mm) with a composition of 1.8 wt.% Silicon, 0.5 wt.% Aluminum and the balance of iron was heated to 1000 ° C, and then hot-rolled to a hot-rolled material with a thickness of 2.5 mm. 800 ° C. Next, continuous annealing was performed at 900 ° C. for 100 seconds, and pickling was performed to form an annealed material. Then, the annealed material was cold rolled to a thickness of 0.5 mm to form a cold rolled material. After that, the cold-rolled material was subjected to a final annealing process at 930 ° C for 60 seconds, and then cooled at 5 ° C / sec. Speed cooling to obtain the electromagnetic steel sheet of Example 2.

Comparative Example 1

Comparative Example 1 was performed using similar process conditions to Example 1. The series of process conditions different from those in Example 1 are shown in Table 1, and will not be repeated here.

Comparative Example 2

Comparative Example 2 was performed using similar process conditions to Example 2. The series of process conditions different from those in Example 2 are shown in Table 1, and will not be repeated here.

As can be seen from Table 1 above, in Examples 1 and 2 of the present invention, the silicon and aluminum contents in the specification are used, and specific parameters of hot rolling, first annealing process, cold rolling, and second annealing process (or final annealing process) can be used to produce An electromagnetic steel sheet having predetermined magnetic characteristics is obtained. On the other hand, the silicon or aluminum content of Comparative Examples 1 and 2 exceeds the predetermined range, and / or the process parameters are outside the use range. Therefore, the low magnetic field magnetic flux density and high magnetic field magnetic flux density of the electromagnetic steel sheets of Comparative Examples 1 and 2 , Iron loss value and apparent power cannot fully meet the predetermined standards. If the electromagnetic steel sheet that does not meet the predetermined magnetic characteristics is used in the manufacturing process of the iron core, and the stress relief annealing process is omitted, there is a disadvantage of poor core properties. For details, please refer to Examples 3 to 4 and Comparative Examples 3 to 8 below.

Manufacturing iron cores from electromagnetic steel sheets

Example 3

Example 3 is a semi-finished product formed by applying the EI stamping, core stacking, and packaging into a wire of the electromagnetic steel sheet of Example 1. The center leg size of this semi-finished product is 1.5 inches. The core semi-finished product of Example 3 was subjected to core iron loss (P _ex ; unit: W), exciting current (I _ex ; unit: Arms), apparent power (unit: VA / Kg), and core core unit weight iron loss ( Unit: W / Kg). Table 2 shows the magnetic characteristics and corresponding standards of Example 3.

Example 4

Example 4 is a method of making the electromagnetic steel sheet of Example 2 into a semi-finished product according to the method implemented in Example 3. The center leg size of the semi-finished product is 1.75 inches. Table 3 shows the magnetic characteristics and corresponding standards of Example 4.

Comparative Example 3

In Comparative Example 3, the electromagnetic steel sheet of Comparative Example 1 was fabricated into a semi-finished product according to the method performed in Example 3. The size of the central leg portion of the semi-finished product was 1.5 inches. Table 2 shows the magnetic characteristics and corresponding standards of Comparative Example 3.

Comparative Example 4

Comparative Example 4 is performed in a similar manner to Comparative Example 3, except that the manufacturing process of the core of Comparative Example 4 is further included between the core stacking and the wire entry, and an additional stress relief annealing process is performed. The process parameters of this stress relief annealing process are as follows: at a temperature rise rate of 200 ° C / hour, the laminated core is heated The temperature was maintained at 750 ° C for 2 hours; after that, the temperature was lowered to 400 ° C at a speed of 70 ° C / hour; then, additional nitrogen was passed in and the temperature was lowered to 200 ° C and the furnace was released. Table 2 shows the respective magnetic characteristics and corresponding standards of Comparative Example 4.

Comparative Example 5

The electromagnetic steel sheet of Comparative Example 5 was produced using a manufacturing method similar to that of Example 1, but the electromagnetic steel sheet of Comparative Example 5 was not subjected to the final annealing process, and belongs to a half-process electromagnetic steel sheet. After this electromagnetic steel sheet was made into a semi-finished product according to the method of Comparative Example 4, the magnetic characteristics were tested. Table 2 shows the magnetic characteristics and corresponding standards of Comparative Example 5.

Comparative Example 6

Comparative Example 6 is a semi-finished product made of the electromagnetic steel sheet of Comparative Example 2 according to the method performed in Example 4, wherein the central leg size of the semi-finished product is 1.75 inches. Table 3 shows the respective magnetic characteristics and corresponding standards of Comparative Example 6.

Comparative Example 7

Comparative Example 7 is performed in a similar manner to Comparative Example 6, except that the manufacturing process of the core of Comparative Example 7 is further included between the core stacking and the wire entry, and an additional stress relief annealing process is performed. The process parameters of this stress relief annealing process are as follows: at a temperature increase rate of 200 ° C / hour, the laminated iron core is heated to 750 ° C and held at a temperature for 2 hours, and then cooled to 70 ° C / hour and reduced to 400 ° C. Then, additional nitrogen was passed in and the temperature was lowered to 200 ° C and the furnace was released. Table 3 shows the respective magnetic characteristics and corresponding standards of Comparative Example 7.

