Technical Field
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The present disclosure relates to a steel material and a preparation method therefor, and in particular to a wire rod and a preparation method therefor.
Background
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Soft magnetic materials refer to materials where magnetization mainly occurs when the magnetic field strength H is no greater than 1000 A/m. They possess low coercivity and high magnetic permeability. Soft magnetic materials are easy to magnetize and also easy to demagnetize. Electromagnetic pure iron is a typical type of soft magnetic material. With the rapid development of industries such as electronics and telecommunications, the application fields of electromagnetic pure iron have been continuously expanding, and its demand has been growing at a very fast rate.
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The main magnetic properties of electromagnetic pure iron comprise coercivity, aging increment of coercivity, maximum magnetic permeability, maximum magnetic induction intensity, etc. Among these properties, the magnitude of maximum magnetic induction intensity depends on the composition of the material. The physical state corresponding to it is the neat arrangement of magnetization vectors inside the material. It refers to the number of magnetic field lines passing through the unit cross-sectional area of the iron core, also known as magnetic flux density. It represents the magnetization ability of the material, with the unit of T. Coercivity is a quantity indicating the difficulty of magnetizing a material, which depends on the material's composition and defects (such as impurities, stress, etc.). Magnetic permeability is the ratio of B to H corresponding to any point on the hysteresis loop, and it is closely related to the material structure and the working state of the device. Coercivity is defined as follows: after a magnetic material is magnetically saturated, its magnetic induction intensity B does not return to zero when the external magnetic field is reduced to zero. Only by applying a magnetic field of a certain magnitude in the opposite direction of the original magnetization field can the magnetic induction intensity return to zero. This magnetic field is called the coercive magnetic field, also known as coercivity. For soft magnetic materials, the smaller the coercivity, the easier it is to magnetize and demagnetize. In practical applications, this enables faster realization of the conversion of electrical energy parameters in circuits and improves the response speed. Therefore, it is expected to reduce the coercivity of electromagnetic pure iron materials.
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For example, the Chinese patent document with publication No.
CN100457385C, publication date of February 4, 2009 , and titled "A Cold-Rolled Thin Sheet Material of Electromagnetic Pure Iron with Low Coercivity and High Magnetic Permeability" adopts a composition ratio of C ≤ 0.010%, Si ≤ 0.10%, Mn ≤ 0.20%, P ≤ 0.015%, S ≤ 0.010%, Al = 0.50% - 0.80%, [O], [N] < 40 ppm, electrolytic inclusions < 60 ppm, and the rest being Fe, to obtain a DT4C grade product with low coercivity and high magnetic permeability.
Summary
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One of the objects of the present disclosure is to provide a wire rod with low coercivity. By means of optimized design of alloy composition and microstructure control, a soft magnetic material is obtained. This material has low coercivity, making it easier to magnetize and demagnetize, which improves the response speed and magnetic properties of electronic components.
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To achieve the above object, the present disclosure provides a wire rod with low coercivity. The wire rod comprises Fe and unavoidable impurities, and additionally comprises the following chemical elements in the mass percentage as specified below:
- Mn: 0.1-0.2%;
- Al: 0.30-0.45%;
- O: 0.0015-0.0035%;
- N: 0.001-0.003%;
- Ca: 0.0005-0.0015%.
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Further, the present disclosure also provides a wire rod with low coercivity, and the mass percentage content of each chemical element thereof is as follows:
- Mn: 0.1-0.2%;
- Al: 0.30-0.45%;
- O: 0.0015-0.0035%;
- N: 0.001-0.003%;
- Ca: 0.0005-0.0015%;
- with a balance of Fe and unavoidable impurities.
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In the low-coercivity wire rod according to the present disclosure, the design principles of each chemical element are specifically described as follows:
C: C is an important element used in the steel production process. Through blast furnace ironmaking, converter or electric furnace smelting, carbon is retained in the final product. After the steel is cooled after rolling or subjected to annealing heat treatment, carbon will precipitate in the form of cementite. The presence of cementite will provide pinning for domain wall movement and increase the coercivity of the material. Therefore, the upper limit of C content is controlled to 0.003% in the present disclosure. In some embodiments, the mass percentage of C in the low-coercivity wire rod of the present disclosure is 0.001-0.003%.
