High-saturation-magnetic-induction low-loss soft magnetic alloy and production method thereof
阅读说明：本技术 一种高饱和磁感低损耗软磁合金及其生产方法 (High-saturation-magnetic-induction low-loss soft magnetic alloy and production method thereof ) 是由 薛佳宁 李重阳 徐明舟 杨帆 王卫丽 张�荣 于 2021-10-08 设计创作，主要内容包括：本发明公开了一种高饱和磁感低损耗软磁合金及其生产方法,合金含有以下组分：2.0-8.0wt％Co,1.0-4.0wt％Si,2.0-8.0wt％Cr,0-2.0wt％Mo,0-2.0wt％Al,0-2.0wt％Mn,0-0.06wt％C,余量为Fe；生产方法包括以下步骤：S1、称取以上原料；S2、在1550-1650℃下熔炼各原料并浇铸成合金铸锭；S3、去掉合金铸锭氧化皮,在900-1200℃下锻造得合金扁坯；S4、去掉合金扁坯氧化皮,在900-1200℃下热轧得合金热轧带材；S5、去掉合金热轧带材氧化皮后冷轧开坯,然后中间退火,然后继续冷轧得到高饱和磁感低损耗软磁合金；中间退火的温度范围为800-1100℃,时间范围0.5-10min。本发明公开的高饱和磁感低损耗软磁合金兼顾高饱和磁感、高电阻率、低矫顽力、低损耗、良好力学性能等优异的性能组合,相比现有合金优势明显,且生产成本显著降低。(The invention discloses a high saturation magnetic induction low loss soft magnetic alloy and a production method thereof, wherein the alloy comprises the following components: 2.0-8.0 wt% of Co, 1.0-4.0 wt% of Si, 2.0-8.0 wt% of Cr, 0-2.0 wt% of Mo, 0-2.0 wt% of Al, 0-2.0 wt% of Mn, 0-0.06 wt% of C and the balance of Fe; the production method comprises the following steps: s1, weighing the raw materials; s2, smelting all raw materials at 1550-; s3, removing oxide skin of the alloy ingot, and forging at the temperature of 900-; s4, removing oxide skin of the alloy slab, and carrying out hot rolling at 900-1200 ℃ to obtain an alloy hot rolled strip; s5, removing oxide skins of alloy hot rolled strips, cold rolling and cogging, then performing intermediate annealing, and then continuously performing cold rolling to obtain the high-saturation-magnetic-induction low-loss soft magnetic alloy; the temperature range of the intermediate annealing is 800-1100 ℃, and the time range is 0.5-10 min. The high-saturation-magnetic-induction low-loss soft magnetic alloy disclosed by the invention has excellent performance combinations of high saturation magnetic induction, high resistivity, low coercive force, low loss, good mechanical properties and the like, has obvious advantages compared with the existing alloy, and obviously reduces the production cost.)
1. The high saturation magnetic induction low loss soft magnetic alloy is characterized by comprising the following components in percentage by mass: 2.0-8.0 wt% of Co, 1.0-4.0 wt% of Si, 2.0-8.0 wt% of Cr, 0-2.0 wt% of Mo, 0-2.0 wt% of Al, 0-2.0 wt% of Mn, 0-0.06 wt% of C and the balance of Fe.
2. The high saturation induction low loss soft magnetic alloy according to claim 1, wherein the sum of the mass percentages of Al and Si in the high saturation induction low loss soft magnetic alloy is less than or equal to 4.0 wt%.
3. The high saturation induction and low loss soft magnetic alloy as claimed in claim 1, wherein the sum of the mass percentages of Cr and Mn in the high saturation induction and low loss soft magnetic alloy is greater than or equal to 4.0 wt%.
4. The high saturation induction low loss soft magnetic alloy according to claim 1, wherein the high saturation induction low loss soft magnetic alloy comprises the following components by mass percent:
4.0-8.0 wt% of Co, 2.0-3.0 wt% of Si, 3.0-5.0 wt% of Cr, 0.2-1.0 wt% of Mo, 0.2-1.0 wt% of Al, 0-2.0 wt% of Mn, 0-0.03 wt% of C and the balance of Fe.
5. A method for producing the high saturation induction low loss soft magnetic alloy of claim 1, comprising the steps of:
s1, weighing the following raw materials in percentage by mass:
2.0-8.0 wt% of Co, 1.0-4.0 wt% of Si, 2.0-8.0 wt% of Cr, 0-2.0 wt% of Mo, 0-2.0 wt% of Al, 0-2.0 wt% of Mn, 0-0.06 wt% of C and the balance of Fe;
s2, smelting all the raw materials weighed in the S1, wherein the smelting temperature range is 1550-;
s3, removing oxide skin of the alloy ingot, and forging at a first heating temperature to obtain an alloy flat blank, wherein the first heating temperature range is 900-1200 ℃;
s4, removing oxide skin of the alloy flat blank, and performing hot rolling at a second heating temperature to obtain an alloy hot rolled strip, wherein the second heating temperature range is 900-1200 ℃;
s5, removing oxide skin of the alloy hot rolled strip, then performing cold rolling cogging on the alloy hot rolled strip to obtain an alloy cold rolled strip, then performing intermediate annealing on the alloy cold rolled strip, and then continuously performing cold rolling to obtain the high-saturation-magnetic-induction low-loss soft magnetic alloy; the temperature range of the intermediate annealing is 800-1100 ℃, and the time range is 0.5-10 min; the deformation of the high saturation magnetic induction low loss soft magnetic alloy is more than or equal to 50% compared with the alloy cold-rolled strip after the intermediate annealing.
