High-magnetic-induction soft-magnetic pure-iron precision thin strip and manufacturing method thereof

Abstract

The invention discloses a high magnetic induction soft magnetic pure iron precision thin strip and a manufacturing method thereof, the method comprises the steps of continuous casting billet production, electroslag remelting, hot rolling, cold rolling, magnetic heat treatment and the like, pure iron components are controlled to be smaller than or equal to 0.0080% of C, smaller than or equal to 0.01% of Si, 0.05-0.10% of Mn, smaller than or equal to 0.0040% of P, smaller than or equal to 0.0015% of S, 0.010-0.030% of Al, smaller than or equal to 0.0020% of Ti, smaller than or equal to 0.010% of Ni and smaller than or equal to 0.0040% of O. A continuous annealing furnace heat treatment process is matched twice in the cold rolling process, and magnetic heat treatment is performed by adopting a continuous annealing process after cold rolling is finished. The thickness of the high-magnetic-induction soft-magnetic pure-iron precision thin strip product ranges from 0.05 mm to 0.1 mm, the width is smaller than or equal to 600 mm, the magnetic induction intensity B10000 is larger than or equal to 1.85 T, the maximum magnetic conductivity mu m is larger than or equal to 0.02 H / m, and the high-magnetic-induction soft-magnetic pure-iron precision thin strip product is high in purity, extremely thin in specification, good in magnetic conductivity and good in application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of pure iron soft magnetic material production, and specifically relates to a high magnetic induction soft magnetic pure iron precision thin strip and a manufacturing method thereof. Background Art

[0002] In recent years, the aviation industry, electronic components, communications, and magnetic shielding industries have developed rapidly. The demand for pure iron soft magnetic materials has increased year by year, and the requirements for product dimensional accuracy, magnetic properties and other indicators have become more stringent. The thickness of cold-rolled coils is above 0.5 mm. Due to factors such as purity and immature pure iron rolling technology, thinner pure iron products have not yet been developed. At the same time, the magnetic conductivity of conventional industrial pure iron is relatively low, such as the magnetic induction intensity B 10000 At around 1.83T, the maximum magnetic permeability μ m At the level of 0.015 to 0.018 H / m, the magnetic properties requirements of pure iron soft magnetic materials cannot be met.

[0003] Industrial pure iron is cheap and has wide promotion value when used as soft magnetic material, but its performance indicators cannot meet the needs of industry development. Therefore, it is a technical problem that technical personnel in this field need to urgently solve to develop a production process for pure iron precision thin strips with a thickness of 0.05 to 0.1 mm and at the same time improve the magnetic properties of pure iron precision thin strip products to meet the requirements of pure iron soft magnetic materials for magnetic properties and ensure the functional accuracy of terminal products. Summary of the invention

[0004] In order to solve the above technical problems existing in the prior art, the present invention provides a method for manufacturing a high magnetic induction soft magnetic pure iron precision thin strip, comprising the following steps:

[0005] S1, continuous casting billet production: converter smelting, VOD refining, and continuous casting are carried out based on the target composition of pure iron, wherein the target composition of pure iron is designed by mass percentage as follows: C≤0.0080%, Si≤0.01%, Mn: 0.05-0.10%, P≤0.0040%, S≤0.0015%, Al: 0.010-0.030%, Ti≤0.0020%, Ni≤0.010%, O≤0.0040%, and the rest are unavoidable impurities and iron. The specific implementation process of continuous casting billet production includes:

[0006] During converter smelting, the phosphorus content of pure iron and the amount of slag in steel tapping are controlled, wherein the phosphorus content in converter steel tapping is controlled to be P≤0.0025%, and the amount of slag is controlled to be ≤1.5kg per ton of pure iron;

[0007] VOD refining includes: (1) after the converter pure iron enters the VOD, it is decarburized under high vacuum conditions, the decarburization time is controlled to be 15 to 20 minutes, and the vacuum system pressure is controlled to be below 65 Pa; (2) after the decarburization is completed, 1.2 to 1.5 kg of aluminum is added per ton of pure iron for deoxidation; (3) 10 to 13 kg of lime is added per ton of pure iron for desulfurization, and the desulfurization stirring time is controlled to be ≥10 minutes. The composition of pure iron out of the VOD station is controlled to be: C ≤ 0.0060%, Si ≤ 0.005%, Mn: 0.05 to 0.10%, P ≤ 0.0030%, S ≤ 0.0020%, Al: 0.010 to 0.030%, Ti ≤ 0.0015%, Ni ≤ 0.010%, O ≤ 0.0040%, and the rest are unavoidable impurities and iron;

[0008] During the continuous casting process, pure iron is continuously cast into slabs, wherein the temperature of pure iron before continuous casting is controlled at 1600-1610°C, the thickness of the continuous casting slab is controlled at 200-280mm, the width of the continuous casting slab is controlled at 1000-1260mm, and the length of the continuous casting slab is controlled at 3000-4000mm;

[0009] S2, electroslag remelting: including (1) using continuous casting slabs to cut and weld to make electrode blanks; (2) controlling the electroslag remelting power to ensure that the melting rate is ≤12kg / min; (3) the weight proportion of lime in the slag-making material of electroslag remelting is controlled to be ≥50%; (4) the weight of the electroslag ingot is controlled to be 8-10 tons / piece, and the composition of pure iron obtained after electroslag remelting is controlled to be: C≤0.0080%, Si≤0.01%, Mn: 0.05-0.10%, P≤0.0040%, S≤0.0015%, Al: 0.010-0.030%, Ti≤0.0020%, Ni≤0.010%, O≤0.0040%, and the rest are unavoidable impurities and iron;

