A copper-containing low-temperature oriented silicon steel and a manufacturing method thereof

Abstract

The invention discloses a copper-containing low-temperature oriented silicon steel, which contains Fe and inevitable impurities, and further contains the following chemical elements in the following mass percentages: C: 0.04-0.09%, Si: 2.9-4.0%, Mn: 0.05-0.2%, S: 0.005-0.01%, Als: 0.015-0.035%, N: 0.0010-0.01%, Sn: 0.01-0.1%, and Cu, wherein the Cu content satisfies: 3%≤Si+Cu≤4.4%, 0.05≤Cu / Si≤0.13, 24≤(Mn+Cu) / S≤118. In addition, the present invention also discloses a method for manufacturing the above-mentioned copper-containing low-temperature oriented silicon steel, which comprises the following steps: (1) smelting and casting; (2) hot rolling; (3) two-stage normalizing annealing; (4) cold rolling; (5) decarburization annealing, nitriding, and coating of a high-temperature isolation agent; (6) high-temperature annealing; (7) coating of an insulating coating, and hot stretching and flattening annealing.

Description

Technical Field

[0001] The invention relates to a metal material and a manufacturing method thereof, and in particular to an oriented silicon steel and a manufacturing method thereof. Background Art

[0002] In recent years, under the general background of energy conservation and emission reduction, the market demand for high-end oriented silicon steel has been greatly increased. It is expected that the elimination of low-end electrical steel will be accelerated in the future, and a large amount of high-performance electrical steel will be used.

[0003] At present, the demand for oriented electrical steel with higher magnetic induction and thinner specifications is greatly increasing in many fields such as the national "eight vertical and eight horizontal" UHV projects, high-speed rail and rail transportation, subway construction, photovoltaic power generation, real estate, and new energy vehicle charging piles. Based on this demand, oriented silicon steel is constantly developing towards low cost, low iron loss, and environmental friendliness.

[0004] In the prior art, the traditional oriented silicon steel manufacturing method can be further divided into two manufacturing processes according to the hot rolling heating temperature. One is called the high temperature process, in which the slab heating temperature is between 1250-1320℃, and AlN and Cu inhibitors are used; the other is called the low temperature process, in which the slab heating temperature is between 1100-1250℃, and AlN, CuS and other inhibitors are used, and the method of forming acquired inhibitors by nitriding after decarburization is required to obtain the inhibitory ability. Among them, the low temperature process is basically called the mainstream process for the current oriented silicon steel production due to its advantages such as low energy consumption and high yield rate.

[0005] In recent years, in order to improve the magnetic properties of oriented silicon steel products, people have tried to use various technical means to optimize the design. For example, the Chinese patent document with the publication number CN103834908A, the publication date of June 4, 2014, and the name of "A production method for improving the electromagnetic properties of oriented silicon steel" discloses a production method for improving the electromagnetic properties of oriented silicon steel, which controls the infiltrated nitrogen content according to the proportion of 30-100nm AlN precipitates in the steel sheet after normalization, and obtains high magnetic induction oriented silicon steel with excellent magnetic properties; however, the patent is mainly for the inhibitor component system mainly based on AlN.

[0006] Another example: the Chinese patent document with publication number CN110055393A, publication date July 26, 2019, and titled "A method for producing thin-gauge low-temperature high-magnetic induction oriented silicon steel strip", discloses a method for producing thin-gauge low-temperature high-magnetic induction oriented silicon steel strip, which adjusts the soaking temperature and nitriding process of decarburization annealing according to the change degree of raw material composition and hot rolling final rolling temperature, thereby optimizing the performance of thin-gauge oriented silicon steel. However, in this technical solution, on-site decarburization and nitriding are both carried out in the decarburization annealing unit production line, which requires simultaneous regulation of the temperatures of the two, and on-site control is quite difficult.

[0007] Another example: the Chinese patent document with publication number CN112522609A, publication date March 19, 2021, and titled "A high magnetic induction oriented silicon steel containing composite inhibitors and production method", can effectively avoid the excessive size of the initial grains by adding Cu; adding MgSO4 to the magnesium oxide additive can generate acquired inhibitors with Cu to form a dual inhibitor system to avoid the generation of a large amount of N2 during high-temperature annealing while ensuring the stability of magnetic properties. However, since this technical solution is to add inhibitors to magnesium oxide, it still has the problem of uneven distribution of inhibitors.

