CN116287626B - Method for improving magnetic uniformity of oriented silicon steel - Google Patents
Method for improving magnetic uniformity of oriented silicon steel Download PDFInfo
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- CN116287626B CN116287626B CN202310290762.9A CN202310290762A CN116287626B CN 116287626 B CN116287626 B CN 116287626B CN 202310290762 A CN202310290762 A CN 202310290762A CN 116287626 B CN116287626 B CN 116287626B
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- 229910000976 Electrical steel Inorganic materials 0.000 title claims abstract description 75
- 238000000034 method Methods 0.000 title claims abstract description 43
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 169
- 239000010959 steel Substances 0.000 claims abstract description 169
- 238000005096 rolling process Methods 0.000 claims abstract description 55
- 238000010438 heat treatment Methods 0.000 claims abstract description 28
- 230000005389 magnetism Effects 0.000 claims abstract description 6
- 238000005121 nitriding Methods 0.000 claims description 77
- 238000002347 injection Methods 0.000 claims description 51
- 239000007924 injection Substances 0.000 claims description 51
- 238000000137 annealing Methods 0.000 claims description 40
- 238000001816 cooling Methods 0.000 claims description 19
- 238000002791 soaking Methods 0.000 claims description 16
- 239000006104 solid solution Substances 0.000 claims description 16
- 230000008569 process Effects 0.000 claims description 15
- 230000001133 acceleration Effects 0.000 claims description 12
- 238000005098 hot rolling Methods 0.000 claims description 9
- 239000000498 cooling water Substances 0.000 claims description 8
- 230000007246 mechanism Effects 0.000 claims description 8
- 238000009749 continuous casting Methods 0.000 claims description 6
- 238000003756 stirring Methods 0.000 claims description 4
- 238000005266 casting Methods 0.000 claims description 3
- 230000006698 induction Effects 0.000 abstract description 17
- 238000004519 manufacturing process Methods 0.000 abstract description 10
- 238000005097 cold rolling Methods 0.000 abstract description 8
- 239000007789 gas Substances 0.000 description 54
- 239000003112 inhibitor Substances 0.000 description 21
- 239000013078 crystal Substances 0.000 description 16
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 16
- 230000000052 comparative effect Effects 0.000 description 11
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 8
- 230000000087 stabilizing effect Effects 0.000 description 8
- 238000001953 recrystallisation Methods 0.000 description 7
- 239000002244 precipitate Substances 0.000 description 6
- 238000001556 precipitation Methods 0.000 description 6
- 238000010008 shearing Methods 0.000 description 5
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- 238000002156 mixing Methods 0.000 description 4
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- 238000005261 decarburization Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 229910052757 nitrogen Inorganic materials 0.000 description 3
- 238000010899 nucleation Methods 0.000 description 3
- 230000006911 nucleation Effects 0.000 description 3
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- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 230000004075 alteration Effects 0.000 description 2
- 230000003111 delayed effect Effects 0.000 description 2
- 229910001873 dinitrogen Inorganic materials 0.000 description 2
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- 230000001376 precipitating effect Effects 0.000 description 2
- 238000004321 preservation Methods 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000009966 trimming Methods 0.000 description 2
- 208000010392 Bone Fractures Diseases 0.000 description 1
- 229910000519 Ferrosilicon Inorganic materials 0.000 description 1
- 206010017076 Fracture Diseases 0.000 description 1
- NIPNSKYNPDTRPC-UHFFFAOYSA-N N-[2-oxo-2-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)ethyl]-2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidine-5-carboxamide Chemical compound O=C(CNC(=O)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F)N1CC2=C(CC1)NN=N2 NIPNSKYNPDTRPC-UHFFFAOYSA-N 0.000 description 1
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Classifications
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
- C21D8/1216—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the working step(s) being of interest
- C21D8/1222—Hot rolling
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
- C21D8/1216—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the working step(s) being of interest
- C21D8/1233—Cold rolling
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
- C21D8/1244—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the heat treatment(s) being of interest
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Manufacturing & Machinery (AREA)
- Electromagnetism (AREA)
- Mechanical Engineering (AREA)
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Abstract
The application discloses a method for improving magnetic uniformity of oriented silicon steel, belonging to the technical field of high magnetic induction oriented silicon steel production and aiming at solving the technical problem of large magnetic fluctuation of oriented silicon steel, comprising the following steps: obtaining hot rolled strip steel; the hot rolled strip steel is heated after being sequentially connected, and the heating temperature of the head part and the tail part of each hot rolled strip steel is controlled to be 100-300 ℃ higher than the heating temperature of the middle part; and (3) carrying out cold continuous rolling on the heated hot rolled strip steel, and controlling the cold rolling rate of the middle part of each hot rolled strip steel to be higher than that of the head part and the tail part so as to obtain the oriented silicon steel with uniform magnetism. By adopting the method provided by the application, the maximum value of the longitudinal magnetic induction polar difference of the oriented silicon steel is 0.001-0.005T, and the longitudinal magnetic induction uniformity of the oriented silicon steel is good.
Description
Technical Field
The application belongs to the technical field of high-magnetic induction oriented silicon steel production, and particularly relates to a method for improving magnetic uniformity of oriented silicon steel.
Background
The high magnetic induction oriented silicon steel refers to oriented silicon steel with magnetic induction intensity not lower than 1.88T, and is an important ferrosilicon alloy for manufacturing magnetic devices such as transformer cores and the like. The oriented silicon steel is generally obtained through the processes of steelmaking, continuous casting, hot rolling, normalized pickling, cold rolling, decarburization nitriding, high-temperature annealing, stretching and leveling annealing and the like.
The length of the single roll of the oriented silicon steel is long, the length is more than 10000m by taking 0.23mm as an example, the working condition difference in the length direction is large in the production process, the tissue of the strip steel in the length direction is extremely easy to be uneven, the magnetic performance fluctuation of the finished oriented silicon steel in the length direction is large, the performance fluctuation among different formed magnetic devices is large, and meanwhile the process of separating and trimming the oriented silicon steel is difficult.
Disclosure of Invention
In order to solve the technical problems, the application provides a method for improving the magnetic uniformity of oriented silicon steel, which can improve the magnetic uniformity of oriented silicon steel in the length direction.
