Production process of low-temperature and high-magnetic-induction oriented silicon steel

Abstract

The present invention aims to disclose a production process for low-temperature, high-magnetic-induction oriented silicon steel, comprising the following steps: S1: preparing a steel slab, wherein the chemical composition of the steel slab includes C, Si, Mn, Als, N, Sn, Cr, P, and S, and the remainder is Fe and unavoidable impurities; S2: heating, hot-rolling, normalizing, pickling, and cold-rolling the steel slab to obtain a cold-rolled sheet; S3: decarburizing and nitriding the cold-rolled sheet; S4: applying an annealing isolation coating to the surface of the steel and coiling it; S5: During the high-temperature annealing process, the steel coils are subjected to a humidification treatment of the hydrogen and nitrogen mixture introduced during the 750°C to 1000°C heating stage to control the dew point in the high-temperature annealing furnace at -20°C to 25°C. This beneficial effect is that by humidifying the atmosphere during the high-temperature annealing stage, the mixed gas has a certain degree of oxidizing properties, causing some Alr to be oxidized to ineffective Al2O3, thereby regulating the actual Alr content and stabilizing and improving the magnetic properties of the grain-oriented silicon steel.

Description

Technical Field

[0001] The present invention relates to the technical field of steel smelting, and in particular to a production process of low-temperature high-magnetic-induction oriented silicon steel. Background Art

[0002] Oriented silicon steel refers to steel with {110} <001> Texture (i.e. Goss texture) of soft magnetic silicon-iron alloy material containing about 3% silicon, during the high temperature annealing process, secondary recrystallization of oriented silicon steel occurs to obtain a perfect single {110} <001> Texture. The crystal plane of the Goss texture is parallel to the rolling surface, and the crystal direction is parallel to the rolling direction. Therefore, the rolling direction of the steel plate is the direction of easy magnetization, and it has excellent magnetic level.

[0003] High magnetic induction oriented silicon steel refers to J 800 Grain-oriented silicon steel with a thickness of ≥1.88T. Low-temperature, high-magnetic-induction grain-oriented silicon steel is produced using low-temperature slab heating technology. Precise control of AlS (acid-soluble aluminum) is a key production factor. AlS refers to the amount of aluminum in the steel that exists in a non-Al2O3 state, including the Al content in AlN and the solid-solution aluminum (Alr) content. During the continuous casting, hot rolling, and normalizing processes of grain-oriented silicon steel production, some AlN is formed. Those that meet specific size and distribution requirements are called intrinsic inhibitors. After decarburization and nitriding, the newly introduced nitrogen is primarily concentrated on the surface of the sample, where it combines with Si in the steel to form Si3N4. During the subsequent high-temperature annealing process, the newly formed Si3N4 decomposes, and some N continues to diffuse toward the core of the steel strip, combining with AlS to form AlN. These newly formed AlN that meet specific size and distribution requirements are called acquired inhibitors and serve as the primary inhibitor for low-temperature, high-magnetic-induction grain-oriented silicon steel, promoting abnormal grain growth in the Goss direction. During this diffusion process, some N escapes the matrix and enters the high-temperature annealing protective atmosphere. The effective AlN formed by nitriding does not increase linearly with the increase of nitriding amount. Therefore, during high temperature annealing, after the new effective AlN is formed, some Als will still exist in the solid solution aluminum (Alr) state.

[0004] The Alr content has a significant impact on the magnetic level of low-temperature, high-magnetic-induction oriented silicon steel, and precise control is required during its production. Since Als is easily oxidized, it will be lost during the smelting and continuous casting processes, resulting in unstable yields. This makes it difficult for the Als content in the product to stably meet the target value requirements, and there is also a lack of effective means to regulate it in subsequent production processes. During the smelting process, the N content in the molten steel is affected by a variety of factors, including the quality of scrap steel and the quality of protective casting. Therefore, it is also difficult to control the N content in the slab within a fixed range. Since Als and N are difficult to precisely control during steelmaking, the fluctuation range of Alr after smelting often exceeds the reasonable range required for oriented silicon steel, which in turn leads to a deterioration of the magnetic level and even the production of large quantities of scrap.

