A low-cost non-oriented silicon steel and an efficient production method thereof

Abstract

The present invention discloses a low-cost non-oriented silicon steel and an efficient production method thereof, and belongs to the field of non-oriented silicon steel production. The low-cost non-oriented silicon steel of the present invention, the chemical composition of the slab is calculated by weight percentage: C≤0.005%, Si: 0.3~1.9%, Mn: 0.1~0.3%, Als≤0.7%, B: 0.001~0.01%, P: 0.001~0.01%, S≤0.005%, N≤0.005%, Ti≤0.005%, wherein to prevent corrugated defects, Si, Al, P, B elements should satisfy: exp{0.6(Si+Al)‑4.7}≤(P+10B), and the rest are Fe and unavoidable impurities. Through the optimization of hot rolling process, normalized production is cancelled, the non-oriented silicon steel production process is shortened, and the efficient production of the continuous annealing unit is coordinated, while shortening the total production time, the production capacity is greatly improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of non-oriented silicon steel production, and more specifically, relates to a low-cost non-oriented silicon steel and an efficient production method thereof. Background Art

[0002] Silicon steel is the raw material for producing various rotating motors, transformers, generators, etc. It is an important soft magnetic alloy material in power, electronics, military industry and transportation, and is one of the indispensable raw materials for modernization and people's lives. With the development of non-oriented silicon steel in my country, major breakthroughs have been made in the past decade, especially in production capacity, supply quantity, product structure and technological progress.

[0003] In 2020, my country's total silicon steel production capacity reached 12.76 million tons, which is 181 times that of 1978 when it was first put into production, making an important contribution to my country's and even the world's economic development. With the rapid development of the application field of non-oriented silicon steel, the demand for non-oriented silicon steel is showing a rapid growth trend. In the context of the increasing demand for silicon steel in the future, efficient production has become an important means for domestic and foreign silicon steel manufacturers to quickly increase production capacity.

[0004] At the same time, with the introduction of the "carbon peak and carbon neutrality" policy, low-cost manufacturing has become one of the important means for major manufacturers to achieve green, low-carbon, energy-saving and emission reduction. For cold-rolled non-oriented silicon steel, shortening the production process has become an important way to reduce costs. For current silicon steel manufacturers, shortening the production process mainly means canceling the normalized production process. According to current relevant data at home and abroad, when the Si content of molten steel is ≥1.7%, the coarse and elongated (100) columnar crystals cannot be completely broken and recrystallized to retain the deformed banded structure due to the difficulty of dynamic recovery and recrystallization of the (100) orientation relative to other orientations and the difficulty of γ→α phase transformation during hot rolling. During the cold rolling plastic deformation process, the equiaxed crystals before cold rolling are transformed into flat fibers, and the coarse banded structure remains as a coarse deformation band after cold rolling compression deformation. Due to the difference in performance (deformation resistance) between this coarse banded structure and other fine equiaxed crystals, the plate surface after cold rolling has uneven corrugated defects. The uneven corrugated defects along the rolling direction are more obvious after annealing, affecting the use of downstream users. Therefore, at present, silicon steel manufacturers mainly focus on low grades with Si content less than 1.7% for the grades with higher Si content, and even high grades. How to reduce the risk of surface corrugated defects caused by the cancellation of the normalization production process has become a concern of major manufacturers.

[0005] After searching, in order to reduce production costs, patent CN 113737089 A proposed a low-cost, extremely low-aluminum non-oriented electrical steel sheet, with chemical composition Si of 0.1-1.2%, Mn of 0.1-0.5%, P of 0.01-0.2%, Sn of 0.005-0.05%, ALs ≤ 0.001%, mainly relying on the extremely low aluminum content in steel, and the steel and slag containing a moderate amount of oxidizing technical characteristics, to reduce the RH refining deoxidation, alloying special alloy quality, so as to greatly reduce the manufacturing cost of steel. Although this solution technology does not require normalization and is controlled by extremely low aluminum content, in order to improve the magnetic induction of the product, the alloy Sn element is added. The Sn element is a relatively expensive alloy element, which increases the alloy cost.

[0006] In view of the rapid growth in demand for silicon steel in my country and the background of green and low-carbon manufacturing, the development of non-oriented silicon steel with short development process and low cost, as well as how to quickly increase production capacity, have become the key development directions for silicon steel production companies in the future. Summary of the invention

[0007] 1. Problems to be solved

[0008] The present invention intends to provide a low-cost non-oriented silicon steel and an efficient production method thereof. By optimizing the hot rolling process, normal production is eliminated, the production process of non-oriented silicon steel is shortened, and at the same time, the efficient production of the continuous annealing unit is coordinated to shorten the total production time and greatly increase the production capacity.

[0009] 2. Technical solution

[0010] To solve the above problems, the present invention adopts the following technical solutions.

[0011] The invention discloses a method for efficiently producing low-cost non-oriented silicon steel, which has the advantages of short process, high production efficiency and excellent surface quality, conforms to the manufacturing concept of "green, low-carbon and environmentally friendly", and meets the requirements of efficient production of silicon steel as the demand for silicon steel continues to grow in the future.

[0012] Specifically, the chemical composition of the low-cost non-oriented silicon steel of the present invention is as follows by weight: C≤0.005%, Si: 0.3-1.9%, Mn: 0.1-0.3%, Als≤0.7%, B: 0.001-0.01%, P: 0.001-0.01%, S≤0.005%, N≤0.005%, Ti≤0.005%, wherein in order to prevent corrugated defects, Si, Al, P, and B elements should satisfy: exp{0.6(Si+Al)-4.7}≤(P+10B), and the rest are Fe and unavoidable impurities.