[0008] In the current prior art, adding alloy elements is the most common method to improve the magnetic properties of oriented silicon steel products, and usually the Cu element is added to obtain copper-containing oriented silicon steel. As disclosed in the reference "Materials Principles of Electrical Steel", published by Higher Education Press, P491 and P505, adding 0.45% Cu can reduce the heating temperature to 1250-1280°C, but the magnetic properties of the product are not higher than 1.88T. The Cu content added in the aforementioned low-temperature process is controlled at 0.01-0.1%. It can be seen that how to improve the magnetic properties of copper-containing oriented silicon steel is still a technical problem that needs to be solved urgently. Summary of the invention

[0009] One of the purposes of the present invention is to provide a copper-containing low-temperature oriented silicon steel having an iron loss P of 17 / 50 <0.85W / Kg, magnetic induction B8>1.90T, it has excellent magnetic properties and has good promotion prospects and application value.

[0010] In order to achieve the above object, the present invention provides a copper-containing low-temperature oriented silicon steel, which contains Fe and inevitable impurities, and further contains the following chemical elements in the following mass percentages:

[0011] C: 0.04-0.09%, Si: 2.9-4.0%, Mn: 0.05-0.2%, S: 0.005-0.01%, Als: 0.015-0.035%, N: 0.0010-0.01%, Sn: 0.01-0.1%, and Cu. Among them, the Cu content satisfies: 3%≤Si+Cu≤4.4%, 0.05≤Cu / Si≤0.13, 24≤(Mn+Cu) / S≤118.

[0012] Furthermore, in the copper-containing low-temperature oriented silicon steel of the present invention, the mass percentage of each chemical element is:

[0013] C: 0.04-0.09%, Si: 2.9-4.0%, Mn: 0.05-0.2%, S: 0.005-0.01%, Als: 0.015-0.035%, N: 0.0010-0.01%, Sn: 0.01-0.1%, and Cu, with the balance being Fe and other inevitable impurities; wherein the Cu content satisfies: 3%≤Si+Cu≤4.4%, 0.05≤Cu / Si≤0.13, 24≤(Mn+Cu) / S≤118.

[0014] In the copper-containing low-temperature oriented silicon steel of the present invention, the design principles of each chemical element are as follows:

[0015] C: In the copper-containing low-temperature oriented silicon steel described in the present invention, C can mainly form a γ phase during hot rolling. When the C content in the steel is lower than 0.04%, an effective γ phase cannot be formed. However, it should be noted that when the C content in the steel is too high, when the C content exceeds 0.09%, decarburization will be difficult. Therefore, in the copper-containing low-temperature oriented silicon steel described in the present invention, the mass percentage of the C element is controlled between 0.04 and 0.09%.

[0016] Si: In the copper-containing low-temperature oriented silicon steel described in the present invention, the Si element can effectively increase the resistivity of the material and reduce the iron loss of the steel. However, it should be noted that the higher the Si content in the steel, the worse the manufacturability. When the Si content in the steel is higher than 4.0%, the cold rolling break rate will increase; and if the Si content in the steel is lower than 2.9%, it will not effectively reduce the iron loss and improve the performance. Based on this, in order to ensure the beneficial effect of the Si element, in the copper-containing low-temperature oriented silicon steel described in the present invention, the mass percentage of the Si element is controlled between 2.9 and 4.0%.

[0017] Mn: In the copper-containing low-temperature oriented silicon steel described in the present invention, the role of the Mn element is similar to that of the Si element. The Mn element can also increase the resistivity of the material and reduce the iron loss of the steel. In addition, the Mn element and the S element can also combine to form MnS as an inhibitor. However, it should be noted that when the Mn element content in the steel is lower than 0.05%, the above-mentioned role cannot be achieved; and when the Mn element content in the steel is higher than 0.2%, the formed MnS is relatively coarse, which will also lead to a decrease in the hot rolling processability and magnetic properties of the steel. Based on this, in order to ensure the beneficial effects of the Mn element, in the copper-containing low-temperature oriented silicon steel described in the present invention, the mass percentage of the Mn element is controlled between 0.05 and 0.2%.