[0005] In view of this, it is necessary to develop a low-temperature, high-magnetic-induction oriented silicon steel production process that can accurately control the Alr content to solve the above problems. Summary of the Invention

[0006] The purpose of the present invention is to disclose a low-temperature, high-magnetic-induction oriented silicon steel production process. By humidifying the hydrogen and nitrogen mixture introduced in a specified temperature range (750°C-1000°C) during the high-temperature annealing process, the dew point in the high-temperature annealing furnace is precisely controlled, thereby adjusting the actual Alr content.

[0007] To achieve the above-mentioned object of the invention, the present invention provides a low-temperature high-magnetic-induction oriented silicon steel production process, comprising the following steps:

[0008] S1: preparing a steel slab, wherein the chemical composition of the steel slab, in terms of weight percentage, includes C: 0.040% to 0.080%, Si: 2.81% to 3.60%, Mn: 0.05% to 0.30%, Als: 0.0200% to 0.0350%, N: 0.006% to 0.009%, Sn: 0.02% to 0.10%, Cr: ≤ 0.20%, P: ≤ 0.050%, S: 0.003% to 0.010%, and the remainder is Fe and unavoidable impurities;

[0009] S2: The steel slab is heated, hot rolled, normalized, pickled, and cold rolled to obtain a cold rolled sheet;

[0010] S3: Decarburizing and nitriding the cold-rolled sheet obtained in step S2;

[0011] S4: coating the steel material obtained in step S3 with an annealed barrier coating and coiling the steel material to obtain a steel coil;

[0012] S5: The steel coil obtained in step S4 is subjected to high temperature annealing treatment at 750°C.

[0013] During the temperature rise stage to 1000℃, the hydrogen and nitrogen mixed gas introduced is humidified to control the dew point in the high temperature annealing furnace at -20℃~25℃.

[0014] Preferably, the calculation formula for the Alr content in the steel slab is: Alr=Als-(27 / 14)*N.

[0015] Preferably, the cold-rolled plate has a thickness of 0.22 mm to 0.36 mm.

[0016] Preferably, in step S3, the carbon content in the steel is controlled to be below 30 ppm, the oxygen content is controlled to be between 350 ppm and 1300 ppm, and the nitrogen content is controlled to be between 130 ppm and 300 ppm.

[0017] Preferably, the annealed isolation coating comprises MgO and TiO2, and the moisture content of the annealed isolation coating is 1.5% to 4.0%.

[0018] Preferably, when the Alr content is ≤0.0109%, the dew point in the high-temperature annealing furnace is controlled at -20°C to -10°C.

[0019] Preferably, when the Alr content is 0.0110%≤0.0129%, the dew point in the high-temperature annealing furnace is controlled at -10°C to 5°C.

[0020] Preferably, when the Alr content is 0.0130%≤0.0145%, the dew point in the high-temperature annealing furnace is controlled at -5°C to 10°C.

[0021] Preferably, when the Alr content is 0.0146%≤0.0154%, the dew point in the high-temperature annealing furnace is controlled at 0°C to 15°C.

[0022] Preferably, when the Alr content is ≥0.0155%, the dew point in the high-temperature annealing furnace is controlled at 5°C to 25°C.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) By humidifying the atmosphere (humidifying the hydrogen and nitrogen mixture introduced) during the high-temperature annealing heating stage (750℃~1000℃), the mixed gas is given a certain degree of oxidizing properties, causing some Alr to oxidize and transform into ineffective Al2O3, thereby regulating the actual Alr content. This allows the Alr content to reach the reasonable range required for the production of oriented silicon steel, thereby stabilizing and improving the magnetic properties of oriented silicon steel.

[0025] (2) Adjust the dew point (water vapor content) of the gas in the furnace during the high-temperature annealing stage of 750℃-1000℃ to cause different degrees of oxidation of Alr, thereby making the actual Alr content of the steel before secondary recrystallization reach a reasonable range, thereby achieving the purpose of stabilizing and improving the magnetic level of the product. DETAILED DESCRIPTION

[0026] The present invention is described in detail below in conjunction with various embodiments, but it should be noted that these embodiments are not limitations of the present invention, and any equivalent transformations or substitutions in functions, methods, or structures made by ordinary technicians in this field based on these embodiments are all within the scope of protection of the present invention.

