A kind of high magnetic induction oriented silicon steel and preparation method thereof

Abstract

The invention provides a high magnetic induction oriented silicon steel and a preparation method thereof. The high magnetic induction oriented silicon steel comprises the following components in mass percentage: C 0.052-0.062%, Si 3.2-3.3%, Als 0.0265-0.0295%, Mn 0.09-0.12%, P 0.027-0.033%, S≤0.008%, N≤0.0085%, Sn 0.040-0.060%, and the balance is Fe and impurities.

Description

Technical Field

[0001] The invention belongs to the technical field of steel materials, and in particular relates to high magnetic induction oriented silicon steel and a preparation method thereof. Background Art

[0002] At present, the national steel industry is suffering from large-scale losses. The steel industry has entered a period of losses or small profits, and this trend is not expected to change fundamentally in the short term. Therefore, making the company bigger and stronger and not being swallowed up in the future wave of mergers and reorganizations in the steel industry is the only way for steel companies to survive. Enriching the company's product structure and improving product cost-effectiveness and market competitiveness are one of the important tasks for the healthy and sustainable development of steel companies.

[0003] Since the finished grains of oriented silicon steel have the characteristics of sharp Gaussian texture and preferential orientation, they are easily magnetized in the rolling direction and can obtain a high saturation magnetic induction intensity. Oriented silicon steel is used to make large transformers. It is an important ferrosilicon alloy used in the transformer (iron core) manufacturing industry, with high magnetic induction and low iron loss characteristics. However, the existing market price of oriented silicon steel is high, the process is complex, and the manufacturing technology is strict. Once it is not well controlled, the performance of the final product is difficult to meet the process and customer requirements.

[0004] The existing technology reduces iron loss by increasing the Si / Al alloy element content, improving the material resistivity, and reducing the thickness of the silicon steel product to reduce eddy current loss. However, increasing the Si / Al alloy content will increase the brittleness of the material, causing the oriented silicon steel to easily break during the cold rolling process, reducing the cold rolling yield of oriented silicon steel. Reducing the thickness of the oriented silicon steel product will increase the difficulty of cold rolling production and reduce the efficiency of the punching process. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a high magnetic induction oriented silicon steel and a preparation method thereof. The high magnetic induction oriented silicon steel of the present invention reasonably adjusts the content of elements such as Si, Als, Mn, P, and strictly controls the content of Fe and impurities, and reasonably adds the alloy element Sn, so that the prepared high magnetic induction oriented silicon steel has no broken bands and has the performance of high magnetic induction and low iron loss to meet user requirements.

[0006] In a first aspect, the present invention provides a high magnetic induction oriented silicon steel comprising the following components in percentage by mass:

[0007]

[0008] The balance is Fe and impurities.

[0009] In the present invention, carbon (C) is an extremely harmful element. It forms an interstitial solid solution with iron, lattice distortion, increased coercive force, reduced magnetic permeability, and significantly reduced magnetism. Carbon is the main element that produces magnetic aging. If magnetic aging occurs in electrical equipment, the iron loss will increase significantly, resulting in damage to the equipment. Therefore, carbon is extremely harmful to the magnetism of silicon steel. If the mass percentage of carbon in oriented silicon steel is reduced to below 0.062%, magnetic aging will not occur. In the present invention, the mass percentage of C is controlled to be 0.052-0.062%; preferably, the mass percentage of C is controlled to be 0.052-0.06%.

[0010] Adding silicon (Si) to steel can increase resistivity, reduce eddy current loss, promote grain coarsening, reduce coercive force and hysteresis loss, and thus reduce iron loss. Therefore, silicon is the main element to improve the magnetic properties of electrical steel, but too high silicon content increases the brittleness of silicon steel and deteriorates cold processing. In addition, as the Si content increases, the thermal conductivity and thermal expansion coefficient of silicon steel decrease, and continuous casting billets are prone to cracks. In the present invention, the mass percentage of Si is 3.2-3.3%; preferably, the mass percentage of Si is 3.22-3.28%.

[0011] Aluminum (Al) is added to oriented silicon steel. Aluminum, as a good deoxidizer, can increase resistivity, reduce coercivity, reduce iron loss, reduce magnetic aging, and increase magnetic induction. In general silicon steel, the aluminum content of 0.05-0.14% is easy to form fine AlN particles. AlN particles are precipitated during cold rolling annealing, hindering grain growth and increasing iron loss. In the present invention, the mass percentage of Als is 0.0265-0.0295%; preferably, the mass percentage of Als is 0.027-0.029%.

[0012] Adding manganese (Mn) to silicon steel can reduce iron loss, but too high a content will make the steel brittle. Therefore, reasonably controlling the mass percentage of Mn to 0.09-0.12% can not only effectively reduce iron loss, but also avoid steel embrittlement. Preferably, the mass percentage of Mn is 0.10-0.11%.

