Method for improving magnetic properties of silicon-iron soft magnetic alloy

Abstract

This invention discloses a method for improving the magnetic properties of ferrosilicon soft magnetic alloys. The method further includes forging heating of the alloy at a temperature of 850℃±10℃. The alloy is formed by batching and smelting multiple alloying elements in the following weight percentages: C 0.03%, Si 2.5%, Mn 0.05%, P 0.18%, S, Al, with the balance being Fe. The method also includes a heat treatment process: heat treatment at 950℃~980℃ for 4 hours, followed by cooling to 500℃ at a rate of 100℃ / h, and then cooling to below room temperature at a rate of 50℃ / h~150℃ / h before unloading. This invention enables the ferrosilicon alloy magnetic material to possess high saturation magnetic induction (Bs) characteristics while exhibiting low remanence (Br), thereby improving the magnetic stability and reliability of the ferrosilicon alloy magnetic material.

Description

Technical Field

[0001] This invention relates to a method for improving the magnetic properties of ferrosilicon soft magnetic alloys, belonging to the field of alloy material technology. Background Technology

[0002] Ferrosilicon (Si 2.5%) soft magnetic alloys are widely used in control devices such as motor rotors and solenoid valves due to their high magnetic flux density and resistivity, which facilitates the miniaturization of electromagnetic devices and reduces eddy current losses. The magnetic properties of ferrosilicon soft magnetic alloys are influenced by the material element placement points, alloy smelting and hot working processes, and heat treatment processes.

[0003] The forging heating temperature determines the magnetic properties and processing performance of ferrosilicon alloys. Too low a forging heating temperature will prevent the grains from growing sufficiently after heat treatment, resulting in lower magnetic properties. In addition, too low a forging heating temperature will increase the deformation resistance of the alloy, which is not conducive to hot working plastic deformation. Too high a forging heating temperature will cause the Si element to burn out, and will result in coarse grains, which will increase the brittleness of the alloy and make it difficult to machine the alloy in the future.

[0004] Different annealing temperatures and annealing cooling rates during heat treatment can lead to significant differences in the microstructure, grain size, and magnetic properties of the material.

[0005] While China has made some progress in the research and application of ferrosilicon soft magnetic alloys, problems such as low magnetic properties and overall application performance, as well as poor batch stability still exist. In order to enable ferrosilicon alloy magnetic materials to have high saturation magnetic induction Bs characteristics and low remanence Br, a method to improve the magnetic properties of ferrosilicon soft magnetic alloys has been designed, which is of great significance for their application in the industry. Summary of the Invention

[0006] The purpose of this invention is to provide a method for improving the magnetic properties of ferrosilicon soft magnetic alloys. This method enables ferrosilicon alloy magnetic materials to possess high saturation magnetic induction (Bs) while exhibiting low remanence (Br), thereby improving the magnetic stability and reliability of the ferrosilicon alloy magnetic materials.

[0007] The technical solution of the present invention is a method for improving the magnetic properties of ferrosilicon soft magnetic alloy, the method further comprising forging heating of the alloy, wherein the forging heating temperature is 850℃±10℃.

[0008] In the aforementioned method for improving the magnetic properties of ferrosilicon soft magnetic alloy, the alloy is formed by smelting multiple alloying elements, wherein the weight percentage of P element is 0.18%.

[0009] In the aforementioned method for improving the magnetic properties of ferrosilicon soft magnetic alloy, the alloy is formed by mixing and smelting the following alloying elements in the following weight percentages: C 0.03%, Si 2.5%, Mn 0.05%, P 0.18%, with the balance being Fe.

[0010] In the aforementioned method for improving the magnetic properties of ferrosilicon soft magnetic alloys, the smelting process employs a vacuum smelting furnace with a smelting vacuum degree of 0.5 Pa.

[0011] In the aforementioned method for improving the magnetic properties of ferrosilicon soft magnetic alloy, the method further includes a heat treatment process, which is as follows: heat treatment at 950℃~980℃ for 4 hours, then cooling to 500℃ at a rate of 100℃ / h, and then cooling to below room temperature at a rate of 50℃ / h~150℃ / h before unloading from the furnace.