[0013] The role of each element in steel is as follows:

[0014] C: Although the C element can improve the mechanical properties, it is a harmful element for non-oriented silicon steel and will deteriorate the magnetic properties of silicon steel. The present invention belongs to a medium-low non-oriented silicon steel product, and the C content is not more than 0.005%.

[0015] Si: Si element can improve resistivity, reduce product iron loss, and reduce the γ phase region. When Si ≥ 1.9%, partial phase change or no phase change is very likely to occur during the hot rolling process, resulting in difficulty in refining columnar crystals in the slab and increasing the risk of corrugated defects in the finished product. The upper limit of Si content control in the present invention is 1.9%, while ensuring the magnetic properties of the product, the Si content is ≥ 0.3%.

[0016] Mn: Mn and S elements form MnS, which reduces the S dissolved in the slab during heating and can effectively suppress the hot brittleness during heating. However, if the Mn content is too high, fine MnS precipitates will be produced during hot rolling, which will prevent the grains from growing and deteriorate the magnetic properties. In the present invention, the Mn / S content ratio should be controlled within the range of 20 to 60. Considering that the S content is ≤0.005%, the purpose can be achieved when the Mn content is greater than 0.15%. Therefore, the Mn content in the present invention is controlled within the range of 0.1% to 0.30%.

[0017] P: In silicon steel, the P element can increase the resistivity ρ, reduce the γ phase area, increase the strain energy in the ferrite grains during hot rolling, promote dynamic recrystallization, make the grains grow, and can increase the favorable texture components and reduce the unfavorable texture components; however, the P element has a grain boundary segregation effect, which can easily cause embrittlement. A P content exceeding 0.10% will significantly deteriorate the processability. Therefore, the P content should not be too high. The P content of the present invention needs to be controlled at 0.001% to 0.10%.

[0018] Als: Al is similar to Si and can improve the magnetic properties of the product. Considering the control range of Si content in the product, Als in the present invention is less than 0.7%.

[0019] B: B element and N element form BN, as well as B compounds, which can promote the refinement of ferrite grains, narrow the width of ferrite grains in the central area of ​​the strip thickness direction, reduce the non-recrystallized area, and reduce the risk of corrugated defects.

[0020] S, N, Ti: S, N, and Ti are harmful elements. In order to reduce the impact on the magnetic properties of the product, the S content is ≤0.005%, the N content is ≤0.005%, and the Ti content is ≤0.005%.

[0021] The above-mentioned low-cost and efficient production method of non-oriented silicon steel of the present invention specifically comprises the following process:

[0022] S1. Molten steel is continuously cast into a slab with a thickness of 200 to 260 mm. "Low-temperature casting" can prevent the formation of coarse columnar crystals in the center of the ingot, increase the proportion of equiaxed crystals, and reduce the appearance of corrugated defects in the finished product. The present invention requires "low-temperature casting" in the casting process, and the casting temperature is required to be ≤1530°C. At the same time, "electromagnetic stirring" is used during continuous casting. Electromagnetic stirring can significantly reduce the columnar crystals in the ingot and increase the equiaxed crystals, ensuring that the proportion of equiaxed crystals in the ingot is greater than 65%, which can further reduce the corrugated defects on the surface of the finished plate.

[0023] S2. Directly load the continuous casting slabs meeting the above requirements into the heating furnace for heating. The temperature of the heating furnace is controlled at 1150-1250°C. In order to minimize the production time and improve the production efficiency, the slabs can be heated evenly. It is required that the total heating time is not more than 210 minutes under the condition that the center temperature of the slab reaches the temperature of the heating furnace;

[0024] S3, hot rolling the slab at high temperature. To ensure the "high temperature final rolling" of the hot-rolled plate, the temperature of the slab after rough rolling is required to be not less than 940°C, and hot rolling is performed for 7 passes to a hot-rolled plate with a thickness of 2.2-2.6 mm. Considering that the present invention does not undergo a normalizing process, "high temperature curling" is required. To ensure that the temperature of the strip before hot rolling curling meets the requirements of the present invention, a heat preservation cover is used to keep the temperature in the rough rolling to final rolling section. To ensure the high temperature requirement before the strip curling, the final rolling temperature is required to be controlled at 860-920°C.

[0025] S4. Considering that the post-process of the present invention does not use a normalizing process, hot rolling curling requires "high-temperature curling". High-temperature curling can make the grains of the hot-rolled plate grow, the structure is more uniform, and the corrugated defects are prevented; at the same time, high-temperature curling can weaken the {111} and {112} components of the finished product, enhance the {100} and {110} components, and improve the magnetic properties of the product, especially improve the magnetic induction, and make up for the reduction in magnetic induction caused by the lack of normalization. In order to ensure that the hot-rolled curling is performed at a higher temperature, the hot-rolled plate is directly high-temperature curled without laminar cooling after the final rolling, and the strip is insulated with a heat preservation cover before curling. If necessary, the strip can be heated by a high-frequency rapid heating method to ensure that the strip temperature before curling is greater than 800°C, and to ensure that the hot-rolled strip structure of the hot-rolled plate is recrystallized after curling.

