Non-oriented silicon steel and method for manufacturing the same, silicon steel product

Abstract

This application discloses a non-oriented silicon steel, its preparation method, and silicon steel products. The preparation method of the non-oriented silicon steel includes: providing molten steel for non-oriented silicon steel; subjecting the molten steel to RH vacuum treatment to obtain RH vacuum-treated molten steel; continuously casting the RH vacuum-treated molten steel to obtain a billet, wherein the billet, by mass percentage, comprises the following components: C: ≤0.0025wt%, Si: 1.7wt%~2wt%, Mn: 0.7wt%~1wt%, P: ≤0.03wt%, S: ≤0.0035wt%, Als: 0.25wt%~0.55wt%, N: ≤0.003wt%, Ti: ≤0.002wt%, Sn: 0.030wt%~0.05wt%, with the remainder being Fe and unavoidable trace elements, and the equiaxed crystal ratio of the billet is 50%~70%; and heating the billet to obtain a heated steel billet. The heated steel billet is subjected to hot rolling, coiling, cooling, pickling, cold rolling, annealing, and coating processes sequentially to obtain non-oriented silicon steel. The non-oriented silicon steel prepared by the method of this application can combine lower production costs with higher performance.

Description

Technical Field

[0001] This application belongs to the field of metallurgical technology, and in particular relates to a non-oriented silicon steel, its preparation method, and silicon steel products. Background Technology

[0002] Non-oriented electrical steel, as a key core material for electromagnetic equipment such as motors and transformers, directly determines the operating efficiency, energy consumption level, and service life of downstream equipment. It is an important basic material for the upgrading and development of emerging industries such as power electronics, new energy vehicles, and industrial equipment, as well as traditional manufacturing industries. At present, although the existing non-oriented electrical steel production process has formed a relatively mature technical system, in actual production, it often faces the problem of balancing performance and cost. Summary of the Invention

[0003] This application provides a non-oriented silicon steel, its preparation method, and silicon steel products. The non-oriented silicon steel prepared by the method of this application can have both low production cost and high performance.

[0004] In a first aspect, embodiments of this application provide a method for preparing non-oriented silicon steel, comprising: providing molten steel for non-oriented silicon steel; subjecting the molten steel to RH vacuum treatment to obtain RH vacuum-treated molten steel; continuously casting the RH vacuum-treated molten steel to obtain a billet, wherein, by mass percentage, the billet comprises the following components: C: ≤0.0025wt%, Si: 1.7wt%~2wt%, Mn: 0.7wt%~1wt%, P: ≤0.03wt%, S: ≤0.0035wt%, Als: 0.25wt%~0.55wt%, N: ≤0.003wt%, Ti: ≤0.002wt%, Sn: 0.030wt%~0.05wt%, with the remainder being Fe and unavoidable trace elements, and the equiaxed crystal ratio of the billet being 50%~70%; heating the billet to obtain a heated steel billet; and hot-rolling the heated steel billet to obtain a hot-rolled plate. Hot-rolled steel sheets are coiled and cooled to obtain cooled hot-rolled steel sheets. The cooled hot-rolled steel sheets are then pickled and cold-rolled to obtain cold-rolled thin sheets. The cold-rolled thin sheets are then annealed and coated to obtain non-oriented silicon steel.

[0005] According to the embodiments of this application, the preparation method of non-oriented silicon steel significantly improves the comprehensive performance and production adaptability of non-oriented silicon steel through the synergistic effect of precisely controlled special element composition and equiaxed crystal ratio of the billet, combined with the optimization of the entire process. The synergistic control of Sn and Al elements can promote the nucleation and growth of equiaxed crystals during the solidification process of the billet, ensuring the stable realization of 50%~70% equiaxed crystal ratio; while the uniform equiaxed crystal structure can make beneficial elements such as Sn and Si uniformly distributed in the crystal, avoiding local performance degradation caused by element segregation, and further amplifying the effect of element optimization on magnetic properties and processing performance.

[0006] Furthermore, the ultra-low C, S, N, and Ti content results in pure steel, while suitable elements such as Si, Als, Mn, and P ensure the presence of a two-phase region consisting of ferrite and austenite, guaranteeing a surface free of corrugation defects even under high-speed drawing and non-normalizing processes. The preparation method of this application eliminates the need for traditional normalizing annealing processes, directly saving the energy consumption of high-temperature heating, holding, and cooling during normalizing. This also reduces billet oxidation and burn-off caused by normalizing, lowering the raw material loss rate. In addition, eliminating the normalizing process simplifies the production flow, shortens the production cycle, reduces inter-process transfer and waiting time, and effectively improves the continuous operation efficiency and capacity utilization of the production line.

[0007] In some alternative embodiments, in the step of providing molten non-oriented silicon steel, the molten non-oriented silicon steel satisfies at least one of the following: (1) the mass percentage of carbon in the molten steel is 0.03wt% to 0.05wt%. (2) the mass percentage of oxygen in the molten steel is 0.06wt% to 0.08wt%. (3) the temperature of the molten steel is 1635℃ to 1675℃.