6. The production method according to claim 5, further comprising a step S6, wherein the step S6 is specifically:
performing heat treatment on the high saturation induction and low loss soft magnetic alloy obtained in the step S5, wherein the specific parameters of the heat treatment can be the temperature range of 700 and 900 ℃, the heat preservation time is 4-12h, and cooling is performed after the heat preservation is finished; the protective atmosphere is one of dry hydrogen or vacuum, and the cooling mode is one of furnace cooling or furnace discharging air cooling.
7. The production method according to claim 6, wherein in step S6, the specific parameters of the heat treatment are:
the protective atmosphere is one of dry hydrogen or vacuum, the temperature range is 900-.
8. The production method as claimed in claim 6, wherein after the heat treatment, the high saturation induction low loss soft magnetic alloy has a single α -phase structure at room temperature.
9. The production method according to claim 6, wherein after the heat treatment, the saturation induction of the high saturation induction low loss soft magnetic alloy is not less than 1.95T, and the resistivity is not less than 0.70 x 10-6Ω·m。
Technical Field
The invention relates to the field of metal materials, in particular to a high-saturation-magnetic-induction low-loss soft magnetic alloy and a production method thereof.
Background
Soft magnetic alloys are a class of magnetic alloys with low coercivity and high magnetic permeability, most of which are applied under ac magnetization conditions and therefore require lower power losses. Because of different requirements for the performance of magnetic materials in different fields, the alloy can be classified into high-magnetic induction alloy, high-permeability alloy, constant-permeability magnetic alloy, temperature compensation alloy, giant magnetostrictive alloy and the like according to alloy characteristics. In many applications, high saturation induction determines the relative size of the soft magnetic element, coercivity determines the magnetization current, and resistivity determines the eddy current loss in an alternating magnetic field. For dc applications, the main consideration in the choice of material is magnetic permeability; for ac applications, the energy losses generated by the material when operating in the system are of major concern, and the losses increase with increasing excitation and frequency, and the total power losses can be divided into hysteresis losses, eddy current losses and anomalous losses. Hysteresis loss can be reduced by lowering the intrinsic coercivity of the material; eddy current loss is generated by eddy current energy dissipation caused by internal induction change of the material, and the eddy current loss can be reduced by increasing the resistivity of the material and manufacturing a laminated material; abnormal losses associated with local eddy currents caused by domain wall motion within the material can be reduced by suppressing domain wall motion.
In recent years, with the continuous development of technologies, the market has continuously improved the capability of power equipment and the design requirement of electronic devices, and the electronic devices gradually and rapidly develop towards the directions of high efficiency, weight reduction, low cost and the like. For example, modern electrical applications require solenoid valves that operate at frequencies above 1kHz, which requires soft magnetic materials with high resistivity to reduce eddy current induced loss increases. Silicon steel commonly used in the original 50/60Hz transformer is not suitable for application under higher frequency, and MnZn soft magnetic ferrite suitable for high-frequency application has relatively low saturation induction, and the manufactured magnetic core has large volume. In addition, soft magnetic materials are mainly applied to motor cores, and with the rapid development of pure electric vehicles in the international market, the performance requirements of driving motors of electric vehicles are higher and higher, such as maximum power and torque density, high efficiency, minimum volume and weight, low cost, high reliability and the like. The soft magnetic alloy is used as the raw material of the iron core of the stator and the rotor, and is an important functional material which greatly contributes to the improvement of the performance and the efficiency of the motor. These materials are prepared into strips by cold rolling, processed into specific shapes, and made into laminated stator or rotor cores. In order to achieve the performance required by the driving motor, the soft magnetic material is required to have higher magnetic induction under a certain magnetic field intensity; in addition, in order to improve motor efficiency, a driving motor applied at high frequency is required to have a low iron loss of an iron core material, an improved magnetization characteristic, and an improved mechanical property.
At present, traditional soft magnetic materials widely applied are mainly divided into silicon steel, Fe-Co alloy, Fe-Ni alloy, soft magnetic ferrite, amorphous nanocrystalline soft magnetic alloy and the like.
The silicon steel is generally added with 0-6.5 wt% of Si element, and is divided into low carbon steel, non-oriented silicon steel and oriented silicon steel, and the non-oriented silicon steel added with 1-3.5 wt% of Si is mainly applied to alternating current motors. Si element can improve resistivity, reduce iron loss and reduce saturation magnetic induction; and Si contents exceeding 4 wt% cause severe process brittleness of the material, which is difficult to mass-produce by conventional processing methods. With the requirements of miniaturization, lightweight and high efficiency of the existing driving motor, the performance requirements of high saturation magnetic induction, low loss and the like of the iron core material of the driving motor are stricter. And the traditional silicon steel is mature in development, so that the performance is difficult to break through. Aiming at the problems of reducing loss and the like, the main development direction of silicon steel is thickness reduction at present, namely, the thinner the plate thickness is, the eddy current is inhibited, so that the iron loss is reduced. However, the excessively thin plate thickness increases the iron loss, and the saturation induction cannot be further improved. Therefore, the use of new energy-saving soft magnetic materials to replace the original silicon steel is an important direction for improving the operation efficiency of the motor.