[0026] S5. Considering the "high temperature curling" adopted in the present invention, and the fact that water spraying is not used for dephosphorization during hot rolling, the strip surface has a lot of iron oxide scale at high temperature. The strip is shot blasted + pickled before cold rolling. The pickling liquid is HCl + HF aqueous solution, wherein the volume fraction of hydrochloric acid is 55-60%, the amount of hydrofluoric acid added is 80-100g / L, and the pickling temperature is 75°C to 80°C, to ensure that the strip surface is clean and free of impurities such as iron oxide scale;

[0027] The pickled steel strip is directly cold rolled. Considering the high tension requirement of the steel strip in the furnace adopted by the efficient continuous annealing production method of the present invention, in order to reduce the influence of the steel strip tension on the magnetic properties of the product, the target thickness of the finished product is 0.50-0.65 mm, and the total cold rolling reduction rate is between 70.4% and 80.7%.

[0028] S6. The cold-rolled sheet is continuously annealed in a high-speed continuous annealing furnace. Compared with the "single-pass" operation of the conventional continuous annealing furnace, the present invention adopts a multi-layer "reciprocating" operation of the strip in the high-speed continuous annealing furnace. Specifically, a three-layer "reciprocating" operation can be adopted. Under the condition of ensuring that the strip reaches the time required for recrystallization and grain growth, it has the ability of high-speed production. Specifically, Figure 1 As shown, in the continuous annealing furnace heating section 100 and the continuous annealing furnace soaking section 101, the strip steel 103 is used in cooperation with the carbon sleeve rollers 102, both of which adopt a three-layer reciprocating operation.

[0029] In the present invention, the temperature of the strip in the soaking section of the continuous annealing furnace is 800-930°C. In order to ensure that the strip stays in the soaking section of the continuous annealing furnace for more than 30 seconds required for re-graining and grain growth, according to the current length of the continuous annealing soaking furnace in the industry of 60m-70m, the running speed of the strip in the furnace can reach 250-300m / min, the production efficiency can be increased by 2-3 times, and the hourly production capacity can reach more than 70 tons, significantly improving the production capacity. In order to ensure the high-speed operation stability of the strip, the unit tension of the strip in the furnace is required to be greater than 2KN. At the same time, in order to reduce the deterioration of magnetic anisotropy caused by tension, resulting in an increase in the magnetic anisotropy of the finished product, and to ensure that the magnetic anisotropy of the finished product is less than 10%, the unit tension of the strip is required to be less than 2.5KN, that is, 2.0KN <F / (h×C) <2.5KN, where F is the total tension of the strip, h is the thickness of the strip, and C is the width of the strip. The reducing atmosphere in the furnace adopts H 2 and N 2 Mixed gas, H 2 The volume content is 5-15%. When the C content is greater than 0.0030%, a wet atmosphere with a dew point greater than 15°C is required in the continuous annealing furnace; when the C content is less than 0.0030%, no requirement is made for the dew point in the furnace. After the strip is annealed, the insulating coating is applied by the coating roller and the insulating coating is cured at 380-650°C.

[0030] The non-oriented silicon steel product obtained by the above-mentioned inventive process has low cost, short process and high efficiency compared with the traditional production process, while taking into account the excellent magnetic properties and surface quality of the product, meeting the requirements of "low-carbon" manufacturing and efficient production, and the thickness of the final product is 0.50-0.65mm, and the iron loss P 1.5 / 50 At 2.80~5.5W / kg, B 5000 At 1.71~1.75T, magnetic anisotropy is less than 10%. Among them: iron loss P 1.5 / 50The core loss when the frequency of the alternating magnetic field is 50Hz and the maximum magnetic flux density is 1.5T; the magnetic induction B 5000 is the magnetic flux density under the condition of magnetic field strength of 5000A / m.

[0031] 3. Beneficial effects

[0032] Compared with the prior art, the low-cost and efficient production method of non-oriented silicon steel of the present invention shortens the production process of non-oriented silicon steel by optimizing the hot rolling process. While eliminating the normal production process, the product still has high magnetic properties and no corrugated defects on the surface of the strip. And through the efficient production of the continuous annealing unit, the total production time is shortened and the production capacity is greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the three-layer reciprocating operation state of the strip steel in the continuous annealing furnace of the present invention;

[0034] Figure 2 This is a schematic diagram of the microstructure of a hot-rolled plate with a Si content of 1.4% in the present invention.

[0035] In the figure:

[0036] 100. Heating section of continuous annealing furnace; 101. Soaking section of continuous annealing furnace; 102. Carbon sleeve rollers; 103. Strip steel. DETAILED DESCRIPTION

[0037] The present invention is further described below in conjunction with specific embodiments.

[0038] Example 1

[0039] The high-efficiency production method of low-cost non-oriented silicon steel of this embodiment specifically comprises the following steps:

[0040] S1. The molten steel refined in the RH furnace is continuously cast into a slab with a thickness of 230 mm. The casting temperature is 1530°C. Electromagnetic stirring is used during continuous casting. The chemical compositions of the slab are C: 0.004%; Si: 0.90%; Mn: 0.30%; Als: 0.30%; B: 0.008%; P: 0.001%; ​​S: 0.005%, N: 0.005%, Ti: 0.005%, and the rest are Fe and unavoidable impurity elements.

[0041] S2. The slab is directly loaded into the heating furnace for heating. The temperature of the heating furnace is controlled at 1160°C. To improve production efficiency, the heating and heat preservation time is 200 minutes.

[0042] S3, the rough rolling temperature of the slab is 960℃, the rough rolling to the final rolling section is kept warm with a heat preservation cover, and the hot-rolled plate is finished by 7 hot rolling passes to a thickness of 2.6mm, and the final rolling temperature is controlled at 890℃;

[0043] S4. After the hot rolled plate is finished rolled, it is directly coiled without laminar cooling. Before coiling, the strip is kept warm by a heat preservation cover, and the coiling temperature is 820°C.