[0010] S3, hot rolling: the electroslag ingot is hot rolled to form a blank and further hot rolled into a pure iron hot rolled coil, the thickness of the pure iron hot rolled coil is controlled to be 2.0-2.3 mm, and the width is controlled to be ≤1200 mm;

[0011] S4, cold rolling: before cold rolling, the pure iron hot rolled coil is trimmed and longitudinally slit to obtain a pure iron coil with a width of ≤600 mm. The cold rolling is carried out in 6 to 8 passes, and a heat treatment is carried out during the cold rolling, specifically including: (1) after the second pass of cold rolling, the thickness of the pure iron strip is controlled to be 0.5±0.03 mm, and then a continuous annealing process is used for heat treatment. Argon or nitrogen is used for protection in the annealing furnace, the annealing furnace temperature is controlled at 680 to 700°C, and the annealing speed is controlled at 80 to 100 m / min; (2) the fourth pass of cold rolling is carried out. After the first pass, the thickness of the pure iron strip is controlled at 0.15±0.02mm, and then a continuous annealing process is used for heat treatment. Argon or nitrogen is used for protection in the annealing furnace. The temperature of the annealing furnace is controlled at 660-680°C, and the annealing speed is controlled at 80-100m / min; (3) according to the finished product thickness requirement of 0.05-0.1mm, the 5th to 8th pass of cold rolling is carried out, and the surface roughness of the working roll used in the last pass is selected to be ≤0.06μm, so as to obtain a pure iron precision thin strip with a thickness of 0.05-0.1mm;

[0012] S5, magnetic heat treatment: The magnetic heat treatment is carried out by continuous annealing process, and argon or nitrogen is used for protection in the annealing furnace. The temperature of the annealing furnace is controlled at 930-950°C, the annealing speed is controlled at 15-20m / min, and the passing time of the pure iron precision thin strip at any position in the annealing furnace is controlled to be ≥3 minutes, and the temperature of the pure iron precision thin strip at the outlet of the annealing furnace is controlled to be ≤450°C.

[0013] Furthermore, in the above-mentioned method for manufacturing high magnetic induction soft magnetic pure iron precision thin strip, during the VOD refining process, 0.9 to 1.1 kg of electrolytic manganese is added per ton of pure iron with reference to the target composition of pure iron for manganese alloying.

[0014] Furthermore, in the above-mentioned method for manufacturing high magnetic induction soft magnetic pure iron precision thin strip, if the pure iron temperature after VOD refining is lower than 1600°C, an LF furnace heating treatment is performed before continuous casting to raise the pure iron temperature to 1600-1610°C.

[0015] Furthermore, in the above-mentioned method for manufacturing high magnetic induction soft magnetic pure iron precision thin strip, during the VOD refining process, when deoxidation is performed by adding 1.2 to 1.5 kg of aluminum per ton of pure iron, aluminum is added for fine adjustment based on the actual aluminum content in the pure iron with reference to the pure iron target composition.

[0016] Furthermore, in the above-mentioned method for manufacturing high magnetic induction soft magnetic pure iron precision thin strip, cold rolling is carried out using a six-roll rolling mill or a twenty-roll rolling mill, and the total number of cold rolling passes is not less than 6 and not more than 8.

[0017] Furthermore, in the above-mentioned method for manufacturing high magnetic induction soft magnetic pure iron precision thin strip, the pure iron precision thin strip is subjected to alkali washing and degreasing treatment before magnetic heat treatment.

[0018] In addition, the present invention also provides a high magnetic induction soft magnetic pure iron precision thin strip, which is prepared by the above-mentioned high magnetic induction soft magnetic pure iron precision thin strip manufacturing method, and the components of the high magnetic induction soft magnetic pure iron precision thin strip are as follows by mass percentage: C≤0.0080%, Si≤0.01%, Mn: 0.05-0.10%, P≤0.0040%, S≤0.0015%, Al: 0.010-0.030%, Ti≤0.0020%, Ni≤0.010%, O≤0.0040%, and the rest are inevitable impurities and iron, and the magnetic induction intensity B of the high magnetic induction soft magnetic pure iron precision thin strip is 10000 ≥1.85T, maximum magnetic permeability μ m ≥0.02H / m.

[0019] Furthermore, the thickness of the high magnetic induction soft magnetic pure iron precision thin strip is 0.05-0.1 mm and the width is ≤600 mm.

[0020] The high magnetic induction soft magnetic pure iron precision thin strip and the manufacturing method thereof of the present invention have the following advantages and beneficial effects: the thickness of the high magnetic induction soft magnetic pure iron precision thin strip product of the present invention is 0.05-0.1 mm, the width is ≤600 mm, and the magnetic induction intensity B 10000 ≥1.85T, maximum magnetic permeability μ m ≥0.02H / m, the product has high purity, extremely thin specifications, and good magnetic conductivity. It is helpful to promote technological progress in special fields of the country and has good social significance and application prospects. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0022] In the present application, the term "pure iron precision thin strip" refers to a cold-rolled pure iron strip with a thickness specification of 0.05 to 0.1 mm.