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Si: Si is a non-metallic element. In the present disclosure, an excessively high content of Si will lead to a decrease in the magnetic properties of the alloy. However, Si cannot be completely removed during the steel smelting process. Meanwhile, considering the smelting cost and performance, the upper limit of Si content is controlled to 0.01% in the present disclosure. In some embodiments, the mass percentage of Si in the low-coercivity wire rod of the present disclosure is 0.001-0.01%.
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Mn: Mn is prone to combine with the harmful element S to form MnS, thereby reducing the harm of S. Meanwhile, the solid solution of Mn in steel is beneficial to grain growth during the annealing process. To give full play to the role of Mn, the content of Mn is controlled to be greater than or equal to 0.1% in the present disclosure. However, for the present disclosure, when the Mn content is excessively high, it will increase the difficulty in controlling the controlled cooling microstructure of the wire and reduce the magnetic properties. Therefore, the added amount of Mn is controlled to be less than or equal to 0.20%.
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Al: Al is often added to steel as a deoxidizing element. Meanwhile, the addition of Al will affect the phase transformation of the alloy. When Al is dissolved in ferrite, it will increase the austenite transformation temperature, while the addition of Mn will expand the austenite phase region and reduce the phase transformation temperature. In the present disclosure, the interaction between Al and Mn is considered simultaneously. Through calculation and experimental research, it is found that when the addition amount of Al is higher than 0.3%, the alloy phase transformation point of the material can be higher than 930°C, which is beneficial to the growth of ferrite equiaxed grains during the annealing process after wire drawing. However, when the Al content in the steel is excessively high, the replacement of iron by Al will reduce the magnetic properties of the alloy, and at the same time, it will promote the growth of oxide size and increase the coercivity. Therefore, the added amount of Al is controlled to be less than or equal to 0.45%.
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O: O is an element that inevitably exists during the steel smelting process. In the present disclosure, O in the liquid molten steel will combine with Al to form aluminum oxide precipitates. By adding Al 2-3 times during the refining process of steelmaking, the size of aluminum oxide particles can be controlled to not exceed 3µm. These particles provide nucleation sites for the solidification of molten steel during the continuous casting process, promote the formation of equiaxed grain structure, and prevent excessive segregation of residual elements caused by overgrowth of columnar grains (which would reduce the material's processability and magnetic properties), thus facilitating the homogenization of the structure. Therefore, the O content in the steel is controlled to be greater than or equal to 0.0015% in the present disclosure. However, excessively high oxygen content will lead to an increase in the number and size of inclusions in the steel, which greatly affects the material's drawability and magnetic properties and increases coercivity. Thus, the O content needs to be controlled to be less than or equal to 0.0035%.
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N: In the present disclosure, when N is solid-dissolved in ferrite, it will reduce the phase transformation temperature and magnetic properties of the alloy, so its content needs to be controlled below 0.003%. During the cooling process of the alloy, N tends to combine with Al and precipitate out, meanwhile, residual C will combine with other alloying elements to form carbides. The size of such precipitates is small, controlled within the nanoscale range, which can prevent abnormal grain growth during the heating process, promote the uniform growth of ferrite grains, and improve the uniformity of the material's structure and properties. Based on this, to give full play to the role of N, its content is controlled to be greater than or equal to 0.001%.
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Ca: In the present disclosure, adding Ca with a content of greater than or equal to 0.0005% is beneficial to the dispersed distribution of aluminum oxide particles. However, excessively high Ca content will increase the difficulty of alloy smelting and raise the cost. Therefore, the Ca content is controlled to be less than or equal to 0.0015%.
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Further, among other unavoidable impurities elements in the low-coercivity wire rod according to the present disclosure: Ti ≤ 0.003%, P ≤ 0.015%, and S ≤ 0.008%.
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The unavoidable impurities in the present disclosure are mainly P, S, and Ti. Among them, Ti tends to combine with N to form coarse-grained TiN, therefore, the Ti content is preferably controlled to not exceed 0.003%. Residual P and S in steel will increase the brittleness of the steel and reduce the material's formability, thus, the P content is preferably controlled to not exceed 0.015%, and the S content is preferably controlled to not exceed 0.008%.
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Further, in the low-coercivity wire rod of the present disclosure, the mass percentage of its chemical elements shall also satisfy at least one of the following items: (Al+100Ca)/(Ti+N)≥85; Mn/S≥20; each chemical element is substituted with the numerical value before the percentage sign of its corresponding mass percentage content in the formulae.