[0044] S5. The hot-rolled plate is subjected to shot blasting and pickling before cold rolling. The pickling solution is HCl+HF aqueous solution, wherein the volume fraction of hydrochloric acid is 56%, the amount of hydrofluoric acid added is 80g / L, and the pickling temperature is 75°C. Before cold rolling, ensure that the surface of the strip is clean and free of impurities such as iron oxide scale;

[0045] The pickled steel strip is cold rolled to a target thickness of 0.50 mm, and the total reduction ratio of the cold rolling is 80.7%.

[0046] S6. The cold-rolled sheet is fed into a continuous annealing furnace and continuously annealed in a three-layer reciprocating operation in the furnace. The temperature of the continuous annealing soaking section is 840°C and the continuous annealing speed is 250m / min. To ensure the high-speed running stability of the strip, the unit tension of the strip in the furnace is 2.3KN. The reducing atmosphere in the furnace adopts H 2 and N 2 Mixed gas, H 2 The volume content is 8%, and the continuous annealing furnace adopts a wet atmosphere with a dew point of 20°C. After the strip is annealed, the insulating coating is applied by a coating roller, and the insulating coating is cured at 380-650°C.

[0047] The non-oriented electrical steel manufactured by the above process has an equiaxed crystal ratio of 69% and an iron loss of P 1.5 / 50 4.50W / Kg, magnetic induction B 5000 It is 1.73T, the magnetic anisotropy is 8.5%, and the hourly production capacity of finished products can reach 70.2 tons.

[0048] Example 2

[0049] The high-efficiency production method of low-cost non-oriented silicon steel of this embodiment specifically comprises the following steps:

[0050] S1. The molten steel refined in the RH furnace is continuously cast into a slab with a thickness of 230 mm. The casting temperature is 1530°C. Electromagnetic stirring is used during continuous casting. The chemical composition weight percentages of the slab are C: 0.005%; Si: 0.30%; Mn: 0.20%; Als: 0.20%; B: 0.001%; ​​P: 0.006%; S: 0.004%, N: 0.004%, Ti: 0.004%, and the rest are Fe and unavoidable impurity elements.

[0051] S2, the slab is directly loaded into the heating furnace for heating, and the temperature of the heating furnace is controlled at 1150° C. In order to improve production efficiency, considering the low Si and Al contents in this embodiment, the heating and heat preservation time is 190 min;

[0052] S3, the rough rolling temperature of the slab is 940℃, the rough rolling to the final rolling section is kept warm with a heat preservation cover, and the hot-rolled plate is finished by 7 passes to a thickness of 2.4mm, and the final rolling temperature is controlled at 860℃;

[0053] S4. After the hot rolled plate is finally rolled, it is directly coiled without laminar cooling. Before coiling, the strip is kept warm by a heat preservation cover, and the coiling temperature is 800°C.

[0054] S5. The hot-rolled sheet is subjected to shot blasting and pickling before cold rolling. The pickling solution is HCl+HF aqueous solution, wherein the volume fraction of hydrochloric acid is 55%, the amount of hydrofluoric acid added is 80g / L, and the pickling temperature is 75°C. Before cold rolling, ensure that the surface of the strip is clean and free of impurities such as iron oxide scale;

[0055] The pickled steel strip is cold rolled to a target thickness of 0.50 mm, and the total reduction ratio of the cold rolling is 79.2%.

[0056] S6. The cold-rolled sheet is subjected to continuous annealing in a continuous annealing furnace with a "three-layer reciprocating" continuous annealing temperature of 800°C, a continuous annealing speed of 270m / min, and a unit tension of 2.4KN. The reducing atmosphere in the furnace is H 2 and N 2 Mixed gas, H 2 The volume content is 8%, and the continuous annealing furnace adopts a wet atmosphere with a dew point of 20°C. After the strip is annealed, the insulating coating is applied by a coating roller, and the insulating coating is cured at 380-650°C.

[0057] The non-oriented electrical steel manufactured by the above process has an equiaxed crystal ratio of 71% and an iron loss of P 1.5 / 50 5.60W / Kg, magnetic induction B 5000 It is 1.75T, the magnetic anisotropy is 8.8%, and the hourly production capacity of finished products is 75.8 tons.

[0058] Example 3

[0059] The high-efficiency production method of low-cost non-oriented silicon steel of this embodiment specifically comprises the following steps:

[0060] S1. The molten steel refined in the RH furnace is continuously cast into a slab with a thickness of 200 mm. The casting temperature is 1525°C. Electromagnetic stirring is used during continuous casting. The chemical composition weight percentages of the slab are C: 0.0025%; Si: 1.40%; Mn: 0.10%; Als: 0.70%; B: 0.008%; P: 0.005%; S: 0.003%, N: 0.003%, Ti: 0.003%, and the rest are Fe and unavoidable impurity elements.

[0061] S2, the slab is directly loaded into the heating furnace for heating, the temperature of the heating furnace is controlled at 1180℃, and the heating and holding time is 205min;

[0062] S3, the rough rolling temperature of the slab is 980℃, the rough rolling to the final rolling section is kept warm with a heat preservation cover, and the hot-rolled plate is finished by 7 passes to a thickness of 2.2mm, and the final rolling temperature is controlled at 890℃;

[0063] S4. After the hot rolled plate is finished rolled, it is directly coiled without laminar cooling. Before coiling, the strip is kept warm by a heat preservation cover, and the coiling temperature is 840°C.