Fe-Co alloy has high saturation magnetic induction, but has lower resistivity, expensive cost and poorer cold processing performance; the Fe-Ni alloy has higher magnetic conductivity and smaller loss of the soft magnetic ferrite under a weak field, but the two materials are very easy to saturate under a stronger magnetic field, and have smaller saturation magnetic induction (the saturation magnetic induction of the Fe-Ni soft magnetic alloy is not more than 1.6T, and the saturation magnetic induction of the soft magnetic ferrite is not more than 0.5T), so the Fe-Ni soft magnetic ferrite is not suitable for the application environment of a high-power strong magnetic field.
The amorphous nanocrystalline soft magnetic alloy has the characteristics of low coercive force, high magnetic conductivity, high resistivity and the like because of no magnetocrystalline anisotropy. The transformer made of the amorphous nanocrystalline material can show the advantages of low hysteresis loss, low noise and the like. However, since the amorphizing ability is insufficient, it is currently mainly applied in a low-dimensional shape such as a thin strip, a powder, etc. In addition, the amorphous nanocrystalline thin band is very fragile, the preparation technical requirement is higher, and the difficulty of large-scale industrialization is increased. The amorphous nanocrystalline belongs to a metastable phase, the crystallization temperature is low, the working temperature is not more than 100-150 ℃, and the matrix is crystallized by long-term aging at a high temperature, so that the magnetic property is deteriorated. Therefore, the application of the amorphous nanocrystalline material is limited in terms of the use condition and the mechanical property of the material.
In summary, in order to meet the demand for increasingly miniaturization of magnetic components at high frequencies, there is a need to develop a soft magnetic alloy with high saturation magnetic induction, low loss and good mechanical properties, so that the properties of the soft magnetic alloy can be transformed into an optimized design with smaller volume and higher efficiency for electric components such as driving motors, etc., and the soft magnetic alloy should have the capability of mass production under the conventional metallurgical technology and processing level.
Disclosure of Invention
Therefore, embodiments of the present invention provide a high saturation induction and low loss soft magnetic alloy and a production method thereof, so as to solve the problems in the prior art.
In order to achieve the above object, the embodiments of the present invention provide the following technical solutions:
in a first aspect, an embodiment of the present invention provides a high saturation induction and low loss soft magnetic alloy, which contains the following components by mass:
2.0-8.0 wt% of Co, 1.0-4.0 wt% of Si, 2.0-8.0 wt% of Cr, 0-2.0 wt% of Mo, 0-2.0 wt% of Al, 0-2.0 wt% of Mn, 0-0.06 wt% of C and the balance of Fe.
Preferably, the sum of the mass percentages of Al and Si in the high saturation induction low loss soft magnetic alloy is less than or equal to 4.0 wt%.
Preferably, the sum of the mass percentages of Cr and Mn in the high saturation induction low loss soft magnetic alloy is more than or equal to 4.0 wt%.
Preferably, the high saturation induction low loss soft magnetic alloy comprises the following components in percentage by mass:
4.0-8.0 wt% of Co, 2.0-3.0 wt% of Si, 3.0-5.0 wt% of Cr, 0.2-1.0 wt% of Mo, 0.2-1.0 wt% of Al, 0-2.0 wt% of Mn, 0-0.03 wt% of C and the balance of Fe.
In a second aspect, an embodiment of the present invention further provides a method for producing the above high saturation induction low loss soft magnetic alloy, including the following steps:
s1, weighing the following raw materials in percentage by mass:
2.0-8.0 wt% of Co, 1.0-4.0 wt% of Si, 2.0-8.0 wt% of Cr, 0-2.0 wt% of Mo, 0-2.0 wt% of Al, 0-2.0 wt% of Mn, 0-0.06 wt% of C and the balance of Fe;
s2, smelting all the raw materials weighed in the S1, wherein the smelting temperature range is 1550-;
s3, removing oxide skin of the alloy ingot, forging at a first heating temperature to obtain an alloy flat blank, wherein the first heating temperature range is 900-1200 ℃;
s4, removing oxide skin of the alloy flat blank, and performing hot rolling at a second heating temperature to obtain an alloy hot rolled strip, wherein the second heating temperature range is 900-1200 ℃;
s5, removing oxide skin of the alloy hot rolled strip, then carrying out cold rolling cogging on the alloy hot rolled strip to obtain an alloy cold rolled strip, then carrying out intermediate annealing on the alloy cold rolled strip, and then continuously carrying out cold rolling to obtain the high-saturation-magnetic-induction low-loss soft magnetic alloy; the temperature range of the intermediate annealing is 800-1100 ℃, and the time range is 0.5-10 min; compared with the alloy cold-rolled strip subjected to intermediate annealing, the deformation of the high-saturation-magnetic-induction low-loss soft magnetic alloy is more than or equal to 50%.