[0023] The purpose of the present invention is to develop a production process for pure iron precision thin strips with a thickness of 0.05 to 0.1 mm according to the needs of the aviation industry, electronic components, communications, magnetic shielding and other industries, and at the same time improve the magnetic properties of the pure iron precision thin strips. To this end, the present invention takes the lead in adopting the process steps of continuous casting billet production → electroslag remelting → hot rolling → cold rolling → magnetic heat treatment. Through component design, process flow optimization, rolling process control, and magnetic heat treatment process control, the purity of pure iron is reliably guaranteed, the problems of edge cracking and strip breakage caused by cold rolling work hardening are solved, and the magnetic properties of the pure iron precision thin strips are effectively controlled. Finally, the pure iron precision thin strips with a thickness of 0.05 to 0.1 mm and a width of ≤600 mm can be produced and prepared. The magnetic induction intensity B of the pure iron precision thin strips is 2.347 W, 2.10 W, and 2.33 W. 10000 ≥1.85T, maximum magnetic permeability μ m ≥0.02H / m, fully meeting the requirements of pure iron soft magnetic materials for magnetic properties.

[0024] Specifically, the method for manufacturing a high magnetic induction soft magnetic pure iron precision thin strip of the present invention comprises the following steps:

[0025] S1, continuous casting billet production, converter smelting, VOD refining, continuous casting based on pure iron target composition, wherein the pure iron target composition is designed by mass percentage as follows: C≤0.0080%, Si≤0.01%, Mn: 0.05-0.10%, P≤0.0040%, S≤0.0015%, Al: 0.010-0.030%, Ti≤0.0020%, Ni≤0.010%, O≤0.0040%, and the rest are unavoidable impurities and iron. The specific implementation process of continuous casting billet production includes:

[0026] During converter smelting, the phosphorus content of pure iron and the amount of slag in steel tapping are controlled, wherein the phosphorus content in converter steel tapping is controlled to be P≤0.0025%, and the amount of slag is controlled to be ≤1.5kg per ton of pure iron;

[0027] VOD refining includes: (1) after the converter pure iron enters the VOD, it is decarburized under high vacuum conditions, the decarburization time is controlled to be 15 to 20 minutes, and the vacuum system pressure is controlled to be below 65 Pa; (2) after the decarburization is completed, 1.2 to 1.5 kg of aluminum is added per ton of pure iron for deoxidation; (3) 10 to 13 kg of lime is added per ton of pure iron for desulfurization, and the desulfurization stirring time is controlled to be ≥10 minutes. The composition of pure iron leaving the VOD station is controlled to be: C≤0.0060%, Si≤0.005%, Mn: 0.05 to 0.10%, P≤0.0030%, S≤0.0020%, Al: 0.010 to 0.030%, Ti≤0.0015%, Ni≤0.010%, O≤0.0040%, and the rest are unavoidable impurities and iron;

[0028] During the continuous casting process, pure iron is continuously cast into slabs, wherein the temperature of the pure iron before continuous casting is controlled at 1600-1610°C, the thickness of the continuous casting slab is controlled at 200-280mm, the width of the continuous casting slab is controlled at 1000-1260mm, and the length of the continuous casting slab is controlled at 3000-4000mm.

[0029] S2, electroslag remelting. The main purpose of electroslag remelting is to further improve the purity of pure iron and obtain pure iron ingots with high purity, low sulfur content, uniform and dense structure. The specific operations of electroslag remelting include: (1) using continuous casting slabs to make electrode blanks through cutting and welding according to the requirements of electroslag process; (2) controlling the electroslag remelting power to ensure that the melting rate is ≤12kg / min; (3) the weight proportion of lime in the slag-making material of electroslag remelting is controlled to be ≥50% (4) The weight of the electroslag ingot is controlled at 8-10 tons / piece, and the composition of the pure iron obtained after electroslag remelting is controlled as follows: C≤0.0080%, Si≤0.01%, Mn: 0.05-0.10%, P≤0.0040%, S≤0.0015%, Al: 0.010-0.030%, Ti≤0.0020%, Ni≤0.010%, O≤0.0040%, and the rest are inevitable impurities and iron.

[0030] S3, hot rolling, the electroslag ingot is hot rolled to open the blank and further hot rolled into pure iron hot rolled coil, the thickness of the pure iron hot rolled coil is controlled to be 2.0-2.3 mm, and the width is controlled to be ≤1200 mm. Preferably, the target thickness of the pure iron hot rolled coil is controlled to be 2.2 mm.

[0031] S4, cold rolling, before cold rolling, the pure iron hot rolled coil is trimmed and longitudinally slit to obtain a pure iron coil with a width of ≤600 mm, and the cold rolling is carried out in 6 to 8 passes. During the cold rolling, heat treatment is performed to improve the rolling effect, specifically including: (1) after the second pass of cold rolling, the thickness of the pure iron strip is controlled to be 0.5±0.03 mm, and then a continuous annealing process is used for heat treatment. Argon or nitrogen is used in the annealing furnace to prevent oxidation of the pure iron strip. The temperature of the annealing furnace is controlled at 680 to 700°C, and the annealing speed is controlled at 80 to 100 m / min; (2) After the fourth rolling pass, the thickness of the pure iron strip is controlled at 0.15±0.02 mm, and then a continuous annealing process is used for heat treatment. Argon or nitrogen is used in the annealing furnace to prevent oxidation of the pure iron strip. The temperature of the annealing furnace is controlled at 660-680°C, and the annealing speed is controlled at 80-100 m / min. (3) According to the finished product thickness requirement of 0.05-0.1 mm, the 5th to 8th cold rolling passes are carried out. The surface roughness of the working roll used in the last pass is selected to be ≤0.06 μm, and a pure iron precision thin strip with a thickness of 0.05-0.1 mm is obtained.