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In the present disclosure, to promote the sufficient precipitation of Al nitrides and carbon elements and exert the effect of Ca element, the mass percentage of each chemical element in the material is further controlled to satisfy (Al+100Ca)/(Ti+N) ≥85. In some embodiments, 85 ≤(Al+100Ca)/(Ti+N) ≤170.
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Mn easily combines with the harmful element S to form MnS. To reduce its harm, the present disclosure controls Mn/S ≥ 20. In some embodiments, 20 ≤ Mn/S ≤ 200.
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The microstructure of the low-coercivity wire rod according to the present disclosure comprises ferrite grains. Further, in the low-coercivity wire rod of the present disclosure, a size of the ferrite grains ranges from 200µm to 800µm. This microstructural characteristic can effectively reduce the coercivity of the material, endowing it with excellent soft magnetic properties.
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The microstructure of the low-coercivity wire rod according to the present disclosure comprises aluminum oxide and aluminum carbonitride precipitates. Further, in the low-coercivity wire rod of the present disclosure, a size of the aluminum oxide and aluminum carbonitride precipitates is ≤ 3 µm. This microstructural characteristic can effectively reduce the coercivity of the material, enabling it to have good soft magnetic properties. In some embodiments, the size of the aluminum oxide and aluminum carbonitride precipitates in the low-coercivity wire rod of the present disclosure ranges from 0.1µm to 3µm.
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Further, a coercivity of the low-coercivity wire rod according to the present disclosure is ≤ 25 A/m. In some embodiments, the coercivity of the low-coercivity wire rod of the present disclosure ranges from 5 A/m to 25 A/m, such as 10 A/m, 15 A/m, and 20 A/m.
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Another object of the present disclosure is to provide a manufacturing method for a low-coercivity wire rod. The method adopts a relatively simple processing technology and can produce soft magnetic material wire rods that meet the requirement of low coercivity.
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Based on the above object, the present disclosure also provides a manufacturing method for the low-coercivity wire rod, comprising the following steps:
- (1) smelting;
- (2) continuous casting;
- (3) primary rolling;
- (4) heating: heating to 900-1150°C, e.g., 950-1150°C, and holding for 1.5-2.5 hours;
- (5) wire rod rolling;
- (6) Stelmor fan cooling;
- (7) wire rod drawing;
- (8) annealing: an annealing heating temperature is 870-910°C, a holding time is 1-2 hours, and then cooling to below 500°C at a cooling rate of ≤ 50°C/h.
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In some embodiments, in the primary rolling step of the manufacturing method according to the present disclosure, the smelting can be carried out by electric furnace or converter, followed by LF (Ladle Furnace) refining, VD (Vacuum Degassing) or RH (Ruhrstahl-Heraeus) degassing treatment, and then calcium wire feeding.
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Further, in the primary rolling step of the manufacturing method according to the present disclosure, a bloom or slab is heated to 1100-1250°C and then rolled into a small bloom with a size of 140-220 mm.
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Further, in the wire rod rolling step of the manufacturing method according to the present disclosure, a rolling speed is controlled to be 20-110 m/s.
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Further, in the wire rod rolling step of the manufacturing method according to the present disclosure, an inlet temperature of the finishing mill train is controlled to be 900-980 °C, an inlet temperature of the reducing and sizing mill train is controlled to be 900-980 °C, and a laying temperature is controlled to be 890-960 °C.
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Further, in the Stelmor fan cooling step of the manufacturing method according to the present disclosure, an air volume of the F1-F3 fans in the Stelmor fan bank is controlled to be 0-50%.
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Further, in the wire rod drawing step of the manufacturing method according to the present disclosure, a drawing area reduction rate is controlled to be 10-30%.
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Further, in the annealing step of the manufacturing method according to the present disclosure, a cooling rate is controlled to be 30-50°C/h.
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The low-coercivity wire rod according to the present disclosure has the following advantages and beneficial effects:
The low-coercivity wire rod according to the present disclosure has a uniform microstructure, with ferrite grain size ranging from 200µm to 800µm and coercivity of ≤ 25 A/m. It exhibits excellent magnetic properties, which can meet the processing requirements for iron cores of high-performance, fast-switching relays and parts of communication electronic devices, thus having broad application prospects.
Detailed Description
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The following will further explain and illustrate the low-coercivity wire rod and its preparation method according to the present disclosure in combination with specific examples. However, such explanation and illustration shall not unduly limit the technical solution of the present disclosure.