[0027] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate directions or positional relationships based on directions or positional relationships, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as limiting the present invention.

[0028] The specific implementation process of the present invention is described below through multiple embodiments.

[0029] Example 1:

[0030] Embodiment 1 provides a low-temperature high-magnetic-induction oriented silicon steel production process, comprising the following steps:

[0031] S1: Prepare a steel slab, wherein the chemical composition of the steel slab, in percentage by weight, includes C: 0.0450%, Si: 3.25%, Mn: 0.28%, Als: 0.0325%, N: 0.0080%, Sn: 0.074%, Cr: 0.18%, P: 0.041%, S: 0.0091%, and the remainder is Fe and unavoidable impurities. Specifically, steel is smelted in a converter, refined in a vacuum furnace, and continuously cast into a slab. The Alr content in the steel slab is calculated as follows: Alr = Als - (27 / 14) * N = 0.0325% - (27 / 14) *

[0032] 0.0080%=0.0171%.

[0033] S2: The steel slab is heated, hot rolled, normalized, pickled, and cold rolled to obtain a cold rolled sheet.

[0034] The thickness of the cold-rolled plate is 0.30 mm;

[0035] S3: Decarburizing and nitriding the cold-rolled steel obtained in step S2 to control the carbon content, oxygen content, and nitrogen content of the steel to 28 ppm, 700 ppm, and 164 ppm, respectively;

[0036] S4: Coating the steel material surface with an annealed barrier coating obtained in step S3 and coiling the steel material to obtain a steel coil, wherein the annealed barrier coating comprises MgO and TiO2, and the moisture content of the annealed barrier coating is 3.4%;

[0037] S5: The steel coil obtained in step S4 is subjected to high temperature annealing treatment at 750°C.

[0038] During the temperature rise stage to 1000℃, the hydrogen and nitrogen mixed gas introduced is humidified to control the dew point in the high temperature annealing furnace at 10℃~23℃.

[0039] AlN is the primary inhibitor in low-temperature, high-magnetic-induction grain-oriented silicon steel. It inhibits grain growth before the secondary recrystallization temperature during high-temperature annealing. After reaching a specific temperature, AlN decomposes, causing abnormal growth of Gossian grains and the onset of secondary recrystallization, ultimately forming grain-oriented silicon steel with a single orientation. Alr (Al2O3) is the portion of Al2O3 (acid-soluble aluminum) that does not form AlN. Alr affects the precipitation distribution of the AlN inhibitor, and its content significantly influences the magnetic properties of the product.

[0040] Through the above steps S1-S5, especially in step S5, the atmosphere is humidified (the hydrogen and nitrogen mixed gas is humidified) during the temperature rise stage (750°C to 1000°C) of the high-temperature annealing, so that the mixed gas has a certain oxidizing property, causing some Alr to be oxidized and converted into ineffective Al2O3, thereby adjusting the actual Alr content to a reasonable range required for the production of grain-oriented silicon steel, thereby stabilizing and improving the magnetic properties of the grain-oriented silicon steel.

[0041] By adjusting the dew point of the furnace gas during the high-temperature annealing stage of 750℃-1000℃, Alr is oxidized to varying degrees, thereby bringing the actual Alr content of the steel into a reasonable range before secondary recrystallization, thereby achieving the goal of stabilizing and improving the magnetic level of the product.

[0042] The average iron loss and average magnetic polarization intensity of the grain-oriented silicon steel of Example 1 were detected and compared with the grain-oriented silicon steel produced by the conventional high-temperature annealing process of Comparative Example 1 (other process conditions were the same as those of this Example). The comparison results are shown in Table 1. The average magnetic polarization intensity of Example 1 is improved and the average iron loss is reduced.

[0043] Table 1 Performance of Example 1 and Comparative Example 1

[0044]

[0045] Example 2:

[0046] Example 2 provides a low-temperature high-magnetic-induction oriented silicon steel production process, comprising the following steps:

[0047] S1: A steel slab is prepared. The chemical composition of the steel slab, in percentage by weight, includes C: 0.0554%, Si: 3.451%, Mn: 0.21%, Als: 0.0231%, N: 0.0071%, Sn: 0.088%, Cr: 0.13%, P: 0.031%, S: ≤ 0.0082%, with the remainder being Fe and unavoidable impurities. Specifically, the steel is smelted in a converter, refined in a vacuum furnace, and continuously cast into the slab. The Alr content in the steel slab is calculated as follows: Alr = Als - (27 / 14) * N = 0.0231% - (27 / 14) * 0.0071% = 0.0094%.