[0018] S: In the copper-containing low-temperature oriented silicon steel described in the present invention, the S element is mainly combined with Mn, Cu, etc. to form MnS or CuS as an inhibitor. When the S element content in the steel is lower than 0.005%, it cannot effectively play the above role, and if the S element content in the steel is higher than 0.01%, it will cause purification and desulfurization difficulties. Based on this, in the copper-containing low-temperature oriented silicon steel described in the present invention, the mass percentage of the S element is controlled between 0.005 and 0.01%.

[0019] Als: In the copper-containing low-temperature oriented silicon steel described in the present invention, Als mainly forms AlN inhibitor with N. When the Als content in the steel is too high, the Als content is higher than 0.035%, the quality of the bottom layer will deteriorate; and when the Als content in the steel is too low, the Als content is lower than 0.015%, it will not play an inhibitory role. Therefore, in order to give full play to the beneficial effects of Als, in the copper-containing low-temperature oriented silicon steel described in the present invention, the mass percentage of Als is controlled between 0.015 and 0.035%.

[0020] N: In the copper-containing low-temperature oriented silicon steel described in the present invention, N can form an AlN inhibitor with Als. If the N content in the steel is less than 0.0010%, the inhibitor is insufficient, and if the N content in the steel is higher than 0.01%, the steelmaking casting is prone to bulging, and the product will have peeling and blistering defects. Therefore, in order to give full play to the beneficial effects of the N element, in the copper-containing low-temperature oriented silicon steel described in the present invention, the mass percentage of the N element is controlled between 0.0010 and 0.01%.

[0021] Sn: In the copper-containing low-temperature oriented silicon steel described in the present invention, Sn is a grain boundary segregation element, which can have the effect of segregation and inhibition, thereby further increasing the inhibition ability; but it should be noted that when the Sn element content in the steel exceeds 0.1%, it will make the bottom layer control difficult, and when the Sn element content in the steel is less than 0.01%, it will not have the effect of segregation and inhibition. Based on this, in the copper-containing low-temperature oriented silicon steel described in the present invention, the mass percentage of the Sn element is controlled between 0.01 and 0.1%.

[0022] Cu: In the copper-containing low-temperature oriented silicon steel described in the present invention, the Cu element can increase the resistivity and reduce the iron loss. At the same time, the Cu element is an austenite stabilizing element like the Si element. When the Cu element content in the steel is too low, the above beneficial effects cannot be achieved. When the Cu element content in the steel is too high, it will increase the difficulty of rolling, increase the strip breakage rate, and make the bottom layer difficult to control, similar to the aforementioned Si element. Therefore, in the present invention, 3%≤Si+Cu≤4.4%, 0.05≤Cu / Si≤0.13, 24≤(Mn+Cu) / S≤118 are defined. At this time, Cu can react with the S element to generate CuS, thereby playing the role of an inhibitor. Controlling the Cu element content within this range can give full play to the beneficial effects of the Cu element.

[0023] Based on this, in the copper-containing low-temperature oriented silicon steel of the present invention, the mass percentage of Cu element is controlled according to three conditions: 3%≤Si+Cu≤4.4%, 0.05≤Cu / Si≤0.13, 24≤(Mn+Cu) / S≤118.

[0024] Furthermore, in the copper-containing low-temperature oriented silicon steel described in the present invention, its thickness is ≤0.23 mm.

[0025] Furthermore, in the copper-containing low-temperature oriented silicon steel of the present invention, the iron loss P 17 / 50 < 0.85W / Kg, magnetic induction B8>1.90T.

[0026] Furthermore, in the copper-containing low-temperature oriented silicon steel described in the present invention, the average grain size of the secondary recrystallization is 10-20 mm, and the average grain deviation is <5 mm.

[0027] Accordingly, another object of the present invention is to provide a method for manufacturing the above-mentioned copper-containing low-temperature oriented silicon steel, which can be implemented by transformation on the original production line, is simple and feasible, and can effectively improve the magnetic performance level of the copper-containing low-temperature oriented silicon steel. The iron loss P of the copper-containing low-temperature oriented silicon steel prepared by the manufacturing method is 17 / 50 <0.85W / Kg, magnetic induction B8>1.90T, it has excellent magnetic properties.

