A high magnetic induction oriented electrical steel and its manufacturing method

Abstract

The present invention relates to the technical field of steel production, and particularly to a high magnetic induction oriented electrical steel and a manufacturing method thereof; the chemical composition of the electrical steel by mass percentage is C: 0.001 - 0.075%, Si: 3.0 - 4.0%, Mn: 0.05 - 0.8%, Als: 0.002 - 0.060%, P: 0.007 - 0.080%, S: 0.001 - 0.020%, N: 0.003 - 0.020%, Sn: 0.05 - 0.28%, B: 0.0005 - 0.0050%, Sb: 0.005 - 0.015%, Mo: 0.0006 - 0.002%, Ni: 0.002 - 0.008%, Cr: 0.003 - 0.008%, and the rest is Fe and inevitable impurities; a manufacturing method of the high magnetic induction oriented electrical steel is also provided. By adjusting the contents of Mn, Al, P, S, N, Sn, B, Sb, Mo, Ni, Cr, etc., and adjusting the process parameters such as normalizing pickling, cold rolling, denitriding and nitriding, the production process is simplified, and finally the production of low iron loss and high magnetic induction oriented electrical steel is realized.

Description

Technical Field

[0001] The invention relates to the technical field of steel production, and in particular to a high magnetic induction oriented electrical steel and a manufacturing method thereof. Background Art

[0002] The traditional process flow of high magnetic induction oriented electrical steel is: smelting-continuous casting-hot rolling-normalizing pickling-cold rolling-annealing-coating. The commonly used production method is: steelmaking in a converter, refining outside the furnace, and continuous casting into slabs. Its basic chemical composition is C: 0.04-0.10%, Si: 3.0-4.0%, Mn: 0.03-0.12%, S: 0.015-0.055%, Als: 0.02-0.06%, N: 0.002-0.010%. Some component systems also contain at least one of the elements such as Cu, Se, and B, and the rest are iron and unavoidable impurities. The slab is heated to a temperature above 1360-1400 ℃ in a special high-temperature heating furnace, and is kept warm for at least 120 minutes to fully dissolve the favorable inclusions MnS and AlN, and then rolled. The final rolling temperature reaches above 950 ℃, and it is quickly sprayed with water to cool to below 600 ℃, and then coiled. In order to precipitate fine and dispersed AlN second phase particles in the silicon steel matrix, the hot-rolled plate needs to be normalized and then pickled, then cold rolled to the finished thickness, and finally decarburized annealed and coated with an isolation agent. During the high-temperature annealing process, the steel plate undergoes secondary recrystallization to form a Mg2SiO4 bottom layer and purify the steel. After the insulating coating and stretch annealing, a high magnetic induction oriented silicon steel with low iron loss is obtained.

[0003] The disadvantages of traditional oriented silicon steel production methods are:

[0004] 1) Inhibitors are formed at the beginning of steelmaking, and the process parameters of each subsequent process will affect the inhibitors, making production very difficult;

[0005] 2) Due to the high temperature, overoxidation occurs, which increases the amount of heating loss (3.5%-6.0%), which is about 4 times higher than that of ordinary carbon steel;

[0006] 3) The 2FeO∙SiO2 oxide layer formed at high temperature has a melting point of only 1200℃. Therefore, during high-temperature heating, the oxide layer melts and flows to the bottom of the furnace. On average, the slag needs to be cleaned after heating 4000t of ingots, and maintenance is required after heating about 8000t. The output is low and the labor conditions for furnace maintenance are poor.

[0007] 4) Due to the coarsening of ingot grains and oxidation of grain boundaries at the edges, edge cracks are easily generated during hot rolling, and edge trimming is required during pickling, which reduces the yield rate;

[0008] 5) Al, Si and C in the surface layer of the ingot combine with O, their content decreases, the magnetic properties of the product become uneven and decrease, and the insulating film properties deteriorate.

[0009] To effectively solve the above problems, the present invention aims to provide a high magnetic induction oriented electrical steel to meet the development needs of electrical steel. In addition, the present invention also provides a production method for the above electrical steel, effectively overcoming the disadvantages of high energy consumption and high production difficulty existing in the production process of traditional high magnetic induction oriented electrical steel. Summary of the Invention

[0010] To solve the above problems, the present invention provides a high magnetic induction oriented electrical steel and its manufacturing method to promote energy conservation and environmental protection and reduce the production difficulty.

