A post-treatment process for iron-nickel soft magnetic alloys

Abstract

The application discloses a post-processing technology of iron-nickel soft magnetic alloy, which comprises the following steps: pre-pressing metal powder to obtain a block, twice melting of the block, multiple forging of the melted material, warm rolling treatment of the forged material after natural cooling, milling cutting treatment of the warm-rolled material, subsequent cryogenic treatment, heat treatment of the cryogenically treated material, and completion of the post-processing technology of the iron-nickel soft magnetic alloy. The iron-nickel soft magnetic alloy is prepared by vacuum induction melting, and then subjected to multiple forging, warm rolling treatment, cryogenic treatment and heat treatment. Compared with the existing iron-nickel alloy products on the market, the iron-nickel soft magnetic alloy obtained by the post-processing technology has better compactness, more uniform element composition distribution and more uniform grain distribution, the yield strength is 200 MPa, the tensile strength is 470 MPa, the yield strength ratio is 0.43, and the plasticity of the material is obviously improved, so that the iron-nickel soft magnetic alloy can be used for subsequent flow spinning forming.

Description

Technical Field

[0001] This invention belongs to the field of magnetic materials technology, and more specifically, this invention relates to a post-processing process for iron-nickel soft magnetic alloys. Background Technology

[0002] Magnetism refers to the magnetic force experienced by a substance when placed in a non-uniform magnetic field. All substances possess magnetism, only differing in magnitude. The strength of a substance's magnetism can be determined by the magnitude and direction of the magnetic force it experiences in a non-uniform magnetic field. Industrially used magnetic materials are permanent magnets and soft magnetic materials. The main difference between these two types is that after magnetization, if an opposing magnetic field is applied, soft magnetic materials easily revert to their unmagnetized state, while permanent magnets are difficult to return to their previous state. The area enclosed by the hysteresis loop is related to the material's loss, indicating that soft magnetic materials have lower magnetic loss. Because soft magnetic materials are easily magnetized under the influence of an external magnetic field and easily demagnetized when the magnetic field disappears, they are frequently used as information functional materials. When using soft magnetic materials, it is desirable for them to respond quickly to changes in the external magnetic field and to generate low losses during use. Therefore, soft magnetic materials generally have several characteristics: high initial permeability and maximum permeability; low coercivity; high saturation magnetic induction intensity, resulting in a wide range of applications; low power loss to reduce the loss of electrical energy converted into magnetic energy; and high stability, meaning that the soft magnetic properties of the material will not change significantly when the usage environment changes. The existing post-processing technology of iron-nickel soft magnetic alloy materials is difficult to meet the requirements of uniform distribution of alloy elements, uniform grain structure, and good plasticity, which leads to a decrease in the soft magnetic properties of iron-nickel alloy materials. The following are some basic problems with domestic soft magnetic alloys: (1) There is still a certain gap between the alloy and foreign products in terms of permeability, saturation magnetic induction intensity, and coercivity. (2) Factors affecting the magnetic properties of soft magnetic alloys include: chemical composition, purity, alloy structure, annealing method, annealing temperature, holding time, cooling rate, annealing atmosphere, surface quality, etc. How to effectively control them still needs in-depth research; (3) How to accurately control alloys with a certain composition. Summary of the Invention

[0003] One object of the present invention is to solve at least the above-mentioned problems and / or defects, and to provide at least the advantages described below.

[0004] To achieve these objectives and other advantages according to the present invention, a post-processing method for iron-nickel soft magnetic alloys is provided, comprising the following steps:

[0005] Step 1: Pre-press the metal powder to obtain a block, and then melt the block twice.

[0006] Step 2: Forge the smelted material multiple times;

[0007] Step 3: Allow the forged material to cool naturally to a certain temperature and then perform warm rolling.

[0008] Step 4: Mill the warm-rolled material, and then perform deep cryogenic treatment;

[0009] Step 5: Perform heat treatment on the cryogenically treated material to complete the post-processing of the iron-nickel soft magnetic alloy.

[0010] Preferably, in step one, the metal powder comprises Fe, Ni, Mn, Si, Cr, and Ti, wherein the mass percentage of Fe powder is 51%, the mass percentage of Ni powder is 47%, the mass percentage of Mn powder is 0.6%, the mass percentage of Si powder is 0.4%, the mass percentage of Cr powder is 0.6%, and the mass percentage of Ti powder is 0.4%.