Examples 1-10 and Comparative Examples 1-3
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The low-coercivity wire rods in Examples 1-10 were all prepared through the following steps:
- (1) After being smelted in an electric furnace, LF refining and RH degassing processes were conducted. The content of P in the steel was controlled to be ≤ 0.015%, and S ≤ 0.008%, Ti ≤ 0.003%. Meanwhile, the content of O in the steel was controlled to be 0.0015-0.0035%, and N 0.001-0.003%. After refining, calcium wire was fed, and the Ca content in the steel was controlled to be 0.0005-0.0015%.
- (2) A bloom continuous casting machine was used for casting under argon protection to obtain continuous casting blooms or slabs. The size of the blooms was ≤ 450 mm, and the thickness of the slabs was ≤ 400 mm. By adjusting the parameters of casting speed, cooling, and soft reduction at the end during the continuous casting process, the uniform distribution of precipitates was controlled and the segregation of elements in the core of the bloom was reduced. The chemical compositions of the blooms or slabs were shown in Table 1.
- (3) The slabs were longitudinally cut into blooms with a size of ≤ 400 mm. Specifically, the slabs in Examples 6-7 were cut into 400 mm blooms, those in Examples 8-9 were cut into 350 mm blooms, and that in Example 10 was cut into 250 mm blooms. The continuous casting blooms or blooms cut from slabs were heated to 1100-1250 °C and then rolled into small blooms with a size of 140-200 mm. The small blooms underwent eddy current testing, magnetic particle testing, grinding wheel dressing, supplementary magnetic particle testing, and grinding to remove defects such as surface cracks and pits on the cast blooms, with the defect depth ≤ 0.5 mm.
- (4) The small blooms were heated to 900-1150 °C (e.g., 950-1150 °C) and held for 1.5-2.5 hours.
- (5) Wire rod rolling: The rolling speed was controlled to be 20-110 m/s, the inlet temperature of the finishing mill train was controlled to be 900-980 °C, the inlet temperature of the reducing and sizing mill train was controlled to be 900-980 °C, and the laying temperature was controlled to be 890-960 °C. The rolled wire rods had a size specification of Φ 5.5-16 mm.
- (6) Stelmor fan cooling: The air volume of the F1-F3 fans was 0-50%. The Stelmor line was equipped with 27 heat preservation covers each with a length of 3 m, among which the 1-5# heat preservation covers were opened and the 6-27# heat preservation covers were closed.
- (7) The hot-rolled wire rods were subjected to single-pass drawing, and the drawing area reduction rate was controlled to be 10-30%.
- (8) Annealing: The annealing heating temperature was 870-910°C, the holding time was 1-2 hours, and then the wire rods were cooled to below 500 °C at a cooling rate of ≤ 50 °C/h.
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The comparative wire rods in Comparative Examples 1-3 were also prepared through the same procedural steps as those described above. However, their chemical compositions and the specific process parameters in various steps failed to meet the design requirements of the present disclosure.
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Table 1 lists the mass percentage ratios of each chemical element in the low-coercivity wire rods of Examples 1-10 and the comparative wire rods of Comparative Examples 1-3.
