Fe-si soft magnetic material with yield strength of 750mpa and manufacturing method thereof

Abstract

The application discloses a Fe-Si soft magnetic material with a yield strength of 750 MPa, which contains Fe and inevitable impurities, and further contains the following chemical elements with mass percentage as follows: Si: 3.4%-4.0%, Mn: 0.2-1.1%, Cr: 0.3-1.5%, Cu: 0.2-1.0%, and Al: 0.7-1.5%. The application discloses a manufacturing method of the Fe-Si soft magnetic material with the yield strength of 750 MPa, which comprises the following steps: smelting and casting, hot rolling, annealing of the hot-rolled plate, cold rolling, product annealing, coating of an insulating coating, and the like.

Description

Technical Field

[0001] This invention relates to a metallic material, and more particularly to an Fe-Si soft magnetic material. Background Technology

[0002] With the development of multi-electric / all-electric drive aircraft and the new energy vehicle industry, the demand for drive motors, one of the core components of the power system, is increasing, and the performance requirements are also becoming higher. In particular, aviation drive motors need to withstand a wide temperature range of -55 to +150℃, which places stringent requirements on the efficiency, weight, size and safety of drive motors.

[0003] Taking a typical permanent magnet synchronous drive motor as an example, it needs to have the characteristics of high power density, high reliability, and miniaturization. High speed is one of the important means to improve power density. Under the same power conditions, increasing the rotor speed leads to a reduction in material usage and weight.

[0004] For soft magnetic materials that make up motors, when used as rotors, they need to have sufficiently high strength; when used as stators, they need to have high frequency and low loss to meet the risk of fracture failure under high speed conditions required by high power density drive motors, while reducing energy loss.

[0005] Chinese patent document CN108044100A, published on May 18, 2018, entitled "A Method for Preparing Fe-6.5%Si Soft Magnetic Material Thin Strips by Powder Rolling," discloses a method for preparing Fe-6.5%Si soft magnetic material thin strips by powder rolling. The method involves mixing iron powder and high-purity ferrosilicon powder, powder rolling, degreasing and sintering, multiple cold rolling processes, and multiple intermediate densification sintering processes to obtain 0.1-0.5mm sheet material. This sheet material is then homogenized and sintered at 1265-1335℃ to finally obtain the Fe-6.5%Si alloy strip. However, the preparation process described in this patent document is cumbersome and complex, and it does not specify requirements for the high-frequency iron loss level and mechanical properties of the soft magnetic material. Summary of the Invention

[0006] One of the objectives of this invention is to provide a Fe-Si soft magnetic material with a yield strength of 750 MPa. This soft magnetic material, through the design of its composition, microstructure, and control of special grain boundaries, possesses ultra-high strength, high frequency, and low loss, which can meet the requirements of high efficiency, miniaturization, and high reliability of high power density drive motors.

[0007] To achieve the above objectives, the present invention provides a Fe-Si soft magnetic material with a yield strength of 750 MPa, which contains Fe and unavoidable impurities, and also contains the following chemical elements in the following mass percentages:

[0008] Si: 3.4%-4.0%, Mn: 0.2-1.1%, Cr: 0.3-1.5%, Cu: 0.2-1.0%, Al: 0.7-1.5%.

[0009] Furthermore, in the Fe-Si soft magnetic material with a yield strength of 750 MPa described in this invention, the mass percentage content of each chemical element is as follows:

[0010] Si: 3.4%-4.0%, Mn: 0.2%-1.1%, Cr: 0.3%-1.5%, Cu: 0.2%-1.0%, Al: 0.7%-1.5%; balance Fe and unavoidable impurities.