[0048] S2: The steel slab is heated, hot rolled, normalized, pickled, and cold rolled to obtain a cold rolled sheet.

[0049] The thickness of the cold-rolled plate is 0.35 mm;

[0050] S3: Decarburizing and nitriding the cold-rolled steel obtained in step S2 to control the carbon content, oxygen content, and nitrogen content in the steel to 24 ppm, 412 ppm, and 144 ppm, respectively;

[0051] S4: Coating the steel material surface with an annealed barrier coating obtained in step S3 and coiling the steel material to obtain a steel coil, wherein the annealed barrier coating comprises MgO and TiO2, and the moisture content of the annealed barrier coating is 3.1%;

[0052] S5: The steel coil obtained in step S4 is subjected to high temperature annealing treatment at 750°C.

[0053] During the temperature rise stage to 900℃, the hydrogen and nitrogen mixed gas introduced is humidified to control the dew point in the high temperature annealing furnace at -20℃~-14℃.

[0054] AlN is the primary inhibitor in low-temperature, high-magnetic-induction grain-oriented silicon steel. It inhibits grain growth before the secondary recrystallization temperature during high-temperature annealing. After reaching a specific temperature, AlN decomposes, causing abnormal growth of Gossian grains and the onset of secondary recrystallization, ultimately forming grain-oriented silicon steel with a single orientation. Alr (Al2O3) is the portion of Al2O3 (acid-soluble aluminum) that does not form AlN. Alr affects the precipitation distribution of the AlN inhibitor, and its content significantly influences the magnetic properties of the product.

[0055] Through the above steps S1-S5, especially in step S5, by humidifying the atmosphere during the temperature rise stage of high-temperature annealing (humidification treatment of the introduced hydrogen and nitrogen mixed gas), the mixed gas is given a certain oxidizing property, causing some Alr to be oxidized and converted into ineffective Al2O3, thereby adjusting the actual Alr content to a reasonable range required for the production of grain-oriented silicon steel, thereby stabilizing and improving the magnetic properties of the grain-oriented silicon steel.

[0056] By adjusting the dew point of the furnace gas during the high-temperature annealing stage of 750℃-900℃, Alr is oxidized to varying degrees, thereby bringing the actual Alr content of the steel before secondary recrystallization into a reasonable range, thereby achieving the goal of stabilizing and improving the magnetic level of the product.

[0057] The average iron loss and average magnetic polarization intensity of the grain-oriented silicon steel of Example 2 were detected and compared with the grain-oriented silicon steel produced by the conventional high-temperature annealing process of Comparative Example 2 (other process conditions were the same as those of this Example). The comparison results are shown in Table 2. The average magnetic polarization intensity of Example 2 is improved and the average iron loss is reduced.

[0058] Table 2 Performance of Example 2 and Comparative Example 2

[0059]

[0060] Example 3:

[0061] Example 3 provides a low-temperature high-magnetic-induction oriented silicon steel production process, comprising the following steps:

[0062] S1: A steel slab is prepared. The chemical composition of the steel slab, in percentage by weight, includes C: 0.0612%, Si: 3.10%, Mn: 0.17%, Als: 0.0266%, N: 0.0072%, Sn: 0.052%, Cr: 0.11%, P: 0.020%, S: 0.0070%, and the remainder is Fe and unavoidable impurities. Specifically, the steel is smelted in a converter, refined in a vacuum furnace, and continuously cast into the slab. The Alr content in the steel slab is calculated as follows: Alr = Als - (27 / 14) * N = 0.0266% - (27 / 14) * 0.0072% = 0.0127%.

[0063] S2: The steel slab is heated, hot rolled, normalized, pickled, and cold rolled to obtain a cold rolled sheet.