[0013] Tin (Sn) is a ferromagnetic element that can effectively increase the resistivity of silicon steel and improve the magnetic induction intensity of the finished product. At the same time, the Sn element can effectively improve the corrosion resistance of silicon steel and reduce the oxidation of the cross-section matrix after punching. Compared with other elements that reduce iron loss, Sn has a smaller effect on magnetic induction loss. At the same time, Sn can improve the room temperature toughness of high-grade silicon steel, thereby improving the rollability of high-grade silicon steel, greatly reducing the proportion of broken strips during the cold rolling process of high-grade oriented silicon steel, and improving rolling production efficiency. In the present invention, the mass percentage of Sn is 0.04-0.06%; preferably, the mass percentage of Sn is 0.045-0.055%.

[0014] Phosphorus (P) can make the grains grow, increase the resistivity, reduce the iron loss, and alleviate the magnetic aging. However, phosphorus is a grain boundary segregation element, and excessive content will deteriorate the cold workability. In the present invention, the mass percentage of P is 0.027-0.033%; preferably, the mass percentage of P is 0.028-0.032%.

[0015] Sulfur (S) is the second most harmful element after carbon. S increases iron loss and coercivity and reduces magnetic permeability and magnetic induction. Therefore, the content of S in silicon steel must be strictly controlled. In the present invention, the mass percentage of S is ≤0.008%; preferably, the mass percentage of S is ≤0.007%.

[0016] Nitrogen (N) can form fine AlN to produce magnetic aging. When the N content is too high, bubbles are likely to appear in the steel plate, causing broken bands, and oxygen forms oxide inclusions, which are harmful to the magnetic properties of silicon steel. Therefore, the lower the N content, the better. In the present invention, the mass percentage of N is ≤0.0085%; preferably, the mass percentage of N is ≤0.0070%.

[0017] Furthermore, the mass percentage of Si and P C1=Si+P is 3.25-3.33%.

[0018] Phosphorus is a grain boundary segregation element. Too high a content of phosphorus can deteriorate cold workability and significantly reduce the plasticity and toughness of steel. Silicon can also reduce plasticity and toughness. In order to ensure the plasticity and toughness of steel, it is necessary to reasonably control the total content of Si and P. In the present invention, the mass percentage of Si and P is controlled to be 3.25-3.33%.

[0019] Furthermore, the mass percentage ratio C2=Mn / S is ≥12.

[0020] Manganese and sulfur in steel form manganese sulfide (MnS). Controlling the mass ratio of Mn to S, when Mn / S ≥ 12, can not only prevent hot brittleness during rolling, but also improve the hot rolling plasticity of silicon steel.

[0021] Furthermore, the mass percentage ratio C3=Si / Als is 110-120.

[0022] In the present invention, Al and Si have similar effects, which can improve the resistivity of steel, reduce iron loss, and reduce magnetic induction intensity, but both Al and Si will make the material brittle and affect the hardness of the product, so it is necessary to reasonably control the content of Al and Si. Among them, the mass percentage of Si is controlled to be 3.2-3.3%, and the mass percentage of Als is controlled to be 0.0265-0.0295%. In addition, Al and Si each have certain characteristics, especially Al is beneficial to magnetism, reducing magnetic aging phenomenon, and controlling the mass percentage ratio C3=Si / Als to be 110-120 at the same time can make the product have both good hardness and magnetic induction intensity.

[0023] Furthermore, the mass percentage ratio C4=Sn / (Si+Als) is 0.012-0.017.

[0024] In the present invention, the amount of Sn added is closely related to the content of Si and Al elements in the steel. When the steel contains only Si and Al but no Sn, the brittleness of the strip increases and the strip breaking problem is prone to occur during the cold rolling process. When an appropriate amount of Sn is added and C4=Sn / (Si+Als) is controlled to be 0.012-0.017, the toughness of the material can be improved and the cold rolling performance can be improved.

[0025] In a second aspect, the present invention provides a method for preparing high magnetic induction oriented silicon steel, comprising the following steps:

[0026] Step S1: molten iron pretreatment: desulfurization of the molten iron;

[0027] Step S2: converter smelting: adding the desulfurized molten iron into a converter, introducing nitrogen into the converter, adding aluminum iron for pre-deoxidation at the beginning of smelting, adding lime and ferrosilicon for alloying, and obtaining crude molten steel;

[0028] Step S3: LF furnace refining: adding the crude molten steel into the LF furnace, passing argon gas, fixing oxygen, performing aluminum wire feeding operation, adding lime and aluminum powder, and adding ferrosilicon to adjust the silicon content in the molten steel, stopping passing argon gas, and starting passing nitrogen gas to obtain the first refined molten steel;

[0029] Step S4: RH furnace refining: adding the molten steel obtained by the first refining into the RH furnace and performing refining treatment under vacuum conditions to obtain the molten steel obtained by the second refining;

[0030] Step S5: continuous casting and rolling: adopting the slab continuous casting and rolling production process to prepare high magnetic induction oriented silicon steel from the second refined molten steel.

[0031] Wherein, in step S1, the S content of the molten iron after desulfurization treatment is ≤0.001%.