[0011] The design principles of each chemical element in the Fe-Si soft magnetic material with a yield strength of 750 MPa described in this invention are as follows:

[0012] Si: In the Fe-Si soft magnetic material with a yield strength of 750 MPa described in this invention, Si is an element that increases the resistivity of the alloy. Si can reduce iron loss and also plays a role in solid solution strengthening. To achieve the effects of this invention, the Si content needs to be above 3.4%. However, when the mass percentage of Si is too high, the room temperature processing performance will deteriorate sharply. Therefore, in the Fe-Si soft magnetic material with a yield strength of 750 MPa described in this invention, the mass percentage of Si is controlled between 3.4% and 4.0%.

[0013] Mn: In the Fe-Si soft magnetic material with a yield strength of 750 MPa described in this invention, adding a certain amount of Mn can improve hot rolling plasticity and also increase the material resistivity and reduce losses. However, when the mass percentage of Mn is too high, it will react with residual impurity S to form a large number of fine MnS precipitates, which degrades the electromagnetic properties. Therefore, in the Fe-Si soft magnetic material with a yield strength of 750 MPa described in this invention, the mass percentage of Si is controlled between 0.2% and 1.1%.

[0014] Cr: In the Fe-Si soft magnetic material with a yield strength of 750 MPa described in this invention, Cr can increase the alloy resistivity and reduce iron loss. Simultaneously, Cr has a tendency to segregate at grain boundaries, which can hinder the development of {111} fiber texture and is beneficial to the alloy's magnetism. Therefore, in the Fe-Si soft magnetic material with a yield strength of 750 MPa described in this invention, the mass percentage of Cr is controlled between 0.3% and 1.5%.

[0015] Cu: In the Fe-Si soft magnetic material with a yield strength of 750 MPa described in this invention, adding an appropriate amount of Cu element can improve the material strength through solid solution strengthening without degrading iron loss. To achieve the desired effect, the amount of Cu element added is controlled to be above 0.2%. However, if the mass percentage of Cu element is too high, it will increase the manufacturing cost. Therefore, in the Fe-Si soft magnetic material with a yield strength of 750 MPa described in this invention, the mass percentage of Cu element is controlled between 0.2% and 1.0%.

[0016] Al: In the Fe-Si soft magnetic material with a yield strength of 750 MPa described in this invention, Al element increases both the alloy resistivity and the material strength. To achieve the desired effect, the amount of Al added is above 0.7%. However, excessively high Al content increases the difficulty of smelting. Therefore, in the Fe-Si soft magnetic material with a yield strength of 750 MPa described in this invention, the mass percentage of Al element is controlled between 0.7% and 1.5%.

[0017] Furthermore, the Fe-Si soft magnetic material with a yield strength of 750 MPa described in this invention also contains at least one of the following:

[0018] Sn or Sb: 0.02%-0.45%;

[0019] 0 < REM ≤ 0.01%.

[0020] In the above technical solution of this invention, in order to further optimize the performance of Fe-Si soft magnetic materials with a yield strength of 750 MPa, the steel may also contain Sn or Sb elements and REM rare earth elements. Wherein:

[0021] Sn and Sb: In the Fe-Si soft magnetic material with a yield strength of 750 MPa described in this invention, Sn and Sb are grain boundary segregation elements. Sn and Sb elements can refine the recrystallized structure, utilizing grain refinement to strengthen the material and improve its strength. Furthermore, the segregation of Sn and Sb elements at grain boundaries can prevent internal oxidation during the strip annealing process and improve the material texture, thereby enhancing the magnetic properties of the Fe-Si soft magnetic material. However, when the mass percentage of Sn or Sb is too high, it will refine the grain structure and increase the alloy cost. Therefore, in the high-strength Fe-Si soft magnetic material described in this invention, the mass percentage of Sn and Sb elements is controlled between 0.02% and 0.45%.

[0022] REM: In the Fe-Si soft magnetic material with a yield strength of 750 MPa described in this invention, REM rare earth elements can improve the morphology of oxide inclusions in the molten metal during the smelting process of the soft magnetic material, thereby purifying the liquid. This can promote further grain growth during stress-relief annealing and reduce iron loss P after stress-relief annealing. 10 / 400(S) However, when the mass percentage of REM element is too high, it can lead to surface quality defects in the alloy strip. Therefore, in the high-strength Fe-Si soft magnetic material described in this invention, the mass percentage of REM element is controlled to be 0 < REM ≤ 0.01%.