[0011] On the one hand, the present invention provides a high magnetic induction oriented electrical steel, the mass percentage of the chemical composition of the molten steel is: C: 0.001 - 0.075%, Si: 3.0 - 3.4%, Mn: 0.05 - 0.8%, Als: 0.002 - 0.060%, P: 0.007 - 0.080%, S: 0.001 - 0.020%, N: 0.003 - 0.020%, Sn: 0.05 - 0.28%, B: 0.0005 - 0.0050%, Sb: 0.005 - 0.015%, Mo: 0.0006 - 0.002%, Ni: 0.002 - 0.008%, Cr: 0.003 - 0.008%, and satisfying: -0.1111 + 0.0385Si + 0.0058Als - 2.816B < N < -0.1100 + 0.039Si + 0.0059Als - 2.815B, where Si, Als, B, and N are the contents of the corresponding components respectively, and the rest are Fe and inevitable impurities.

[0012] On the other hand, the present invention also provides a manufacturing method for a high magnetic induction oriented electrical steel, including the following steps:

[0013] Step S1: Steelmaking, the mass percentage of the chemical composition of the molten steel is: C: 0.001 - 0.075%, Si: 3.0 - 3.4%, Mn: 0.05 - 0.8%, Als: 0.002 - 0.060%, P: 0.007 - 0.080%, S: 0.001 - 0.020%, N: 0.003 - 0.020%, Sn: 0.05 - 0.28%, B: 0.0005 - 0.0050%, Sb: 0.005 - 0.015%, Mo: 0.0006 - 0.002%, Ni: 0.002 - 0.008%, Cr: 0.003 - 0.008%, and satisfying: -0.1111 + 0.0385Si + 0.0058Als - 2.816B < N < -0.1100 + 0.039Si + 0.0059Als - 2.815B, where Si, Als, B, and N are the contents of the corresponding components respectively, and the rest are Fe and inevitable impurities;

[0014] Step S2: Thin strip continuous casting. The molten steel in S1 is introduced into a crystallizing roll to prepare a cast strip. After hot rolling the cast strip, it is coiled to obtain a hot-rolled strip.

[0015] Step S3: Normalizing and pickling. The normalizing temperature is 950 - 1250 °C, the normalizing time is 30 - 220 s. The cooling process is as follows: cooling at a cooling rate of 5 - 10 °C / s to 800 - 1000 °C, holding for 60 - 90 s, then cooling at a cooling rate of 10 - 15 °C / s to 500 - 600 °C, and finally cooling at a cooling rate greater than the previous two to below 80 °C.

[0016] Step S4: Cold rolling. The normalized and pickled strip in S3 is cold-rolled on 4 - 7 stands to obtain a cold-rolled sheet.

[0017] Step S5: Decarburization and nitriding. The decarburization atmosphere is N2 + H2 + H2O, the H2 content is 0 - 50%, the partial pressure ratio P H2O / P H2 is between 0.30 and 0.80, the annealing temperature is 800 - 950 °C, and the holding time is 100 - 300 s; the nitriding atmosphere is N2 + H2 + NH3, the N2 partial pressure is 10 - 90%, the H2 partial pressure is 5 - 60%, the NH3 partial pressure is 0.5 - 15%, the nitriding temperature is 650 - 900 °C, the nitriding time is 15 - 60 s. After nitriding, an isolation layer is coated, and the nitrogen content [N1] in the steel should satisfy: 170 + 20Als + 1400B - 1100N < [N1] < 200 + 30Als + 1600B - 800N, where Als, B, and N are the contents of the corresponding components in the molten steel.

[0018] Step S6: High-temperature annealing.

[0019] Step S7: Hot stretching. An insulating coating is applied on the hot stretching machine.

[0020] Furthermore, in step S2, the molten steel is introduced into a twin-roll type crystallizing roll, the casting temperature is 1500 - 1600 °C, the crystallizing roll speed is 20 - 100 m / min, and the cast strip is cooled at a cooling rate of 15 - 25 °C / s to 900 - 1150 °C in a protective atmosphere before hot rolling.