[0032] The prepared high magnetic induction oriented silicon steel includes the following components in mass percentage: C 0.052-0.062%, Si 3.2-3.3%, Als 0.0265-0.0295%, Mn 0.09-0.12%, P 0.027-0.033%, S≤0.008%, N≤0.0085%, Sn 0.040-0.060%, and the balance is Fe and impurities, and the impurity content does not exceed 0.01%.

[0033] Furthermore, the converter smelting comprises the following steps:

[0034] Adding the desulfurized molten iron into a converter, and introducing nitrogen into the converter;

[0035] At the beginning of smelting, 50-80 kg / t of aluminum iron is added for pre-deoxidation. When the smelting time is 1 / 6-1 / 5 of the total smelting time, 300-400 kg / t of lime and 40-42 kg / t of ferrosilicon are added for alloying.

[0036] When the smelting time is 4 / 5 to 5 / 6 of the total smelting time, all the ferrosilicon is added and crude molten steel is obtained.

[0037] Furthermore, the crude molten steel comprises the following components in mass percentage: C≤0.045%, Si: 3.0-3.10%, Mn: residual manganese, P≤0.02%, S≤0.005%, N≤0.030%, Sn: 0.046-0.050%, and the rest is Fe and inevitable impurities. Among them, the content of Mn (residual manganese) does not exceed 0.001%, and the impurity content does not exceed 0.01%.

[0038] Further, the LF furnace refining comprises the following steps:

[0039] The crude molten steel is added into the LF furnace, and after passing argon for 1 to 2 minutes, the bottom blowing pressure is adjusted to 0.1 to 0.2 MPa, the temperature is measured and the oxygen is determined, and the aluminum wire feeding operation is performed according to the oxygen value of the molten steel to make the Als content in the molten steel 0.030 to 0.033%;

[0040] Add 500-600 kg / t of lime, then add aluminum powder to perform white slag operation, and add ferrosilicon to adjust the silicon content in the molten steel to make the Si content in the molten steel 3.00-3.10%; wherein, 0.14 kg / t of ferrosilicon can be added for every 0.01% increase in Si content;

[0041] Stop the argon flow and start the nitrogen flow with a nitrogen flow rate of 500-700NL / min to obtain the first refined molten steel.

[0042] Furthermore, the first refined molten steel comprises the following components in mass percentage: C≤0.05%, Si: 3.0-3.10%, Mn: residual manganese, P≤0.03%, S≤0.005%, Als≤0.029%, Sn: 0.048-0.052%, and the rest is Fe and inevitable impurities. Among them, the content of Mn (residual manganese) does not exceed 0.001%, and the impurity content does not exceed 0.01%.

[0043] Further, the RH furnace refining comprises the following steps:

[0044] The first refined molten steel is added to the RH furnace, and the composition of the molten steel is finely adjusted under vacuum conditions. The lifting gas is argon gas with a flow rate of 800-1400Nl / min. After the vacuum is stable, the lifting gas is switched to nitrogen for nitrogen adjustment. After the nitrogen adjustment is completed, the lifting gas is switched to argon gas again, and the composition of the molten steel is adjusted to obtain the second refined molten steel. The composition of the molten steel is adjusted by adding ferrosilicon, ferromanganese, ferrotin and other components.

[0045] Furthermore, the second refined molten steel comprises the following components in mass percentage: C 0.052-0.062%, Si 3.2-3.3%, Als 0.0265-0.0295%, Mn 0.09-0.12%, P 0.027-0.033%, S≤0.008%, N≤0.0085%, Sn 0.040-0.060%, and the remainder is Fe and impurities, wherein the impurity content does not exceed 0.01%.

[0046] Furthermore, the continuous casting and rolling comprises the following steps:

[0047] The molten steel refined for the second time is subjected to a continuous casting process, a finishing process, a steel rolling process, a normalizing process, a cold rolling process, and an annealing process to prepare high magnetic induction oriented silicon steel.

[0048] Furthermore, in the continuous casting process, the continuous casting speed is 0.9 to 1.0 m / min.

[0049] Furthermore, in the finishing process, the temperature of the ingot entering the heating furnace is ≥350°C, preferably, the temperature of the ingot entering the heating furnace is ≥500°C.

[0050] Furthermore, in the steel rolling process, the edge temperature of the ingot entering the furnace is ≥500°C, the time in the furnace is ≥160min, and the out-of-furnace temperature is 1080-1120°C; the temperature of the first heating section is 950-1000°C, the temperature of the second heating section is 1050-1080°C, the temperature of the third heating section is 1140-1160°C, and the temperature of the soaking section is 1150-1170°C; the R5 temperature is 1000±20°C, the finishing rolling temperature is 990±20°C, the final rolling temperature is 900±15°C, and the coiling temperature is 580±15°C.

[0051] Furthermore, the annealing process includes a heating section, a soaking section and a cooling section; the heating rate of the heating section is 35-45°C / s, and the unit tension of the heating section and the soaking section is 3.0-4.0N / mm 2 .