[0064] The thickness of the cold-rolled plate is 0.27 mm;

[0065] S3: Decarburizing and nitriding the cold-rolled steel obtained in step S2 to control the carbon content in the steel to 16 ppm, the oxygen content to 1230 pm, and the nitrogen content to 243 ppm;

[0066] S4: Coating the steel material surface with an annealed barrier coating obtained in step S3 and coiling the steel material to obtain a steel coil, wherein the annealed barrier coating comprises MgO and TiO2, and the moisture content of the annealed barrier coating is 2.6%;

[0067] S5: The steel coil obtained in step S4 is subjected to high temperature annealing treatment at 750°C.

[0068] During the temperature rise stage to 1000℃, the hydrogen and nitrogen mixed gas introduced is humidified to control the dew point in the high temperature annealing furnace at -10℃~4℃.

[0069] AlN is the primary inhibitor in low-temperature, high-magnetic-induction grain-oriented silicon steel. It inhibits grain growth before the secondary recrystallization temperature during high-temperature annealing. After reaching a specific temperature, AlN decomposes, causing abnormal growth of Gossian grains and the onset of secondary recrystallization, ultimately forming grain-oriented silicon steel with a single orientation. Alr (Al2O3) is the portion of Al2O3 (acid-soluble aluminum) that does not form AlN. Alr affects the precipitation distribution of the AlN inhibitor, and its content significantly influences the magnetic properties of the product.

[0070] Through the above steps S1-S5, especially in step S5, by humidifying the atmosphere during the temperature rise stage of high-temperature annealing (humidification treatment of the introduced hydrogen and nitrogen mixed gas), the mixed gas is given a certain oxidizing property, causing some Alr to be oxidized and converted into ineffective Al2O3, thereby adjusting the actual Alr content to a reasonable range required for the production of grain-oriented silicon steel, thereby stabilizing and improving the magnetic properties of the grain-oriented silicon steel.

[0071] By adjusting the dew point of the furnace gas during the high-temperature annealing stage of 750℃-1000℃, Alr is oxidized to varying degrees, thereby bringing the actual Alr content of the steel into a reasonable range before secondary recrystallization, thereby achieving the goal of stabilizing and improving the magnetic level of the product.

[0072] The average iron loss and average magnetic polarization intensity of the grain-oriented silicon steel of Example 3 were detected and compared with the grain-oriented silicon steel produced by the conventional high-temperature annealing process of Comparative Example 3 (other process conditions were the same as those of this embodiment). The comparison results are shown in Table 3. The average magnetic polarization intensity of Example 3 is improved and the average iron loss is reduced.

[0073] Table 3 Performance of Example 3 and Comparative Example 3

[0074]

[0075] Example 4:

[0076] The fourth embodiment provides a low-temperature high-magnetic-induction oriented silicon steel production process, comprising the following steps:

[0077] S1: A steel slab is prepared. The chemical composition of the steel slab, in percentage by weight, includes C: 0.0657%, Si: 2.93%, Mn: 0.10%, Als: 0.0283%, N: 0.0067%, Sn: 0.042%, Cr: 0.07%, P: 0.013%, S: 0.0048%, and the remainder is Fe and unavoidable impurities. Specifically, the steel is smelted in a converter, refined in a vacuum furnace, and continuously cast into the slab. The Alr content in the steel slab is calculated as follows: Alr = Als - (27 / 14) * N = 0.0283% - (27 / 14) * 0.0067% = 0.0154%.

[0078] S2: The steel slab is heated, hot rolled, normalized, pickled, and cold rolled to obtain a cold rolled sheet.

[0079] The thickness of the cold-rolled plate is 0.23 mm;

[0080] S3: Decarburizing and nitriding the cold-rolled steel obtained in step S2 to control the carbon content in the steel to 7 ppm, the oxygen content to 832 pm, and the nitrogen content to 237 ppm;

[0081] S4: Coating the steel material surface with an annealed barrier coating obtained in step S3 and coiling the steel material to obtain a steel coil, wherein the annealed barrier coating comprises MgO and TiO2, and the moisture content of the annealed barrier coating is 2.1%;

[0082] S5: The steel coil obtained in step S4 is subjected to high temperature annealing treatment at 750°C.

[0083] During the temperature rise to 980℃, the hydrogen and nitrogen mixed gas introduced is humidified to control the dew point in the high temperature annealing furnace at 0℃~13℃.