Preferably, the method further includes step S6, which is specifically:
carrying out heat treatment on the high saturation induction low loss soft magnetic alloy obtained in the step S5, wherein the specific parameters of the heat treatment can be the temperature range of 700-; the protective atmosphere is one of dry hydrogen or vacuum, and the cooling mode is one of furnace cooling or furnace discharging air cooling.
Further, the specific parameters of the heat treatment in step S6 may also be:
the protective atmosphere is one of dry hydrogen or vacuum, the temperature range is 900-.
Further, after the heat treatment, the high saturation induction low loss soft magnetic alloy has a single alpha phase structure at room temperature.
Further, after heat treatment, the saturation induction of the high saturation induction low loss soft magnetic alloy is more than or equal to 1.95T, and the resistivity is more than or equal to 0.70 multiplied by 10-6Ω·m。
Compared with the prior art, the embodiment of the invention at least has the following beneficial effects:
(1) according to the high-saturation-magnetic-induction low-loss soft magnetic alloy provided by the embodiment of the invention, the alloy elements such as Co, Cr, Si, Al, Mo, Mn, C and the like are accurately blended to obtain excellent comprehensive properties, particularly: the saturation magnetic induction is improved by adding Co element with specific content; the specific contents of Cr, Si, Al, Mn and other elements are added to improve the resistivity, so that the eddy current loss is obviously reduced; the homogenized microstructure can be obtained after heat treatment through the specific Al + Si and Cr + Mn contents, abnormal growth of crystal grains is avoided, and abnormal loss of the alloy is effectively reduced; by reasonably designing the element components and adding specific amounts of Cr and Mo elements for improving plasticity and Si element for improving the strength of the alloy, the alloy has good processing plasticity while improving the strength at room temperature.
(2) The high saturation induction low loss soft magnetic alloy provided by the embodiment of the invention has low manufacturing cost and is suitable for large-scale production and application.
(3) The high-saturation-magnetic-induction low-loss soft magnetic alloy provided by the embodiment of the invention has excellent performance combinations of high saturation magnetic induction, high resistivity, low coercive force, low loss, good mechanical properties and the like, is suitable for application ranges of power frequency, higher frequency and higher magnetic field, such as application fields of driving motors, transformers and the like, and enables the performance to be converted into an optimized design with smaller volume and higher efficiency for the motors.
(4) The high-saturation-magnetic-induction low-loss soft magnetic alloy provided by the embodiment of the invention has high resistivity, uniform microstructure and excellent soft magnetic property, so that the alloy has P1.0/400Low loss less than or equal to 10W/kg (belt thickness d is 0.15 mm); and has the advantages of higher mechanical strength and the like compared with the traditional materials such as silicon steel and the like.
(5) The high saturation induction low loss soft magnetic alloy provided by the embodiment of the invention can obtain more excellent comprehensive performance by carrying out heat treatment on the alloy. Because the high saturation induction low loss soft magnetic alloy provided by the embodiment of the invention has alpha phase (ferrite) at about 900 DEG CBeta phase (austenite) transformation, so that when the heat treatment temperature exceeds the transformation temperature, after rapid coolingAustenite phase remains to deteriorate magnetic properties; the microstructure of the alloy cannot be further improved effectively due to the excessively low heat treatment temperature, and the structural sensitivity performance parameters such as coercive force, resistivity and the like of the alloy are influenced; the preparation method of the high saturation magnetic induction low-loss soft magnetic alloy provided by the embodiment of the invention adopts the heat treatment process route 1 with lower heat treatment temperature and longer heat preservation time or the heat treatment process route 2 with higher heat treatment temperature and slow cooling mode kept near the phase transition temperature to prevent austenite residue, so that the high saturation magnetic induction low-loss soft magnetic alloy provided by the embodiment of the invention can obtain more excellent microstructure and magnetic performance.
(6) After the soft magnetic alloy prepared by the preparation method of the high saturation magnetic induction low loss soft magnetic alloy provided by the embodiment of the invention is subjected to heat treatment, the saturation magnetic induction is more than or equal to 1.95T, and the resistivity is more than or equal to 0.70 multiplied by 10-6Omega.m, compared with the soft magnetic ferrite applied by the high frequency alternating current at present, the high-frequency alternating current soft magnetic ferrite has higher saturation induction, has higher resistivity compared with the commercial crystalline state soft magnetic alloy at present, obviously reduces the eddy current loss, has excellent processing plasticity and mechanical strength compared with the amorphous nanocrystalline soft magnetic alloy, obviously enhances the tolerance capability to the service environment, has good aging resistance, and obviously reduces the production cost.
Drawings
In order to more clearly illustrate the technical solution of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly described below. It should be apparent that the drawings in the following description are merely exemplary, and that other drawings may be derived from the provided drawings by those of ordinary skill in the art without inventive effort.
The drawings are only for purposes of illustration and description, and are not intended to limit the scope of the invention, which is defined by the claims, which follow.