[0032] S5, magnetic heat treatment. The main purpose of magnetic heat treatment is to improve the pure iron structure, realize recrystallization and promote uniform grain growth, thereby improving the magnetic properties of the product. Continuous annealing process is used for magnetic heat treatment. Argon or nitrogen is used for protection in the annealing furnace to prevent oxidation of the pure iron precision thin strip. The temperature of the annealing furnace is controlled at 930-950°C, the annealing speed is controlled at 15-20m / min, and the passing time of the pure iron precision thin strip at any position in the annealing furnace is controlled to be ≥3 minutes, and the temperature of the pure iron precision thin strip at the outlet of the annealing furnace is controlled to be ≤450°C.

[0033] In the method for manufacturing high magnetic induction soft magnetic pure iron precision thin strip of the present invention, during the VOD refining process, when deoxidation is performed by adding 1.2 to 1.5 kg of aluminum per ton of pure iron, aluminum can be added for fine adjustment according to the actual aluminum content in the pure iron with reference to the pure iron target composition.

[0034] In the method for manufacturing high magnetic induction soft magnetic pure iron precision thin strip of the present invention, during the VOD refining process, 0.9 to 1.1 kg of electrolytic manganese is added per ton of pure iron with reference to the target composition of pure iron for manganese alloying; it goes without saying that ferromanganese or other manganese-containing alloys can also be added for manganese alloying. In the case of adding ferromanganese or other manganese-containing alloys for manganese alloying, it is necessary to make a corresponding conversion based on the actual manganese content of the manganese alloy, and the amount of other impurity elements introduced should also be considered.

[0035] In the method for manufacturing high magnetic induction soft magnetic pure iron precision thin strip of the present invention, if the pure iron temperature after VOD refining is lower than 1600°C, LF furnace heating treatment is performed before continuous casting to raise the pure iron temperature to 1600-1610°C.

[0036] In the method for manufacturing high magnetic induction soft magnetic pure iron precision thin strip of the present invention, cold rolling is carried out by a six-roll rolling mill or a twenty-roll rolling mill, and the total number of cold rolling passes is not less than 6 and not more than 8.

[0037] In the method for manufacturing high magnetic induction soft magnetic pure iron precision thin strip of the present invention, the pure iron precision thin strip is subjected to alkali washing and oil removal treatment before magnetic heat treatment.

[0038] In addition, in another aspect of the present invention, a high magnetic induction soft magnetic pure iron precision thin strip is provided, and the high magnetic induction soft magnetic pure iron precision thin strip is prepared by the above-mentioned high magnetic induction soft magnetic pure iron precision thin strip manufacturing method, and its components are as follows by mass percentage: C≤0.0080%, Si≤0.01%, Mn: 0.05-0.10%, P≤0.0040%, S≤0.0015%, Al: 0.010-0.030%, Ti≤0.0020%, Ni≤0.010%, O≤0.0040%, and the rest are inevitable impurities and iron, and the magnetic induction intensity B of the high magnetic induction soft magnetic pure iron precision thin strip is 10000 ≥1.85T, maximum magnetic permeability μ m≥0.02H / m.

[0039] Furthermore, the thickness of the high magnetic induction soft magnetic pure iron precision thin strip is 0.05-0.1 mm and the width is ≤600 mm.

[0040] The method for manufacturing high magnetic induction soft magnetic pure iron precision thin strip of the present invention is described in detail below in conjunction with specific embodiments.

[0041] Example 1

[0042] Embodiment 1 of the present invention adopts the process steps of continuous casting billet production → electroslag remelting → hot rolling → cold rolling → magnetic heat treatment according to the target composition requirements of the product, and produces a high magnetic induction soft magnetic pure iron precision thin strip with excellent magnetic properties and a thickness of 0.05 to 0.1 mm, including the following steps:

[0043] S1, continuous casting billet production, based on the following pure iron target composition, converter smelting, VOD refining, continuous casting casting: C: 0.0056%, Si: 0.0075%, Mn: 0.09%, P: 0.0034%, S: 0.0011%, Al: 0.019%, Ti: 0.0016%, Ni: 0.007%, O: 0.0030%, the rest are unavoidable impurities and iron. The specific implementation process of continuous casting billet production includes:

[0044] During converter smelting, the phosphorus content of pure iron and the amount of slag are controlled. The phosphorus content of converter steel is P: 0.0023%, and the amount of slag is 1.2 kg per ton of pure iron.