[0021] Furthermore, in step S2, the final rolling temperature of hot rolling is 800 - 950 °C, the total reduction is 10 - 50%, and after hot rolling, it is cooled at a cooling rate of 15 - 35 °C / s to 500 - 700 °C, and coiled to obtain a hot-rolled strip with a thickness of 0.5 - 3.5 mm.

[0022] Furthermore, in step S3, the normalizing treatment atmosphere is an inert gas.

[0023] Further, in step S3, shot peening for descaling is first performed, and then pickling is carried out with 5 - 15% HCl for 60 - 150 s.

[0024] Further, in step S4, the total cold rolling reduction rate is 40 - 90%, and the thickness of the cold rolled sheet is 0.15 - 0.50 mm.

[0025] Further, in step S5, the isolation layer is MgO.

[0026] Further, in step S6, the annealing temperature is 1150 - 1250 °C.

[0027] Further, in step S7, the hot stretch annealing temperature is 550 - 950 °C.

[0028] Due to the adoption of the above technical solutions, the present invention has the following beneficial effects compared with the prior art:

[0029] 1) By adjusting the contents of Mn, Al, P, S, N, Sn, B, Sb, Mo, Cr, etc., and adjusting the process parameters of normalizing pickling, hot rolling, denitriding and nitriding, etc., the present invention finally realizes the production of grain - oriented electrical steel with low iron loss and high magnetic induction.

[0030] 2) The manufacturing method of the high - magnetic - induction grain - oriented electrical steel of the present invention, during the manufacturing process, the short process from steelmaking to thin strip continuous casting replaces the conventional process of steelmaking → continuous casting → hot rolling. The entire production process is greatly shortened compared with the traditional method, achieving the effects of low energy consumption, high production efficiency, low production cost and excellent product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a flowchart of the manufacturing method of the high - magnetic - induction grain - oriented electrical steel in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

[0033] On the one hand, the present invention provides a high magnetic induction oriented electrical steel, and the mass percentage of the chemical components of the molten steel is as follows: C: 0.001-0.075%, Si: 3.0-3.4%, Mn: 0.05-0.8%, Als: 0.002-0.060%, P: 0.007-0.080%, S: 0.001-0.020%, N: 0.003-0.020%, Sn: 0.05-0.28%, B: 0.0005-0.0050%, Sb: 0.005-0.015%, Mo: 0.0006-0.002%, Ni: 0.002-0.008%, Cr: 0.003-0.008%, and it satisfies: -0.1111 + 0.0385Si + 0.0058Als - 2.816B < N < -0.1100 + 0.039Si + 0.0059Als - 2.815B, where Si, Als, B, and N are the contents of the corresponding components respectively, and the rest are Fe and inevitable impurities.

[0034] As an important element in the manufacture of oriented silicon steel, C is an element that expands the austenite phase. For high magnetic induction oriented electrical steel, C can promote the hot-rolled strip deformation structure and refine the structure after hot rolling; C can increase the proportion of the austenite region during normalizing annealing. Since the solubility of N in austenite is much higher than that in ferrite, the solid solution amount of N can be increased, promoting the precipitation of AlN particles during subsequent rapid cooling; C also makes the primary grains obtained during annealing after cold rolling fine and uniform, promoting the development of secondary recrystallization. If C < 0.001%, the improvement effect is not obvious; however, if C > 0.075%, it will cause too long decarburization time and difficult decarburization, affecting production efficiency. Therefore, preferably, C needs to be controlled within 0.001-0.075%.

[0035] Si can increase the resistivity of the material and is the most effective element for reducing iron loss. When the Si content exceeds 3.4%, the steel material will be too brittle, causing difficulties in cold rolling and poor welding performance; if the Si content is less than 3.0%, the iron loss of the finished material is too high; therefore, preferably, the Si content needs to be controlled in the range of 3.0-3.4%.

[0036] Like Si, Mn can increase the resistivity of the material to reduce iron loss, and through nitriding treatment, react with Si and N to form precipitates of (Al, Si, Mn)N, inhibiting the growth of primary recrystallization grains and promoting the formation of secondary recrystallization. If Mn > 0.8%, a large amount of (Fe, Mn) oxides and Mn oxides will easily form on the steel plate surface, which will hinder the formation of the bottom layer during high-temperature annealing; and it is easy to combine with S to form large MnS precipitates, reducing magnetism. When Mn < 0.05%, hot brittleness is likely to occur. Therefore, preferably, the Mn content should be controlled within 0.05-0.8%.