FIG. 1 is an XRD spectrum of an alloy after heat treatment provided in examples 1 and 6 of the present invention;
FIG. 2 is a metallographic photograph of an alloy of the present invention obtained in example 1 after heat treatment;
FIG. 3 is a metallographic picture of an alloy according to example 3 of the present invention after heat treatment;
FIG. 4 is a metallographic photograph of an alloy according to comparative example 2 of the present invention after heat treatment;
FIG. 5 is a metallographic photograph of an alloy according to comparative example 3 of the present invention after heat treatment;
FIG. 6 is a DSC curve of the alloys provided in example 2 of the present invention and comparative example 3.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
In the description of the present invention, the terms "comprises," "comprising," and any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements specifically listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus or additional steps or elements based on further optimization of the inventive concepts.
Examples 1 to 6 and comparative examples 1 to 3 provide alloys in which the mass percentages of the respective components are as shown in table 1 below.
Table 1-examples 1 to 6 and comparative examples 1 to 3 provide alloys in which each component is present in percentage by mass (unit: wt%)
The preparation methods of the high saturation induction and low loss soft magnetic alloy provided in examples 1 to 6 are as follows:
s1, weighing the raw materials according to the table 1;
the high saturation magnetic induction low loss soft magnetic alloy provided by the embodiments 1-6 of the invention has the effect of adding a proper amount of Co element, so that the material has higher saturation magnetic induction to improve the efficiency, torque and other performances of electrical elements such as a motor. However, since too high Co content significantly increases the production cost of the alloy and causes deterioration of workability, the Co content is controlled to a specific level in examples 1 to 6 of the present invention to ensure the performance; in addition, the addition of elements such as Cr, Si, Al, Mn and the like obviously improves the resistivity of the material, effectively reduces the eddy current loss and improves the service efficiency of the alloy at higher frequency; cr and Mn play a role in improving the uniformity of the structure, effectively avoid abnormal growth in the heat treatment process of crystal grains and reduce abnormal loss; cr and Mo play a role in improving the plasticity of the alloy; the mechanical property of the alloy can be improved by adding elements such as Si, Al, C and the like, the alloy has better tensile strength and hardness, and the service strength of the material is improved while the high efficiency and low loss of a soft magnetic device are met;
in examples 1 to 6 of the present invention, the sum of the Al and Si contents was not more than 4.0 wt%, because the resistivity of the alloy was significantly increased by the addition of Al and Si elements as shown by the alloy composition design experiment, and the resistivity of the alloy was (10) in the composition range of examples 1 to 6 of the present invention-6Omega m) is in direct proportion to the contents (wt%) of Al and Si, the proportionality coefficient is about 0.1, however, the excessive addition of Al and Si elements can cause abnormal growth of the grain size of the alloy after heat treatment, which leads to the remarkable increase of abnormal loss in alternating current magnetization application, tests determine that the sum of the contents of Al and Si in the alloy needs to be controlled to be not more than 4.0 wt%, which not only ensures that the material has larger resistivity to remarkably reduce eddy current loss, but also can prevent abnormal loss increase caused by abnormal growth of grains by regulating and controlling microstructure, thereby obtaining soft magnetic alloy with remarkably reduced total loss levelGold;
in embodiments 1 to 6 of the present invention, the sum of the mass percentages of Cr and Mn is not less than 4.0 wt%, because the Cr and Mn elements have an effect of improving the uniformity of the microstructure of the alloy, and have a certain inhibiting effect on abnormal growth of crystal grains during a high temperature heat treatment process, so that the corrugation defect due to abnormal growth of intermediate columnar crystal grains is not generated during a high temperature heating process of a forging or hot rolling process of the alloy, and the uniform refinement of the microstructure can reduce the local eddy current effect to reduce the abnormal loss, and in addition, the addition of the Cr element can also improve the plasticity of the alloy; however, the excess Cr element adversely affects the saturation induction, and the Cr content is determined to be not more than 8.0 wt%, preferably not more than 5.0 wt%; the addition of both Cr and Mn significantly increased the resistivity of the alloy, which was determined to be within the compositional range of examples 1-6 of the present invention (10)-6Ω · m) is proportional to the contents (wt%) of Cr and Mn, and the proportionality coefficient is about 0.05, so that the sum of the addition amounts of Cr and Mn elements should be not less than 4.0 wt% in order to obtain a soft magnetic alloy having high resistivity and uniform microstructure;
in the embodiments 1-6 of the invention, the processing plasticity of the alloy is improved by adding a proper amount of elements such as Cr, Mo and Mn, the hardness and tensile strength of the alloy are improved by adding a proper amount of elements such as Si, Al and a small amount of C, and the high saturation magnetic induction low-loss soft magnetic alloy with good plasticity and mechanical strength is obtained by regulating and controlling the addition range of the elements, which is beneficial to improving the service strength of the material;
the compositions of examples 1 to 6 of the present invention contain inevitable impurities which are introduced into the alloy because the raw materials cannot reach 100% purity, and in order to reduce the influence of the impurities on the magnetic properties of the alloy, the content of the impurities in examples 1 to 6 of the present invention is not more than 0.5 wt%, preferably not more than 0.1 wt%;