[0008] In some optional embodiments, in the step of heat-treating the cast billet to obtain a heated steel billet, the temperature of the cast billet after heat treatment is 1100℃~1140℃. And / or, the heat treatment time is 150min~350min. And / or, the temperature of the heated steel billet is 1080℃~1120℃.

[0009] In some alternative embodiments, in the step of hot rolling the heated steel billet to obtain a hot-rolled plate, the final rolling temperature of the hot rolling is 860°C to 900°C.

[0010] In some optional embodiments, in the step of coiling and cooling the hot-rolled sheet to obtain a cooled hot-rolled sheet, the temperature of the coiling process is 660°C to 700°C; and / or, the temperature of the cooled hot-rolled sheet is ≥300°C.

[0011] In some alternative embodiments, in the step of pickling and cold rolling the cooled hot-rolled sheet to obtain a cold-rolled sheet, the relative reduction rate of the cold rolling process is 80% to 85%.

[0012] In some optional embodiments, the steps of annealing and coating the cold-rolled sheet to obtain the non-oriented silicon steel satisfy at least one of the following: (1) the annealing temperature is 970℃~980℃. (2) the holding time of the annealing is 1.5min~2min. (3) the annealing speed is 130m / min~150m / min. (4) a semi-organic coating is used for the coating treatment.

[0013] Secondly, embodiments of this application provide a non-oriented silicon steel, which is prepared by the preparation method of the first aspect.

[0014] In some alternative embodiments, the non-oriented silicon steel satisfies at least one of the following: (1) the metallographic structure of the non-oriented silicon steel has a two-phase region of ferrite and austenite; (2) the iron loss of the non-oriented silicon steel is ≤3.3W / Kg, preferably, the iron loss of the non-oriented silicon steel is ≤3.2W / Kg; (3) the magnetic induction of the non-oriented silicon steel is ≥1.7T.

[0015] Thirdly, embodiments of this application provide a silicon steel product prepared by the non-oriented silicon steel of the second aspect. Detailed Implementation

[0016] To make the purpose, technical solution, and beneficial technical effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the implementation details described in this specification are merely for illustrative purposes and are not intended to limit the scope of this application.

[0017] For simplicity, this application only explicitly discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form a range not explicitly stated; and any lower limit can be combined with other lower limits to form a range not explicitly stated, just as any upper limit can be combined with any other upper limit to form a range not explicitly stated. Furthermore, although not explicitly stated, every point or individual value between the endpoints of the range is included within that range. Therefore, each point or individual value can be used as its own lower or upper limit and combined with any other point or individual value or with other lower or upper limits to form a range not explicitly stated.

[0018] It should be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0019] Unless otherwise stated, the values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (e.g., they can be tested according to the methods given in the embodiments of this application). Unless otherwise stated, the test temperature for all parameters mentioned in this application is 25°C and the test pressure is standard atmospheric pressure.

[0020] The foregoing description of this application is not intended to describe every disclosed implementation or method. Instead, the following description provides more specific examples of exemplary embodiments. Throughout the application, guidance is provided through a series of embodiments, which can be used in various combinations. The examples listed are representative only and should not be construed as exhaustive.

[0021] Non-oriented electrical steel is a key core material for electromagnetic equipment such as motors and transformers. Its product performance directly determines the operating efficiency, energy consumption level and service life of downstream equipment. It is an important basic material for the upgrading and development of emerging industries such as power electronics, new energy vehicles, and industrial equipment, as well as traditional manufacturing industries.

[0022] Currently, although the existing non-oriented electrical steel production process has formed a relatively mature technical system, there are still technical bottlenecks in actual production, namely "it is difficult to achieve both high quality and high efficiency" and "performance improvement and cost control are mutually restrictive": some process solutions can produce high-quality products with low iron loss and high magnetic induction, but the production process is complex, energy consumption is high, and production efficiency is low, resulting in high product costs and insufficient cost-effectiveness; other process solutions focus on improving production efficiency and controlling costs, but the product performance is difficult to meet the stringent requirements of the high-end motor industry, especially in core indicators such as iron loss control and magnetic induction stability, where there is room for improvement.

[0023] To address the problems of the prior art, this application provides a non-oriented silicon steel, its preparation method, and silicon steel products. The non-oriented silicon steel prepared by the method of this application can have both lower production costs and higher performance.

[0024] The non-oriented silicon steel of this application, its preparation method, and silicon steel products will be described below with reference to embodiments.

[0025] Preparation method of non-oriented silicon steel In a first aspect, embodiments of this application provide a method for preparing non-oriented silicon steel, comprising: S100 provides molten steel for non-oriented silicon steel.

[0026] S200 is used to perform RH vacuum treatment on molten non-oriented silicon steel to obtain RH vacuum treated molten steel.