[0052] The present invention has the following beneficial effects:

[0053] The high magnetic induction oriented silicon steel of the present invention reasonably adjusts the contents of elements such as Si, Als, Mn, and P, strictly controls the contents of Fe and impurities, and reasonably adds the alloy element Sn, improves the resistivity of silicon steel and the strength of finished products, and can also improve the corrosion resistance of silicon steel. At the same time, Sn can improve the room temperature toughness of high-grade silicon steel, thereby improving the rollability of high-grade silicon steel, solving the problem of cold-rolled broken strips of high-grade oriented silicon steel, and the silicon content of high-grade oriented silicon steel can be further increased, and the iron loss of finished products is further reduced. The present invention not only reasonably controls the content of each element, but also optimizes the parameters of key process control points of steelmaking and steel rolling, so that the high magnetic induction oriented silicon steel has no broken strips and has the performance of high magnetic induction and low iron loss to meet user requirements. DETAILED DESCRIPTION

[0054] The experimental methods in the following examples of the present invention without specifying specific conditions are usually carried out under conventional conditions. Various commonly used chemical reagents used in the examples are all commercially available products.

[0055] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0056] The terms "including" and "having" and any variations thereof of the present invention are intended to cover non-exclusive inclusions. For example, a process, method, device, product or equipment comprising a series of steps is not limited to the listed steps or modules, but may optionally include steps not listed, or may optionally include other steps inherent to these processes, methods, products or equipment.

[0057] The term "multiple" in the present invention refers to two or more than two. "Or / and" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A or / and B can represent: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0058] The specific technical scheme of the present invention is described in detail below in conjunction with specific embodiments 1 to 5.

[0059] Example 1

[0060] This embodiment provides a method for producing oriented silicon steel, comprising the following steps:

[0061] (1) Hot metal pretreatment: The hot metal is desulfurized, wherein the sulfur content of the hot metal is ≤ 0.001%;

[0062] (2) Converter smelting: Add the desulfurized molten iron into the converter, and introduce nitrogen into the converter; at the beginning of smelting, add 60 kg / t of ferroaluminum for pre-deoxidation; when the smelting time is 1 / 5 of the total smelting time, add 350 kg / t of lime and 40 kg / t of ferrosilicon for alloying; when the smelting time is 4 / 5 of the total smelting time, all the ferrosilicon is added to obtain crude molten steel;

[0063] (3) LF furnace refining: the crude molten steel is added into the LF furnace, argon is introduced for 1 min, the bottom blowing pressure is adjusted to 0.2 MPa, the temperature is measured, the oxygen is determined, and the aluminum wire is fed according to the oxygen value of the molten steel to make the Als content in the molten steel 0.033%;

[0064] Add 500 kg / t of lime, then add aluminum powder to perform white slag operation, and add ferrosilicon to adjust the silicon content in the molten steel to 3.10%; wherein, 0.14 kg / t of ferrosilicon can be added for every 0.01% increase in Si content;

[0065] Stop passing argon gas and start passing nitrogen gas at a nitrogen flow rate of 600 NL / min to obtain the first refined molten steel;

[0066] Among them, the inlet temperature of the LF refining furnace continuous casting is 1570-1595℃, the ladle temperature is 1600-1610℃; the nitrogen content of molten steel is 60-80ppm;

[0067] (4) RH furnace refining: The molten steel from the first refining is added to the RH furnace, and the composition of the molten steel is finely adjusted under vacuum conditions. The lifting gas is argon gas with a flow rate of 800-1200 Nl / min. After the vacuum is stable, the lifting gas is switched to nitrogen for nitrogen adjustment. After the nitrogen adjustment is completed, the lifting gas is switched to argon gas again, and ferrosilicon, ferromanganese, and ferrotin are added to adjust the composition of the molten steel to obtain the second refined molten steel;

[0068] (5) Continuous casting and rolling: The molten steel obtained from the second refining is subjected to a continuous casting process, a finishing process, a steel rolling process, a normalizing process, a cold rolling process, and an annealing process to prepare high magnetic induction oriented silicon steel;

[0069] Among them, the continuous casting billet heating temperature is 1160℃, and the heating time is 190min;

[0070] After rough rolling and finish rolling of the continuous casting billet, the thickness of the hot rolled strip product is 2.2mm, the hot rolling final rolling temperature is 850℃, the coiling temperature is 630℃, and the convexity C40 of the hot rolled product is controlled at 25±5μm;

[0071] The normalizing annealing temperature is 910℃, the soaking time is 120s, and the average grain size after normalizing is 95μm;

[0072] Cold rolling adopts five-stand continuous rolling, the thickness of the rolled product is 0.25mm, and the reduction rate of each pass is controlled at 30-40%;

[0073] The unit tension of the annealing heating section and the soaking section is controlled at 4.0N / mm 2 The annealing heating rate is controlled at 30℃ / s, the annealing soaking temperature is 1000℃, the soaking time is 60s, and in order to reduce the internal stress generated during the cooling process, the cooling rate is controlled within 5℃ / s. Pure N2 protection is used during the annealing process, and the dew point is controlled at -20℃.