s2, alloy smelting: smelting raw materials such as Fe, Co, Si, Cr, Mo, Al, Mn, C and the like through a smelting furnace, wherein the refining temperature range is 1550-1650 ℃, and casting the raw materials into an alloy ingot after complete melting. In the refining temperature range, the alloy solution can be uniformly mixed, and the phenomenon of excessive volatilization of Al and Mn elements caused by overhigh temperature is avoided;
s3, hot pressing of steel ingots: removing oxide scales from the alloy ingot obtained in S2, and forging at the temperature of 900-1200 ℃, specifically 1050 ℃ to obtain a round rod with the diameter of 50 mm;
s4, hot rolling: grinding the alloy flat blank obtained in the step S3 to remove oxide skin, and then carrying out hot rolling at the temperature of 900-1200 ℃, specifically 1050 ℃ to obtain an alloy hot rolled strip with the thickness of 6 mm;
in the embodiments 1 to 6 of the present invention, when the high saturation magnetic induction low loss soft magnetic alloy is prepared, the first heating temperature and the second heating temperature are both controlled within the range of 900 to 1200 ℃, because, through experiments, the phenomena of overburning and overheating of Al element can occur when the heating temperature is too high, and the alloy grains are coarse, and the mechanical properties are reduced; if the heating temperature is too low, the hot working operation time is shortened, the hot working deformation is difficult, the internal stress is increased, and even cracks are generated;
s5, cold rolling: removing oxide skin of the alloy hot rolled strip obtained in the step S4, then carrying out cold rolling cogging to obtain an alloy cold rolled strip, carrying out intermediate annealing on the alloy cold rolled strip, and continuing to carry out cold rolling after annealing to obtain the high saturation magnetic induction low loss soft magnetic alloy; the intermediate annealing temperature range of the cold rolling step is 800-1100 ℃, and specifically is 1000 ℃; compared with the alloy cold-rolled strip after intermediate annealing, the deformation of the high-saturation-magnetic-induction low-loss soft magnetic alloy is more than or equal to 50 percent; the finished strip has two specifications, namely 0.15mm thick and 0.35mm thick;
the interannealing effect in the cold rolling step is to soften or recrystallize the metal strip to restore plasticity and reduce deformation resistance for subsequent cold working;
s6, heat treatment: carrying out heat treatment on the high saturation magnetic induction low loss soft magnetic alloy obtained in the step S5, wherein the heat treatment atmosphere is dry hydrogen or vacuum; a heat treatment process route 1 may be employed: the heat treatment temperature range is 700-; or adopting a heat treatment process route 2: the heat treatment temperature range is 900-; the routes specifically adopted in examples 1-6 are all route 2, with the specific parameters: heating to 1100 deg.C, holding for 8h, cooling to 600 deg.C at a cooling rate of 150 deg.C/h, and cooling to room temperature to obtain the alloy.
Because the high saturation induction low loss soft magnetic alloy provided by the embodiments 1-6 of the invention has alpha phase (ferrite) at about 900 DEG CBeta phase (austenite) transformation, and thus when the heat treatment temperature exceeds the transformation temperature, austenite phase remains after rapid cooling, deteriorating magnetic properties; and the ultra-low heat treatment temperature can not effectively improve the microstructure of the alloy, and influences the structural sensitivity performance parameters of the alloy, such as coercive force, resistivity and the like. Therefore, the soft magnetic alloys provided in examples 1 to 6 of the present invention can achieve more excellent microstructure and magnetic properties by using either the heat treatment process route 1 having a longer holding time at a lower heat treatment temperature or the heat treatment process route 2 having a higher heat treatment temperature and keeping a slow cooling manner around the transformation temperature to prevent the occurrence of austenite residues.
After heat treatment, the soft magnetic alloys provided in embodiments 1 to 6 of the present invention all had a single α -phase (ferrite) structure at room temperature;
after heat treatment, the saturation induction of the soft magnetic alloy provided by the embodiments 1 to 6 of the invention is more than or equal to 1.95T, and the resistivity is more than or equal to 0.70 multiplied by 10-6Omega.m, compared with the soft magnetic ferrite applied by high frequency alternating current at present, the high-frequency alternating current soft magnetic ferrite has higher saturation induction, has higher resistivity compared with the commercial crystalline state soft magnetic alloy at present, obviously reduces the eddy current loss, has excellent processing plasticity and mechanical strength compared with amorphous nanocrystalline soft magnetic alloy, obviously enhances the tolerance capability to the service environment, has good aging resistance, and obviously reduces the production cost. The soft magnetic alloy provided by the embodiments 1 to 6 of the present invention has excellent combinations of properties such as high saturation induction, low loss, and good mechanical strength, and can satisfy optimization designs such as lighter, higher power, higher efficiency, and the like for electrical components such as driving motors and the like.
Comparative examples 1 to 3 were prepared in the same manner as in examples 1 to 6.
A series of performance tests were next conducted on the alloys provided in examples 1-6 and the alloys provided in comparative examples 1-3 to illustrate the beneficial effects of the present invention.
Test 1
XRD tests were performed on the alloys provided in examples 1 to 6 of the present invention, respectively, to determine the phase structures thereof, and the results showed that the alloys were all single α -phase (ferrite) structures. The XRD patterns of the alloys provided in examples 1 and 6 of the present invention are shown in fig. 1, and it can be seen from fig. 1 that no other impurity phase except the α -phase characteristic peak appears.