Table 1. (wt.%, the balance being Fe and other unavoidable impurities except P, S, Ti) | No. | C | Si | Mn | Al | O | N | Ti | P | S | Ca | (Al+100Ca)/(Ti+N) | Mn/S |
| Ex. 1 | 0.001 | 0.002 | 0.12 | 0.45 | 0.003 | 0.0025 | 0.0005 | 0.008 | 0.002 | 0.0005 | 167 | 60.0 |
| Ex. 2 | 0.003 | 0.006 | 0.15 | 0.40 | 0.0025 | 0.0026 | 0.001 | 0.009 | 0.003 | 0.001 | 139 | 50.0 |
| Ex. 3 | 0.001 | 0.0015 | 0.2 | 0.42 | 0.0019 | 0.0018 | 0.0025 | 0.012 | 0.008 | 0.0012 | 126 | 25.0 |
| Ex. 4 | 0.002 | 0.0035 | 0.1 | 0.39 | 0.0026 | 0.001 | 0.0024 | 0.006 | 0.005 | 0.0009 | 141 | 20.0 |
| Ex. 5 | 0.0018 | 0.0019 | 0.19 | 0.31 | 0.0015 | 0.0028 | 0.0012 | 0.001 | 0.001 | 0.0014 | 113 | 190.0 |
| Ex. 6 | 0.003 | 0.0011 | 0.11 | 0.30 | 0.0019 | 0.0016 | 0.0019 | 0.015 | 0.0008 | 0.0005 | 100 | 137.5 |
| Ex. 7 | 0.0022 | 0.008 | 0.16 | 0.45 | 0.0029 | 0.0011 | 0.003 | 0.014 | 0.008 | 0.0014 | 144 | 20.0 |
| Ex. 8 | 0.0015 | 0.0091 | 0.17 | 0.38 | 0.0035 | 0.001 | 0.0028 | 0.009 | 0.007 | 0.001 | 126 | 24.3 |
| Ex. 9 | 0.0026 | 0.01 | 0.18 | 0.45 | 0.0033 | 0.003 | 0.0017 | 0.01 | 0.002 | 0.0011 | 119 | 90.0 |
| Ex. 10 | 0.002 | 0.004 | 0.2 | 0.33 | 0.0024 | 0.0025 | 0.003 | 0.005 | 0.006 | 0.0015 | 87 | 33.3 |
| CEx. 1 | 0.01 | 0.005 | 0.2 | 0.35 | 0.0020 | 0.004 | 0.002 | 0.008 | 0.005 | 0.0005 | 67 | 40.0 |
| CEx. 2 | 0.002 | 0.15 | 0.15 | 0.025 | 0.001 | 0.0025 | 0.005 | 0.004 | 0.010 | 0.0003 | 7 | 15.0 |
| CEx. 3 | 0.001 | 0.01 | 0.35 | 0.20 | 0.004 | 0.0006 | 0.01 | 0.017 | 0.002 | 0.0021 | 39 | 175.0 |
| Note: In the above formulae (Al + 100Ca)/(Ti + N) and Mn/S, the values substituted for each chemical element in the formulae are the numerical values before the percentage sign of the corresponding chemical element's mass percentage content. |
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Table 2-1 and Table 2-2 list the specific process parameters of the low-coercivity wire rods of Examples 1-10 and the comparative wire rods of Comparative Examples 1-3 in the above steps.
Table 2-1. | No. | Bloom or slab from casting (mm) | Size of the bloom obtained from primary rolling (mm) | Heating temperature of primary rolling (°C) | Heating temperature (°C) | Holding time of heating (h) | Rolling speed of wire rod rolling (m/s) | Inlet temperature of the finishing mill train (°C) | Inlet temperature of the reducing and sizing mill train (°C) | Laying temperature (°C) |
| Ex. 1 | 450×450 bloom | 220×220 | 1100 | 900 | 1.5 | 110 | 900 | 900 | 890 |
| Ex. 2 | 450×450 bloom | 220×220 | 1100 | 900 | 1.5 | 100 | 900 | 900 | 890 |
| Ex. 3 | 350×350 bloom | 220×220 | 1100 | 900 | 1.5 | 90 | 900 | 900 | 890 |
| Ex. 4 | 350×350 bloom | 160×160 | 1150 | 950 | 2 | 80 | 920 | 910 | 900 |
| Ex. 5 | 260×260 bloom | 140×140 | 1250 | 950 | 2 | 70 | 920 | 910 | 900 |
| Ex. 6 | 400 slab | 220×220 | 1100 | 1050 | 2.5 | 20 | 940 | 940 | 930 |
| Ex. 7 | 400 slab | 160×160 | 1150 | 1050 | 2.5 | 25 | 940 | 940 | 930 |
| Ex. 8 | 350 slab | 160×160 | 1150 | 1050 | 2.5 | 90 | 940 | 940 | 930 |
| Ex. 9 | 350 slab | 160×160 | 1150 | 1150 | 2.5 | 30 | 980 | 980 | 960 |
| Ex. 10 | 250 slab | 140×140 | 1250 | 1150 | 2.5 | 45 | 980 | 980 | 960 |
| CEx. 1 | 500×450 bloom | 160×160 | 1100 | 1050 | 2.5 | 115 | 900 | 890 | 880 |
| CEx. 2 | 250 slab | 140×140 | 1050 | 1000 | 3 | 80 | 880 | 880 | 850 |
| CEx. 3 | 350×350 bloom | 135×135 | 1200 | 1200 | 2 | 20 | 990 | 980 | 960 |
Table 2-2. | No. | Air volume of the F1-F3 fans (%) | Drawing area reduction rate (%) | Annealing heating temperature (°C) | Annealing holding time (h) | Annealing cooling rate (°C/h) | Wire rod size (mm) |
| Ex. 1 | 0 | 10 | 870 | 1 | 50 | 5.5 |
| Ex. 2 | 0 | 10 | 870 | 1 | 50 | 8 |
| Ex. 3 | 10 | 15 | 875 | 1.2 | 45 | 10 |