Comparative Example 8

The electromagnetic steel sheet of Comparative Example 8 is similar to that of Example 2. The electromagnetic steel sheet obtained by the manufacturing method, but the electromagnetic steel sheet of Comparative Example 8 is not subjected to the final annealing process, and belongs to a half-process electromagnetic steel sheet. After this electromagnetic steel sheet was made into a semi-finished product according to the method of Comparative Example 7, the magnetic characteristics were tested. Table 3 shows the respective magnetic characteristics and corresponding standards of Comparative Example 8.

According to Table 2 and Table 3 above, the iron cores prepared from the electromagnetic steel sheets of Examples 1 and 2 (Examples 3 and 4) do not require stress relief annealing at the application end, and can meet the requirements of the application. Compliant magnetic characteristics standards. On the other hand, the iron cores produced from the electromagnetic steel sheets of Comparative Examples 1 and 2 cannot meet the magnetic characteristics of the application side if stress relief annealing is not performed, as shown in Comparative Examples 3 and 6. Sexual standards. For the application side, although Comparative Examples 4 and 7 can meet its standards, an additional stress relief annealing process must be performed, resulting in an increase in the cost of the application side. In addition, if an electromagnetic steel sheet (such as comparisons 5 and 8) is not used for the final iron core manufacturing for the iron core, stress relief annealing is also required in order to meet the standards specified at the application end.

By applying the manufacturing method of the electromagnetic steel sheet of the present invention, by adjusting the composition of the alloy embryo, controlling the temperature and slow cooling rate of the final thermal annealing process, the growth of the grains, the reduction of the crystal interfacial area, the reduction of the differential discharge, and the residual stress are achieved so that Effect of low magnetic field magnetic flux density increase. According to this, after the manufactured electromagnetic steel sheet is made into an iron core, a predetermined standard of magnetic characteristics of the iron core can be achieved without additional stress relief annealing, so as to reduce the cost of those who apply the electromagnetic steel sheet.

Although the present invention has been disclosed as above in the embodiments, it is not intended to limit the present invention. Any person with ordinary knowledge in the technical field to which the present invention pertains can make various changes and modifications without departing from the spirit and scope of the present invention. Retouching, so the scope of protection of the present invention shall be determined by the scope of the attached patent application.

Claims (8)

A method for manufacturing an electromagnetic steel sheet, comprising: providing an alloy embryo, the alloy embryo comprising: 1.8 weight percent (wt.%) To 2.5 wt.% Silicon; 0.1 wt.% To 1.5 wt.% Aluminum; and A hot rolling process of the alloy blank to form a hot rolled material, wherein the reheating temperature of the hot rolling process is 1000 ° C to 1200 ° C, but does not include 1200 ° C; An annealing process forms an annealed material, wherein the first annealing process is performed at 850 ° C to 1150 ° C; a cold rolling process is performed on the annealed material to form a cold rolled material, wherein a reduction rate of one of the cold rolling processes Not less than 60%; and a second annealing process is performed on the cold-rolled material to obtain an electromagnetic steel sheet, wherein the second annealing process is performed at 900 ° C to 1000 ° C for 50 seconds to 100 seconds, and Cooling at a cooling rate greater than 10 ° C / sec. The method for manufacturing an electromagnetic steel sheet according to item 1 of the scope of patent application, wherein the first annealing process is performed for 50 seconds to 300 seconds. The method for manufacturing an electromagnetic steel sheet according to item 1 of the scope of the patent application, wherein the first annealing process further includes an pickling step after annealing. The electromagnetic steel sheet as described in the first patent application The manufacturing method, wherein the first annealing process and the cold rolling process are performed once respectively. The method for manufacturing an electromagnetic steel sheet according to item 1 of the scope of the patent application, wherein the hot rolling process has a finishing temperature of 800 ° C to 950 ° C. According to the manufacturing method of the electromagnetic steel sheet described in item 5 of the patent application scope, after the rolling, the hot rolling process further includes a coiling step, and one of the coiling steps has a temperature of 550 ° C to 750 ° C. An electromagnetic steel sheet is produced by the method for manufacturing an electromagnetic steel sheet according to any one of claims 1 to 6, wherein the electromagnetic steel sheet has an iron loss value of not more than 3.85 W / Kg ( W _15/60 ), a magnetic flux density B ₃ of not less than 1.37T, a magnetic flux density B _{50 of} not less than 1.70T, and an apparent power of not more than 4.7VA / Kg. A method for manufacturing an iron core includes: providing an electromagnetic steel sheet as described in item 7 of the scope of patent application; performing a stamping process on the electromagnetic steel sheet to form a plurality of iron chips; stacking the iron chips to form an iron A core; and packaging the core, wherein the manufacturing method of the core excludes performing a stress relief annealing process.