[0045] VOD refining includes: (1) after the converter pure iron enters the VOD, it is decarburized under high vacuum conditions, the decarburization time is 17 minutes, and the vacuum system pressure is below 60Pa; (2) after decarburization, 1.4 kg of aluminum is added per ton of pure iron for deoxidation, and aluminum is added according to the actual aluminum content in reference to the target composition, and the aluminum content in the pure iron is adjusted to 0.020%; (3) according to the target composition, 1.0 kg of electrolytic manganese is added per ton of pure iron for manganese alloying; (4) according to the actual aluminum content per ton, 1.4 kg of aluminum is added per ton of pure iron for deoxidation; (5) according to the actual aluminum content per ton, 1.4 kg of aluminum is added per ton of pure iron for deoxidation; (6) according to the actual aluminum content per ton, 1.4 kg of aluminum is added per ton of pure iron for deoxidation; (7) according to the actual aluminum content per ton, 1.4 kg of aluminum is added per ton of pure iron for deoxidation; (8) according to the actual aluminum content per ton, 1.4 kg of aluminum is added per ton of pure iron for deoxidation; (9) according to the actual aluminum content per ton, 1.4 kg of aluminum is added per ton of pure iron for deoxidation; (10) according to the actual aluminum content per ton, 1.4 kg of aluminum is added per ton of pure iron for deoxidation; (11) according to the actual aluminum content per ton, 1.4 kg of aluminum is added per ton of pure iron for deoxidation; (12) according to the actual aluminum content per ton, 1.4 kg of aluminum is added per ton of pure iron; (13) according to the actual aluminum content per ton, 1.4 kg of aluminum is added per ton of pure iron; (14) according to the actual aluminum content per ton, 1.4 kg of aluminum is added per ton of pure iron 11kg of lime is added to pure iron for desulfurization. The desulfurization stirring time is 13 minutes. The VOD outlet temperature is 1619℃. The VOD outlet pure iron composition is: C: 0.0040%, Si: 0.0045%, Mn: 0.08%, P: 0.0029%, S: 0.0016%, Al: 0.020%, Ti: 0.0010%, Ni: 0.006%, O: 0.0031%, and the rest are inevitable impurities and iron;

[0046] During the continuous casting process, the temperature of the pure iron when it is hoisted to the continuous casting machine is 1606℃, which meets the casting temperature requirement. The pure iron is continuously cast into slabs with a thickness of 220mm, a width of 1260mm and a length of 4000mm.

[0047] S2, electroslag remelting, the specific operations include: (1) cutting and welding the continuous casting slab to obtain an electrode billet with a thickness of 440 mm, a width of 630 mm and a length of 4000 mm; (2) controlling the electroslag remelting power so that the actual melting rate is 11.3 kg / min; (3) the weight of lime accounts for 56% of the slag-making material of electroslag remelting; (4) the weight of the electroslag ingot is 8.7 tons / piece, and the pure iron composition obtained after electroslag remelting is: C: 0.0056%, Si: 0.0075%, Mn: 0.09%, P: 0.0034%, S: 0.0011%, Al: 0.019%, Ti: 0.0016%, Ni: 0.007%, O: 0.0030%, and the rest are unavoidable impurities and iron.

[0048] S3, hot rolling, the electroslag ingot is hot-rolled to open the blank and further hot-rolled into a pure iron hot-rolled coil, the pure iron hot-rolled coil has a thickness of 2.21 mm and a width of 1100 mm.

[0049] S4, cold rolling. Before cold rolling, the pure iron hot rolled coil is trimmed and longitudinally slit to obtain a pure iron coil with a width of 540 mm. The cold rolling is carried out in 6 passes using a six-roll rolling mill. During the cold rolling, heat treatment is performed to improve the rolling effect. Specifically, the following steps are included: (1) After the second pass of cold rolling, the pure iron strip has a thickness of 0.53 mm. After that, a continuous annealing process is used for heat treatment. Argon gas is used in the annealing furnace to prevent oxidation of the pure iron strip. The temperature of the annealing furnace is controlled at 690 ± 10 ℃, annealing speed is 85m / min; (2) After the 4th cold rolling, the thickness of the pure iron strip is 0.16mm, and then a continuous annealing process is used for heat treatment. Argon gas is used in the annealing furnace to prevent oxidation of the pure iron strip. The temperature of the annealing furnace is controlled at 670±10℃, and the annealing speed is 95m / min; (3) Before the 6th rolling, the working roll is replaced, and the surface roughness of the working roll is 0.05μm. After the 6th rolling, the thickness of the pure iron strip is 0.09mm.

[0050] S5, magnetic heat treatment. Before the magnetic heat treatment, the pure iron precision thin strip is subjected to alkali washing and oil removal treatment, and then a continuous annealing process is used for magnetic heat treatment. Argon gas protection is used in the annealing furnace to prevent the pure iron precision thin strip from oxidizing. The annealing furnace temperature is 945°C, the annealing speed is 16m / min, and the pure iron precision thin strip travels in the annealing furnace for 4 minutes. The temperature of the pure iron precision thin strip at the outlet of the annealing furnace is 410°C.

[0051] The high magnetic induction soft magnetic pure iron precision ribbon produced by Example 1 of the present invention has a thickness of 0.09 mm and a width of 540 mm. The chemical composition is C: 0.0056%, Si: 0.0075%, Mn: 0.09%, P: 0.0034%, S: 0.0011%, Al: 0.019%, Ti: 0.0016%, Ni: 0.007%, O: 0.0030%, and the rest are inevitable impurities and iron. Sampling is carried out according to the national standard GB / T 13012 "Measurement method of DC magnetic properties of soft magnetic materials" for actual detection. The magnetic induction intensity B of the high magnetic induction soft magnetic pure iron precision ribbon of Example 1 is 10000 1.86T, maximum magnetic permeability μ m It is 0.022H / m.