The technical scheme of the application is as follows: the method for improving the magnetic uniformity of the oriented silicon steel comprises the following steps:
obtaining hot rolled strip steel;
the hot rolled strip steel is heated after being sequentially connected, and the heating temperature of the head part and the tail part of each hot rolled strip steel is controlled to be 100-300 ℃ higher than the heating temperature of the middle part;
and (3) carrying out cold continuous rolling on the heated hot rolled strip steel, and controlling the cold continuous rolling speed of the middle part of each hot rolled strip steel to be higher than that of the head part and the tail part so as to obtain the oriented silicon steel with uniform magnetism.
In some embodiments, the heating temperature of the middle portion of each of the hot rolled strips is 80-150 ℃ and the heating temperature of the head portion and the tail portion of each of the hot rolled strips is 180-450 ℃.
In some embodiments, the cold continuous rolling speed of the middle part of each hot rolled strip is 500-1500 mpm, and the cold continuous rolling speed of the head part and the tail part of each hot rolled strip is 100-500 mpm.
In some embodiments, the distance between the tail deceleration position of the former hot-rolled strip and the head acceleration position of the latter hot-rolled strip is 400 m-1000 m.
In some embodiments, the acceleration of the tail deceleration of the preceding hot rolled strip and the head acceleration of the following hot rolled strip is between 0.35 and 1m/s 2 。
In some embodiments, the obtaining hot rolled strip comprises:
continuously casting molten steel to form a plate blank;
the slab is subjected to hot rolling and coiling to form a hot rolled coil;
the hot rolled coil is normalized to obtain hot rolled strip steel; in the normalizing treatment, the solid solution temperature of the head part and the tail part of the hot rolled coil is controlled to be 10-30 ℃ lower than that of the middle part, and the soaking temperature of the head part and the tail part of the hot rolled coil is controlled to be 10-30 ℃ higher than that of the middle part.
In some embodiments, in the normalizing treatment, the solution temperature of the head and tail of the hot rolled coil is 1000-1190 ℃ and the solution temperature of the middle of the hot rolled coil is 1030-1200 ℃; the soaking temperature of the head part and the tail part of the hot rolled coil is 860-1000 ℃, and the soaking temperature of the middle part of the hot rolled coil is 850-970 ℃.
In some embodiments, in the coiling, the temperature of the head part and the tail part of the steel plate is controlled to be 10-50 ℃ higher than the temperature of the middle part;
in the coiling, the temperature of the head part and the tail part of the steel plate is controlled to be 510-750 ℃, and the temperature of the middle part of the steel plate is controlled to be 500-700 ℃.
In some embodiments, the electromagnetic stirring intensity is controlled to be 150-400A and the cooling intensity of the secondary cooling water is controlled to be 0.5-1.5L/min in the continuous casting process.
In some embodiments, the cold continuous rolling of the heated hot rolled strip steel specifically includes:
cold continuous rolling and nitriding annealing are carried out on the heated hot rolled strip steel;
nitriding annealing's temperature is 750 ~ 950 ℃, nitriding annealing adopts nitriding device to carry out, nitriding device includes the nitriding mechanism that multiunit along the length direction of belted steel interval set gradually, nitriding mechanism includes two are located respectively the nitriding unit of belted steel top and below, nitriding unit includes:
the two ends of the jet pipe are closed, the jet pipe is provided with an air inlet for communicating a nitriding gas source and a plurality of jet holes which are sequentially distributed along the width direction of the strip steel and used for jetting nitriding gas to the strip steel, and the aperture of the jet holes at the two ends of the jet pipe is smaller than that of the jet holes at the middle part of the jet pipe; the distance between two adjacent air injection holes positioned at two ends of the injection pipe is smaller than the distance between two adjacent air injection holes positioned in the middle of the injection pipe.
The beneficial effects of the application at least comprise:
the application provides a method for improving magnetic uniformity of oriented silicon steel, which comprises the following steps: obtaining hot rolled strip steel; the hot rolled strip steel is heated after being sequentially connected, and the heating temperature of the head part and the tail part of each hot rolled strip steel is controlled to be 100-300 ℃ higher than the heating temperature of the middle part; and (3) carrying out cold continuous rolling on the heated hot rolled strip steel, and controlling the cold continuous rolling speed of the middle part of each hot rolled strip steel to be higher than that of the head part and the tail part so as to obtain the oriented silicon steel with uniform magnetism. The cold continuous rolling speed of the middle part of the hot rolled strip steel is controlled to be higher than that of the head part and the tail part, so that the risk of fracture at the joint of the head part and the tail part due to low connection strength can be reduced, and the production efficiency of cold continuous rolling can be improved; the heating temperature of the head part and the tail part of the hot rolled strip steel is controlled to be higher than that of the middle part, so that the temperature loss caused by low cold continuous rolling speed and fast heat dissipation of the head part and the tail part of the hot rolled strip steel can be compensated, and the tissue uniformity of the head part, the tail part and the middle part of the hot rolled strip steel in the cold continuous rolling process is improved, thereby ensuring the magnetic uniformity of the oriented silicon steel in the length direction. By adopting the method provided by the application, the maximum value of the longitudinal magnetic induction polar difference of the oriented silicon steel is 0.001-0.005T, and the longitudinal magnetic induction uniformity of the oriented silicon steel is good.
Drawings
FIG. 1 is a process step diagram of a method for improving magnetic uniformity of oriented silicon steel according to an embodiment of the present application;
fig. 2 shows an electron micrograph of a slab according to an embodiment of the present application.
FIG. 3 shows an electron micrograph of a slab with a quench strength of 0.4L/min.
Fig. 4 shows a schematic structural view of a nitriding apparatus according to an embodiment of the present application.
Fig. 5 shows a schematic structural view of an injection pipe in the nitriding apparatus of fig. 4.
Reference numerals illustrate:
100-band steel; 2000-nitriding mechanism, 200-nitriding unit, 210-jet pipe, 211-jet hole, 220-pressure stabilizing pipe and 230-communicating pipe.