[0037] P can promote the growth of primary grains, avoid non-uniform grains after nitriding treatment, increase the starting temperature of secondary recrystallization, and increase the proportion of Goss grains in the finished product. At the same time, P is a grain boundary segregation element, which can improve the inhibition ability, increase the component of {110} in the primary recrystallization texture, and the secondary grains are small. Moreover, P segregates around MnS and AlN, which can prevent the coarsening of precipitated particles and promote the more uniform distribution of precipitated particles, so the electromagnetic properties of the material can be improved. However, if the content is too high, the brittleness of the material becomes larger, resulting in difficult rolling. Therefore, preferably, the P content should be controlled within 0.007 - 0.080%.

[0038] S is an element with a high solution temperature and severe segregation during hot rolling. When it is >0.020%, it is easy to cause hot brittleness; when it is <0.001%, the number of MnS after hot rolling is too small, reducing the initial inhibition ability. Therefore, preferably, the S content should be controlled within 0.001 - 0.020%.

[0039] N combines with Al to form a grain growth inhibition phase. If it is >0.0020%, the primary grain size will be too small, and there will be easy swelling during casting, and defects such as peeling and blistering will appear in the product; if it is <0.003%, it will cause smelting difficulties and increase the time of subsequent nitriding treatment, reducing production efficiency. Therefore, preferably, N should be controlled within 0.003 - 0.020%.

[0040] After Al combines with N, it precipitates in the form of AlN. During nitriding treatment, nitrides such as (Al, Si, Mn)N and AlN will precipitate dispersedly, which can effectively inhibit grain growth. When Als < 0.008, the quantity and volume fraction of precipitates formed are both relatively low, and the growth of grains cannot be fully inhibited; when Als > 0.060%, the size of the precipitates is too large, reducing the inhibition effect on grain growth. Therefore, preferably, Als should be controlled within 0.002 - 0.060%.

[0041] Sn is a grain boundary segregation element, which has the effect of hindering grain boundary movement, so it can be used as an inhibitor of grain growth. It can also increase the proportion of Goss-oriented grains in the primary recrystallized structure, increase the nuclei of Goss orientation in the secondary recrystallized structure, reduce the size of secondary recrystallized grains, and reduce the iron loss of the finished product. In addition, Sn can also prevent the growth of (Al, Si, Mn)N and AlN particles during high-temperature annealing and reduce the effect of inhibiting grain growth. If Sn < 0.05%, the effect is not obvious; if Sn > 0.28%, the inhibitory force of grain growth is too strong, so the temperature of decarburization annealing needs to be reduced to reduce the size of primary recrystallized grains and increase the driving force of grain growth, which will result in an inappropriate thickness of the oxide layer during primary annealing and prevent the formation of a good bottom layer during high-temperature annealing. Therefore, preferably, the Sn content is controlled within 0.005 - 0.28%.

[0042] The chemical combination force of B and N is stronger than that of Al, and the diffusion rate is also faster. BN preferentially precipitates during hot rolling and can be used as an inhibitor for grain growth. When B < 0.0005%, the effect is not obvious. However, if B > 0.0050%, since BN easily leads to unstable secondary recrystallization, the electromagnetic properties are poor. Therefore, preferably, the B content is controlled within 0.0005 - 0.0050%.

[0043] Sb increases the proportion of Goss-oriented grains and improves the battery performance, but Sb hinders decarburization. Therefore, preferably, the Sb content is controlled within 0.005 - 0.015%.

[0044] Mo enriches on the surface, which can prevent grain boundary oxidation at high temperatures and can also reduce surface oxidation and improve the quality of the bottom layer. When Mo is too high, the surface oxidation is too little and the quality of the bottom layer changes. When it is too low, the effect is not obvious. Therefore, preferably, the Mo content is controlled within 0.0006 - 0.002%.

[0045] Ni can refine the primary grains, increase the proportion of Goss-oriented grains, and improve the electromagnetic properties. When it is too low, the effect is not obvious. When it is too high, the secondary recrystallization temperature is too high. Therefore, preferably, the Ni content is controlled within 0.002 - 0.008%.