[0052] Example 2

[0053] Embodiment 2 of the present invention adopts the process steps of continuous casting billet production → electroslag remelting → hot rolling → cold rolling → magnetic heat treatment according to the target composition requirements of the product, and produces a high magnetic induction soft magnetic pure iron precision thin strip with excellent magnetic properties and a thickness of 0.05 to 0.1 mm, including the following steps:

[0054] S1, continuous casting billet production, based on the following pure iron target composition, converter smelting, VOD refining, LF furnace heating, continuous casting casting: C: 0.0031%, Si: 0.0060%, Mn: 0.08%, P: 0.0035%, S: 0.0013%, Al: 0.010%, Ti: 0.0019%, Ni: 0.0080%, O: 0.0025%, the rest are unavoidable impurities and iron. The specific implementation process of continuous casting billet production includes:

[0055] During converter smelting, the phosphorus content of pure iron and the amount of slag are controlled. The phosphorus content of converter steel is P: 0.0021%, and the amount of slag is 1.5 kg per ton of pure iron.

[0056] VOD refining includes: (1) after the converter pure iron enters the VOD, it is decarburized under high vacuum conditions, the decarburization time is 19 minutes, and the vacuum system pressure is below 53Pa; (2) after the decarburization is completed, 1.3 kg of aluminum is added per ton of pure iron for deoxidation, and aluminum is added according to the actual aluminum content in reference to the target composition, and the aluminum content in the pure iron is adjusted to 0.016%; (3) according to the target composition, 1.3 kg of ferromanganese with a manganese content of 75% is added per ton of pure iron for manganese alloying; (4) 13kg lime is added for desulfurization per ton of pure iron, the desulfurization stirring time is 10 minutes, the VOD outlet temperature is 1596℃, and the VOD outlet pure iron composition is: C: 0.0015%, Si: 0.0049%, Mn: 0.07%, P: 0.0025%, S: 0.0015%, Al: 0.016%, Ti: 0.0013%, Ni: 0.0071%, O: 0.0039%, and the rest are inevitable impurities and iron;

[0057] The LF furnace is heated up, and the pure iron is hoisted to the LF furnace for power supply and heating. The temperature out of the station is 1614℃, and the temperature when it is hoisted to the continuous casting machine is 1603℃, which meets the needs of continuous casting;

[0058] During the continuous casting process, pure iron is continuously cast into slabs with a thickness of 230 mm, a width of 1260 mm, and a length of 3600 mm.

[0059] S2, electroslag remelting, the specific operations include: (1) cutting and welding the continuous casting slab to obtain an electrode billet with a thickness of 460 mm, a width of 630 mm and a length of 3600 mm; (2) controlling the electroslag remelting power so that the actual melting rate is 10.9 kg / min; (3) the weight of lime accounts for 53% of the slag-making material of electroslag remelting; (4) the weight of the electroslag ingot is 8.45 tons / piece, and the pure iron composition obtained after electroslag remelting is: C: 0.0031%, Si: 0.0060%, Mn: 0.08%, P: 0.0035%, S: 0.0013%, Al: 0.010%, Ti: 0.0019%, Ni: 0.0080%, O: 0.0025%, and the rest are unavoidable impurities and iron.

[0060] S3, hot rolling, the electroslag ingot is hot-rolled to open the blank and further hot-rolled into a pure iron hot-rolled coil, the pure iron hot-rolled coil has a thickness of 2.0 mm and a width of 1100 mm.

[0061] S4, cold rolling. Before cold rolling, the pure iron hot rolled coil is trimmed and longitudinally slit to obtain a pure iron coil with a width of 540 mm. The cold rolling is carried out in 8 passes using a six-roll rolling mill. During the cold rolling, heat treatment is performed to improve the rolling effect. Specifically, the following steps are included: (1) After the second pass of cold rolling, the pure iron strip has a thickness of 0.49 mm. After that, a continuous annealing process is used for heat treatment. Nitrogen is used in the annealing furnace to prevent oxidation of the pure iron strip. The temperature of the annealing furnace is controlled at 690 ± 10 ℃, annealing speed is 95m / min; (2) After the 4th cold rolling, the thickness of the pure iron strip is 0.13mm, and then a continuous annealing process is used for heat treatment. Nitrogen protection is used in the annealing furnace to prevent oxidation of the pure iron strip. The temperature of the annealing furnace is controlled at 670±10℃, and the annealing speed is 90m / min; (3) Before the 8th rolling, the working roll is replaced, and the surface roughness of the working roll is 0.04μm. After the 8th rolling, the thickness of the pure iron strip is 0.06mm.

[0062] S5, magnetic heat treatment. Before the magnetic heat treatment, the pure iron precision strip is subjected to alkali washing and oil removal treatment, and then a continuous annealing process is used for magnetic heat treatment. Nitrogen protection is used in the annealing furnace to prevent oxidation of the pure iron precision strip. The annealing furnace temperature is 930°C, the annealing speed is 15m / min, and the pure iron precision strip travels in the annealing furnace for 4 minutes and 30 seconds. The temperature of the pure iron precision strip at the annealing furnace outlet is 430°C.