Detailed Description
In order to make the present application more clearly understood by those skilled in the art, the following detailed description of the technical scheme of the present application will be given by way of specific examples with reference to the accompanying drawings.
The head and tail portions of the strip steel and the middle portion of the strip steel referred to in this embodiment refer to the head, tail and middle portions along the length direction of the strip steel, which are also rolling directions, and the head and tail portions of the steel sheet and the middle portion of the steel sheet refer to the head, tail and middle portions along the length direction of the steel sheet. The head of the strip steel can be a part from the head end of the strip steel to the length L along the running direction of the strip steel, the value of L can be 5-200 m, the tail of the strip steel can be a part from the tail end of the strip steel to the length L along the running direction of the strip steel, and the value of L can be 5-200 m; the head and the tail of the steel plate are respectively the same as the head and the tail of the strip steel.
The embodiment of the application provides a method for improving the magnetic uniformity of oriented silicon steel, which can improve the magnetic uniformity of oriented silicon steel in the length direction and the width direction, ensures the stability of the performance of a formed magnetic device, and is convenient for coiling and trimming the oriented silicon steel.
Referring to fig. 1, the method for improving magnetic uniformity of oriented silicon steel provided by the embodiment of the application includes the following steps:
s1, obtaining hot rolled strip steel;
the hot rolled strip may be a chemical composition of high magnetic induction oriented silicon steel (B.gtoreq.1.88T), in some embodiments, the mass fraction of Si in the hot rolled strip is 2.5-4.0%, the silicon content is high, and the brittleness is greater in cold continuous rolling. In other embodiments, the hot rolled strip may be composed of the following chemical components in mass fraction: 0.045-0.075% of C, 2.5-4.0% of Si, 0.08-0.2% of Mn, 0.01-0.05% of P, 0.005-0.012% of S, 0.025-0.035% of A1, 0.005-0.0100% of N, 0-0.25% of Cu, 0.05-0.25% of Cr, 0.03-0.15% of Sn+Mo, less than or equal to 0.015% of Nb+V+Ti+B, and the balance of Fe and unavoidable impurities. 0.03 to 0.15 percent of Sn and 0.03 to 0.15 percent of sum of mass fraction of Sn and mass fraction of Mo, and less than or equal to 0.015 percent of Nb+V+Ti+B and not more than 0.015 percent of sum of mass fraction of Nb, mass fraction of V, mass fraction of Ti and mass fraction of B.
Specifically, a hot rolled strip steel is obtained, specifically comprising:
s11, continuously casting molten steel to form a plate blank;
in some embodiments, in the continuous casting process, the electromagnetic stirring intensity is controlled to be 150-400A, the cooling intensity of the secondary cooling water is controlled to be 0.5-1.5L/min, the cooling intensity of the secondary cooling water can enable the precipitates in the slab to be more dispersed uniformly (as shown in figure 2), fine and uniformly distributed precipitates in the slab can be uniformly pinned for dislocation movement in the subsequent hot rolling process, so that a more uniform hot rolling structure is obtained, and a foundation is provided for improving the magnetic uniformity; in addition, the cooling intensity and the electromagnetic stirring intensity of the secondary cooling water are controlled, and the equiaxed crystal rate of the slab can be controlled to be 50-100%, namely the volume ratio of the equiaxed crystal in the slab is 50-100%, the fluctuation of the volume ratio is not more than 50%, and the size of crystal grains in the equiaxed crystal is uniform, so that the uniform structure can be generated in the subsequent process; if the cooling strength of the secondary cooling water is too low, the number of precipitates can be reduced to a certain extent (see fig. 3), the deformation of the hot rolled coil is uneven due to the fact that the number of the precipitates in the slab is too small, the size of the equiaxed crystal grains at the positions with more precipitates is small, and the size of the grains is large at the positions with less precipitates in the dynamic recrystallization process of the hot rolled coil. If the cooling strength of the secondary cooling water is too high, cracks occur in the slab. The volume ratio of the equiaxed crystal can influence the area of a shearing band formed by cold continuous rolling, generally, the volume ratio of the equiaxed crystal is small, the shearing band area of the cold continuous rolling is small, nucleation points in dynamic recrystallization are fewer, and the grains have enough space for growth; for the position with large volume ratio of the equiaxed crystals, the shearing area formed by cold continuous rolling is large, nucleation points in dynamic recrystallization are more, grains are mutually inhibited, the grain size of the oriented silicon steel is smaller, if the volume ratio of the equiaxed crystals fluctuates too much, the grain size of the formed oriented silicon steel at some positions is large, the grain size of the formed oriented silicon steel at some positions is small, the structure is uneven, and the magnetic property fluctuation of the oriented silicon steel is large.
S12, hot rolling and coiling the plate blank to form a hot rolled coil;
in some embodiments, in the coiling, the temperature of the head part and the tail part of the steel plate is controlled to be 10-50 ℃ higher than the temperature of the middle part;
the difference between the coiling temperature of the head and tail portions of the steel plate and the coiling temperature of the middle portion of the steel plate can be realized through cooling control of the steel plate, or can be realized through a heat preservation means, in general, a laminar cooling mode is adopted in the cooling mode, and in other embodiments, an ultra-fast cooling mode can also be adopted, so that the application is not particularly limited. After the hot rolling is finished, the steel plate has higher temperature, the temperature of the steel plate can be reduced through cooling, and meanwhile, the formation of a target structure inside the steel plate is ensured; after the steel plate is coiled into a hot rolled coil, the head part and the tail part of the steel plate respectively form an inner ring and an outer ring of the hot rolled coil, and compared with the middle part (middle ring) of the hot rolled coil, the inner ring and the outer ring are in more contact with air and radiate heat faster, and the middle part of the hot rolled coil has better relative heat preservation effect, so that the temperature of the head part and the tail part of the hot rolled coil is lower than that of the middle part; in the cooling process before coiling, the temperature of the head and the tail of the steel plate is controlled to be higher than the temperature of the middle part, namely a U-shaped coiling temperature curve is formed, so that the temperature loss caused by the excessively fast heat dissipation of the head and the tail of the hot rolled coil after the coiling action is finished can be compensated, the temperature of the hot rolled coil in the length direction is more uniform, the volume ratio of an isometric crystal area in the length direction of the strip steel is 10% -20%, the volume ratio of the isometric crystal area in the width direction of the strip steel is 10% -20%, the fluctuation range of the ratio of the isometric crystal area is small, the isometric crystal can grow greatly after the subsequent normalizing treatment, a shearing band is formed in cold continuous rolling, the shearing band can provide nucleation points for forming grains in annealing, the grains of the oriented silicon steel are more uniform in the length direction of the strip steel, the tissue uniformity of the strip steel in the length direction is ensured, and the magnetic uniformity of the oriented silicon steel is improved. If the temperature of the head part and the tail part of the steel plate is the same as the temperature of the middle part in cooling, the temperature of the inner ring and the outer ring of the hot rolled coil is lower than the temperature of the middle ring after coiling, and the volume ratio fluctuation of the equiaxed crystal area of the strip steel in the length direction is too large, so that the grain size fluctuation of the oriented silicon steel is large, and the magnetic uniformity of the oriented silicon steel is deteriorated.