[0046] Cr can promote the surface oxidation of the steel plate during decarburization annealing and improve the quality of the bottom layer during secondary annealing. When the Cr content is too low, the effect is not obvious. When it is higher than 0.008%, the oxide layer is too thick and the quality is reduced. Therefore, preferably, the Cr content is controlled within 0.003 - 0.008%.

[0047] On the other hand, as shown in the Figure 1 specification appendix, the present invention provides a method for manufacturing a high magnetic induction oriented electrical steel, specifically including the following steps:

[0048] Step S1: Smelt molten steel. During the smelting process, first perform converter smelting, and then perform refining treatment to obtain molten steel;

[0049] Step S2: Thin strip continuous casting. The molten steel in S1 is introduced into a crystallization roll to prepare a cast strip. The crystallization roll is preferably a twin-roll type crystallization roll. Of course, crystallization rolls with other structures can also be used. The casting temperature is 1500 - 1600 °C, the speed of the crystallization roll is 20 - 100 m / min, and a cast strip with a thickness of 0.8 - 4.0 mm × a width of 500 - 1500 mm is obtained. The temperature of the cast strip coming out of the crystallization roll is relatively high, and it is cooled in a protective atmosphere such as Ar and / or N2 at a cooling rate of 15 - 25 °C / s. The temperature of the cast strip is controlled at 900 - 1150 °C, and then it is hot rolled on 1 - 3 stands. The final rolling temperature of the hot rolling is 800 - 950 °C, and the total reduction is 10 - 50%. After hot rolling, it is cooled to 500 - 700 °C at a cooling rate of 15 - 35 °C / s. Cooling can be carried out by spraying water, and then it is coiled at 500 - 700 °C to obtain a hot rolled strip with a thickness of 0.5 - 3.5 mm;

[0050] Step S3: Normalizing and pickling. The hot rolled strip obtained in S2 is subjected to normalizing and pickling treatment on a normalizing and pickling unit. The atmosphere for the normalizing treatment is Ar, N2 or other inert gases, preferably N2 atmosphere, the temperature is 1120 °C, and the holding time is 30 - 220 s, or it is first heated to 950 - 1250 °C, and the time above 1020 - 1250 °C is 30 - 60 s. The cooling process is as follows: first, it is cooled at a cooling rate of 5 - 10 °C / s to 800 - 1000 °C, held for 60 - 90 s, then cooled at a cooling rate of 10 - 15 °C / s to 500 - 600 °C, and finally cooled to below 80 °C at a cooling rate faster than the previous two times. The last cooling is carried out as fast as possible, and then shot blasting is carried out to remove phosphorus until the surface cleanliness is above Sa 2.0, and pickling is carried out with 5 - 15% HCl. The pickling time is 60 - 150 s. Of course, the pickling solution can also be an acidic solution such as H2SO4. After pickling, a normalized and pickled strip is obtained;

[0051] Step S4: Cold rolling. The normalized and pickled strip is cold rolled on 4 - 7 stands. A 6-high continuous rolling mill or a 6-high or 18-high or 20-high single stand can be used. The total cold rolling reduction rate is 40 - 90%, and a cold rolled sheet with a thickness of 0.15 - 0.50 mm is obtained;

[0052] Step S5: Decarburization and nitriding. The cold rolled sheet in S4 is subjected to annealing treatment for decarburization and nitriding in a controlled atmosphere. The decarburization atmosphere is N2 + H2 + H2O, and the H2 content is 0 - 50%. Reasonably control the partial pressures of H2O and H2 so that the partial pressure P H2O / P H2Between 0.30 and 0.80, the annealing temperature is 800 - 950 °C, and the holding time is 100 - 300 s; then nitriding treatment is carried out in an atmosphere of N2 + H2 + NH3, where the partial pressure of N2 is 10 - 90%, the partial pressure of H2 is 5 - 60%, the partial pressure of NH3 is 0.5 - 15%, the nitriding temperature is 650 - 900 °C, and the nitriding time is 15 - 60 s; after nitriding, the nitrogen content [N1] in the steel satisfies: 170 + 20Als + 1400B - 1100N < [N1] < 200 + 30Als + 1600B - 800N, where Als, B, and N are the contents of the corresponding components in the molten steel; after annealing, a MgO isolation layer is coated on the surface;

[0053] Among them, during the nitriding treatment, the nitriding parameters satisfy the following relational formula:

[0054] 570.0 + 249.3×h + 1.64×[N1] - 9.21×t < T < 580.0 + 249.4×h + 1.65×[N1] - 9.20×t

[0055] In the formula, h is the thickness of the cold-rolled strip, unit: mm;

[0056] T is the nitriding temperature, unit: °C;

[0057] t is the treatment time, unit: s;

[0058] [N1] is the nitrogen content in the steel after nitriding;

[0059] Step S6: High-temperature annealing, annealing treatment is carried out at a temperature of 1150 - 1250 °C;

[0060] Step S7: Hot stretching, an insulating coating is coated on the hot stretching machine set, and then the high magnetic induction oriented electrical steel in the present application can be obtained. The hot stretching annealing temperature is 550 - 950 °C.

[0061] In the above process, the overall preparation process is shortened compared with the traditional process, which is short-process manufacturing with low energy consumption; in the normalizing treatment, different cooling rates are used for cooling multiple times, which can improve the normalizing effect of the hot-rolled strip.

[0062] The following will be described with three embodiments:

[0063] Example 1 Example 2 Example 3 C, wt% 0.045 0.048 0.050 Si, wt% 3.14 3.18 3.22 Mn, wt% 0.008 0.10 0.13 Als, wt% 0.0020 0.0035 0.0042 P, wt% 0.030 0.015 0.010 S, wt% 0.002 0.006 0.008 N, wt% 0.0058 0.0062 0.0075 Sn, wt% 0.15 0.16 0.18 B, wt% 0.0020 0.0025 0.0030 Sb 0.005 0.008 0.010 Mo 0.0006 0.0010 0.0015 Ni 0.002 0.003 0.005 Cr 0.003 0.004 0.006 Casting strip thickness, mm 1.80 1.60 2.10 Hot rolling starting temperature, °C 960 980 1000 Hot rolled strip thickness, °C 1.44 1.20 1.785 Hot rolling reduction ratio, % 20 25 15 Hot rolling finishing temperature, °C 950 950 950 Hot rolling coiling temperature, °C 550 550 550 Normalizing temperature, °C 1120 1120 1120 Normalizing holding time, s 160 180 200 Cold rolled strip thickness, mm 0.27 0.27 0.27 Decarburizing annealing temperature, °C 820 820 820 Decarburizing annealing atmosphere, % <![CDATA[80% N2 + 20% H2]]> <![CDATA[80% N2 + 20% H2]]> <![CDATA[80% N2 + 20% H2]]> Decarburizing annealing atmosphere dew point, °C 55 55 55 Nitriding temperature, °C 750 750 750 Nitriding time, s 45 45 45 Nitriding protective gas, % <![CDATA[89% N2 + 10% H2 + 1% NH3]]> <![CDATA[89% N2 + 10% H2 + 1% NH3]]> <![CDATA[89% N2 + 10% H2 + 1% NH3]]> High temperature annealing, °C 1200 1200 1200 <![CDATA[P 17 / 50 , W / kg]]> 0.860 0.845 0.820 <![CDATA[B 800 ,T]]> 1.919 1.921 1.922

[0064] Through the above three embodiments, the iron loss P of the electrical steel 17 / 50 ≤0.86 kW / kg, and the magnetic induction intensity B 800 ≥1.919 T, among which the electrical steel prepared in Embodiment 3 has the most excellent performance, and is far higher than the performance of products produced by the usual production methods (P 17 / 50= 0.89 W / kg, B 800 = 1.91 T), further indicating that the manufacturing method of the high magnetic induction oriented electrical steel provided by the present invention can manufacture electrical steel with excellent performance.

[0065] Those skilled in the art of the present technology should understand that the present invention can be implemented in many other specific forms without departing from the spirit and scope of the present invention. Although embodiments of the present invention have been described, it should be understood that the present invention should not be limited to these embodiments, and those skilled in the art of the present technology can make changes and modifications within the spirit and scope of the present invention as defined in the appended claims.