[0028] In order to achieve the above object, the present invention proposes the above-mentioned method for manufacturing copper-containing low-temperature oriented silicon steel, which comprises the steps of:

[0029] (1) Smelting and casting;

[0030] (2) Hot rolling;

[0031] (3) Two-stage normalizing annealing: the first stage is at 1100-1150°C for 60-120s, the second stage is at 900-950°C for 60-120s, and then water-cooled with a cooling rate of ≥30°C / s, so that the volume ratio of AlN and (Cu, Mn)S precipitates with a size of 30-100nm in the steel plate after normalization accounts for 30-80% of the total precipitates;

[0032] (4) Cold rolling: Control the cold rolling reduction rate to 88-92%;

[0033] (5) decarburization annealing, nitriding, and coating of high-temperature isolating agent; wherein the decarburization temperature is controlled to be T=804.5+56.5×A+6.2×B, wherein A represents the volume ratio of 30-100nm AlN and (Cu, Mn)S precipitates to the total precipitates after normalization, and B represents the cold rolling reduction rate; the nitrogen content in the steel plate after nitriding is 200-300ppm;

[0034] (6) High temperature annealing;

[0035] (7) Applying insulation coating, and hot stretching and flattening annealing.

[0036] In the present invention, based on a reasonable chemical composition design, the inventors have optimized and designed a new manufacturing process through a large amount of research. The manufacturing method of copper-containing low-temperature oriented silicon steel can effectively improve the magnetic properties of copper-containing low-temperature oriented silicon steel products.

[0037] It should be noted that in the production process of copper-containing low-temperature oriented silicon steel, the control of inhibitors is crucial. Studies have shown that precipitates below 30nm after normalization will dissolve and decompose in the subsequent production process, while precipitates larger than 100nm will not act as inhibitors.

[0038] Therefore, in step (3) of the manufacturing method of the present invention, it is necessary to strictly control the volume ratio of AlN and (Cu, Mn) S precipitates with a size of 30-100 nm in the steel plate after normalization to the total precipitates; when this volume ratio is lower than 30%, it will lead to insufficient inhibition and poor magnetic properties of the finished product; and when this volume ratio is higher than 80%, it will lead to excessive inhibition and it is still difficult to obtain excellent magnetic properties. Based on this, in the present invention, after adopting two-stage normalization annealing, it is necessary to control the volume ratio of AlN and (Cu, Mn) S precipitates with a size of 30-100 nm in the steel plate after normalization to the total precipitates between 30% and 80%.

[0039] Accordingly, in step (4) of the above-mentioned manufacturing method of the present invention, it is necessary to control the cold rolling reduction rate to 88-92%. This is because: different cold rolling reduction rates will lead to different dislocation densities, and the dislocation energy stored after cold rolling will also be different, so the driving effect on the primary recrystallization process will also be different; when the cold rolling reduction rate is lower than 88%, the driving force for the growth of the primary recrystallization grains is insufficient; and when the cold rolling reduction rate is higher than 92%, the driving force for the growth of the primary recrystallization grains is too strong, and it is difficult to obtain a good primary recrystallization size.

[0040] The optimal primary recrystallization grain size is the basis for obtaining a perfect secondary recrystallization oriented silicon steel product, and the present invention is achieved by controlling the decarburization temperature of the decarburization annealing. Therefore, in order to meet the suppression capacity and obtain a good secondary recrystallization structure, in step (5) of the manufacturing method of the present invention, the decarburization temperature is controlled to be T=804.5+56.5×A+6.2×B, where A represents the volume ratio of 30-100nm AlN and (Cu, Mn)S precipitates to the total precipitates after normalization, and B represents the cold rolling reduction rate. Therefore, when the nitrogen content in the steel plate after nitriding is controlled to be 200-300ppm in the subsequent nitriding step, the suppression capacity can be met and a better secondary recrystallization structure can be obtained.

[0041] In addition, it should be noted that in the above step (5) of the present invention, the high-temperature isolation agent applied can be MgO.

[0042] Furthermore, in the manufacturing method of the present invention, in step (2), the heating temperature is controlled to be 1050-1150°C.

[0043] Furthermore, in the manufacturing method of the present invention, in step (2), the thickness of the hot-rolled plate is controlled to be 1.5-2.9 mm.

[0044] Furthermore, in the manufacturing method described in the present invention, in step (6), the temperature is raised to 500-700°C and kept warm; when the temperature is further raised to 700-1050°C, the annealing atmosphere adopts a dry N2+H2 mixture with a volume percentage of not less than 50%; when the temperature is further raised to 1050-1150°C, the annealing atmosphere adopts a dry N2+H2 mixture with a volume percentage of less than 50%; when the temperature is further raised to 1150-1200°C, the annealing atmosphere adopts pure H2.