[0074] The composition of the high magnetic induction oriented silicon steel of Example 1 is shown in Table 1.

[0075] Example 2

[0076] This embodiment provides a method for producing oriented silicon steel, comprising the following steps:

[0077] (1) Hot metal pretreatment: The hot metal is desulfurized, wherein the sulfur content of the hot metal is ≤ 0.001%;

[0078] (2) Converter smelting: Add the desulfurized molten iron into the converter, and introduce nitrogen into the converter; at the beginning of smelting, add 50 kg / t of ferroaluminum for pre-deoxidation; when the smelting time is 1 / 6 of the total smelting time, add 300 kg / t of lime and 41 kg / t of ferrosilicon for alloying; when the smelting time is 5 / 6 of the total smelting time, all the ferrosilicon is added to obtain crude molten steel;

[0079] (3) LF furnace refining: the crude molten steel is added into the LF furnace, argon is introduced for 2 minutes, the bottom blowing pressure is adjusted to 0.15 MPa, the temperature is measured, the oxygen is determined, and the aluminum wire is fed according to the oxygen value of the molten steel to make the Als content in the molten steel 0.031%;

[0080] Add 600 kg / t of lime, then add aluminum powder to perform white slag operation, and add ferrosilicon to adjust the silicon content in the molten steel to 3.00%; wherein, 0.14 kg / t of ferrosilicon can be added for every 0.01% increase in Si content;

[0081] Stop passing argon and start passing nitrogen at a nitrogen flow rate of 500 NL / min to obtain the first refined molten steel;

[0082] Among them, the inlet temperature of the LF refining furnace continuous casting is 1565-1590℃, the ladle temperature is 1595-1615℃; the nitrogen content of molten steel is 65-75ppm;

[0083] (4) RH furnace refining: The molten steel from the first refining is added to the RH furnace, and the composition of the molten steel is finely adjusted under vacuum conditions. The lifting gas is argon gas with a flow rate of 1000-1200 Nl / min. After the vacuum is stable, the lifting gas is switched to nitrogen for nitrogen adjustment. After the nitrogen adjustment is completed, the lifting gas is switched to argon gas again, and ferrosilicon, ferromanganese, and ferrotin are added to adjust the composition of the molten steel to obtain the second refined molten steel;

[0084] (5) Continuous casting and rolling: The molten steel obtained from the second refining is subjected to a continuous casting process, a finishing process, a steel rolling process, a normalizing process, a cold rolling process, and an annealing process to prepare high magnetic induction oriented silicon steel;

[0085] Among them, the continuous casting billet heating temperature is 1160℃, and the heating time is 200min;

[0086] After rough rolling and finish rolling of the continuous casting billet, the thickness of the hot rolled strip product is 2.0mm, the hot rolling final rolling temperature is 845℃, the coiling temperature is 620℃, and the convexity C40 of the hot rolled product is controlled at 25±5μm;

[0087] The normalizing annealing temperature is 915℃, the soaking time is 120s, and the average grain size after normalizing is 96μm;

[0088] Cold rolling adopts five-stand continuous rolling, the thickness of the rolled product is 0.30mm, and the reduction rate of each pass is controlled at 25-40%;

[0089] The unit tension of the annealing heating section and the soaking section is controlled at 3.5N / mm 2 The annealing heating rate is controlled at 25℃ / s, the annealing soaking temperature is 1000℃, the soaking time is 60s, and in order to reduce the internal stress generated during the cooling process, the cooling rate is controlled within 5℃ / s. Pure N2 protection is used during the annealing process, and the dew point is controlled at -20℃.

[0090] The composition of the high magnetic induction oriented silicon steel of Example 2 is shown in Table 1.

[0091] Example 3

[0092] This embodiment provides a method for producing oriented silicon steel, comprising the following steps:

[0093] (1) Hot metal pretreatment: The hot metal is desulfurized, wherein the sulfur content of the hot metal is ≤ 0.001%;

[0094] (2) Converter smelting: Add the desulfurized molten iron into the converter, and introduce nitrogen into the converter; at the beginning of smelting, add 80 kg / t of ferroaluminum for pre-deoxidation; when the smelting time is 1 / 5 of the total smelting time, add 400 kg / t of lime and 42 kg / t of ferrosilicon for alloying; when the smelting time is 4 / 5 of the total smelting time, all the ferrosilicon is added to obtain crude molten steel;

[0095] (3) LF furnace refining: the crude molten steel is added into the LF furnace, argon is introduced for 2 minutes, the bottom blowing pressure is adjusted to 0.1 MPa, the temperature is measured, the oxygen is determined, and the aluminum wire is fed according to the oxygen value of the molten steel to make the Als content in the molten steel 0.030%;

[0096] Add 500 kg / t of lime, then add aluminum powder to perform white slag operation, and add ferrosilicon to adjust the silicon content in the molten steel to 3.10%; wherein, 0.14 kg / t of ferrosilicon can be added for every 0.01% increase in Si content;