[0064] S5. The hot-rolled sheet is subjected to shot blasting and pickling before cold rolling. The pickling solution is HCl+HF aqueous solution, wherein the volume fraction of hydrochloric acid is 55%, the amount of hydrofluoric acid added is 90g / L, and the pickling temperature is 75°C. Before cold rolling, ensure that the surface of the strip is clean and free of impurities such as iron oxide scale;

[0065] The pickled steel strip is cold rolled to a target thickness of 0.65 mm, and the total reduction ratio of the cold rolling is 70.4%.

[0066] S6. The cold-rolled sheet is continuously annealed in a continuous annealing furnace with a multi-layer reciprocating annealing process. The temperature of the continuous annealing section is 870°C, the continuous annealing speed is 260m / min, and the unit tension of the strip in the furnace is 2.3KN. The reducing atmosphere in the furnace is H 2 and N 2 Mixed gas, H 2 The volume content is 15%, and the continuous annealing furnace adopts dry atmosphere. After the strip is annealed, the insulating coating is applied by the coating roller, and the insulating coating is cured at 380-650℃.

[0067] The non-oriented electrical steel manufactured by the above process has an equiaxed grain ratio of 68% and an iron loss of P 1.5 / 50 4.50W / Kg, magnetic induction B 5000 It is 1.72T, the magnetic anisotropy is 8.5%, and the hourly production capacity of finished products is 73 tons.

[0068] Example 4

[0069] The high-efficiency production method of low-cost non-oriented silicon steel of this embodiment specifically comprises the following steps:

[0070] S1. The molten steel refined in the RH furnace is continuously cast into a slab with a thickness of 260 mm. The casting temperature is 1520°C. Electromagnetic stirring is used during continuous casting. The chemical composition weight percentages of the slab are C: 0.002%; Si: 1.70%; Mn: 0.10%; Als: 0.55%; B: 0.007%; P: 0.005%; S: 0.005%, N: 0.003%, Ti: 0.003%, and the rest are Fe and unavoidable impurity elements.

[0071] S2, the slab is directly loaded into the heating furnace for heating. The temperature of the heating furnace is controlled at 1200℃, and the heating and holding time is 210min;

[0072] S3, the rough rolling temperature of the slab is 990℃, the rough rolling to the final rolling section is kept warm with a heat preservation cover, and the hot-rolled plate is finished by 7 hot rolling passes to a thickness of 2.2mm, and the final rolling temperature is controlled at 920℃;

[0073] S4. After the hot rolled plate is finally rolled, it is directly coiled without laminar cooling. Before coiling, the strip is heated by a high-frequency rapid heating method to ensure that the coiling temperature is 860°C.

[0074] S5. The hot-rolled plate is subjected to shot blasting and pickling before cold rolling. The pickling solution is HCl+HF aqueous solution, wherein the volume fraction of hydrochloric acid is 58%, the amount of hydrofluoric acid added is 100g / L, and the pickling temperature is 80°C. Before cold rolling, ensure that the surface of the strip is clean and free of impurities such as iron oxide scale;

[0075] The pickled steel strip is cold rolled to a target thickness of 0.50 mm, and the total reduction ratio of the cold rolling is 77.3%.

[0076] S6. The cold-rolled sheet is subjected to continuous annealing in a continuous annealing furnace with a multi-layer reciprocating annealing process. The temperature of the continuous annealing soaking section is 920°C, the continuous annealing speed is 250m / min, and the unit tension of the strip in the furnace is 2.5KN. The reducing atmosphere in the furnace is H 2 and N 2 Mixed gas, H 2 The volume content is 15%, and the continuous annealing furnace adopts dry atmosphere. After the strip is annealed, the insulating coating is applied by the coating roller, and the insulating coating is cured at 380-650℃.

[0077] The non-oriented electrical steel manufactured by the above process has an equiaxed crystal ratio of 67% and an iron loss of P 1.5 / 50 3.10W / Kg, magnetic induction B 5000 It is 1.71T, the magnetic anisotropy is 9.1%, and the hourly production capacity of finished products is 69 tons.

[0078] Example 5

[0079] The high-efficiency production method of low-cost non-oriented silicon steel of this embodiment specifically comprises the following steps:

[0080] S1. The molten steel refined in the RH furnace is continuously cast into a slab with a thickness of 240 mm. The casting temperature is 1530°C. Electromagnetic stirring is used during continuous casting. The chemical composition weight percentages of the slab are C: 0.0025%; Si: 0.90%; Mn: 0.25%; Als: 0.30%; B: 0.01%; P: 0.005%; S: 0.005%, N: 0.003%, Ti: 0.003%, and the rest are Fe and unavoidable impurity elements.

[0081] S2. The slab is directly loaded into the heating furnace for heating. The temperature of the heating furnace is controlled at 1160°C and the heating and holding time is 200 minutes.

[0082] S3, the rough rolling temperature of the slab is 960℃, the rough rolling to the final rolling section is kept warm with a heat preservation cover, and the hot-rolled plate is finished by 7 hot rolling passes to a thickness of 2.6mm, and the final rolling temperature is controlled at 890℃;

[0083] S4. After the hot rolled plate is finally rolled, it is directly coiled without laminar cooling. Before coiling, a heat preservation cover is used for heat preservation. The coiling temperature is 820°C.

[0084] S5. The hot-rolled sheet is subjected to shot blasting and pickling before cold rolling. The pickling solution is HCl+HF aqueous solution, wherein the volume fraction of hydrochloric acid is 55%, the amount of hydrofluoric acid added is 80g / L, and the pickling temperature is 75°C. Before cold rolling, ensure that the surface of the strip is clean and free of impurities such as iron oxide scale;

[0085] The pickled steel strip is cold rolled to a target thickness of 0.65 mm, and the total reduction ratio of the cold rolling is 75.0%.