[0045] Furthermore, in the manufacturing method of the present invention, in step (6), when the temperature is raised to 500-700°C, the heat preservation time is ≥20h.

[0046] Compared with the prior art, the copper-containing low-temperature oriented silicon steel and the manufacturing method thereof described in the present invention have the following advantages and beneficial effects:

[0047] Compared with the prior art, the beneficial effect of the present invention is that perfect secondary recrystallization grains are obtained by adjusting the composition and controlling the volume ratio of AlN and (Cu, Mn)S precipitates with a size of 30-100 nm in the steel plate after normalization, the cold rolling reduction rate, the decarburization temperature, the nitriding amount and the size of the primary recrystallization grains after decarburization annealing. It does not require special on-site modification to obtain copper-containing low-temperature oriented silicon steel products with good magnetic properties, and the magnetic properties of the obtained copper-containing low-temperature oriented silicon steel are improved by at least half a grade.

[0048] The manufacturing method of the copper-containing low-temperature oriented silicon steel of the present invention is simple and feasible. The iron loss P of the copper-containing low-temperature oriented silicon steel prepared by the manufacturing method is 17 / 50 <0.85W / Kg, magnetic induction B8>1.90T, with good promotion prospects and application value. DETAILED DESCRIPTION

[0049] The copper-containing low-temperature oriented silicon steel and the method for manufacturing the same according to the present invention will be further explained and illustrated below in conjunction with specific embodiments. However, such explanation and illustration do not constitute an improper limitation on the technical solution of the present invention.

[0050] Examples 1-9 and Comparative Examples 1-10

[0051] Table 1 lists the mass percentages of various chemical elements in the copper-containing low-temperature oriented silicon steels of Examples 1-9 and the comparative steel plates of Comparative Examples 1-10.

[0052] Table 1. (wt%, the balance is Fe and other unavoidable impurities)

[0053]

[0054] The copper-containing low-temperature oriented silicon steels of Examples 1-9 of the present invention are all prepared by the following steps:

[0055] (1) Smelting and casting are carried out according to the chemical composition shown in Table 1.

[0056] (2) Hot rolling: The heating temperature is controlled to be 1050-1150°C, and rolling is performed to control the thickness of the hot rolled plate to be 1.5-2.9 mm.

[0057] (3) Two-stage normalizing annealing: the first stage is at a temperature of 1100-1150°C for 60-120s, the second stage is at a temperature of 900-950°C for 60-120s, and then water-cooled with a cooling rate of ≥30°C / s, so that the volume ratio of AlN and (Cu, Mn)S precipitates with a size of 30-100nm in the steel plate after normalization accounts for 30-80% of the total precipitates.

[0058] (4) Cold rolling: The cold rolling reduction rate is controlled to be 88-92%.

[0059] (5) Decarburization annealing, nitriding, and coating of high-temperature isolating agent; wherein the decarburization temperature is controlled to be T=804.5+56.5×A+6.2×B, wherein A represents the volume ratio of 30-100nm AlN and (Cu,Mn)S precipitates to the total precipitates after normalization, and B represents the cold rolling reduction rate; the nitrogen content in the steel plate after nitriding is 200-300ppm; and the high-temperature isolating agent is MgO.

[0060] (6) High temperature annealing: raise the temperature to 500-700°C and keep warm for ≥20h; when the temperature is further raised to 700-1050°C, the annealing atmosphere shall be a dry N2+H2 mixture with a volume percentage of not less than 50%; when the temperature is further raised to 1050-1150°C, the annealing atmosphere shall be a dry N2+H2 mixture with a volume percentage of less than 50%; when the temperature is further raised to 1150-1200°C, the annealing atmosphere shall be pure H2.

[0061] (7) Applying insulation coating, and hot stretching and flattening annealing.

[0062] It should be noted that, in the present invention, the copper-containing low-temperature oriented silicon steels of Examples 1-9 described in the present invention are all prepared by the process flow of the above steps (1) to (7), and their chemical composition and related process parameters meet the control requirements of the design specifications of the present invention.

[0063] Although the comparative steels of Comparative Examples 1-10 are also produced by the above process flow, they all have at least one parameter of chemical composition and process parameters that fails to meet the design requirements of the present invention.