In some embodiments, in the coiling, the temperature of the head and the tail of the steel plate is controlled to be 510-750 ℃, and the temperature of the middle of the steel plate is controlled to be 500-700 ℃, so that the temperature of the head and the tail of the steel plate is higher than the temperature of the middle.
S13, obtaining hot-rolled strip steel after normalizing the hot-rolled coil; in the normalizing treatment, the solid solution temperature of the head part and the tail part of the hot rolled coil is controlled to be 10-30 ℃ lower than that of the middle part, and the soaking temperature of the head part and the tail part of the hot rolled coil is controlled to be 10-30 ℃ higher than that of the middle part.
In the normalizing treatment, crystal grain growth occurs in the hot rolled coil and an inhibitor AlN is formed, in the subsequent high-temperature annealing, the temperature of the strip steel rises in a coil shape, and the temperature of the inner ring and the outer ring (corresponding to the head and the tail of the strip steel) rises quickly, so that the decomposition window period of the inhibitor in the inner ring and the outer ring is short, the secondary recrystallization is delayed after the inhibitor is decomposed, the secondary recrystallization temperature is increased, and the growth of Gaussian textures at the head and the tail of the strip steel is influenced, so that the head and the tail of the oriented silicon steel are different from the middle magnetic property. In the normalizing annealing process, the process of firstly carrying out solid solution and then precipitating of the inhibitor can be completed in the hot rolled coil, the solid solution temperature of the head part and the tail part of the hot rolled coil is low, the solid solution amount of the inhibitor can be reduced, the soaking temperature of the head part and the tail part of the hot rolled coil is high, the cooling rate is too slow, the precipitation amount of the inhibitor can be reduced, that is, the solid solution temperature of the head part and the tail part of the hot rolled coil is reduced, the soaking temperature of the head part and the tail part of the hot rolled coil is improved, the solid solution amount of the inhibitor of the head part and the tail part of the hot rolled coil is reduced, the precipitation amount of the inhibitor of the head part and the tail part of the hot rolled coil is reduced, the inhibitor of the head part and the tail part of the strip steel is less than the inhibitor of the middle part of the strip steel in quantity, and even if the window period of the head part and the tail part of the strip steel is short in high-temperature annealing is not delayed for secondary recrystallization to a certain extent, the normal growth of Gaussian texture is ensured, the head part and the tail part of the strip steel is close to the middle part of the secondary recrystallization temperature of the strip steel, and the magnetic uniformity in the length direction of the strip steel is improved. If the difference between the temperature of the head and the tail of the hot rolled coil and the temperature of the middle part is too small, the quantity of the inhibitor is limited, the difference generated in the high-temperature annealing process can not be compensated to a certain extent, and the magnetic uniformity of the strip steel in the length direction can be weakened.
In some embodiments, in the normalizing treatment, the solution temperature of the head and tail of the hot rolled coil is 1000-1190 ℃ and the solution temperature of the middle of the hot rolled coil is 1030-1200 ℃; the soaking temperature of the head part and the tail part of the hot rolled coil is 860-1000 ℃, and the soaking temperature of the middle part of the hot rolled coil is 850-970 ℃.
The hot rolled coil is subjected to the process of firstly carrying out solid solution and then precipitating of the inhibitor AlN after the normalizing treatment to obtain enough AlN inhibitor which is finely and uniformly distributed, the solid solution temperature of the hot rolled coil is too low, the solid solution quantity of the inhibitor is reduced to a certain extent, the precipitation quantity of the inhibitor is small, otherwise, the solid solution temperature is too high, the solid solution quantity of the inhibitor is large to a certain extent, the quantity of the inhibitor is large, and the energy waste is caused. When the soaking temperature of the hot rolled coil is too high, the cooling rate is too slow, the precipitation quantity of the inhibitor is too small, and meanwhile, the soaking temperature is too high, and the precipitation grows too large; otherwise, if the soaking temperature of the strip steel is too low, the cooling rate is too high, and the precipitation quantity of the inhibitor is too high.
S2, sequentially connecting and then heating the hot rolled strip steel, and controlling the heating temperature of the head part and the tail part of each hot rolled strip steel to be 100-300 ℃ higher than the heating temperature of the middle part.
The plurality of hot rolled strip steel are connected in sequence, namely the tail part of the former strip steel is connected with the head part of the latter strip steel, and the connection mode is generally selected to be welded so as to realize the subsequent cold continuous rolling process. The plasticity of the hot rolled strip steel can be improved by heating the hot rolled strip steel, and the risk of interrupting the strip in the subsequent cold continuous rolling is reduced. The high heating temperature of the head part and the tail part of the hot rolled strip steel is matched with the low cold rolling speed of the head part and the tail part in the subsequent hot rolled strip steel cold continuous rolling, the low heating temperature of the middle part of the hot rolled strip steel is matched with the low temperature cold continuous rolling speed of the subsequent hot rolled strip steel, and the strip steel after cold continuous rolling has good structural uniformity in the length direction.
In some embodiments, the heating temperature of the middle portion of each of the hot rolled strips is 80-150 ℃ and the heating temperature of the head portion and the tail portion of each of the hot rolled strips is 180-450 ℃.