[0086] S6. The cold-rolled sheet is continuously annealed in a continuous annealing furnace with a multi-layer reciprocating annealing process. The temperature of the continuous annealing section is 840°C, the continuous annealing speed is 290 m / min, and the unit tension of the strip in the furnace is 2.1 KN. The reducing atmosphere in the furnace is H 2 and N 2 Mixed gas, H 2 The volume content is 10%, and the continuous annealing furnace adopts dry atmosphere. After the strip is annealed, the insulating coating is applied by the coating roller, and the insulating coating is cured at 380-650℃.

[0087] The non-oriented electrical steel manufactured by the above process has an equiaxed crystal ratio of 69% and an iron loss of P 1.5 / 50 4.8W / Kg, magnetic induction B 5000 It is 1.735T, the magnetic anisotropy is 8.3%, and the hourly production capacity of finished products can reach 104 tons.

[0088] Example 6

[0089] The high-efficiency production method of low-cost non-oriented silicon steel of this embodiment specifically comprises the following steps:

[0090] S1. The molten steel refined in the RH furnace is continuously cast into a slab with a thickness of 220 mm. The casting temperature is 1525°C. Electromagnetic stirring is used during continuous casting. The chemical composition weight percentages of the slab are C: 0.0020%; Si: 1.9%; Mn: 0.15%; Als: 0.40%; B: 0.006%; P: 0.01%; S: 0.003%, N: 0.003%, Ti: 0.003%, and the rest are Fe and unavoidable impurity elements.

[0091] S2. The slab is directly loaded into the heating furnace for heating. The temperature of the heating furnace is controlled at 1250°C and the heating and holding time is 210 minutes.

[0092] S3, the rough rolling temperature of the slab is 980℃, the rough rolling to the final rolling section is kept warm with a heat preservation cover, and the hot-rolled plate is finished by 7 passes to a thickness of 2.2mm, and the final rolling temperature is controlled at 920℃;

[0093] S4. After the hot rolled plate is finally rolled, it is directly coiled without laminar cooling. Before coiling, a heat preservation cover is used for heat preservation. The coiling temperature is 860°C.

[0094] S5. The hot-rolled sheet is subjected to shot blasting and pickling before cold rolling. The pickling solution is HCl+HF aqueous solution, wherein the volume fraction of hydrochloric acid is 60%, the amount of hydrofluoric acid added is 100g / L, and the pickling temperature is 78°C. Before cold rolling, ensure that the surface of the strip is clean and free of impurities such as iron oxide scale;

[0095] The pickled strip steel is cold rolled to a target thickness of 0.65 mm, and the total reduction ratio of the cold rolling is 70.45%;

[0096] S6. The cold-rolled sheet is subjected to continuous annealing in a continuous annealing furnace with a multi-layer reciprocating annealing process. The temperature of the continuous annealing section is 930°C, the continuous annealing speed is 300m / min, and the unit tension of the strip in the furnace is 2.0KN. The reducing atmosphere in the furnace is H 2 and N 2 Mixed gas, H 2 The volume content is 10%, and the continuous annealing furnace adopts dry atmosphere. After the strip is annealed, the insulating coating is applied by the coating roller, and the insulating coating is cured at 380-650℃.

[0097] The non-oriented electrical steel manufactured by the above process has an equiaxed grain ratio of 66% and an iron loss of P 1.5 / 50 3.5W / Kg, magnetic induction B 5000 It is 1.73T, the magnetic anisotropy is 8.0%, and the hourly production capacity of finished products can reach 107 tons.

[0098] Comparative Example 1

[0099] A method for producing non-oriented silicon steel in this comparative example specifically comprises the following steps:

[0100] 1) The molten steel refined in the RH furnace is continuously cast into a slab with a thickness of 230 mm at a casting temperature of 1550°C. The chemical compositions of the slab are as follows by weight: C: 0.003%; Si: 2.10%; Mn: 0.30%; Als: 0.75%; P: 0.002%; B: 0.001%; ​​S: 0.003%, N: 0.003%, Ti: 0.003%, and the rest are Fe and unavoidable impurity elements.

[0101] 2) The slab is directly loaded into the heating furnace for heating. The temperature of the heating furnace is controlled at 1180°C and the heating and holding time is 200 minutes;

[0102] 3) The slab is rough-rolled at 960°C, and then hot-rolled for 7 passes to a hot-rolled plate with a thickness of 2.2 mm, and the final rolling temperature is controlled at 860°C;

[0103] 4) After the hot rolled plate is finished rolled, it is laminar cooled and then coiled at a coiling temperature of 800°C;

[0104] 5) The hot-rolled plate is subjected to shot blasting and pickling before cold rolling, wherein the pickling solution is HCl aqueous solution, wherein the volume fraction of hydrochloric acid is 55%, and the pickling temperature is 75° C.;

[0105] 6) cold rolling the pickled steel strip to a target thickness of 0.50 mm;

[0106] 7) The above cold-rolled sheet is continuously annealed in a continuous annealing furnace with a temperature of 940°C in the continuous annealing section and a continuous annealing speed of 250m / min. The unit tension of the strip in the furnace is 2.3KN. The reducing atmosphere in the furnace is H 2 and N 2 Mixed gas, H 2 The volume content is 5%, and a wet atmosphere is used in the continuous annealing furnace. After the strip is annealed, the insulating coating is applied by a coating roller, and the insulating coating is cured at 380-650°C.