[0064] Table 2-1 and Table 2-2 list the specific process parameters of the copper-containing low-temperature oriented silicon steel of Examples 1-9 and the comparative steel plates of Comparative Examples 1-10 in the step flow of the above-mentioned manufacturing method.

[0065] Table 2-1.

[0066]

[0067]

[0068] Table 2-2.

[0069]

[0070] It should be noted that, after completing the two-stage normalizing annealing in the above step (3) according to the process parameters shown in Table 2, Examples 1-9 and Comparative Examples 1-10 can be sampled after normalization of the steel plates of each Example and Comparative Example, and the sample steel plates after normalization annealing of each Example and Comparative Example are observed and analyzed. It is found that the steel plates all have AlN and (Cu, Mn) S precipitates. The specific observation data results are listed in Table 3 below.

[0071] Table 3 lists the observation and analysis results of the sample steel plates after normalizing annealing in various embodiments and comparative examples.

[0072] Table 3.

[0073]

[0074] The finished thin-gauge copper-containing low-temperature oriented silicon steels of Examples 1-9 and the comparative steels of Comparative Examples 1-10 obtained by the above process were sampled respectively, and the magnetic induction B8 and iron loss P of the steel plates of the examples and comparative examples were further measured. 17 / 50 The test results are listed in Table 4 below.

[0075] The relevant performance testing methods are as follows:

[0076] Magnetic induction B8 and iron loss P 17 / 50 Test: Referring to GB / T13789, the magnetic induction B8 and iron loss P of the steel plates of each embodiment and comparative example were measured. 17 / 50 .

[0077] Secondary recrystallization grain size measurement: Referring to the intercept method in GB / T 6394-2017 Metal Average Grain Size Determination Method, the secondary recrystallization average grain size and deviation of the steel plates of each embodiment and comparative example sample were measured.

[0078] Table 4 lists the magnetic induction B8 and iron loss P of the copper-containing low-temperature oriented silicon steel of Examples 1-9 and the comparative steel of Comparative Examples 1-10. 17 / 50 Test results.

[0079] Table 4.

[0080]

[0081] As shown in Table 4, in the present invention, compared with the comparative steel sheets of Comparative Examples 1-10, the copper-containing low-temperature oriented silicon steels of Examples 1-9 have lower iron loss P 17 / 50 At the same time, it also has a higher magnetic induction B8, and its iron loss P 17 / 50The magnetic induction B8 is between 0.75 and 0.83, and the magnetic induction B8 is between 1.91 and 1.94, which has more excellent magnetic properties. At the same time, the average grain size of the secondary recrystallization of the copper-containing low-temperature oriented silicon steel of Examples 1-9 is 10-16 mm, and the average grain deviation is between 1.2 and 4 mm.

[0082] It can be seen from the above Tables 1 to 4 that, in the comparative steel plates of Comparative Examples 1 to 10, the Cu element content of Comparative Examples 1 to 2 exceeds the design range of the present invention, and thus the magnetic properties are relatively poor; while the copper-containing low-temperature oriented silicon steel of Example 1 to 9 that meets the design requirements of the present invention has significantly better magnetic properties.

[0083] The chemical element composition design adopted in Comparative Example 3-4 is exactly the same as that in Example 2. However, since the volume ratio of AlN and (Cu, Mn)S precipitates with a size of 30-100 nm in the steel plate to the total precipitates in Comparative Example 3-4 after the two-stage normalizing annealing treatment in step (3) exceeds the design range of the present invention, the magnetic properties of the comparative steel finally obtained in Comparative Example 3-4 are not good.

[0084] Correspondingly, the chemical element composition design adopted in Comparative Example 5-6 is exactly the same as that in Example 3. However, since the cold rolling reduction rate of Comparative Example 5-6 in the cold rolling stage of step (4) exceeds the design range of the present invention, the magnetic properties of the comparative steel finally obtained in Comparative Example 5-6 are poor.

[0085] The chemical element composition design used in Comparative Example 7-8 is exactly the same as that in Example 4. However, since the decarburization temperature in the decarburization annealing stage in step (5) of Comparative Example 7-8 does not meet the design requirements of the present invention, the magnetic properties of the comparative steel finally obtained in Comparative Example 7-8 are poor.