The heating temperature of the middle part and the heating temperature of the head part and the tail part of the hot rolled strip steel are controlled, so that the plasticity is improved, the risk of cold continuous rolling of the strip is reduced, and the production efficiency is improved. And the magnetic uniformity of the oriented silicon steel in the length direction is ensured by matching with the rolling speed, and in addition, the energy is saved.
S3, cold continuous rolling is carried out on the heated hot rolled strip steel, and the cold rolling rate of the middle part of each hot rolled strip steel is controlled to be higher than that of the head part and the tail part so as to obtain the oriented silicon steel with uniform magnetism.
The joint of the two hot rolled strip steels is welded, brittle failure easily occurs in cold continuous rolling, so that the cold rolling speed of the head part and the tail part of each strip steel is controlled to be lower than that of the middle part, the stability of the strip steel in the rolling process is ensured, and the cold rolling efficiency is improved; meanwhile, the cold continuous rolling speed of the hot rolled strip steel at different positions is matched with the heating temperature before cold continuous rolling, so that the tissue uniformity of the strip steel after cold continuous rolling is further improved to a certain extent, and the magnetic uniformity of the oriented silicon steel is ensured.
In some embodiments, the cold rolling rate of the middle portion of each of the hot rolled strips is 500-1500 mpm and the cold rolling rate of the head and tail portions of each of the hot rolled strips is 100-500 mpm.
If the rolling speed at the joint transition of two hot rolled strips is too high, the joint welding seam of two adjacent hot rolled strips is cracked to a certain extent, and the strip breakage risk is caused; if the rolling rate at the junction transition of two hot rolled strips is too slow, the production efficiency is affected to some extent. During cold continuous rolling, the speed of the connecting transition part is increased as much as possible, and the speed is further close to the speed of the middle part of the strip steel, so that the tissue uniformity of the strip steel in the length direction can be improved, the strip breakage risk of the cold continuous rolling can be reduced, and the cold continuous rolling smooth operation of the oriented silicon steel is ensured.
In some embodiments, the distance between the tail deceleration position of the former hot rolled strip and the head acceleration position of the latter hot rolled strip is 400 m-1000 m, which is too short, and may increase the risk of strip breakage to some extent, and which may decrease the production efficiency to some extent.
In some embodiments, the acceleration of the tail deceleration of the preceding hot rolled strip and the head acceleration of the following hot rolled strip is between 0.35 and 1m/s 2 . The equipment is easy to damage due to overlarge acceleration, the acceleration is too small, and the production efficiency can be reduced.
In some embodiments, the cold continuous rolling of the heated hot rolled strip steel specifically includes: and carrying out cold continuous rolling and nitriding annealing on the heated hot rolled strip steel. The nitriding annealing is generally performed after the decarburization annealing, that is, cold continuous rolling is performed followed by decarburization annealing and nitriding annealing in this order. The nitriding annealing is performed at 750-950 ℃, and is performed by using a nitriding device, referring to fig. 4 and 5, the nitriding device comprises a plurality of groups of nitriding mechanisms 2000, the groups of nitriding mechanisms 2000 are sequentially arranged at intervals along the length direction of the strip steel 100 to improve nitriding efficiency, the nitriding mechanisms 2000 comprise two nitriding units 200 which are respectively arranged above and below the strip steel 100 to simultaneously nitrid the upper surface and the lower surface of the strip steel 100, the nitriding units 200 comprise injection pipes 210, two ends of the injection pipes 210 are sealed to form blind ends, the injection pipes 210 are provided with air inlets for communicating nitriding air sources and a plurality of air holes 211 which are sequentially distributed along the width direction of the strip steel 100 and are used for blowing nitriding air to the strip steel 100, and the diameters of the air holes 211 at the two ends of the injection pipes 210 are smaller than the diameters of the air holes 211 at the middle part of the injection pipes 210, so that nitrogen gas blown to the two sides of the width direction of the strip steel 100 is higher than nitrogen gas at the middle part of the width of the strip steel 100.
In the related art, the jet pipe 210 extends along the width direction of the strip steel 100, that is, the oriented silicon steel, one end of the jet pipe 210 is closed to form a blind end, the other end of the jet pipe 210 is communicated with a nitrogen-containing gas source, the jet pipe 210 is uniformly provided with a plurality of jet holes 211 along the length direction, the nitrogen-containing gas source is sprayed onto the surface of the strip steel 100 through the uniformly provided plurality of jet holes 211, because one end of the jet pipe 210 is the blind end, the pressure of the nitrogen-containing gas at the position becomes larger, the flow rate of the nitrogen-containing gas sprayed out of the jet hole 211 close to the blind end is larger, the other end of the jet pipe 210 is communicated with the nitrogen-containing gas source, the flow rate of the nitrogen-containing gas sprayed out of the jet hole 211 close to the other end of the jet pipe 210 is also larger, the flow rate of the nitrogen-containing gas sprayed out of the jet hole 211 in the middle of the jet pipe 210 is weaker, so that the nitrogen-containing gas sprayed out of the middle part of the jet hole 211 in the middle is less, the nitrogen-containing gas in the middle part in the width direction of the strip steel 100 is less, a flow field with more nitrogen-containing gas at two sides in the width direction of the strip steel 100 is formed, the performance of the strip steel 100 is the magnetic high, and the magnetic property of the middle part in the width direction of the strip steel 100 is low. In the application, blind ends are formed at both ends of the injection pipe 210, and the aperture of the air holes 211 at both ends of the injection pipe 210 is smaller than that of the air holes 211 at the middle part of the injection pipe 210, so that the flow rate of nitrogen-containing gas at the middle part of the strip steel 100 in the width direction can be improved, the uniformity of air injection quantity of the strip steel 100 in the width direction can be improved, the uniformity of nitriding quantity of the strip steel 100 in the width direction can be improved, and the magnetic property of the strip steel 100 in the width direction can be more uniform.
