An ultra-high strength fe-si soft magnetic material and a method of manufacturing the same

Abstract

The application discloses a kind of super high strength Fe-Si soft magnetic materials, it contains Fe and inevitable impurities, it also contains the following each chemical element with mass percentage content as follows: Si: 3.4%-4.4%, Co: 0.05-1.5%, Al: 0.4-1.5%, Mn: 0.5-1.8%.The application also discloses a kind of super high strength Fe-Si soft magnetic material manufacturing method, it includes the following steps: smelting and casting;Hot rolling and pickling;First cold rolling;Intermediate annealing;Second cold rolling;Finished annealing: control holding temperature is 660 DEG C-800 DEG C, holding time is 10s-20s;Coating insulating coating.The super high strength Fe-Si soft magnetic material is controlled by the composition design of material, so that it has the performance of super high strength, high frequency low loss, can satisfy the requirement of high power density drive motor high efficiency, miniaturization, high reliability.

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 aerospace vehicles 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 more stringent. In particular, aerospace drive motors need to withstand a wide temperature range of -55 to +150℃. Faced with the harsh working environment and the limitations of the power supply system, stringent requirements are placed on the efficiency, weight, size, and safety of drive motors.

[0003] Taking a typical permanent magnet synchronous drive motor as an example, high power density, high reliability, and miniaturization are the main development directions of electric drive systems. High speed is one of the important means to improve power density. Under the same power conditions, as the rotor speed increases, the torque decreases accordingly, and the motor size will decrease, resulting in less material usage and weight reduction.

[0004] For soft magnetic materials that make up motors, when used as rotors, they need to have sufficiently high strength, and when used as stators, they need to have high frequency and low loss, so as 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. This method involves mixing water-atomized iron powder and high-purity ferrosilicon powder to obtain a mixed powder of Fe-4.5% to 6.7%Si. Then, through powder rolling, degreasing and sintering, multiple cold rolling processes, multiple intermediate densification sintering processes, and homogenization high-temperature sintering, a 0.1-0.5 mm thick Fe-6.5%Si alloy strip is obtained. However, the preparation process described in this patent document is cumbersome and complex, unsuitable for large-scale production, and it also does not disclose 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 an ultra-high strength Fe-Si soft magnetic material. This ultra-high strength Fe-Si soft magnetic material, through the control of the material composition design, possesses ultra-high strength, high frequency and low loss properties, 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 an ultra-high strength Fe-Si soft magnetic material, which contains Fe and unavoidable impurities, and also contains the following chemical elements in the following mass percentages:

[0008] Si: 3.4%-4.4%, Co: 0.05-1.5%, Al: 0.4-1.5%, Mn: 0.5-1.8%.

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

[0010] Si: 3.4%-4.4%, Co: 0.05%-1.5%, Al: 0.4%-1.5%, Mn: 0.5%-1.8%; balance Fe and unavoidable impurities.

[0011] The design principles of each chemical element in the ultra-high strength Fe-Si soft magnetic material described in this invention are as follows:

[0012] Si: In the ultra-high strength Fe-Si soft magnetic material described in this invention, Si is the main alloying element. Si increases the resistivity of the alloy and reduces losses; furthermore, Si atoms dissolve into the matrix, providing solid solution strengthening. To achieve the desired effect, the Si content needs to be above 3.4%. However, excessively high Si content leads to an ordered structure, drastically degrading cold-rolling performance. Therefore, in the ultra-high strength Fe-Si soft magnetic material described in this invention, the Si content is controlled between 3.4% and 4.4% by mass.

[0013] Co: In the ultra-high strength Fe-Si soft magnetic material described in this invention, Co is a magnetically beneficial element that can increase magnetic induction intensity and also play a solid solution strengthening role, thereby improving the material strength. To achieve the high strength effect of this invention, the addition amount is above 0.05%. However, when the mass percentage of Co is too high, it will increase the manufacturing cost. Therefore, in the ultra-high strength Fe-Si soft magnetic material described in this invention, the mass percentage of Co is controlled between 0.05% and 1.5%.

[0014] Al: In the ultra-high strength Fe-Si soft magnetic material described in this invention, Al can promote recrystallization grain growth and reduce hysteresis loss. Simultaneously, Al can also increase the alloy resistivity and reduce eddy current loss. To achieve the desired effects, the Al content is controlled to be above 0.4%. However, when the mass percentage of Al is too high, it increases the viscosity of the molten metal, increasing the risk of blockage during casting. Therefore, in the ultra-high strength Fe-Si soft magnetic material described in this invention, the mass percentage of Al is controlled between 0.4% and 1.5%.