[0012] The beneficial effects of the present invention: Compared with the prior art, the method of the present invention has the following advantages:

[0013] 1. The material element placement points of this invention are reasonable, and the measured values ​​from smelting meet the specified requirements;

[0014] 2. The alloy smelting process of the present invention adjusts the forging heating temperature and solves the cracking problem during the forging process;

[0015] 3. The heat treatment process of the present invention adjusts the annealing temperature and annealing cooling rate, thus solving the problem of excessive coercivity. Attached Figure Description

[0016] Figure 1 This is a flowchart of the present invention;

[0017] Figure 2 Images of billets forged using existing processes;

[0018] Figure 3 Images of billets forged using the process of this invention;

[0019] Figure 4 Image of the metallographic structure of the alloy in the heat-treated state (900℃);

[0020] Figure 5 Image of the metallographic structure of the alloy in the heat-treated state (950℃);

[0021] Figure 6 Image of the metallographic structure of the alloy in the heat-treated state (980℃). Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the present invention.

[0023] An embodiment of the present invention: A method for improving the magnetic properties of ferrosilicon soft magnetic alloys, comprising the following steps:

[0024] 1. Material element allocation points

[0025] Using a vacuum smelting furnace with a smelting vacuum of 0.5 Pa, steel ingots were smelted and cast. The smelting was carried out according to the alloy element composition of the original process. It was found that the measured value of P element was close to the upper limit of the specified value.

[0026] In this invention, the P alloying element composition inlet point is adjusted to 0.18%, and the measured value of P element after smelting is in the middle of the specified range.

[0027]

[0028] 2. Alloy smelting process

[0029] When the original process involved forging at 800℃±10℃, such as Figure 2 As shown, microcracks appeared on the surface of the billet, and the billet's deformation resistance was relatively high during processing. Analysis suggests that the main reason for the cracks was the low forging heating temperature and the significant temperature drop during processing. This caused the actual forging temperature of the billet during processing to reach the precipitation temperature of the brittle phases in the phosphorus-containing ferrosilicon alloy, resulting in a decrease in the billet's plasticity.

[0030] In this invention, the forging heating temperature of the ferrosilicon alloy is set at 850℃±10℃, and the deformation resistance during the billet processing is relatively small, such as... Figure 3 As shown, the blank has good surface quality and is easy to process.

[0031] 3. Heat treatment process

[0032] The original process involved a heat treatment of 850℃ for 4 hours, followed by 100℃ / hour, then 500℃, followed by cooling in the furnace to below 200℃ before unloading. Testing revealed that the alloy's magnetic properties were B. 16000 It has a strength of 1.98T and a coercivity Hc as high as 54.57A / m.

[0033] In this invention, the annealing temperature and cooling rate were redesigned. The heat treatment process is as follows: 950℃~980℃×4h→100℃ / h→500℃→50℃ / h~150℃ / h, cooling to below room temperature before unloading. After processing using this invention, the alloy's magnetic properties B... 16000 The coercivity is 1.97T and the coercivity Hc is 27.95 / m. Under the same magnetic induction intensity, the coercivity is increased by more than 50% compared with the original heat treatment process.

[0034] like Figures 4-6As shown, the grain size is grade 4.0 when the annealing temperature is 900℃; grade 2.0 when the annealing temperature is 950℃; and grade 1.0 when the annealing temperature is 980℃. It can be seen that as the annealing temperature increases, the alloy grain size grows from grade 4.0 to grade 1.0, indicating that increasing the annealing temperature helps to increase the alloy grain size, reduce the domain wall movement resistance, and thus gradually improve the alloy's magnetic properties with increasing annealing temperature.

Claims

1. A method for improving the magnetic properties of ferrosilicon soft magnetic alloys, characterized in that: The method also includes alloy forging heating, with the forging heating temperature being 850℃±10℃.

2. The method for improving the magnetic properties of ferrosilicon soft magnetic alloy according to claim 1, characterized in that: The alloy is formed by smelting multiple alloying elements, wherein the weight percentage of P element is 0.18%.

3. The method for improving the magnetic properties of ferrosilicon soft magnetic alloy according to claim 2, characterized in that: The alloy is formed by mixing and smelting the following alloying elements in the following weight percentages: C 0.03%, Si 2.5%, Mn 0.05%, P 0.18%, with the balance being Fe.

4. The method for improving the magnetic properties of ferrosilicon soft magnetic alloy according to claim 2, characterized in that: The smelting process employs a vacuum smelting furnace with a smelting vacuum degree of 0.5 Pa.

5. The method for improving the magnetic properties of ferrosilicon soft magnetic alloy according to claim 1, characterized in that: The method also includes a heat treatment process, which is as follows: heat treatment at 950℃~980℃ for 4 hours, then cooling down to 500℃ at a rate of 100℃ / h, and then cooling to below room temperature at a rate of 50℃ / h~150℃ / h before unloading.

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