[0063] The high magnetic induction soft magnetic pure iron precision ribbon produced by Example 2 of the present invention has a thickness of 0.06 mm and a width of 540 mm. The chemical composition is C: 0.0031%, Si: 0.0060%, Mn: 0.08%, P: 0.0035%, S: 0.0013%, Al: 0.010%, Ti: 0.0019%, Ni: 0.0080%, O: 0.0025%, and the rest are unavoidable impurities and iron. Sampling is carried out according to the national standard GB / T 13012 "Measurement method of DC magnetic properties of soft magnetic materials" for actual testing. The magnetic induction intensity B of the high magnetic induction soft magnetic pure iron precision ribbon of Example 2 is 10000 1.86T, maximum magnetic permeability μ m It is 0.022H / m.

[0064] In summary, compared with the prior art, the high magnetic induction soft magnetic pure iron precision thin strip and the manufacturing method thereof of the present invention have the following advantages and beneficial effects:

[0065] (1) Chemical composition and product purity are important factors affecting the magnetic properties of pure iron. Among them, high carbon, sulfur, titanium and oxygen content are not conducive to improving magnetic properties, and high oxygen content will also lead to a decrease in purity. Adding an appropriate amount of manganese is to eliminate the harmful effects of sulfur, phosphorus will cause the material to be "cold and brittle", and adding an appropriate amount of aluminum is to remove oxygen in pure iron. No precious metal nickel is added, and silicon is controlled as a residual element. Therefore, in the high magnetic induction soft magnetic pure iron precision thin strip and its manufacturing method of the present invention, the composition of pure iron is designed and controlled by mass percentage: C≤0.0080%, Si≤0.01%, Mn: 0.05-0.10%, P≤0.0040%, S≤0.0015%, Al: 0.010-0.030%, Ti≤0.0020%, Ni≤0.010%, O≤0.0040%, and the rest are inevitable impurities and iron. Through the above composition design, good conditions are created for improving the magnetic properties and surface quality of the product.

[0066] (2) Through VOD and electroslag remelting, the sulfur content of soft magnetic pure iron is controlled below 0.0015%, while the purity of pure iron is maximized, which is beneficial to improving the magnetic properties and the surface quality after rolling into precision thin strips.

[0067] (3) In electroslag remelting, continuous casting slabs are used to process electrode billets instead of mold injection steel ingot forging electrode billets, which has lower manufacturing costs, higher electrode billet purity and more stable quality.

[0068] (4) By combining the cold rolling process with two continuous annealing furnace heat treatment processes, the cold rolling dimensional accuracy control is improved, and at the same time, the adverse effects of work hardening on the rolling of soft magnetic pure iron precision thin strips and surface quality control are eliminated, effectively improving the rolling effect.

[0069] (5) By using a continuous annealing process for magnetic heat treatment after cold rolling, the pure iron structure is further improved, recrystallization is achieved, and the grains are promoted to grow uniformly, effectively improving the magnetic properties.

[0070] (6) The high magnetic induction soft magnetic pure iron precision thin strip product of the present invention has a thickness of 0.05-0.1 mm and a width of ≤600 mm, and a magnetic induction intensity B 10000 ≥1.85T, maximum magnetic permeability μ m ≥0.02H / m, the product has high purity, extremely thin specifications, and good magnetic conductivity. It is helpful to promote technological progress in special fields of the country and has good social significance and application prospects.

[0071] It should be noted that, in this article, the term "comprise" or any other variation thereof is intended to cover non-exclusive inclusion, so that an article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such article or device.

[0072] It should also be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the present invention.