[0015] Mn: In the ultra-high strength Fe-Si soft magnetic material described in this invention, Mn can increase the alloy resistivity, reduce iron loss, and also improve strength to a certain extent. Simultaneously, Mn increases the austenite phase region, improving hot-rolling plasticity and microstructure. To achieve the high strength effect of this invention, the addition amount is above 0.5%. However, when the mass percentage of Mn is too high, it increases the risk of strip breakage during cold rolling. Therefore, in the ultra-high strength Fe-Si soft magnetic material described in this invention, the mass percentage of Mn is controlled between 0.5% and 1.8%.

[0016] Furthermore, the ultra-high strength Fe-Si soft magnetic material described in this invention also contains Sn or Sb, with a mass percentage of 0.015%-0.35%.

[0017] In the above technical solution of the present invention, in order to further optimize the ultra-high strength Fe-Si soft magnetic material of the present invention, the steel may also contain Sn or Sb elements. Wherein:

[0018] Sn and Sb: In the ultra-high strength Fe-Si soft magnetic material described in this invention, Sn and Sb are grain boundary segregation elements. Sn and Sb elements can refine the recrystallized structure, utilizing the grain refinement strengthening effect to improve material 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, the alloy cost increases. Therefore, in the ultra-high strength Fe-Si soft magnetic material described in this invention, the mass percentage of Sn or Sb is controlled between 0.015% and 0.35%.

[0019] Furthermore, in the unavoidable impurities of the ultra-high strength Fe-Si soft magnetic material described in this invention, C≤0.01%, P≤0.02%, and S≤0.005%.

[0020] In the ultra-high strength Fe-Si soft magnetic material described in this invention, C, P and S are all impurity elements in the Fe-Si soft magnetic material. 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.

[0021] Furthermore, in the ultra-high strength Fe-Si soft magnetic material described in this invention, the iron loss P... 10 / 400 ≤35W / kg, B 50 ≥1.59T.

[0022] Furthermore, the yield strength of the ultra-high strength Fe-Si soft magnetic material described in this invention is ≥760MPa.

[0023] In this invention, the ultra-high strength Fe-Si soft magnetic material, after annealing, can be directly used as the core rotor of a drive motor. The material exhibits excellent iron loss P at a frequency of 400Hz and a maximum magnetic polarization of 1.0T. 10 / 400 ≤35W / kg, magnetic induction intensity B 50 With a strength of ≥1.59T and a yield strength of ≥760MPa, the rotor can operate at high speed without breaking, while keeping motor losses at a low level.

[0024] Another objective of this invention is to provide a method for manufacturing an ultra-high strength Fe-Si soft magnetic material, which can obtain an ultra-high strength Fe-Si soft magnetic material with high frequency and low loss properties.

[0025] To achieve the above objectives, the present invention provides a method for manufacturing ultra-high strength Fe-Si soft magnetic material, comprising the following steps:

[0026] Smelting and casting;

[0027] Hot rolling and pickling;

[0028] One-time cold rolling;

[0029] Intermediate annealing;

[0030] Secondary cold rolling;

[0031] Finished product annealing: Control the holding temperature at 660℃-800℃ and the holding time at 10s-20s;

[0032] Apply an insulating coating.

[0033] In the manufacturing method described in this invention, during the annealing of the finished product, the holding temperature is controlled within the range of 660-800℃, and the holding time is 10-20s. This is because, in order to obtain a strength of over 760MPa, this invention mainly achieves this through alloy solid solution strengthening and dislocation strengthening. Dislocation strengthening is primarily achieved through the aforementioned finished product annealing process, causing only partial recrystallization of the strip structure. Therefore, the upper limit of the holding temperature should not exceed 800℃, and the holding time should not exceed 20s; otherwise, the yield strength will decrease. Furthermore, to ensure iron loss P... 10 / 400 and magnetic induction intensity B 50 Within the scope of this invention, a certain amount of recrystallization of the strip structure is also required. Therefore, the lower limit of the heat preservation temperature is 660°C, and the heat preservation time is not less than 10 seconds.

[0034] Furthermore, in the hot rolling step of the manufacturing method described in this invention, the final hot rolling temperature is controlled to be 880℃-980℃.

[0035] Furthermore, in the hot rolling step of the manufacturing method described in this invention, the coiling temperature is controlled to be 700℃-800℃.