To further improve nitriding uniformity, in some embodiments, the apertures of the gas injection holes 211 at both ends of the injection pipe 210 are one-fourth to four-fifth of the apertures of the gas injection holes 211 at the middle of the injection pipe 210; in some embodiments, the gas orifices 211 in the middle of the injection tube 210 have a diameter of 10 to 20mm, for example, the gas orifices 211 in the middle of the injection tube 210 have a diameter of 12mm, and the gas orifices 211 at both ends of the injection tube 210 have a diameter of 3 to 9mm; the hole diameter of the gas injection holes 211 positioned in the middle of the injection pipe 210 is 15mm, and the hole diameters of the gas injection holes 211 positioned at both ends of the injection pipe 210 are 3.75-12 mm.
In order to better ensure nitriding uniformity, in some embodiments, please refer to fig. 2, the distance between two adjacent gas injection holes 211 at two ends of the injection pipe 210 is smaller than the distance between two adjacent gas injection holes 211 at the middle of the injection pipe 210, and the distribution of the hole pitch matches with the pore diameter, so that the uniformity of nitriding atmosphere in the width direction of the strip steel is ensured. In some embodiments, the spacing between adjacent gas holes 211 in the middle of the injection pipe 210 is 100-300 mm, for example, when the spacing between adjacent gas holes 211 in the middle is 120mm, the spacing between adjacent gas holes 211 at both ends of the injection pipe 210 is 40-60 mm, and when the spacing between adjacent gas holes 211 in the middle is 150mm, the spacing between adjacent gas holes 211 at both ends of the injection pipe 210 is 50-75 mm. In some embodiments, the number of the gas holes 211 may be 8 to 15, and the number of the gas holes 211 may be adjusted according to the width of the strip steel 100, which is not particularly limited in the present application.
In some embodiments, referring to fig. 4, a plurality of air inlets are provided, and the plurality of air inlets are sequentially spaced apart along the width direction of the strip steel 100, for example, two or three air inlets are provided, and the air inlets are located at the middle of the air inlet in the length direction, and in some embodiments, three air inlets are provided, referring to fig. 4.
With continued reference to fig. 4, the nitriding unit 200 further includes a pressure stabilizing tube 220 for communicating with a nitriding gas source, the pressure stabilizing tube 220 is parallel to the injection tube 210, one end of the pressure stabilizing tube 220 is closed to form a blind end, the other end of the pressure stabilizing tube 220 is communicated with the nitriding gas source, the pressure stabilizing tube 220 is provided with exhaust ports having the same number as that of the gas inlets, the gas inlets are communicated with the corresponding exhaust ports through a communicating tube 230, the inner diameter of the pressure stabilizing tube 220 is not smaller than the inner diameter of the injection tube 210, so as to provide a pressure-stable gas source for the injection tube 210, and the pressure stabilizing tube 220 can further realize uniform mixing of three different gases in the nitriding atmosphere; in certain embodiments, the inner diameter of the isopipe 220 is 1 to 1.5 times, for example 1.2 times, 1.3 times, the inner diameter of the ejector tube 210; in some embodiments, the inner diameter of communicating tube 230 is smaller than the inner diameter of injection tube 210 to increase the pressure of the nitrogen-containing gas source in communicating tube 230, stabilize the gas pressure injected from gas injection holes 211, and simultaneously orient and match injection tube 210 with the smaller inner diameter to ensure uniform mixing of nitriding atmosphere entering injection tube 210; in certain embodiments, the inner diameter of communication tube 230 is 0.2-0.8 times, e.g., 0.3 times, 0.5 times, or 0.7 times, the inner diameter of injection tube 210; in some embodiments, the inner diameter of injection tube 210 may be 120-200 mm, for example, when the inner diameter of injection tube 210 is 150mm, the inner diameter of communication tube 230 is 30-120 mm, and when the inner diameter of injection tube 210 is 180mm, the inner diameter of communication tube 230 is 36-144 mm.
In some embodiments, the angle between the axial direction of the gas injection holes 211 and the strip steel 100 is 30-60 degrees, so that the nitrogen-containing gas source can be in full contact with the upper surface and the lower surface of the strip steel. In some embodiments, the gas orifices 211 may be axially oriented at an angle of 30 °, 40 °, 45 °, 50 °, etc. to the direction of travel of the strip steel 100.
In some embodiments, nitriding annealing is performed in an annealing furnace, the nitriding device is positioned in the annealing furnace, and the difference between the outlet side pressure and the inlet side pressure of the annealing furnace is 5 Pa to 10Pa. The strip steel enters from the inlet side of the annealing furnace, the outlet side of the annealing furnace is discharged, the difference between the outlet side pressure and the inlet side pressure of the annealing furnace is 5-10 Pa, the pressure of the outlet side of the annealing furnace is large, the pressure of the inlet side of the annealing furnace is small, the nitrogen-containing atmosphere is promoted to move from the outlet side to the inlet side, and meanwhile, the nitriding uniformity of the strip steel is improved by matching the included angle between the air injection holes 211 and the strip steel stripping direction. If the pressure difference between the outlet side pressure and the inlet side pressure of the annealing furnace is too large, the sprayed nitrogen-containing gas is difficult to destroy the airflow boundary layer on the surface of the strip steel to a certain extent, so that the strip steel surface cannot be reached, and the nitriding amount is reduced; if the difference between the outlet side pressure and the inlet side pressure of the annealing furnace is too small, the effect of improving the uniformity of the nitrogen-containing gas in the furnace pressure is weakened, and the nitriding uniformity is affected.
In some embodiments, NH in nitriding gas 3 The pressure of the two injection pipes 210 in each nitriding unit 200 is 10 to 40KPa, and the total flow rate of the injected nitriding gas is 10 to 40m 3 Control of NH in nitriding gas 3 Is matched with the distribution and the aperture of the air injection holes 211 in the nitriding device to improve the nitriding uniformity, if NH is in the nitriding gas 3 Too low a pressure will result in a certain degree of NH in the nitriding gas 3 Is not easy to use with other gases such as H 2 And N 2 Mixing, so that the nitriding amount is too low, and the magnetic property of the oriented silicon steel product is reduced. If NH in nitriding gas 3 Will to some extent result in NH3 in the nitriding gas and other gases such as H 2 And N 2 The uneven mixing worsens the uneven nitriding to a certain extent, and the local nitriding amount can be excessively high to a certain extent, so that the surface quality of the oriented silicon steel product is abnormal. If the total flow of nitriding gas is too small, the nitriding amount of the oriented silicon steel is too low to a certain extent, and the magnetic property of the oriented silicon steel product is abnormal. If the total flow of nitriding gas is too large, the nitriding amount is too high to a certain extent, and the surface quality of the oriented silicon steel product is extremely easy to be abnormal.