Claims

1. A manufacturing method of a high magnetic induction oriented electrical steel, characterized in that, It includes the following steps: Step S1: Steelmaking, the mass percentage of chemical components of the molten steel is: C: 0.001~0.075%, Si: 3.0~3.4%, Mn: 0.05~0.8%, Als: 0.002~0.060%, P: 0.007~0.080%, S: 0.001~0.020%, N: 0.003 - 0.020%, Sn: 0.05~0.28%, B: 0.0005~0.0050%, Sb: 0.005~0.015%, Mo: 0.0006~0.002%, Ni: 0.002~0.008%, Cr: 0.003~0.008%, and it satisfies: -0.1111 + 0.0385Si + 0.0058Als - 2.816B < N < -0.1100 + 0.039Si + 0.0059Als - 2.815B, where Si, Als, B, and N are the contents of the corresponding components respectively, and the rest is Fe and inevitable impurities; Step S2: Thin strip continuous casting, introducing the molten steel in S1 into a crystallizing roll to prepare a cast strip; hot rolling the cast strip, the final rolling temperature of hot rolling is 800~950 °C, the total reduction is 10~50%, and after hot rolling, it is cooled to 500~700 °C at a cooling rate of 15~35 °C / s, and coiled to obtain a hot-rolled strip with a thickness of 0.5~3.5 mm; Step S3: Normalizing and pickling, the normalizing temperature is 950~1250 °C, the normalizing time is 30~220 s, and the cooling process is: cooling to 800~1000 °C at a cooling rate of 5~10 °C / s, holding for 60~90 s, then cooling to 500~600 °C at a cooling rate of 10~15 °C / s, and finally cooling to below 80 °C at a cooling rate greater than the previous two times; Step S4: Cold rolling, cold rolling the normalized and pickled strip in step S3 on 4~7 stands to obtain a cold-rolled sheet; Step S5: Decarburizing nitriding. The decarburizing atmosphere is N2 + H2 + H2O, the H2 content is 0 - 50%, and the partial pressure P H2O / P H2 is between 0.30 and 0.

80. The annealing temperature is 800 - 950 °C, and the holding time is 100 - 300 s. The nitriding atmosphere is N2 + H2 + NH3, the N2 partial pressure is 89 - 90%, the H2 partial pressure is 5 - 60%, and the NH3 partial pressure is 0.5 - 15%. The nitriding temperature is 650 - 900 °C, and the nitriding time is 15 - 60 s. After nitriding, an isolation layer is coated, and the nitrogen content [N1] in the steel satisfies: 170 + 20Als + 1400B - 1100N < [N1] < 200 + 30Als + 1600B - 800N, where Als, B, and N are the contents of the corresponding components in the molten steel; The nitriding parameters satisfy the following relational expression: 570.0 + 249.3×h + 1.64×[N1] - 9.21×t < T < 580.0 + 249.4×h + 1.65×[N1] - 9.20×t In the formula, h is the thickness of the cold-rolled strip, unit: mm; T is the nitriding temperature, unit: °C; t is the treatment time, unit: s; [N1] is the nitrogen content in the steel after nitriding; Step S6: High-temperature annealing; Step S7: Hot stretching, applying an insulating coating on the hot stretching machine.

2. The manufacturing method of the high magnetic induction oriented electrical steel according to claim 1, characterized in that, In the said step S2, the molten steel is introduced into a double-roll type crystallizing roll, the casting temperature is 1500~1600 °C, the speed of the crystallizing roll is 20~100 m / min, and the cast strip is cooled to 900~1150 °C at a cooling rate of 15~25 °C / s in a protective atmosphere and then hot rolled.

3. The manufacturing method of the high magnetic induction oriented electrical steel according to claim 1, characterized in that, In the said step S3, the normalizing treatment atmosphere is an inert gas.

4. The manufacturing method of the high magnetic induction oriented electrical steel according to claim 1, characterized in that, In the said step S3, shot blasting for dephosphorization treatment is carried out first, and then pickling with 5~15% HCl is carried out, and the pickling time is 60~150 s.

5. The manufacturing method of the high magnetic induction oriented electrical steel according to claim 1, characterized in that, In the said step S4, the total cold rolling reduction rate is 40~90%, and the thickness of the cold-rolled sheet is 0.15~0.50 mm.

6. The manufacturing method of the high magnetic induction oriented electrical steel according to claim 1, characterized in that, In the step S5, the isolation layer is MgO.

7. The manufacturing method of the high magnetic induction oriented electrical steel according to claim 1, characterized in that, In the step S6, the annealing temperature is 1150 - 1250 °C.

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