[0023] Furthermore, in the unavoidable impurities of the Fe-Si soft magnetic material with a yield strength of 750 MPa described in this invention, C ≤ 0.01%, P ≤ 0.02%, and S ≤ 0.005%.

[0024] In the Fe-Si soft magnetic material with a yield strength of 750MPa described in this invention, C, P and S are all impurity elements in non-oriented electrical steel sheets. Under the condition that technical conditions permit, in order to obtain steel with better performance and higher quality, the content of impurity elements in the steel should be reduced as much as possible.

[0025] Furthermore, in the Fe-Si soft magnetic material with a yield strength of 750 MPa described in this invention, the ratio of the contents of overlapping lattice grain boundaries Σ5 and Σ13 around the {100} textured grains satisfies the following relationship: 0.55 ≤ Σ5 / Σ13 ≤ 0.75.

[0026] It should be noted that in this invention, the content of Σ5 is calculated by dividing the length of the Σ5 grain boundary by the total grain boundary length, and similarly, the content of Σ13 is calculated by dividing the length of the Σ13 grain boundary by the total grain boundary length.

[0027] In this invention, after annealing, the Fe-Si soft magnetic material with a yield strength of 750 MPa exhibits a microstructure containing {100} facets, with the {100} crystal planes parallel to the strip surface. During the magnetization process in rotary electric motor technology, this facet texture contains two easily magnetized directions, which helps reduce magnetic losses. Furthermore, the {100} oriented grains are surrounded by coincident lattice grain boundaries Σ5 and Σ13, with the ratio of their contents satisfying the formula: 0.55 ≤ Σ5 / Σ13 ≤ 0.75. This allows the interface energy between {100} oriented grains to be at a low level, which is beneficial for domain wall movement during magnetization and also for preferential movement and growth of the {100} oriented grain interface during stress-relief annealing.

[0028] Furthermore, the finished Fe-Si soft magnetic material with a yield strength of 750 MPa described in this invention has a higher iron loss P. 10 / 400(A) ≤30W / kg, yield strength ≥750MPa.

[0029] In this invention, Fe-Si soft magnetic material with a yield strength of 750 MPa, after annealing, can be directly used as the core rotor of a drive motor. The material does not require stress-relief annealing after lamination. In its annealed state, the material exhibits low high-frequency iron loss P at a frequency of 400 Hz and a maximum magnetic polarization of 1.0 T. 10 / 400(A) With a strength of ≤30W / kg and a yield strength of ≥750MPa, it can meet the requirements of high-speed rotor operation without breakage, while reducing motor iron loss.

[0030] Furthermore, in the Fe-Si soft magnetic material with a yield strength of 750 MPa described in this invention, its iron loss P after stress-relief annealing is... 10 / 400(S) and finished product iron loss P 10 / 400(A) Satisfying the relation: P 10 / 400(s) / P 10 / 400(A) ≤0.7.

[0031] In this invention, P 10 / 400(A) P represents the specific total loss per kilogram of sample before stress-relief annealing at a frequency of 400 Hz and a maximum magnetic polarization of 1.0 T; 10 / 400(S) This represents the total loss per kilogram of sample after stress-relief annealing at a frequency of 800 Hz and a maximum magnetic polarization of 1.0 T.

[0032] Since the iron loss of a motor mainly consists of stator and rotor iron losses, with the stator side material causing the majority of the iron loss, when the Fe-Si alloy soft magnetic material of this invention is used as the stator core of a drive motor, the iron loss can be further reduced by further stress-relief annealing. The Fe-Si alloy soft magnetic material of this invention contains a {100} texture, and the ratio of the lengths of the coincident lattice grain boundaries Σ5 and Σ13 around the {100} oriented grains satisfies the relationship: 0.55 ≤ Σ5 / Σ13 ≤ 0.75. After stress-relief annealing, the high-frequency iron loss P... 10 / 400(S) The iron loss is further reduced to no more than 0.7 compared to the iron loss before stress-relief annealing, which well meets the design requirements of high power density motors for aerospace and electric vehicle drive motors.