[0036] In the hot rolling process of this invention, the final rolling temperature can be controlled between 880℃ and 980℃, and the coiling temperature can be controlled between 700℃ and 800℃. Within the above control range, the hot-rolled strip structure can undergo a certain degree of recrystallization, which is beneficial to improving the magnetic induction intensity of the Fe-Si alloy. However, the final rolling temperature and coiling temperature should not be too high, otherwise an internal oxide layer will form on the strip, deteriorating iron loss and surface quality.

[0037] Furthermore, in the intermediate annealing step of the manufacturing method described in this invention, the holding temperature is controlled at 900-1000℃ and the holding time is 10-100s.

[0038] In this invention, the holding temperature is controlled between 900-1000℃ and the holding time is controlled between 10-100s. This allows for complete recrystallization of the deformed structure of the rolled hard sheet, thereby improving the texture, increasing the favorable texture strength, enhancing the magnetic induction intensity of the finished strip, and reducing iron loss. However, the holding temperature should not be too high or the holding time too long, otherwise it will increase the difficulty of secondary cold rolling.

[0039] The ultra-high strength Fe-Si soft magnetic material and its manufacturing method described in this invention have the following advantages and beneficial effects:

[0040] The ultra-high strength Fe-Si soft magnetic material and its manufacturing method described in this invention, through the design of material composition and control of process parameters, enable it to possess ultra-high strength, high frequency and low loss properties, which can meet the requirements of high efficiency, miniaturization and high reliability of high power density drive motors.

[0041] In some embodiments, the iron loss P of the ultra-high strength Fe-Si soft magnetic material of the present invention 10 / 400 ≤35W / kg, magnetic induction intensity B 50 ≥1.59T, yield strength ≥760MPa. Detailed Implementation

[0042] The following will further explain and illustrate the ultra-high strength Fe-Si soft magnetic material 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.

[0043] Examples 1-8 and Comparative Examples 1-3

[0044] The ultra-high strength Fe-Si soft magnetic materials of Examples 1-8 and the comparative materials of Comparative Examples 1-3 of the present invention were prepared using the following steps:

[0045] (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.

[0046] (2) Hot rolling and pickling: The billet heating temperature can be 1200℃, the holding time is 1.5h, the final hot rolling temperature is controlled at 880℃-980℃, the coiling temperature is controlled at 700℃-800℃, and finally hot rolled to a thickness of 2.0mm. After hot rolling, pickling is performed to remove the surface iron oxide scale.

[0047] (3) Cold rolling: The pickled plate is cold rolled to 0.7 mm to obtain intermediate hardened plate.

[0048] (4) Intermediate annealing: The intermediate rolled hard plate is annealed, and the holding temperature is controlled at 900-1000℃ and the holding time is 10-100s. The protective atmosphere in the furnace can be 50% H2 + 50% N2 to obtain the intermediate annealed plate.

[0049] (5) Secondary cold rolling: Continue cold rolling the intermediate annealed plate to a thickness of 0.3 mm.

[0050] (6) Finished product annealing: control the holding temperature to 660℃-800℃, the holding time to 10s-20s, and the protective atmosphere in the furnace to be 50%H2+50%N2.

[0051] (7) Applying an insulating coating: After the finished product is annealed, an insulating coating is applied to the surface of the strip.

[0052] Table 1 lists the mass percentage of each chemical element in the ultra-high strength Fe-Si soft magnetic materials of Examples 1-8 and the comparative materials of Comparative Examples 1-3 of the present invention.

[0053] Table 1. (wt%, balance Fe and unavoidable impurities other than C, P and S)

[0054] serial number Si Co Al Mn Sn or Sb C P S Example 1 3.4 1.50 1.50 0.60 - 0.01 0.01 0.002 Example 2 3.5 0.80 0.80 0.80 - 0.005 0.02 0.003 Example 3 3.6 0.50 0.90 1.00 - 0.003 0.006 0.001 Example 4 3.7 0.50 0.50 1.80 - 0.002 0.015 0.005 Example 5 3.8 1.00 0.40 0.50 Sb:0.020 0.003 0.015 0.002 Example 6 4.0 0.10 1.10 0.70 Sn: 0.015 0.006 0.011 0.0008 Example 7 4.2 0.50 0.70 0.90 Sn: 0.300 0.001 0.004 0.002 Example 8 4.4 0.05 0.65 1.40 Sn: 0.35 0.002 0.003 0.002 Comparative Example 1 2.0 - 0.70 0.50 - 0.003 0.01 0.001 Comparative Example 2 3.5 - - 0.20 - 0.002 0.01 0.002 Comparative Example 3 3.7 0.20 0.90 0.50 - 0.001 0.01 0.003

[0055] Table 2 lists the specific process parameters of the ultra-high strength Fe-Si soft magnetic materials of Examples 1-8 and the comparative materials of Comparative Examples 1-3 of the present invention.