[0097] Stop passing argon and start passing nitrogen at a nitrogen flow rate of 700 NL / min to obtain the first refined molten steel;

[0098] Among them, the inlet temperature of the LF refining furnace continuous casting is 1575-1590℃, the ladle temperature is 1600-1620℃; the nitrogen content of molten steel is 65-75ppm;

[0099] (4) RH furnace refining: The molten steel from the first refining is added to the RH furnace, and the composition of the molten steel is finely adjusted under vacuum conditions. The lifting gas is argon gas with a flow rate of 800-1400 Nl / min. After the vacuum is stable, the lifting gas is switched to nitrogen for nitrogen adjustment. After the nitrogen adjustment is completed, the lifting gas is switched to argon gas again, and ferrosilicon, ferromanganese, and ferrotin are added to adjust the composition of the molten steel to obtain the second refined molten steel;

[0100] (5) Continuous casting and rolling: The molten steel obtained from the second refining is subjected to a continuous casting process, a finishing process, a steel rolling process, a normalizing process, a cold rolling process, and an annealing process to prepare high magnetic induction oriented silicon steel;

[0101] Among them, the continuous casting billet heating temperature is 1170℃, and the heating time is 190min;

[0102] After rough rolling and finish rolling of the continuous casting billet, the thickness of the hot rolled strip product is 1.9mm, the hot rolling final rolling temperature is 850℃, the coiling temperature is 600℃, and the convexity C40 of the hot rolled product is controlled at 25±5μm;

[0103] The normalizing annealing temperature is 890℃, the annealing time is 130s, and the average grain size after normalizing is 97μm;

[0104] Cold rolling adopts five-stand continuous rolling, the thickness of the rolled product is 0.18mm, and the reduction rate of each pass is controlled at 20-30%;

[0105] The unit tension of the annealing heating section and the soaking section is controlled at 4.2N / mm 2 The annealing heating rate was controlled at 28℃ / s. The annealing temperature was 1000℃ and the annealing time was 60s. In order to reduce the internal stress generated during the cooling process, the cooling rate was controlled within 5℃ / s. Pure N was used during the annealing process. 2 Protection, dew point controlled at -20℃.

[0106] The composition of the high magnetic induction oriented silicon steel of Example 3 is shown in Table 1.

[0107] Example 4

[0108] This embodiment provides a method for producing oriented silicon steel, comprising the following steps:

[0109] (1) Hot metal pretreatment: The hot metal is desulfurized, wherein the sulfur content of the hot metal is ≤ 0.001%;

[0110] (2) Converter smelting: Add the desulfurized molten iron into the converter, and introduce nitrogen into the converter; at the beginning of smelting, add 60 kg / t of ferroaluminum for pre-deoxidation; when the smelting time is 1 / 5 of the total smelting time, add 350 kg / t of lime and 41 kg / t of ferrosilicon for alloying; when the smelting time is 4 / 5 of the total smelting time, all the ferrosilicon is added to obtain crude molten steel;

[0111] (3) LF furnace refining: the crude molten steel is added into the LF furnace, argon is introduced for 1 to 2 minutes, the bottom blowing pressure is adjusted to 0.15 MPa, the temperature is measured, the oxygen is determined, and the aluminum wire is fed according to the oxygen value of the molten steel to make the Als content in the molten steel 0.032%;

[0112] Add 550 kg / t of lime, then add aluminum powder to perform white slag operation, and add ferrosilicon to adjust the silicon content in the molten steel to 3.10%; wherein, 0.14 kg / t of ferrosilicon can be added for every 0.01% increase in Si content;

[0113] Stop passing argon gas and start passing nitrogen gas at a nitrogen flow rate of 600 NL / min to obtain the first refined molten steel;

[0114] Among them, the inlet temperature of the LF refining furnace continuous casting is 1580-1595℃, the ladle temperature is 1590-1600℃; the nitrogen content of molten steel is 60-70ppm;

[0115] (4) RH furnace refining: The molten steel from the first refining is added to the RH furnace, and the composition of the molten steel is finely adjusted under vacuum conditions. The lifting gas is argon gas with a flow rate of 800-1400 Nl / min. After the vacuum is stable, the lifting gas is switched to nitrogen for nitrogen adjustment. After the nitrogen adjustment is completed, the lifting gas is switched to argon gas again, and ferrosilicon, ferromanganese, and ferrotin are added to adjust the composition of the molten steel to obtain the second refined molten steel;

[0116] (5) Continuous casting and rolling: The molten steel obtained from the second refining is subjected to a continuous casting process, a finishing process, a steel rolling process, a normalizing process, a cold rolling process, and an annealing process to prepare high magnetic induction oriented silicon steel;

[0117] Among them, the continuous casting billet heating temperature is 1190℃, and the heating time is 200min;

[0118] After rough rolling and finish rolling of the continuous casting billet, the thickness of the hot rolled strip product is 2.0mm, the hot rolling final rolling temperature is 850℃, the coiling temperature is 625℃, and the convexity C40 of the hot rolled product is controlled at 25±5μm;

[0119] The normalizing annealing soaking temperature is 895℃, the soaking time is 120s, and the average grain size after normalizing is 98μm;

[0120] Cold rolling adopts five-stand continuous rolling, the thickness of the rolled product is 0.21mm, and the reduction rate of each pass is controlled at 25-35%;

[0121] The unit tension of the annealing heating section and the soaking section is controlled at 4.0N / mm 2 The annealing heating rate is controlled at 30℃ / s. The annealing soaking temperature is 1000℃, the soaking time is 60s, and the cooling rate is controlled within 5℃ / s to reduce the internal stress generated during the cooling process. Pure N2 protection is used during the annealing process, and the dew point is controlled at -20℃.