[0033] Another objective of this invention is to provide a method for manufacturing Fe-Si soft magnetic material with a yield strength of 750 MPa, which can obtain a Fe-Si soft magnetic material with a yield strength of 750 MPa and high-frequency, low-loss properties.

[0034] To achieve the above objectives, the present invention provides a method for manufacturing Fe-Si soft magnetic materials with a yield strength of 750 MPa, comprising the following steps:

[0035] Smelting and casting;

[0036] Hot-rolled;

[0037] Annealing of hot-rolled steel sheet;

[0038] Cold rolling;

[0039] Annealing of finished products: In the heating section, the heating rate is controlled within the range of 300℃ / s-400℃ / s in the range of 610℃-820℃, the temperature of the soaking section is 820℃-900℃, and the holding time of the soaking section is 5s-10s.

[0040] Apply an insulating coating.

[0041] In the manufacturing method described in this invention, the heating rate is controlled within the range of 300℃ / s to 400℃ / s in the heating range of 610℃-820℃ because: when the heating temperature exceeds 610℃, recrystallization nucleation begins inside the alloy strip. By controlling the heating rate in this heating range to be above 300℃ / s, it is beneficial to form more Σ5 grain boundaries around the {100} oriented grains; while when the heating rate exceeds 400℃ / s, the material will generate significant thermal stress, leading to strip deformation. At the same time, if the heating time is too short, it is not conducive to recrystallization nucleation.

[0042] In this invention, the temperature T of the soaking zone is controlled to satisfy: 820℃≤T≤900℃, and the dwell time in the soaking zone is 5s-10s. This allows the grains in the strip to grow appropriately, and the ratio of the lengths of the overlapping lattice grain boundaries Σ5 and Σ13 around the {100} oriented grains is between 0.55 and 0.75. This is beneficial for the preferential growth of {100} oriented grains during stress-relief annealing.

[0043] In this invention, excessively high homogenization temperature or excessively long homogenization time may lead to an increase in recrystallized structures and excessively large grains, thereby reducing the yield strength. Therefore, the upper limit of the homogenization temperature can be controlled to not exceed 900°C, and the upper limit of the homogenization time can be controlled to not exceed 10 seconds.

[0044] Furthermore, in the manufacturing method described in this invention, stress-relief annealing is also included after the step of applying the insulating coating.

[0045] Furthermore, in the stress-relief annealing step of the manufacturing method described in this invention: the annealing temperature is 760℃-860℃, and the holding time is 70-200min.

[0046] In this invention, in order to meet the requirement of lower iron loss in the motor core stator, the finished annealed strip can be further subjected to stress-relieving annealing treatment. The homogenization temperature can be between 760°C and 860°C, and the holding time can exceed 70 minutes to allow the grain structure to grow fully and reduce the iron loss of the material. However, the homogenization time should not exceed 200 minutes, otherwise the production efficiency will be too low and the manufacturing cost will increase.

[0047] The Fe-Si soft magnetic material with a yield strength of 750 MPa and its manufacturing method described in this invention have the following advantages and beneficial effects:

[0048] The Fe-Si soft magnetic material with a yield strength of 750MPa described in this invention, through the design of material composition, microstructure and special grain boundary control, has ultra-high strength, high frequency and low loss, which can meet the requirements of high efficiency, miniaturization and high reliability of high power density drive motors.

[0049] In some embodiments, the finished iron loss P of the Fe-Si soft magnetic material with a yield strength of 750 MPa described in this invention is... 10 / 400(A) ≤30W / kg, yield strength ≥750MPa.