Test 2
The alloys provided in examples 1 to 6 and comparative examples 1 to 3 after the heat treatment were observed by a crystal phase microscope and photographs were taken, wherein the metallographic photographs of example 1, example 3, comparative example 2 and comparative example 3 are shown in fig. 2 to 5, respectively. Comparing the metallographic photos, the microstructure of the embodiment 1 and the embodiment 3 of the invention has good uniformity, and no abnormal growth of crystal grains; in contrast, in comparative examples 2 and 3, the grain size was large, the grain size reached the 00 th order, and abnormal grain growth was observed. According to the embodiment of the invention, the Cr and Mn element content is accurately regulated, so that the alloy microstructure has good uniformity, and the corrugation defect caused by abnormal and thick grains can be avoided at the core part of the alloy in the hot processing process by controlling the sum of the Si and Al element content to be not more than 4.0 wt%, so that the abnormal loss caused by local nonuniformity of the microstructure and movement of a magnetic domain wall can be avoided during alternating current magnetization of the alloy, and the total loss value under the alternating current application can be greatly reduced.
Test 3
The curie temperature and the transformation temperature of the alloys provided in examples 1-6 and comparative examples 1-3 were investigated using Differential Scanning Calorimetry (DSC), respectively. Curie temperature for alloy generation of ferromagnetismTemperature point of paramagnetic transformation, phase transformation temperature is the generation of alpha phase (ferrite) of the alloyBeta phase (Austenitic)Bulk) temperature point of phase transition. The DSC curves of inventive example 2 and comparative example 3 are shown in FIG. 6. As can be seen from fig. 6, the curie temperature of example 2 of the present invention is about 800 ℃, while the curie temperature of the commercial NiFeCoSiB amorphous alloy is only 150 ℃, i.e. the amorphous soft magnetic alloy no longer has ferromagnetism above 150 ℃, which leads to severe performance deterioration. Therefore, compared with the amorphous soft magnetic alloy, the high curie temperature of the high saturation induction low loss soft magnetic alloy provided by the embodiment 2 of the invention enables the use temperature range of the alloy to be remarkably improved. Further, as is clear from FIG. 6, the α phase (ferrite) of comparative example 3The phase transformation temperature of the beta phase (austenite) disappears, which causes the alloy grains to be not completely broken due to slow dynamic recovery and recrystallization during hot working, resulting in the generation of coarse elongated deformed grains near the center of the blank after forging or hot rolling. The Fe-Ni alloy of comparative example 2, which has a structure of beta phase (austenite), also has no alpha phase (ferrite)The beta phase (austenite) transforms, making the grain size coarse after heat treatment. The coarse grains cause a significant increase in abnormal loss upon ac magnetization.
Test 4
The alloys provided in examples 1-6 and comparative examples 1-3 were tested for dc magnetic properties and electrical resistivity after heat treatment, respectively, and the specific data for examples 1-6 are shown in table 2 below.
TABLE 2 DC magnetic Properties and resistivity data for the alloys provided in examples 1-6 after Heat treatment
Alloy (I)
Bs(T)
Hc(A/m)
μm(mH/m)
ρ(10-6Ω·m)
Example 1
1.99
22.5
18.3
0.71
Example 2
1.97
26.2
14.0
0.89
Example 3
2.06
32.5
13.2
0.72
Example 4
2.01
52.2
7.8
0.78
Example 5
2.09
19.4
17.7
0.85
Example 6
2.11
16.8
22.8
0.86
As can be seen from the data in Table 2, the saturation induction of the alloy provided in the examples 1-6 of the present invention after heat treatment increases with the increase of Co content and decreases with the increase of Cr content, but the saturation induction of the alloy in the examples 1-6 is more than 1.95T within the range of the composition of the present invention by precisely controlling the alloy elements. Comparative example 1 crystalline Fe-Si alloy Bs ═ 1.98T; comparative example 2 crystalline Fe — Ni alloy Bs ═ 1.58T; commercial typical MnZn soft magnetic ferrite Bs is 0.50T; commercial NiFeCoSiB amorphous alloy Bs is 0.41T. Although the coercive force level of the soft magnetic ferrite, the amorphous nanocrystalline soft magnetic alloy and the Fe-Ni alloy is low due to small magnetic anisotropy, the application of the soft magnetic materials under high-power strong magnetic fields, such as driving motors of electric automobiles, transformers and the like, is limited by the excessively low saturation induction, and the iron cores wound by the materials are large in size, and the use amount and the cost of the materials are remarkably increased. The inventive examples had high levels of saturation induction, even exceeding the levels of the crystalline Fe-Si alloy (conventional silicon steel) of comparative example 1 except for example 2. In addition, the high saturation induction low loss soft magnetic alloy has a lower coercive force level and a higher maximum magnetic permeability value in a direct current magnetization test. The coercive force Hc of the alloy of the embodiments 1-6 of the invention is less than or equal to 60A/m; the maximum permeability μm exceeds 10mH/m except for example 4. The high saturation induction and the better direct current magnetic performance level enable the soft magnetic alloy provided by the embodiments 1-6 of the invention to well achieve the effects of improving the efficiency, reducing the weight and reducing the cost in application.