[0056] Table 2.

[0057]

[0058]

[0059] Samples were taken from the ultra-high strength Fe-Si soft magnetic materials of Examples 1-8 and the comparative materials of Comparative Examples 1-3, and their iron loss P was analyzed. 10 / 400 Magnetic induction intensity B when magnetized with a magnetic field strength of 5000 A / m 50 The yield strength was tested, and the results are listed in Table 3. The specific testing methods are as follows:

[0060] Magnetic induction intensity B 50 Test: Based on the square ring method of the standard GB / T3655-2008 "Method for measuring the magnetic properties of electrical steel sheets (strips) using Epstein square ring".

[0061] Iron loss P 10 / 800 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)".

[0062] 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.

[0063] Table 3 lists the performance test results of the ultra-high strength Fe-Si soft magnetic materials of Examples 1-8 of the present invention and the comparative materials of Comparative Examples 1-3.

[0064] Table 3.

[0065]

[0066] As can be seen from Table 3 above, the key parameters of the ultra-high strength Fe-Si soft magnetic materials in Examples 1-8 of this invention, including alloy chemical composition control, hot rolling final rolling temperature, coiling temperature, intermediate annealing process, and final annealing process, are all within the design range of this invention. This results in the obtained iron loss P of the finished Fe-Si alloy strip before stress-relief annealing. 10 / 400 All are less than 35W / kg, magnetic induction intensity B 50All values ​​are greater than 1.59T, and all yield strengths are greater than or equal to 760MPa, which meets the requirement that there is no risk of fracture failure during high-speed rotor rotation.

[0067] In contrast, although the manufacturing processes and finished product annealing processes of Comparative Examples 1 and 2 are within the scope of this invention, their chemical composition design is not within the scope of this invention, resulting in their finished products having high-frequency iron loss and yield strength that are not within the scope of this invention.

[0068] In addition, the holding temperature and holding time of the finished product in Comparative Example 3 were not within the scope of the invention, resulting in a lower yield strength of the finished product material.

[0069] 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.

[0070] 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.

[0071] 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 high-strength Fe-Si soft magnetic material, containing Fe and unavoidable impurities, characterized in that, It also contains the following chemical elements in the following mass percentages: Si: 3.4%-4.4%, Co: 0.05-1.5%, Al: 0.4-1.5%, Mn: 0.5-1.8%.

2. The ultra-high strength Fe-Si soft magnetic material as described in claim 1, characterized in that, Its mass percentage content of each chemical element is as follows: Si: 3.4%-4.4%, Co: 0.05%-1.5%, Al: 0.4%-1.5%, Mn: 0.5%-1.8%; balance Fe and unavoidable impurities.

3. The ultra-high strength Fe-Si soft magnetic material as described in claim 1 or 2, characterized in that, It also contains Sn or Sb, with a mass percentage of 0.015%-0.35%.

4. The ultra-high strength Fe-Si soft magnetic material 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 ultra-high strength Fe-Si soft magnetic material as described in claim 1 or 2, characterized in that, Its iron loss P 10 / 400 ≤35W / kg,B 50 ≥1.59T。 6. The ultra-high strength Fe-Si soft magnetic material as described in claim 1 or 2, characterized in that, Its yield strength is ≥760MPa.

7. A method for manufacturing ultra-high strength Fe-Si soft magnetic material as described in any one of claims 1-6, characterized in that, Including the following steps: Smelting and casting; Hot rolling and pickling; One-time cold rolling; Intermediate annealing; Secondary cold rolling; Finished product annealing: Control the holding temperature at 660℃-800℃ and the holding time at 10s-20s; Apply an insulating coating.

8. The manufacturing method as described in claim 7, characterized in that, During the hot rolling process, the final hot rolling temperature is controlled at 880℃-980℃.

9. The manufacturing method as described in claim 7, characterized in that, During the hot rolling process, the coiling temperature is controlled at 700℃-800℃.

10. The manufacturing method as described in claim 7, characterized in that, During the intermediate annealing step, the holding temperature is controlled at 900-1000℃ and the holding time is 10-100s.

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