[0050] In some embodiments, the iron loss P of the Fe-Si soft magnetic material with a yield strength of 750 MPa described in this invention... 10 / 400(S) and finished product iron loss P 10 / 400(A) Satisfying the relation: P 10 / 400(s) / P 10 / 400(A) ≤0.7. Detailed Implementation

[0051] The following will further explain and illustrate the Fe-Si soft magnetic material with a yield strength of 750MPa and its manufacturing method described in this invention with reference to specific embodiments. However, this explanation and illustration do not constitute an undue limitation on the technical solution of this invention.

[0052] Examples 1-7 and Comparative Examples 1-4

[0053] The high-strength Fe-Si soft magnetic materials of Examples 1-7 and the comparative materials of Comparative Examples 1-4 of the present invention were prepared by the following steps:

[0054] (1) Smelting and casting: blast furnace molten iron undergoes molten iron pretreatment, converter smelting, RH refining, and continuous casting and rolling to obtain cast billets.

[0055] (2) Hot rolling: The billet heating temperature can be 1200℃, the holding time is 2h, the final rolling temperature can be 900℃, and finally hot rolled to a thickness of 2.0mm.

[0056] (3) Annealing of hot-rolled plate: In order to fully recrystallize the grain structure of hot-rolled plate, the holding temperature can be 950℃ and the holding time can be 5min.

[0057] (4) Cold rolling: Cold rolling yields a finished product with a thickness of 0.30 mm.

[0058] (5) Finished product annealing: In the heating and heating section, the heating rate is controlled in the range of 300℃ / s-400℃ / s, the temperature of the heat soaking section is 820℃-900℃, and the heat soaking section holding time is 5s-10s.

[0059] (6) Applying an insulating coating: After the finished product is annealed, an insulating coating is applied to the surface of the material.

[0060] In some implementations, stress-relief annealing can be performed after the step of applying the insulating coating.

[0061] In some more specific embodiments, the finished material can be cut into Epstein square magnetic test specimens and then subjected to stress-relief annealing: the stress-relief annealing temperature is 760℃-860℃ and the holding time is 70-200min.

[0062] Table 1 lists the mass percentage of each chemical element in the Fe-Si soft magnetic materials with a yield strength of 750 MPa in Examples 1-7 of the present invention and the comparative materials in Comparative Examples 1-4.

[0063] Table 1. (wt%, balance Fe and unavoidable impurities other than C, P and S)

[0064] serial number Si Mn Cr Cu Al Sn or Sb REM C P S Example 1 3.4 1.1 1.5 0.5 1.5 Sn: 0.45 - 0.01 0.01 0.002 Example 2 3.5 0.8 0.5 0.8 1.0 Sn: 0.30 - 0.004 0.01 0.002 Example 3 3.6 0.5 0.7 0.5 0.9 - 0.001 0.003 0.015 0.003 Example 4 3.7 0.4 1.2 0.8 0.8 - 0.01 0.004 0.01 0.005 Example 5 3.8 0.3 0.6 0.8 1.0 Sb:0.02 - 0.002 0.02 0.002 Example 6 3.9 0.6 0.8 0.5 1.2 Sn: 0.10 - 0.002 0.01 0.002 Example 7 4.0 0.2 0.3 0.2 0.7 - - 0.002 0.015 0.001 Comparative Example 1 2.0 0.5 - 0.6 0.7 - - 0.003 0.015 0.002 Comparative Example 2 2.5 0.2 0.7 - 0.8 - - 0.003 0.015 0.002 Comparative Example 3 3.5 0.5 0.5 0.5 0.8 - - 0.003 0.01 0.002 Comparative Example 4 3.4 1.0 0.5 0.5 0.5 - - 0.003 0.01 0.002

[0065] Table 2 lists the specific process parameters of the Fe-Si soft magnetic materials with a yield strength of 750 MPa in Examples 1-7 of the present invention and the comparative materials in Comparative Examples 1-4.