[0011] Preferably, step one further includes: weighing the metal powder, placing it in a nylon ball mill jar, and performing wet grinding with alcohol, wherein the mass ratio of alcohol to metal powder is 2:1, the ball milling speed is 100–400 rpm, and the ball milling time is 1–6 hours; and drying the ball-milled metal powder in a vacuum oven with a vacuum degree of 10. -2 ~1Pa, drying temperature is 40~80℃; use a tablet press to pre-press the dried metal powder at a pressure of 10~40MPa.

[0012] Preferably, in step one, the melting temperature for both melting processes is 1000–1500°C.

[0013] Preferably, in step two, the forging temperature is 900–1200°C and the forging deformation is 30–50%.

[0014] Preferably, in step three, the forged material is naturally cooled to 200–400°C and then subjected to warm rolling treatment, with a deformation of 40–60% and a rolling speed of 0.4–0.6 m / s.

[0015] Preferably, in step four, the cryogenic treatment temperature is -100 to -70°C, and the holding time is 12 to 36 hours.

[0016] Preferably, in step five, the heat treatment is performed in a vacuum environment with a vacuum degree of 1×10⁻⁶. -3 Below Pa, the heating rate is 5-20℃ / min, and the temperature is raised to 1000-1200℃, then held for 2-6 hours.

[0017] The present invention has at least the following beneficial effects: The present invention uses vacuum induction melting to prepare iron-nickel soft magnetic alloys. After multiple forging and warm rolling processes, it undergoes deep cryogenic treatment and heat treatment. Compared with the iron-nickel alloy products currently on the market, the iron-nickel soft magnetic alloy obtained by the present invention has better density, more uniform elemental composition distribution, more uniform grain distribution, yield strength of 200MPa, tensile strength of 470MPa, yield strength ratio of 0.43, and the plasticity of the material is significantly improved, which can be used for subsequent flow spinning forming.

[0018] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0019] Figure 1 The image shows the XRD pattern of the iron-nickel soft magnetic alloy sample obtained after post-processing in Example 1.

[0020] Figure 2 This is a grain size diagram of the iron-nickel soft magnetic alloy sample obtained after post-processing in Example 1;

[0021] Figure 3 The strain-stress diagrams are shown for the iron-nickel soft magnetic alloy sample prepared in Example 1 and the iron-nickel soft magnetic alloy samples prepared in Comparative Examples 1-3. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0023] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0024] Example 1

[0025] This embodiment provides a post-processing technology for iron-nickel soft magnetic alloys, including the following steps:

[0026] Step 1: Weigh the metal powder and place it in a nylon ball mill jar. Perform wet grinding with alcohol at a mass ratio of 2:1 (alcohol to metal powder), at a milling speed of 300 rpm for 2 hours. Dry the milled metal powder in a vacuum oven at a vacuum degree of 10. -1The drying temperature is 50℃; the dried metal powder is pre-pressed using a tablet press at a pressure of 25MPa; the metal powder includes Fe, Ni, Mn, Si, Cr, and Ti, with Fe powder accounting for 51% by mass, Ni powder accounting for 47% by mass, Mn powder accounting for 0.6% by mass, Si powder accounting for 0.4% by mass, Cr powder accounting for 0.6% by mass, and Ti powder accounting for 0.4% by mass. The pre-pressed block is melted twice at a melting temperature of 1300℃;

[0027] Step 2: Forge the smelted material three times at a forging temperature of 1000℃ and a deformation of 40%.

[0028] Step 3: After the forged material is naturally cooled to 300℃, it is subjected to warm rolling treatment with a deformation of 50% and a rolling speed of 0.5m / s.

[0029] Step 4: Mill the warm-rolled material to remove surface cracks and oxide layer, and then perform deep cryogenic treatment at a temperature of -80℃ for 24 hours.

[0030] Step 5: Perform heat treatment on the cryogenically treated material under vacuum, with a vacuum level of 1×10⁻⁶. - 3 Below Pa, the temperature is increased to 1100℃ at a heating rate of 10℃ / min and held for 4 hours, thus completing the post-processing of the iron-nickel soft magnetic alloy.

[0031] The XRD pattern of the iron-nickel soft magnetic alloy sample obtained after post-processing in this embodiment is shown below. Figure 1 As shown, from Figure 1 As can be seen from the data, the sample is cubic with space group Fm3m, which is basically the same as the standard PDF card. The phase of the sample has not changed.

[0032] The grain size diagram of the iron-nickel soft magnetic alloy sample obtained after post-processing in this embodiment is shown below. Figure 2 As shown, from Figure 2 The data shows that the sample grain size is concentrated around 10μm, accounting for more than 60%, indicating that the sample grain size distribution is uniform.