[0107] The iron loss P of the finished non-oriented electrical steel manufactured by the above process is 1.5 / 50 2.9W / Kg, magnetic induction B 5000 It is 1.712T and the magnetic anisotropy is 8.5%. Although the product has excellent magnetic properties and high production capacity, the product has serious corrugated defects, which affects the product stacking coefficient and downstream users cannot use it.

[0108] Comparative Example 2

[0109] A method for producing non-oriented silicon steel in this comparative example specifically comprises the following steps:

[0110] 1) The molten steel refined in the RH furnace is continuously cast into a slab with a thickness of 240 mm at a casting temperature of 1530°C. The chemical compositions of the slab are as follows by weight: C: 0.006%; Si: 0.90%; Mn: 0.30%; Als: 0.3%; B: 0.001%; ​​P: 0.01%; S: 0.005%, N: 0.006%, Ti: 0.005%, and the rest are Fe and unavoidable impurity elements.

[0111] 2) The slab is directly loaded into the heating furnace for heating. The temperature of the heating furnace is controlled at 1200℃ and the heating and holding time is 210min;

[0112] 3) The slab is rough-rolled at 960°C, and then hot-rolled for 7 passes to a hot-rolled plate with a thickness of 2.4 mm, and the final rolling temperature is controlled at 870°C;

[0113] 4) After the hot rolled plate is finished rolled, it is laminar cooled and then coiled at a coiling temperature of 820°C;

[0114] 5) The hot-rolled sheet is subjected to shot blasting and pickling before cold rolling. The pickling solution is HCl+HF aqueous solution, wherein the volume fraction of hydrochloric acid is 55%, the amount of hydrofluoric acid added is 80g / L, and the pickling temperature is 75°C. Before cold rolling, the surface of the strip is ensured to be clean and free of impurities such as iron oxide scale;

[0115] 6) cold rolling the pickled steel strip to a target thickness of 0.50 mm;

[0116] 7) The above cold-rolled sheet is continuously annealed in a continuous annealing furnace with a "multi-layer reciprocating" annealing temperature of 840°C and a annealing speed of 250m / min. The unit tension of the strip in the furnace is 2.8KN. The reducing atmosphere in the furnace is H 2 and N 2 Mixed gas, H 2 The volume content is 5%, and the continuous annealing furnace adopts dry atmosphere. After the strip is annealed, the insulating coating is applied by the coating roller, and the insulating coating is cured at 380-650℃.

[0117] The iron loss P of the finished non-oriented electrical steel manufactured by the above process is 1.5 / 50 5.1W / Kg, magnetic induction B 5000 It is 1.718T, and the magnetic anisotropy is 10.1%. Although there is no corrugated defect, the magnetic properties of the product are poor.

[0118] Comparative Example 3

[0119] A method for producing non-oriented silicon steel in this comparative example specifically comprises the following steps:

[0120] 1) The molten steel refined in the RH furnace is continuously cast into a slab with a thickness of 230 mm. No electromagnetic stirring is used during continuous casting. The casting temperature is 1550°C. The chemical compositions of the slab are as follows by weight: C: 0.002%; Si: 1.70%; Mn: 0.15%; Als: 0.55%; B: 0.001%; ​​P: 0.01%; S: 0.005%, N: 0.003%, Ti: 0.003%, and the rest are Fe and unavoidable impurity elements.

[0121] 2) The slab is directly loaded into the heating furnace for heating. The temperature of the heating furnace is controlled at 1200℃ and the heating and holding time is 210min;

[0122] 3) The slab is rough-rolled at 920°C and hot-rolled for 7 passes to a hot-rolled plate with a thickness of 2.2 mm. The final rolling temperature is controlled at 800°C.

[0123] 4) After the hot rolled plate is cooled after final rolling, it is coiled at a coiling temperature of 700°C;

[0124] 5) The hot-rolled plate is shot blasted and pickled before cold rolling, and the pickling solution is HCl+HF aqueous solution, wherein the volume fraction of hydrochloric acid is 58%, the amount of hydrofluoric acid added is 100g / L, and the pickling temperature is 78°C;

[0125] 6) cold rolling the pickled steel strip to a target thickness of 0.50 mm;

[0126] 7) The above cold-rolled sheet is continuously annealed in a "multi-layer reciprocating" continuous annealing furnace, with the temperature of the continuous annealing soaking section at 920°C and the continuous annealing speed at 250m / min. The unit tension of the strip in the furnace is 2.5KN. The reducing atmosphere in the furnace is H 2 and N 2 Mixed gas, H 2 The volume content is 5%, and a wet atmosphere is used in the continuous annealing furnace. After the strip is annealed, the insulating coating is applied by a coating roller, and the insulating coating is cured at 380-650°C.

[0127] The iron loss P of the finished non-oriented electrical steel manufactured by the above process is 1.5 / 50 3.3W / Kg, magnetic induction B 5000 It is 1.71T and the magnetic anisotropy is 9.1%. Although the product has high production capacity, the ingot is not subjected to electromagnetic stirring, and low-temperature final rolling and low-temperature curling are adopted without normalization. The product has poor magnetic properties and heavy surface corrugation, which affects user use.

[0128] Comparative Example 4

[0129] A method for producing non-oriented silicon steel in this comparative example specifically comprises the following steps:

[0130] 1) The molten steel refined in the RH furnace is continuously cast into a slab with a thickness of 230 mm. Electromagnetic stirring is adopted during continuous casting. The casting temperature is 1530°C. The chemical composition percentages by weight of the slab are C: 0.005%; Si: 0.30%; Mn: 0.20%; Als: 0.20%; B: 0.007%; P: 0.006%; S: 0.004%, N: 0.004%, Ti: 0.004%, and the rest are Fe and unavoidable impurity elements.