[0086] The chemical element composition design used in Comparative Examples 9-10 is exactly the same as that in Example 5. However, since the nitrogen content in the steel plate after nitriding in step (5) of Comparative Examples 9-10 exceeds the design range of the present invention, the magnetic properties of the comparative steel finally obtained in Comparative Examples 9-10 are poor.

[0087] In summary, compared with comparative examples 1-10, the magnetic properties of the copper-containing low-temperature oriented silicon steel products obtained by using the chemical elements and manufacturing processes of the present invention are better, and the iron loss P 17 / 50 All are < 0.85W / Kg, and the magnetic induction B8 is > 1.90T, which has good promotion prospects and application value.

[0088] It should be noted that the existing technologies in the protection scope of the present invention are not limited to the embodiments given in the present application documents. All existing technologies that do not contradict the solutions of the present invention, including but not limited to prior patent documents, prior public publications, prior public uses, etc., can be included in the protection scope of the present invention. In addition, the combination of various technical features in this case is not limited to the combination described in the claims of this case or the combination described in the specific embodiments. All technical features recorded in this case can be freely combined or combined in any way unless there is a contradiction between them.

[0089] It should also be noted that the above-listed embodiments are only specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and similar changes or modifications made therewith can be directly derived or easily associated with the contents disclosed by those skilled in the art from the present invention, and all should belong to the protection scope of the present invention.

Claims

1. A copper-containing low-temperature oriented silicon steel, characterized in that: The mass percentage of each chemical element is: C: 0.04-0.09%, Si: 2.9-4.0%, Mn: 0.05-0.2%, S: 0.005-0.01%, Als: 0.015-0.035%, N: 0.0010-0.01%, Sn: 0.01-0.1%, and Cu, the balance is Fe and other inevitable impurities; wherein the Cu content satisfies: 3%≤Si+Cu≤4.4%, 0.05≤Cu / Si≤0.13, 24≤(Mn+Cu) / S≤118; The average grain size of its secondary recrystallization is 10-20mm, and the average grain deviation is <5mm.

2. The copper-containing low-temperature oriented silicon steel according to claim 1, characterized in that: Its thickness is ≤0.23mm.

3. The copper-containing low-temperature oriented silicon steel according to claim 1, characterized in that: Its iron loss P 17 / 50 <0.85W / kg, magnetic induction B8>1.90T.

4. The method for producing copper-containing low-temperature oriented silicon steel according to any one of claims 1 to 3, characterized in that: Includes steps: (1) Smelting and casting; (2) Hot rolling; (3) Two-stage normalizing annealing: the first stage is at 1100-1150°C for 60-120s, the second stage is at 900-950°C for 60-120s, and then water-cooled with a cooling rate of ≥30°C / s, so that the volume ratio of AlN and (Cu, Mn)S precipitates with a size of 30-100nm in the steel plate after normalization accounts for 30-80% of the total precipitates; (4) Cold rolling: Control the cold rolling reduction rate to 88-92%; (5) decarburization annealing, nitriding, and coating of high-temperature isolating agent; wherein the decarburization temperature is controlled to be T=804.5+56.5×A+6.2×B, wherein A represents the volume ratio of 30-100nm AlN and (Cu, Mn)S precipitates to the total precipitates after normalization, and B represents the cold rolling reduction rate; the nitrogen content in the steel plate after nitriding is 200-300ppm; (6) High temperature annealing; (7) Applying insulation coating, and hot stretching and flattening annealing.

5. The manufacturing method according to claim 4, characterized in that: In step (2), the heating temperature is controlled to be 1050-1150°C.

6. The manufacturing method according to claim 4, characterized in that: In step (2), the thickness of the hot rolled plate is controlled to be 1.5-2.9 mm.

7. The manufacturing method according to claim 4, characterized in that: In step (6), the temperature is raised to 500-700°C and kept warm; when the temperature is further raised to 700-1050°C, the annealing atmosphere adopts a dry N2+H2 mixed gas with a volume percentage of not less than 50%; when the temperature is further raised to 1050-1150°C, the annealing atmosphere adopts a dry N2+H2 mixed gas with a volume percentage of less than 50%; when the temperature is further raised to 1150-1200°C, the annealing atmosphere adopts pure H2.

8. The manufacturing method according to claim 7, characterized in that: In step (6), when the temperature is raised to 500-700°C, the insulation time is ≥ 20h.

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