[0066] Table 2.

[0067]

[0068] Samples were taken from the Fe-Si soft magnetic materials with a yield strength of 750 MPa obtained in Examples 1-7 and the comparative materials of Comparative Examples 1-4 before and after stress-relief annealing, and the iron loss P after stress-relief annealing was measured. 10 / 400(S) Iron loss P of finished product before stress relief annealing 10 / 400(A) The yield strength and the ratio of Σ5 to Σ13 content of overlapping lattice grain boundaries around the {100} textured grains were tested, and the results are listed in Table 3. The specific testing methods are as follows:

[0069] Iron loss P 10 / 400 Test: Based on the square circle method of the standard "GB / T10129-2019 Measurement Method of Medium Frequency Magnetic Properties of Electrical Steel Strips (Sheets)".

[0070] Yield strength performance index test: based on the standard GB / T 228.1-2010 Metallic materials, tensile testing - Part 1: Test method at room temperature.

[0071] Statistical analysis of overlapping lattice grain boundaries Σ5 and Σ13: Electron backscatter diffraction (EBSD) was used for testing, referring to the standard GB / T 19501-2013 "General Rules for Microbeam Analysis Electron Backscatter Diffraction Analysis". 15*20mm samples were randomly cut from finished annealed strips, with the observation surface being an RD*ND cross section. The samples were ground, mechanically polished, and electrolytically polished, then observed under a field emission scanning electron microscope equipped with an EBSD testing system. The test conditions were set as follows: reference voltage 20kV, current 30μA, scan step 1μm. Four fields of view were randomly selected for each sample, and the total statistical area was no less than 1,000,000μm. 2 Then, the overlapping lattice grain boundary length and total grain boundary length are calculated using the equipment's EBSD data analysis software, and the ratio of Σ5 and Σ13 contents is calculated.

[0072] Table 3 lists the performance test results of the Fe-Si soft magnetic materials with a yield strength of 750 MPa in Examples 1-7 of the present invention and the comparative materials in Comparative Examples 1-4.

[0073] Table 3.

[0074]

[0075] As can be seen from Table 3 above, the key parameters of Examples 1-7 of the present invention, including the control of alloy chemical composition during the smelting process, the heating rate in a specific range during the finished product annealing process, and the holding temperature and time, are all within the design range of the present invention. Therefore, the iron loss P of the obtained Fe-Si soft magnetic material with a yield strength of 750MPa is [not specified]. 10 / 400(A) All values ​​are less than 27.5 W / kg, and the yield strength is greater than or equal to 750 MPa. The iron loss P after stress-relief annealing is... 10 / 400(S) and finished product iron loss P 10 / 400(A) The ratios are all less than 0.689, which meets the requirement that the rotor core can rotate at high speed without the risk of fracture failure.

[0076] Furthermore, in the microstructure of the finished product before stress relief annealing, the ratio of the contents of Σ5 and Σ13 of the overlapping lattice grain boundaries around the {100} oriented grains is between 0.55 and 0.7.

[0077] After stress-relief annealing, the high-frequency iron loss is further significantly reduced, less than 0.7 compared with the iron loss before stress-relief annealing. When used as a stator material for motors, it can meet the requirements of high-frequency low loss of stator.

[0078] In contrast, although the manufacturing process and finished product annealing process of Comparative Examples 1 and 2 are within the scope of this invention, their chemical composition is not within the scope of this invention. Therefore, the high-frequency iron loss and yield strength of the finished products are not within the scope of this invention.

[0079] Furthermore, although the chemical composition of Comparative Example 3 is within the scope of this invention, its heating rate is not within the scope of this invention, and its holding time exceeds 10s, resulting in the ratio of Σ5 and Σ13 of the overlapping lattice grain boundaries around the {100} oriented grains being less than 0.55, thus limiting the reduction of high-frequency iron loss after stress-relief annealing.