In other embodiments, the high-temperature annealing and the hot stretching leveling annealing are performed on the strip steel after nitriding annealing, the grain sizes of the strip steel in the length direction and the width direction are controlled to be 0.5D3-1.5D2 in the high-temperature annealing, D2 is the average grain size after the high-temperature annealing, and D2 is 2-4 cm. In the hot stretching leveling annealing, the head and the tail of the strip steel are controlled by changing the temperature, the temperature of the head and the tail of the strip steel is 5-10 ℃ higher than the temperature of the middle part, and the stress relieving effect of the head and the tail of the strip steel is enhanced.
The method for improving the magnetic uniformity of the oriented silicon steel provided by the application is further described below with reference to specific examples.
Examples 1 to 5 and comparative examples 1 to 5
Examples 1 to 5 provide a method for improving magnetic uniformity of oriented silicon steel, wherein the components of the oriented silicon steel are shown in table 1, examples 1 to 3 are components A1, examples 4 to 5 are components A2, comparative examples 1 to 3 are components A1, and comparative examples 4 to 5 are components A2.
TABLE 1
| Category(s) | C/％ | Si/％ | Mn/％ | P/％ | S/％ | Als/％ | N/％ | Cu/％ | Cr/％ |
| A1 | 0.06 | 3.4 | 0.12 | 0.027 | 0.007 | 0.027 | 0.007 | 0.005 | 0.13 |
| A2 | 0.05 | 3.3 | 0.11 | 0.026 | 0.006 | 0.028 | 0.008 | 0.018 | 0.12 |
Table 1 continuation
| Category(s) | Sn/％ | Mo/％ | Nb/％ | V/％ | Ti/％ | B/％ | Sn+Mo/％ | Nb+V+Ti+B/％ |
| A1 | 0.04 | 0.025 | 0.003 | 0.002 | 0.001 | 0.0005 | 0.065 | 0.011 |
| A2 | 0.07 | 0.05 | 0.005 | 0.004 | 0.003 | 0.001 | 0.120 | 0.013 |
The method comprises the following steps:
step 1: the molten steel conforming to the components is continuously cast, the flow of secondary cold water is controlled in the continuous casting process to form a plate blank, then the plate blank is sent into a heating furnace for heating and then hot rolling, laminar cooling is controlled in the hot rolling process, so that the coiling temperatures of the head part and the tail part of the strip steel are controlled to be higher than the temperature of the middle part, and the temperature control can be seen in table 2.
Step 2: the hot rolled strip was normalized and pickled, and the normalizing process controlled the solution temperature and soaking temperature of the head, tail and middle portions, as shown in table 3.
Step 3: and sending the pickled strip steel into a six-frame continuous rolling unit for cold continuous rolling, wherein the lifting distance, lifting acceleration and middle cold continuous rolling speed of the head part and the tail part are controlled in the cold continuous rolling process, and the specific conditions are shown in table 4.
And 4, decarburizing and nitriding the strip steel subjected to cold continuous rolling in sequence, performing high-temperature annealing treatment, and finally performing hot stretching and leveling annealing to obtain the oriented silicon steel with uniform magnetism.
TABLE 2
TABLE 3 Table 3
TABLE 4 Table 4
TABLE 5
TABLE 6
| Numbering device | Nitrogen content difference/ppm |
| Example 1 | 3 |
| Example 2 | 10 |
| Example 3 | 7 |
| Example 4 | 5 |
| Example 5 | 5 |
| Comparative example 1 | 13 |
| Comparative example 2 | 20 |
| Comparative example 3 | 17 |
| Comparative example 4 | 15 |
| Comparative example 5 | 15 |
TABLE 7
TABLE 8
The nitrided steel strips provided in examples 1 to 5 and comparative examples 1 to 5 were subjected to nitrogen content detection by taking three samples in total at the center and 20mm from the side portion in the width direction, and the maximum value of the difference between the nitrogen content at the center and 20mm from the side portion was calculated as shown in table 6.
The oriented silicon steels provided in examples 1 to 5 and comparative examples 1 to 5 were sampled at the head, tail and middle portions in the length direction, each sample penetrated the width direction of the strip, and then the magnetic properties were measured at the middle portion (corresponding to "middle" in tables 7 and 8) and 20mm from the edge (corresponding to "side 1" and "side 2" in tables 7 and 8) in the strip width direction, respectively, and the measurement results are shown in table 7. And respectively processing the samples of the head, the middle and the tail, respectively calculating the difference value of the maximum value and the minimum value of the transverse three samples of the head, the tail and the middle, calculating the difference value of the maximum value and the minimum value of the magnetic properties of the head sample, the middle sample and the tail sample corresponding to the edge 1, calculating the difference value of the maximum value and the minimum value of the magnetic properties of the head sample, the middle sample and the tail sample corresponding to the width center, and calculating the difference value of the maximum value and the minimum value of the magnetic properties of the head sample, the middle sample and the tail sample corresponding to the edge 2, as shown in table 8.
As can be seen from the data in Table 8, by adopting the methods provided in examples 1 to 5 of the present application, the maximum value of the transverse magnetic induction difference of the oriented silicon steel is 0.001 to 0.005T, the uniformity of the transverse magnetic induction of the oriented silicon steel is good, the maximum value of the longitudinal magnetic induction difference of the oriented silicon steel is 0.001 to 0.005T, and the uniformity of the longitudinal magnetic induction of the oriented silicon steel is good.