[0084] AlN is the primary inhibitor in low-temperature, high-magnetic-induction grain-oriented silicon steel. It inhibits grain growth before the secondary recrystallization temperature during high-temperature annealing. After reaching a specific temperature, AlN decomposes, causing abnormal growth of Gossian grains and the onset of secondary recrystallization, ultimately forming grain-oriented silicon steel with a single orientation. Alr (Al2O3) is the portion of Al2O3 (acid-soluble aluminum) that does not form AlN. Alr affects the precipitation distribution of the AlN inhibitor, and its content significantly influences the magnetic properties of the product.

[0085] Through the above steps S1-S5, especially in step S5, by humidifying the atmosphere during the temperature rise stage of high-temperature annealing (humidification treatment of the introduced hydrogen and nitrogen mixed gas), the mixed gas is given a certain oxidizing property, causing some Alr to be oxidized and converted into ineffective Al2O3, thereby adjusting the actual Alr content to a reasonable range required for the production of grain-oriented silicon steel, thereby stabilizing and improving the magnetic properties of the grain-oriented silicon steel.

[0086] By adjusting the dew point of the furnace gas during the high-temperature annealing stage of 750℃-980℃, Alr is oxidized to varying degrees, thereby bringing the actual Alr content of the steel before secondary recrystallization into a reasonable range, thereby achieving the goal of stabilizing and improving the magnetic level of the product.

[0087] The average iron loss and average magnetic polarization intensity of the grain-oriented silicon steel of Example 4 were detected and compared with the grain-oriented silicon steel produced by the conventional high-temperature annealing process of Comparative Example 4 (other process conditions were the same as those of this Example). The comparison results are shown in Table 4. The average magnetic polarization intensity of Example 4 is improved and the average iron loss is reduced.

[0088] Table 4 Performance of Example 4 and Comparative Example 4

[0089]

[0090] Embodiment 5:

[0091] Example 5 provides a low-temperature high-magnetic-induction oriented silicon steel production process, comprising the following steps:

[0092] S1: A steel slab is prepared. The chemical composition of the steel slab, in weight percentage, includes C: 0.0764%, Si: 3.30%, Mn: 0.06%, Als: 0.0294%, N: 0.0084%, Sn: 0.030%, Cr: 0.01%, P: 0.007%, S: 0.0033%, and the remainder is Fe and unavoidable impurities. Specifically, the steel is smelted in a converter, refined in a vacuum furnace, and continuously cast into the slab. The Alr content in the steel slab is calculated as follows: Alr = Als - (27 / 14) * N = 0.0294% - (27 / 14) * 0.0084% = 0.0132%.

[0093] S2: The steel slab is heated, hot rolled, normalized, pickled, and cold rolled to obtain a cold rolled sheet.

[0094] The thickness of the cold-rolled plate is 0.23 mm;

[0095] S3: Decarburizing and nitriding the cold-rolled steel obtained in step S2 to control the carbon content, oxygen content, and nitrogen content in the steel to 19 ppm, 634 pm, and 276 ppm, respectively;

[0096] S4: Coating the steel material surface with an annealed barrier coating obtained in step S3 and coiling the steel material to obtain a steel coil, wherein the annealed barrier coating comprises MgO and TiO2, and the moisture content of the annealed barrier coating is 1.7%;

[0097] S5: The steel coil obtained in step S4 is subjected to high temperature annealing treatment at 750°C.

[0098] During the temperature rise stage to 930℃, the hydrogen and nitrogen mixed gas introduced is humidified to control the dew point in the high temperature annealing furnace at -5℃~7℃.

[0099] AlN is the primary inhibitor in low-temperature, high-magnetic-induction grain-oriented silicon steel. It inhibits grain growth before the secondary recrystallization temperature during high-temperature annealing. After reaching a specific temperature, AlN decomposes, causing abnormal growth of Gossian grains and the onset of secondary recrystallization, ultimately forming grain-oriented silicon steel with a single orientation. Alr (Al2O3) is the portion of Al2O3 (acid-soluble aluminum) that does not form AlN. Alr affects the precipitation distribution of the AlN inhibitor, and its content significantly influences the magnetic properties of the product.