| Ex. 4 | 10 | 20 | 880 | 1.5 | 45 | 6 |
| Ex. 5 | 15 | 22 | 880 | 1.5 | 40 | 9 |
| Ex. 6 | 15 | 25 | 890 | 1.8 | 40 | 16 |
| Ex. 7 | 20 | 25 | 900 | 1.8 | 35 | 10 |
| Ex. 8 | 25 | 28 | 905 | 2 | 35 | 6 |
| Ex. 9 | 30 | 30 | 910 | 2 | 30 | 14 |
| Ex. 10 | 50 | 30 | 910 | 2 | 30 | 12 |
| CEx. 1 | 0 | 5 | 850 | 3 | 45 | 5.5 |
| CEx. 2 | 45 | 20 | 880 | 2 | 55 | 10 |
| CEx. 3 | 55 | 35 | 950 | 2.5 | 60 | 16 |
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Samples were taken from the wire rods of Examples 1-10 and the comparative wire rods of Comparative Examples 1-3 prepared. The microstructure (ferrite grain size, size of aluminum oxide and aluminum carbonitride precipitates) of the steel plate samples in each example was observed and analyzed using
GB/T 13298-2015 Metallographic Test Methods for Metals. The relevant observation and analysis results are listed in Table 3 below.
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In addition, samples were taken again from the wire rods of Examples 1-10 and the comparative wire rods of Comparative Examples 1-3 obtained through the above process steps. The coercivity was tested in accordance with
GB/T 13012-2008 Measurement Methods for DC Magnetic Properties of Soft Magnetic Materials - Permeability and Saturation Magnetic Induction - Toroidal Sample Method and Permeameter Method, and the test results are listed in Table 3.
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Table 3 lists the test results of microstructural characteristics and coercivity of the wire rods of Examples 1-10 and the comparative wire rods of Comparative Examples 1-3.
Table 3. | No. | Ferrite grain size (µm) | Size of aluminum oxide and aluminum carbonitride precipitates (µm) | Coercivity(A/m) |
| Ex. 1 | 200-550 | 0.5 | 24 |
| Ex. 2 | 410-800 | 2.0 | 10 |
| Ex. 3 | 300-650 | 1.5 | 19 |
| Ex. 4 | 450-750 | 0.3 | 14 |
| Ex. 5 | 250-400 | 3.0 | 20 |
| Ex. 6 | 680-800 | 2.2 | 9 |
| Ex. 7 | 360-540 | 0.2 | 18 |
| Ex. 8 | 260-490 | 0.1 | 22 |
| Ex. 9 | 660-785 | 2.1 | 10 |
| Ex. 10 | 510-795 | 1.2 | 16 |
| CEx. 1 | 35-120 | 4.1 | 105 |
| CEx. 2 | 25-70 | 2.0 | 72 |
| CEx. 3 | 170-350 | 1.5 | 41 |
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As shown in Table 3, the ferrite grain size of the wire rods in Examples 1-10 ranges from 200µm to 800µm, while the ferrite grain size of the comparative examples is all smaller than that of the present disclosure. In addition, the size of aluminum oxide and aluminum carbonitride precipitates in the wire rods of Examples 1-10 of the present disclosure is ≤ 3 µm.
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It can also be seen from Table 3 that the coercivity of the wire rods in Examples 1-10 of the present disclosure is all lower than 25 A/m, while the minimum coercivity of Comparative Examples 1-3 is 41 A/m.
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It should be noted that combinations of the various technical features in this case are not limited to the combinations disclosed in the claims of this case or the combinations disclosed in the specific Examples. All technical features disclosed in this case can be combined freely or associated in any way unless a contradiction occurs.
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It should also be noted that the Examples listed above are only specific embodiments of the present disclosure. Obviously, the present disclosure is not limited to the above Examples, and changes or modifications made thereto can be directly derived from the present disclosure or easily conceived of by those skilled in the art, all of which fall within the protection scope of the present disclosure.