[0122] The composition of the high magnetic induction oriented silicon steel of Example 4 is shown in Table 1.

[0123] Example 5

[0124] This embodiment provides a method for producing oriented silicon steel, comprising the following steps:

[0125] (1) Hot metal pretreatment: The hot metal is desulfurized, wherein the sulfur content of the hot metal is ≤ 0.001%;

[0126] (2) Converter smelting: Add the desulfurized molten iron into the converter, and introduce nitrogen into the converter; at the beginning of smelting, add 70 kg / t of ferroaluminum for pre-deoxidation; when the smelting time is 1 / 6 of the total smelting time, add 300 kg / t of lime and 42 kg / t of ferrosilicon for alloying; when the smelting time is 4 / 5 of the total smelting time, all the ferrosilicon is added to obtain crude molten steel;

[0127] (3) LF furnace refining: the crude molten steel is added into the LF furnace, argon is introduced for 2 minutes, the bottom blowing pressure is adjusted to 0.2 MPa, the temperature is measured, the oxygen is determined, and the aluminum wire is fed according to the oxygen value of the molten steel to make the Als content in the molten steel 0.030%;

[0128] Add 550 kg / t of lime, then add aluminum powder to perform white slag operation, and add ferrosilicon to adjust the silicon content in the molten steel to 3.05%; wherein, 0.14 kg / t of ferrosilicon can be added for every 0.01% increase in Si content;

[0129] Stop passing argon and start passing nitrogen at a nitrogen flow rate of 500 NL / min to obtain the first refined molten steel;

[0130] Among them, the inlet temperature of the LF refining furnace continuous casting is 1580-1595℃, the ladle temperature is 1590-1620℃; the nitrogen content of molten steel is 60-80ppm;

[0131] (4) RH furnace refining: The molten steel from the first refining is added to the RH furnace, and the composition of the molten steel is finely adjusted under vacuum conditions. The lifting gas is argon gas with a flow rate of 1200-1400 Nl / min. After the vacuum is stable, the lifting gas is switched to nitrogen for nitrogen adjustment. After the nitrogen adjustment is completed, the lifting gas is switched to argon gas again, and ferrosilicon, ferromanganese, and ferrotin are added to adjust the composition of the molten steel to obtain the second refined molten steel;

[0132] (5) Continuous casting and rolling: The molten steel obtained from the second refining is subjected to a continuous casting process, a finishing process, a steel rolling process, a normalizing process, a cold rolling process, and an annealing process to prepare high magnetic induction oriented silicon steel;

[0133] Among them, the continuous casting billet heating temperature is 1200℃ and the heating time is 220min;

[0134] After rough rolling and finish rolling of the continuous casting billet, the thickness of the hot rolled strip product is 1.6mm, the hot rolling final rolling temperature is 840℃, the coiling temperature is 600℃, and the convexity C40 of the hot rolled product is controlled at 25±5μm;

[0135] The normalizing annealing soaking temperature is 905℃, the soaking time is 120s, and the average grain size after normalizing is 95μm;

[0136] Cold rolling adopts five-stand continuous rolling, the thickness of the rolled product is 0.16mm, and the reduction rate of each pass is controlled at 20-40%;

[0137] The unit tension of the annealing heating section and the soaking section is controlled at 3.8N / mm 2 The annealing heating rate is controlled at 26℃ / s, the annealing soaking temperature is 1000℃, the soaking time is 60s, and in order to reduce the internal stress generated during the cooling process, the cooling rate is controlled within 5℃ / s. Pure N2 protection is used during the annealing process, and the dew point is controlled at -20℃.

[0138] The composition of the high magnetic induction oriented silicon steel of Example 5 is shown in Table 1.

[0139] Comparative Example 1

[0140] Comparative Example 1 was prepared by referring to the preparation method of Example 4, except that during step (4) RH furnace refining, tin iron was not added to adjust the tin content in the molten steel in Comparative Example 1, and the other steps were the same as those of Example 4. The composition of the silicon steel of Comparative Example 1 is shown in Table 1.

[0141] Comparative Example 2

[0142] Comparative Example 2 was prepared by referring to the preparation method of Example 4, except that a large amount of tin iron was added to adjust the tin content in the molten steel during step (4) RH furnace refining in Comparative Example 2, and the other steps were the same as those of Example 4. The composition of the silicon steel of Comparative Example 2 is shown in Table 1.