[0131] 2) The slab is directly loaded into the heating furnace for heating. The temperature of the heating furnace is controlled at 1150°C and the heating and holding time is 190 minutes;

[0132] 3) The slab is rough-rolled at 940°C and hot-rolled for 7 passes to a hot-rolled plate with a thickness of 2.4 mm. The final rolling temperature is controlled at 860°C.

[0133] 4) After the hot rolled plate is finally rolled and cooled, it is coiled at a coiling temperature of 800°C;

[0134] 5) The hot-rolled plate is subjected to shot blasting and pickling before cold rolling, and the pickling solution is HCl+HF aqueous solution, wherein the volume fraction of hydrochloric acid is 55%, the amount of hydrofluoric acid added is 80g / L, and the pickling temperature is 75°C;

[0135] 6) cold rolling the pickled steel strip to a target thickness of 0.50 mm;

[0136] 7) The above cold-rolled sheet is subjected to single-layer annealing in a continuous annealing furnace, with the temperature of the continuous annealing soaking section at 800°C and the continuous annealing speed at 120 m / min. The unit tension of the strip in the furnace is 1.8 KN. The reducing atmosphere in the furnace is H 2 and N 2 Mixed gas, H 2 The volume content is 5%, and a wet atmosphere is used in the continuous annealing furnace. After the strip is annealed, the insulating coating is applied by a coating roller, and the insulating coating is cured at 380-650°C.

[0137] The non-oriented electrical steel manufactured by the above process has an equiaxed crystal ratio of 71% and an iron loss of P 1.5 / 50 5.6W / Kg, magnetic induction B 5000 It is 1.75T and the magnetic anisotropy is 8.1%. Although the ingot has a high equiaxed crystal ratio and excellent magnetic anisotropy, the continuous annealing speed is low, the hourly production capacity is 33.26 tons, and the output is low.

[0138] The examples described in the present invention are merely descriptions of the preferred implementation modes of the present invention, and are not intended to limit the concept and scope of the present invention. Without departing from the design concept of the present invention, various modifications and improvements made to the technical solutions of the present invention by engineers and technicians in this field should all fall within the protection scope of the present invention.

Claims

1. A low-cost and efficient production method for non-oriented silicon steel. It is characterized in that The chemical composition of the non-oriented silicon steel is as follows by weight percentage: C≤0.005%, Si: 1.7%~1.9%, Mn: 0.1~0.3%, Als≤0.7%, B: 0.001~0.01%, P: 0.001~0.01%, S≤0.005%, N≤0.005%, Ti≤0.005%, wherein Si, Al, P, B elements satisfy: exp{0.6(Si+Al)-4.7}≤(P+10B), and the rest are Fe and unavoidable impurities; the iron loss P of the silicon steel is 1.5 / 50 2.80~5.5W / kg, B 5000 1.71~1.75T, magnetic anisotropy <10%; the ratio of Mn / S in the chemical composition is controlled at 20~60; specific production method The process includes: S1. Continuously cast molten steel at low temperature into slabs of suitable thickness, and use electromagnetic stirring during continuous casting; specifically, low-temperature casting is adopted, and the casting temperature is required to be ≤1530℃, and the proportion of equiaxial crystals in the ingot is guaranteed to be greater than 65%; S2. Send the continuous casting slab into a heating furnace for heating. The temperature of the heating furnace is controlled at 1150-1250°C, and the total heating time is not more than 210 minutes. S3, hot rolling the slab at high temperature, the temperature of the slab after rough rolling is not less than 940°C, and the final rolling temperature is 860-920°C; S4. After the hot-rolled plate is finished, it is not cooled by laminar flow and is directly coiled at high temperature. The strip temperature before coiling is greater than 800℃. S5, the strip steel is shot blasted + pickled, and then directly cold rolled, and the total cold rolling reduction rate is between 70.4 and 80.7%; S6. Continuously annealing the cold-rolled sheet, and applying and curing the insulating coating after annealing; specifically, the cold-rolled sheet is annealed in a continuous annealing furnace, and the strip is operated in a multi-layer reciprocating manner in the annealing furnace, including reciprocating in two areas, the continuous annealing furnace heating section (100) and the continuous annealing furnace soaking section (101), firstly in the continuous annealing furnace heating section (100) for multi-layer reciprocating heating, and then in the continuous annealing furnace soaking section (101) for multi-layer reciprocating insulation; and the temperature of the strip in the continuous soaking section of the continuous annealing furnace is 800~930℃, and the running speed of the strip in the furnace reaches 250~300m / min; and the unit tension of the strip is between 2.0KN and 2.5KN.

2. A method for efficiently producing low-cost non-oriented silicon steel according to claim 1, Features: The pickling solution in S5 is HCl+HF aqueous solution, wherein the volume fraction of hydrochloric acid is 55~60%, the amount of hydrofluoric acid added is 80~100g / L, and the pickling temperature is 75℃~80℃.

3. The method for efficiently producing low-cost non-oriented silicon steel according to claim 1, Features: During the slab processing, the initial continuous casting is a slab with a thickness of 200-260mm, which is then hot-rolled for 7 passes to a hot-rolled plate with a thickness of 2.2-2.6mm. The target thickness of the finished product after cold rolling is 0.5-0.65mm.

4. The method for efficiently producing low-cost non-oriented silicon steel according to claim 1, Features: The reducing atmosphere in the furnace is H 2 and N 2 Mixed gas, H 2 The volume content is 5~15%; when the C content is ≥0.0030%, a wet atmosphere with a dew point of >15℃ is required in the continuous annealing furnace.

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