The resistivity data of the soft magnetic alloys provided in examples 1 to 6 after heat treatment are shown in table 2, and the resistivity ρ of the crystalline Fe — Si soft magnetic alloy in comparative example 1 is 0.48 × 10-6Ω · m, comparative example 2 crystalline Fe — Ni soft magnetic alloy resistivity ρ 0.41 × 10-6Omega.m. Because the addition amounts of Si, Al, Cr, Mn and other alloy elements are designed and regulated, the invention has high yieldThe saturation induction low-loss soft magnetic alloy has a remarkably improved resistivity value, and the resistivity rho of the alloy after heat treatment provided by the embodiments 1-6 of the invention is more than or equal to 0.70 multiplied by 10-6Omega.m. The resistivity of the silicon steel in the comparative example was only 0.48 × 10-6Omega m, while the resistivity level of the crystalline Fe-Co alloy is only 0.20 multiplied by 10-6Omega.m. The alloy provided by the embodiments 1-6 of the present invention has significantly improved resistivity, can significantly reduce the eddy current loss of the material in a high-frequency working magnetic field, and effectively reduce the heat loss generated by the material during working, thereby improving the working efficiency of the electrical element.
Test 5
The alloys provided in examples 1 to 6 and comparative examples 1 to 3 were tested for mechanical properties at room temperature after heat treatment, respectively, and the results are shown in table 3 below.
TABLE 3 mechanical properties of the alloys provided in examples 1-6 and comparative examples 1-3 after Heat treatment
Alloy (I)
Rp0.2(Mpa)
Rm(Mpa)
A％
HV
Example 1
455
637
36.5
180
Example 2
531
671
32.5
211
Example 3
542
702
29.0
208
Example 4
508
692
35.5
195
Example 5
564
723
30.5
216
Example 6
586
748
28.0
225
Comparative example 1
371
452
18.5
196
Comparative example 2
170
448
36.0
98
Comparative example 3
547
682
13.5
223
As can be seen from the data in Table 3, the alloys provided in examples 1-6 of the present invention, while having excellent magnetic properties after high temperature heat treatment, have better room temperature mechanical properties than the comparative examples. In mechanical strength, the yield strength Rp of the alloy of the embodiment of the invention is different from that of the embodiment 10.2Basically reaches more than 500MPa, while the tensile strength Rm of the examples 3, 5 and 6 even exceeds 700MPa, the room-temperature mechanical strength is obviously better than that of the crystalline Fe-Si alloy (silicon steel) of the comparative example 1 and the crystalline Fe-Ni alloy of the comparative example 2 which has good plasticity and poor strength. In addition, the alloy of the embodiment of the invention also keeps higher hardness after heat treatment and has better deformation resistance. The high saturation magnetic induction low loss soft magnetic alloy can meet the high strength requirement of high-efficiency electrical components such as the current driving motor under the load of assembly, processing and high-speed operation due to excellent mechanical strength.
In addition, the alloys provided by examples 1-6 of the present invention all have a higher elongation A%, and the elongation of examples 1 and 5 even reaches the level of the crystalline Fe-Ni alloy of comparative example 2, which shows that the alloy of the present invention has better plasticity and excellent processability, while the elongation of comparative examples 1 and 3 is lower, especially comparative example 3. Since the content of Si and Al is more than 4.0 wt%, the total content of Cr, Mo, Mn and other elements for improving plasticity is less than 4.0 wt%, the alloy deformation resistance is increased, the processing brittleness is seriously improved in the comparative example 3, and the alloy thin strip product is difficult to prepare by the conventional process. In conclusion, the excellent plasticity and strength enable the soft magnetic alloy of the invention to have significantly reduced production cost compared with materials such as amorphous nanocrystalline soft magnetic alloy, high silicon steel, Fe-Co soft magnetic alloy and the like, and can be used for large-scale industrial production.
Test 6
After heat treatment of 0.15mm thick strip and 0.35mm thick strip provided in examples 1-6 and comparative examples 1-3, respectively, the power loss (P) of each alloy sample was measured at 400Hz and 1.0T magnetic field1.0/400) The test results of examples 2, 5, 6 and comparative examples 1, 3 are shown in table 4.
Table 4-power loss of alloy strips after heat treatment as provided in examples 2, 5, 6 and comparative examples 1, 3
As can be seen from Table 4, examples 1-6 of the present invention provide alloys having relatively low total power loss at 400Hz due to their relatively high resistivity, uniform microstructure, and relatively low coercivity level. The Fe-Si alloy in the comparative example 1 has a lower resistivity, so that the eddy current loss is remarkably increased at a high frequency; comparative example 3 had a case where the crystal grains were abnormally coarse (as shown in fig. 5), and its abnormal loss was increased. The total power loss of the comparative example two soft magnetic alloys is thus significantly increased. The embodiment of the invention has the advantages that the total power loss of the strip with the thickness d of 0.15mm is less than 10W/kg under the condition of 1.0T/400Hz, and the optimal design of electrical components such as a driving motor and the like with higher efficiency and lighter weight can be well met.
All the technical features of the above embodiments can be combined arbitrarily, and for simplicity of description, all possible combinations of the technical features of the above embodiments are not described; these examples, which are not explicitly described, should be considered to be within the scope of the present description.
The present invention has been described in considerable detail by the general description and the specific examples given above. It should be noted that it is obvious that several variations and modifications can be made to these specific embodiments without departing from the inventive concept, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.