[0033] Comparative Example 1

[0034] This comparative example provides a post-processing process for iron-nickel soft magnetic alloys. The difference between this comparative example and Example 1 is that the deep cryogenic treatment in step four is not performed in this comparative example, while the rest of the process is the same as in Example 1.

[0035] Comparative Example 2

[0036] This comparative example provides a post-processing process for iron-nickel soft magnetic alloys. The difference between this comparative example and Example 1 is that the deep cryogenic treatment in step four and the heat treatment in step five are not performed in this comparative example. The remaining processes are the same as in Example 1.

[0037] Comparative Example 3

[0038] This comparative example provides a post-processing process for iron-nickel soft magnetic alloys. The difference between this comparative example and Example 1 is that the warm rolling process in step three, the cryogenic treatment in step four, and the heat treatment in step five are not performed in this comparative example. The remaining processes are the same as in Example 1.

[0039] The stress-strain data of the iron-nickel soft magnetic alloys obtained after post-processing in Example 1 and Comparative Examples 1-3 were measured respectively, and the results were obtained. Figure 3 ,from Figure 3 As can be seen, the sample prepared in Example 1 has a significantly higher tensile strength than the sample prepared in the comparative example, indicating that the sample prepared in Example 1 has better plasticity. Specifically, the iron-nickel soft magnetic alloy obtained after post-treatment in Example 1 has a yield strength of 200 MPa, a tensile strength of 470 MPa, and a yield-to-tensile ratio of 0.43; the iron-nickel soft magnetic alloy obtained after post-treatment in Comparative Example 1 has a yield strength of 185 MPa, a tensile strength of 400 MPa, and a yield-to-tensile ratio of 0.46; the iron-nickel soft magnetic alloy obtained after post-treatment in Comparative Example 2 has a yield strength of 178 MPa, a tensile strength of 340 MPa, and a yield-to-tensile ratio of 0.52; and the iron-nickel soft magnetic alloy obtained after post-treatment in Comparative Example 3 has a yield strength of 172 MPa, a tensile strength of 320 MPa, and a yield-to-tensile ratio of 0.54.

[0040] The number of devices and processing scale described herein are for the purpose of simplifying the description of the invention. Applications, modifications, and variations of the invention will be readily apparent to those skilled in the art.

[0041] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A post-treatment process of a Fe-Ni soft magnetic alloy, characterized by, Includes the following steps: Step 1: Pre-press the metal powder to obtain a block, and then melt the block twice. Step 2: Forge the smelted material multiple times; Step 3: Allow the forged material to cool naturally to a certain temperature and then perform warm rolling. Step 4: Mill the warm-rolled material, and then perform deep cryogenic treatment; Step 5: Perform heat treatment on the cryogenically treated material to complete the post-processing of the iron-nickel soft magnetic alloy. In step three, the forged material is naturally cooled to 200~400℃ and then subjected to warm rolling treatment. The deformation amount of the warm rolling treatment is 40~60%, and the rolling speed is 0.4~0.6m / s. In step four, the temperature of the cryogenic treatment is -100~-70℃, and the holding time is 12~36h; The heat treatment in the step five is carried out in a vacuum environment, and the vacuum degree is 1x10 -3 The temperature is raised to 1000-1200℃ at a temperature raising speed of 5-20℃ / min, and the temperature is kept for 2-6h.

2. The post-treatment process for iron-nickel soft magnetic alloys according to claim 1, characterized in that, In step one, the metal powder includes Fe, Ni, Mn, Si, Cr, and Ti, wherein the mass percentage of Fe powder is 51%, the mass percentage of Ni powder is 47%, the mass percentage of Mn powder is 0.6%, the mass percentage of Si powder is 0.4%, the mass percentage of Cr powder is 0.6%, and the mass percentage of Ti powder is 0.4%.

3. The post-treatment process for iron-nickel soft magnetic alloys according to claim 1, characterized in that, The step one further comprises: after weighing the metal powder, loading into a nylon ball mill jar, using alcohol wet grinding, the mass ratio of alcohol to metal powder is 2:1, the ball milling speed is 100-400 rpm, the ball milling time is 1-6 h; using a vacuum oven to dry the metal powder after ball milling, the vacuum degree is 10 -2 ~1 Pa, the drying temperature is 40-80℃; using a tablet press to pre-press the dried metal powder, the pressure is 10-40 MPa.

4. The post-treatment process for iron-nickel soft magnetic alloys according to claim 1, characterized in that, In step one, the melting temperature is 1000~1500℃ for both melting processes.

5. The post-treatment process for iron-nickel soft magnetic alloys according to claim 1, characterized in that, In step two, the forging temperature is 900~1200℃ and the forging deformation is 30~50%.

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