[0143] Table 1

[0144]

[0145] The silicon steel products of Examples 1 to 5 and Comparative Examples 1 to 2 were subjected to performance tests, and the test results are shown in Table 2.

[0146] Table 2

[0147] Iron loss (W / kg) Magnetic induction (T) Impact performance(J) Belt breakage rate (%) Example 1 5.35 1.91 21.6 3％ Example 2 5.23 1.92 23.4 2％ Example 3 5.22 1.95 25.2 2％ Example 4 5.28 1.91 22.3 3％ Example 5 5.41 1.95 24.8 2％ Comparative Example 1 6.35 1.88 19.2 15％ Comparative Example 2 5.89 1.89 18.7 35％

[0148] It can be seen from the performance test results in Table 2 that compared with Comparative Example 1, the magnetic induction loss of the high magnetic induction oriented silicon steel of Examples 1 to 5 of the present invention is not large, but the iron loss is significantly reduced, and the impact performance is slightly higher, and the broken belt rate is lower. This is because the appropriate addition of Sn elements can effectively improve the cold rolling rollability. Due to the improved rollability, the normalizing temperature is also increased, the iron loss of the finished product is greatly reduced, and the magnetic properties are further improved. Compared with Comparative Example 2, although the high magnetic induction oriented silicon steel of Examples 1 to 5 of the present invention has considerable magnetic properties, the broken belt rate is greatly reduced. This is because the silicon steel of Comparative Example 2 contains 0.8wt.% Sn, and the Sn content is too much. It is easy to form an ordered phase of Fe-Si-Sn during the normalizing process. The formation of the ordered phase will increase the brittleness of the strip after normalizing and increase the broken belt rate during the cold rolling process. It can be seen that the high magnetic induction oriented silicon steels of Examples 1 to 5 of the present invention are made without broken strips and have the properties of high magnetic induction, low iron loss and high strength by reasonably adding Sn elements and controlling the Sn elements within the range of 0.040% to 0.060%, and reasonably adjusting the contents of elements such as Si, Als, Mn and P, while strictly controlling the contents of Fe and impurities, and optimizing the parameters of key process control points of steelmaking and rolling. This meets user requirements.

[0149] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0150] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A high magnetic induction oriented silicon steel, characterized in that: The following components are included in mass percentage: The balance is Fe and impurities; The mass percentage ratio C4=Sn / (Si+Als) is 0.0122 to 0.017; A method for preparing high magnetic induction oriented silicon steel comprises the following steps: Hot metal pretreatment: Desulfurization of hot metal; Converter smelting: adding the desulfurized molten iron into a converter, introducing nitrogen into the converter, adding aluminum iron for pre-deoxidation at the beginning of smelting, adding lime and ferrosilicon for alloying, and obtaining crude molten steel; LF furnace refining: adding the crude molten steel into the LF furnace, introducing argon for 1-2 minutes, adjusting the bottom blowing pressure to 0.1-0.2MPa, measuring temperature and determining oxygen, feeding aluminum wire operation according to the determined oxygen value of the molten steel, so that the Als content in the molten steel is 0.030-0.033%; Add 500-600 kg / t of lime, then add aluminum powder to perform white slag operation, and add ferrosilicon to adjust the silicon content in the molten steel to make the Si content in the molten steel 3.00-3.10%; Stop passing argon and start passing nitrogen at a nitrogen flow rate of 500-700 NL / min to obtain the first refined molten steel; RH furnace refining: adding the molten steel obtained by the first refining into the RH furnace, and fine-tuning the composition of the molten steel under vacuum conditions, using argon gas with a flow rate of 800-1200Nl / min as the lifting gas, switching the lifting gas to nitrogen for nitrogen adjustment after the vacuum is stable, and switching the lifting gas to argon gas again after the nitrogen adjustment is completed, and adjusting the composition of the molten steel to obtain the second refined molten steel; Continuous casting and rolling: The slab continuous casting and rolling production process is adopted to prepare high magnetic induction oriented silicon steel from the second refined molten steel.

2. The high magnetic induction oriented silicon steel according to claim 1, characterized in that: The mass percentage of Si and P C1=Si+P is 3.25-3.33%.

3. The high magnetic induction oriented silicon steel according to claim 1, characterized in that: The mass percentage ratio C2=Mn / S is ≥12.

4. The high magnetic induction oriented silicon steel according to claim 1, characterized in that: The mass percentage ratio C3=Si / Als is 110-120.

5. The method for preparing high magnetic induction oriented silicon steel according to claim 1, characterized in that: The converter smelting comprises the following steps: Adding the desulfurized molten iron into a converter, and introducing nitrogen into the converter; At the beginning of smelting, 50-80 kg / t of aluminum iron is added for pre-deoxidation. When the smelting time is 1 / 6-1 / 5 of the total smelting time, 300-400 kg / t of lime and 40-42 kg / t of ferrosilicon are added for alloying. When the smelting time is 4 / 5 to 5 / 6 of the total smelting time, all the ferrosilicon is added and crude molten steel is obtained.

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