[0100] Through the above steps S1-S5, especially in step S5, by humidifying the atmosphere during the temperature rise stage of high-temperature annealing (humidification treatment of the introduced hydrogen and nitrogen mixed gas), the mixed gas is given a certain oxidizing property, causing some Alr to be oxidized and converted into ineffective Al2O3, thereby adjusting the actual Alr content to a reasonable range required for the production of grain-oriented silicon steel, thereby stabilizing and improving the magnetic properties of the grain-oriented silicon steel.

[0101] By adjusting the dew point of the furnace gas during the high-temperature annealing stage of 750℃-930℃, Alr is oxidized to varying degrees, thereby bringing the actual Alr content of the steel into a reasonable range before secondary recrystallization, thereby achieving the goal of stabilizing and improving the magnetic level of the product.

[0102] The average iron loss and average magnetic polarization intensity of the grain-oriented silicon steel of Example 5 were detected and compared with the grain-oriented silicon steel produced by the conventional high-temperature annealing process of Comparative Example 5 (other process conditions were the same as those of this embodiment). The comparison results are shown in Table 5. The average magnetic polarization intensity of Example 5 is improved and the average iron loss is reduced.

[0103] Table 5 Performance of Example 5 and Comparative Example 5

[0104] Evaluation indicators Example 5 Comparative Example 5 <![CDATA[Average iron loss (P 1.7 / 50 , W / kg)]]> 0.83 0.96 <![CDATA[Average magnetic polarization intensity (J 800 , T)]]> 1.91 1.90

Claims

1. A low-temperature, high-magnetic-induction oriented silicon steel production process, characterized in that: The following steps are involved: S1: preparing a steel slab, wherein the chemical composition of the steel slab, in terms of weight percentage, includes C: 0.0657%-0.080%, Si: 2.81%, Mn: 0.21%-0.30%, Als: 0.0200%-0.0350%, N: 0.006%, 0.0071%, 0.0080%, 0.0084% or 0.009%, Sn: 0.02%-0.10%, Cr: ≤0.20%, P: ≤0.050%, S: 0.003%-0.010%, and the remainder is Fe and unavoidable impurities; S2: The steel slab is heated, hot-rolled, normalized, pickled, and cold-rolled to obtain a cold-rolled plate, wherein the thickness of the cold-rolled plate is 0.22 mm to 0.27 mm; S3: Decarburizing and nitriding the cold-rolled steel obtained in step S2. In step S3, the carbon content in the steel is controlled to be below 30 ppm, the oxygen content is between 350 ppm and 1300 ppm, and the nitrogen content is between 130 ppm and 300 ppm. S4: Coating the steel material surface with an annealed barrier coating obtained in step S3 and coiling the steel material to obtain a steel coil, wherein the annealed barrier coating comprises MgO and TiO2, and the moisture content of the annealed barrier coating is 1.5% to 4.0%; S5: The steel coil obtained in step S4 is subjected to high temperature annealing. During the high temperature annealing stage of 750°C to 1000°C, the hydrogen and nitrogen mixed gas introduced is humidified to control the dew point in the high temperature annealing furnace to -5°C to 7°C. In step S5, the mixed gas has oxidizing properties, causing part of the Alr to be oxidized and converted into ineffective Al2O3.

2. The low-temperature high-magnetic-induction oriented silicon steel production process according to claim 1, characterized in that: The calculation formula for the Alr content in the steel slab is: .

3. The low-temperature high-magnetic-induction oriented silicon steel production process according to claim 2, characterized in that: When the Alr content is 0.0110%≤0.0129%, the dew point in the high temperature annealing furnace is controlled at -5℃~5℃.

4. The low-temperature high-magnetic-induction oriented silicon steel production process according to claim 2, characterized in that: When the Alr content is 0.0130%≤0.0145%, the dew point in the high-temperature annealing furnace is controlled at -5℃~7℃.

5. The low-temperature high-magnetic-induction grain-oriented silicon steel production process according to claim 2, wherein: When 0.0146%≤Alr content≤0.0154%, the dew point in the high-temperature annealing furnace is controlled at 0℃~15℃.

6. The process for producing low-temperature, high-magnetic-induction grain-oriented silicon steel according to claim 2, wherein: When the Alr content is ≥0.0155%, the dew point in the high-temperature annealing furnace is controlled at 5℃~7℃.

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