[0080] Although Comparative Example 4 has chemical composition and heating rate within the scope of the invention, its soaking temperature and holding time are not within the scope of the invention. This would result in the ratio of Σ5 and Σ13 of the overlapping lattice grain boundaries around the {100} oriented grains being outside the scope of the invention, and the reduction in high-frequency iron loss after stress-relief annealing would be limited.

[0081] It should be noted that the scope of protection of the prior art in this invention is not limited to the embodiments given in this application. All prior art that does not contradict the solution of this invention, including but not limited to prior patent documents, prior publications, prior public uses, etc., can be included in the scope of protection of this invention.

[0082] Furthermore, the combination of the technical features in this case is not limited to the combination methods described in the claims of this case or the combination methods described in the specific embodiments. All technical features described in this case can be freely combined or combined in any way, unless they contradict each other.

[0083] It should also be noted that the embodiments listed above are merely specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and similar changes or modifications made thereto are those that can be directly derived or easily conceived by those skilled in the art from the content disclosed in the present invention, and should all fall within the protection scope of the present invention.

Claims

1. A Fe-Si soft magnetic material with a yield strength of 750 MPa, containing Fe and unavoidable impurities, characterized in that, It also contains the following chemical elements in the following percentages by mass: Si: 3.4%-4.0%, Mn: 0.2-1.1%, Cr: 0.3-1.5%, Cu: 0.2-1.0%, Al: 0.7-1.5%.

2. The Fe-Si soft magnetic material with a yield strength of 750 MPa as described in claim 1, characterized in that, Its mass percentage content of each chemical element is as follows: Si: 3.4%-4.0%, Mn: 0.2%-1.1%, Cr: 0.3%-1.5%, Cu: 0.2%-1.0%, Al: 0.7%-1.5%; balance Fe and unavoidable impurities.

3. The Fe-Si soft magnetic material with a yield strength of 750 MPa as described in claim 1 or 2, characterized in that, It also contains at least one of the following: Sn or Sb: 0.02%-0.45%; 0 < REM ≤ 0.01%.

4. The Fe-Si soft magnetic material with a yield strength of 750 MPa as described in claim 1 or 2, characterized in that, Among the unavoidable impurities, C ≤ 0.01%, P ≤ 0.02%, and S ≤ 0.005%.

5. The Fe-Si soft magnetic material with a yield strength of 750 MPa as described in claim 1 or 2, characterized in that, The ratio of the contents of Σ5 and Σ13 of the overlapping lattice grain boundaries around the {100} textured grains satisfies the following relationship: 0.55≤Σ5 / Σ13≤0.

75.

6. The Fe-Si soft magnetic material with a yield strength of 750 MPa as described in claim 1 or 2, characterized in that, Its finished product iron loss P 10 / 400(A) ≤30W / kg, yield strength ≥750MPa.

7. The Fe-Si soft magnetic material with a yield strength of 750 MPa as described in claim 1 or 2, characterized in that, Its iron loss P after stress-relief annealing 10 / 400(S) and finished product iron loss P 10 / 400(A) Satisfying the relation: P 10 / 400(s) / P 10 / 400(A) ≤0.

7.

8. A method for manufacturing Fe-Si soft magnetic material with a yield strength of 750 MPa as described in any one of claims 1-7, characterized in that, Including the following steps: Smelting and casting; Hot-rolled; Annealing of hot-rolled steel sheet; Cold rolling; Annealing of finished products: In the heating section, the heating rate is controlled within the range of 300℃ / s-400℃ / s in the range of 610℃-820℃, the temperature of the soaking section is 820℃-900℃, and the holding time of the soaking section is 5s-10s. Apply an insulating coating.

9. The manufacturing method as described in claim 8, characterized in that, Stress-relief annealing is also included after the step of applying the insulating coating.

10. The manufacturing method as described in claim 9, characterized in that, In the stress-relief annealing step: the annealing temperature is 760℃-860℃, and the holding time is 70-200min.

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