By adopting the methods provided by comparative examples 1 to 5, the maximum value of the transverse magnetic induction difference of the oriented silicon steel is 0.011 to 0.03T, which is higher than that of examples 1 to 5 of the present application, and the uniformity of the transverse magnetic induction of the oriented silicon steel is poor, the maximum value of the longitudinal magnetic induction difference of the oriented silicon steel is 0.013 to 0.05T, which is higher than that of examples 1 to 5 of the present application, and the uniformity of the longitudinal magnetic induction of the oriented silicon steel is poor.
The application provides a method for improving magnetic uniformity of oriented silicon steel, which has at least the following advantages:
1. the cold continuous rolling oriented silicon steel is adopted, the heating temperature of the head part and the tail part of the hot rolled strip steel is controlled to be higher than the heating temperature of the middle part, and the cold continuous rolling speed of the middle part of the hot rolled strip steel is matched to be higher than the cold continuous rolling speed of the head part and the tail part, so that the risk of strip steel cold continuous rolling strip breakage is reduced, the higher production efficiency is ensured, and meanwhile, the magnetic uniformity of the strip steel in the length direction is ensured.
2. The method has the advantages that the different solid solution temperatures and the different soaking temperatures of the inner ring, the outer ring and the middle ring in the normalizing treatment are controlled, a small amount of inhibitors are formed at the head and the tail of the strip steel, and the problem that the head and the tail inhibitors cannot be rapidly decomposed in the high-temperature annealing is solved to a certain extent.
3. The cooling intensity of secondary cooling water in the continuous casting process is controlled, the fluctuation range of equiaxed crystals is reduced, and the magnetic uniformity of the oriented silicon steel in the length and width directions is improved.
4. Nitriding annealing is carried out by adopting the nitriding device, so that the nitriding uniformity of the strip steel in the width direction is improved, and the magnetic uniformity of the oriented silicon steel in the width direction is improved.
While preferred embodiments of the present application have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. It is therefore intended that the following claims be interpreted as including the preferred embodiments and all such alterations and modifications as fall within the scope of the application.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present application without departing from the spirit or scope of the application. Thus, it is intended that the present application also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
Claims (8)
1. The method for improving the magnetic uniformity of the oriented silicon steel is characterized by comprising the following steps of:
obtaining hot rolled strip steel;
the hot rolled strip steel is heated after being sequentially connected, and the heating temperature of the head part and the tail part of each hot rolled strip steel is controlled to be 100-300 ℃ higher than the heating temperature of the middle part; the heating temperature of the middle part of each hot rolled strip steel is 80-150 ℃, and the heating temperature of the head part and the tail part of each hot rolled strip steel is 180-450 ℃;
and (3) performing cold continuous rolling on the heated hot rolled strip steel, wherein the cold continuous rolling speed of the middle part of each hot rolled strip steel is controlled to be higher than that of the head part and the tail part, the cold continuous rolling speed of the middle part of each hot rolled strip steel is 500-1500 mpm, and the cold continuous rolling speed of the head part and the tail part of each hot rolled strip steel is 100-500 mpm, so that the oriented silicon steel with uniform magnetism is obtained.
2. The method for improving magnetic uniformity of oriented silicon steel according to claim 1, wherein a distance between a tail deceleration position of a former hot rolled strip and a head acceleration position of a latter hot rolled strip is 400 m-1000 m in two hot rolled strips connected.
3. The method for improving magnetic uniformity of oriented silicon steel according to claim 2, wherein acceleration of tail deceleration of said previous hot rolled strip and head acceleration of said next hot rolled strip are both 0.35-1 m/s 2 。
4. A method for improving magnetic uniformity of oriented silicon steel according to any one of claims 1-3, characterized in that said obtaining hot rolled strip comprises in particular:
continuously casting molten steel to form a plate blank;
the slab is subjected to hot rolling and coiling to form a hot rolled coil;
the hot rolled coil is normalized to obtain hot rolled strip steel; in the normalizing treatment, the solid solution temperature of the head part and the tail part of the hot rolled coil is controlled to be 10-30 ℃ lower than that of the middle part, and the soaking temperature of the head part and the tail part of the hot rolled coil is controlled to be 10-30 ℃ higher than that of the middle part.
5. The method for improving magnetic uniformity of oriented silicon steel according to claim 4, wherein in said normalizing treatment, the solid solution temperature of the head and tail of the hot rolled coil is 1000-1190 ℃ and the solid solution temperature of the middle of the hot rolled coil is 1030-1200 ℃; the soaking temperature of the head part and the tail part of the hot rolled coil is 860-1000 ℃, and the soaking temperature of the middle part of the hot rolled coil is 850-970 ℃.
6. The method for improving magnetic uniformity of oriented silicon steel according to claim 4, wherein in the coiling, the temperature of the head and tail of the steel plate is controlled to be 10-50 ℃ higher than the temperature of the middle part;
in the coiling, the temperature of the head part and the tail part of the steel plate is controlled to be 510-750 ℃, and the temperature of the middle part of the steel plate is controlled to be 500-700 ℃.
7. The method for improving magnetic uniformity of oriented silicon steel according to claim 4, wherein in the continuous casting process, electromagnetic stirring intensity is controlled to be 150-400A, and cooling intensity of secondary cooling water is controlled to be 0.5-1.5L/min.
8. The method for improving magnetic uniformity of oriented silicon steel according to any one of claims 1 to 3, wherein the cold continuous rolling of the heated hot rolled strip steel specifically comprises:
cold continuous rolling and nitriding annealing are carried out on the heated hot rolled strip steel;
nitriding annealing's temperature is 750 ~ 950 ℃, nitriding annealing adopts nitriding device to carry out, nitriding device includes the nitriding mechanism that multiunit along the length direction of belted steel interval set gradually, nitriding mechanism includes two are located respectively the nitriding unit of belted steel top and below, nitriding unit includes:
the two ends of the jet pipe are closed, the jet pipe is provided with an air inlet for communicating a nitriding gas source and a plurality of jet holes which are sequentially distributed along the width direction of the strip steel and used for jetting nitriding gas to the strip steel, and the aperture of the jet holes at the two ends of the jet pipe is smaller than that of the jet holes at the middle part of the jet pipe; the distance between two adjacent air injection holes positioned at two ends of the injection pipe is smaller than the distance between two adjacent air injection holes positioned in the middle of the injection pipe.
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