Claims

1. A method for manufacturing a high magnetic induction soft magnetic pure iron precision thin strip, characterized in that: The steps include: S1, continuous casting billet production: converter smelting, VOD refining, and continuous casting are carried out based on the target composition of pure iron, wherein the target composition of pure iron is designed by mass percentage as follows: C≤0.0080%, Si≤0.01%, Mn: 0.05-0.10%, P≤0.0040%, S≤0.0015%, Al: 0.010-0.030%, Ti≤0.0020%, Ni≤0.010%, O≤0.0040%, and the rest are unavoidable impurities and iron. The specific implementation process of continuous casting billet production includes: During converter smelting, the phosphorus content of pure iron and the amount of slag during steel tapping are controlled, wherein the phosphorus content in converter steel tapping is controlled to be P≤0.0025%, and the amount of slag is controlled to be ≤1.5kg per ton of pure iron; VOD refining includes: (1) after the converter pure iron enters the VOD, it is decarburized under high vacuum conditions, the decarburization time is controlled to be 15 to 20 minutes, and the vacuum system pressure is controlled to be below 65 Pa; (2) after the decarburization is completed, 1.2 to 1.5 kg of aluminum is added per ton of pure iron for deoxidation; (3) 10 to 13 kg of lime is added per ton of pure iron for desulfurization, and the desulfurization stirring time is controlled to be ≥10 minutes. The composition of pure iron out of the VOD station is controlled to be: C ≤ 0.0060%, Si ≤ 0.005%, Mn: 0.05 to 0.10%, P ≤ 0.0030%, S ≤ 0.0020%, Al: 0.010 to 0.030%, Ti ≤ 0.0015%, Ni ≤ 0.010%, O ≤ 0.0040%, and the rest are unavoidable impurities and iron; During the continuous casting process, pure iron is continuously cast into slabs, wherein the temperature of pure iron before continuous casting is controlled at 1600-1610°C, the thickness of the continuous casting slab is controlled at 200-280mm, the width of the continuous casting slab is controlled at 1000-1260mm, and the length of the continuous casting slab is controlled at 3000-4000mm; S2, electroslag remelting: including (1) using continuous casting slabs to cut and weld to make electrode blanks; (2) controlling the electroslag remelting power to ensure that the melting rate is ≤12kg / min; (3) the weight proportion of lime in the slag-making material of electroslag remelting is controlled to be ≥50%; (4) the weight of the electroslag ingot is controlled to be 8-10 tons / piece, and the composition of pure iron obtained after electroslag remelting is controlled to be: C≤0.0080%, Si≤0.01%, Mn: 0.05-0.10%, P≤0.0040%, S≤0.0015%, Al: 0.010-0.030%, Ti≤0.0020%, Ni≤0.010%, O≤0.0040%, and the rest are unavoidable impurities and iron; S3, hot rolling: the electroslag ingot is hot rolled to form a blank and further hot rolled into a pure iron hot rolled coil, the thickness of the pure iron hot rolled coil is controlled to be 2.0-2.3 mm, and the width is controlled to be ≤1200 mm; S4, cold rolling: before cold rolling, the pure iron hot rolled coil is trimmed and longitudinally slit to obtain a pure iron coil with a width of ≤600 mm. The cold rolling is carried out in 6 to 8 passes, and a heat treatment is carried out during the cold rolling, specifically including: (1) after the second pass of cold rolling, the thickness of the pure iron strip is controlled to be 0.5±0.03 mm, and then a continuous annealing process is used for heat treatment. Argon or nitrogen is used for protection in the annealing furnace, the annealing furnace temperature is controlled at 680 to 700°C, and the annealing speed is controlled at 80 to 100 m / min; (2) the fourth pass of cold rolling is carried out. After the first pass, the thickness of the pure iron strip is controlled at 0.15±0.02mm, and then a continuous annealing process is used for heat treatment. Argon or nitrogen is used for protection in the annealing furnace. The temperature of the annealing furnace is controlled at 660-680°C, and the annealing speed is controlled at 80-100m / min; (3) according to the finished product thickness requirement of 0.05-0.1mm, the 5th to 8th pass of cold rolling is carried out, and the surface roughness of the working roll used in the last pass is selected to be ≤0.06μm, so as to obtain a pure iron precision thin strip with a thickness of 0.05-0.1mm; S5, magnetic heat treatment: The magnetic heat treatment is carried out by continuous annealing process, and argon or nitrogen is used for protection in the annealing furnace. The temperature of the annealing furnace is controlled at 930-950°C, the annealing speed is controlled at 15-20m / min, and the passing time of the pure iron precision thin strip at any position in the annealing furnace is controlled to be ≥3 minutes, and the temperature of the pure iron precision thin strip at the outlet of the annealing furnace is controlled to be ≤450°C.

2. The method for manufacturing a high magnetic induction soft magnetic pure iron precision thin strip according to claim 1, characterized in that: In the VOD refining process, 0.9 to 1.1 kg of electrolytic manganese is added per ton of pure iron for manganese alloying with reference to the target composition of pure iron.

3. The method for manufacturing a high magnetic induction soft magnetic pure iron precision thin strip according to claim 1, characterized in that: If the pure iron temperature after VOD refining is lower than 1600°C, LF furnace heating treatment is performed before continuous casting to raise the pure iron temperature to 1600-1610°C.

4. The method for manufacturing a high magnetic induction soft magnetic pure iron precision thin strip according to claim 1, characterized in that: In the VOD refining process, when deoxidation is performed by adding 1.2 to 1.5 kg of aluminum per ton of pure iron, aluminum is added for fine adjustment based on the actual aluminum content in the pure iron with reference to the target composition of the pure iron.

5. The method for manufacturing a high magnetic induction soft magnetic pure iron precision thin strip according to claim 1, characterized in that: The cold rolling is carried out using a six-roll mill or a twenty-roll mill, and the total number of cold rolling passes is not less than 6 and not more than 8.

6. The method for manufacturing a high magnetic induction soft magnetic pure iron precision thin strip according to claim 1, characterized in that: The pure iron precision thin strip is subjected to alkali washing and oil removal treatment before magnetic heat treatment.

7. A high magnetic induction soft magnetic pure iron precision thin strip, characterized in that: The high magnetic induction soft magnetic pure iron precision thin strip is prepared by the high magnetic induction soft magnetic pure iron precision thin strip manufacturing method according to any one of claims 1 to 6, and the composition of the high magnetic induction soft magnetic pure iron precision thin strip is as follows by mass percentage: C≤0.0080%, Si≤0.01%, Mn: 0.05-0.10%, P≤0.0040%, S≤0.0015%, Al: 0.010-0.030%, Ti≤0.0020%, Ni≤0.010%, O≤0.0040%, and the rest are inevitable impurities and iron, and the magnetic induction intensity B of the high magnetic induction soft magnetic pure iron precision thin strip is 10000 ≥1.85T, maximum magnetic permeability μ m ≥0.02H / m.

8. The high magnetic induction soft magnetic pure iron precision thin strip according to claim 7, characterized in that: The high magnetic induction soft magnetic pure iron precision thin strip has a thickness of 0.05-0.1 mm and a width of ≤600 mm.