[0027] S300 is a billet obtained by continuous casting of RH vacuum-treated molten steel. The billet comprises the following components by mass percentage: C: ≤0.0025wt%, Si: 1.7wt%~2wt%, Mn: 0.7wt%~1wt%, P: ≤0.03wt%, S: ≤0.0035wt%, Als: 0.25wt%~0.55wt%, N: ≤0.003wt%, Ti: ≤0.002wt%, Sn: 0.030wt%~0.05wt%, with the remainder being Fe and unavoidable trace elements. The equiaxed crystal ratio of the billet is 50%~70%.

[0028] S400 involves heating the cast billet to obtain a heated steel billet.

[0029] S500 is used to hot-roll steel billets to obtain hot-rolled plates.

[0030] S600 is used to coil and cool hot-rolled plates to obtain cooled hot-rolled plates.

[0031] S700 processes pickling and cold rolling of cooled hot-rolled plates to obtain cold-rolled sheets.

[0032] S800 is a non-oriented silicon steel obtained by annealing and coating cold-rolled sheets.

[0033] As an example, the equiaxed crystal ratio of the billet can be 50%, 52%, 55%, 58%, 60%, 62%, 65%, 68%, 70%, or any range of the above values.

[0034] According to the embodiments of this application, the preparation method of non-oriented silicon steel significantly improves the comprehensive performance and production adaptability of non-oriented silicon steel through the synergistic effect of precisely controlled special element composition and equiaxed crystal ratio of the billet, combined with the optimization of the entire process. The synergistic control of Sn and Al elements can promote the nucleation and growth of equiaxed crystals during the solidification process of the billet, ensuring the stable realization of 50%~70% equiaxed crystal ratio; while the uniform equiaxed crystal structure can make beneficial elements such as Sn and Si uniformly distributed in the crystal, avoiding local performance degradation caused by element segregation, and further amplifying the effect of element optimization on magnetic properties and processing performance.

[0035] Furthermore, the ultra-low C, S, N, and Ti content results in pure steel, while suitable elements such as Si, Als, Mn, and P ensure the presence of a two-phase region consisting of ferrite and austenite, guaranteeing a surface free of corrugation defects even under high-speed drawing and non-normalizing processes. The preparation method of this application eliminates the need for traditional normalizing annealing processes, directly saving the energy consumption of high-temperature heating, holding, and cooling during normalizing. This also reduces billet oxidation and burn-off caused by normalizing, lowering the raw material loss rate. In addition, eliminating the normalizing process simplifies the production flow, shortens the production cycle, reduces inter-process transfer and waiting time, and effectively improves the continuous operation efficiency and capacity utilization of the production line.

[0036] The elemental composition of the non-oriented silicon steel in this application is as follows.

[0037] Carbon (C): Carbon is a harmful element. As the carbon content increases, the iron loss P15 value increases. Therefore, the carbon content in the finished product must be as low as possible. This product requires the carbon content to be controlled below 0.0025%.

[0038] Silicon (Si): The main influence of silicon is its decisive effect on the microstructure, texture, and magnetic properties of non-oriented electrical steel. With increasing silicon content, resistivity increases, the austenite phase region shrinks, eddy current loss decreases, grains coarsen, and hysteresis loss decreases, leading to a reduction in both iron loss and magnetic flux density. Silicon can reduce the harmful effects of impurities in the steel, graphitize carbon, and reduce the detrimental effects of carbon on magnetic properties. Silicon has an affinity for oxygen, acting as a deoxidizer, and forms silicon nitride with nitrogen, reducing the solubility of nitrogen in the steel. Considering all influencing factors, the silicon content in this product is designed to be 1.70%~2.00%. As an example, the mass percentage of Si in the non-oriented silicon steel of this application can be 1.7wt%, 1.72wt%, 1.75wt%, 1.78wt%, 1.8wt%, 1.82wt%, 1.85wt%, 1.88wt%, 1.9wt%, 1.92wt%, 1.95wt%, 1.98wt%, 2wt%, or any range of the above values.

[0039] Manganese (Mn): Manganese forms MnS inclusions with sulfur, preventing hot brittleness caused by the formation of low-melting-point FeS along grain boundaries and improving the thermoplasticity of the material. Simultaneously, manganese expands the austenite phase region, promoting the growth of MnS inclusions and facilitating subsequent grain growth. The manganese content is designed to be 0.70%~1.00%. As an example, the mass percentage of Mn in the non-oriented silicon steel of this application can be 0.7wt%, 0.72wt%, 0.75wt%, 0.78wt%, 0.8wt%, 0.82wt%, 0.85wt%, 0.88wt%, 0.9wt%, 0.92wt%, 0.95wt%, 0.98wt%, 1wt%, or any range of the above values.

[0040] Sulfur (S): Sulfur is a harmful element. The MnS inclusions it forms hinder grain growth and increase iron loss. The main effect of sulfur in electrical steel is its detrimental magnetic properties, which are related to the presence of fine manganese sulfide particles in the matrix and free sulfur at grain boundaries. The effects of Mn and S are mainly due to the fact that supersaturated Mn and S in the steel will precipitate out in the form of MnS particles, causing an increase in iron loss. Therefore, the sulfur content should be ≤0.0035%.

[0041] Phosphorus (P): Phosphorus significantly increases hardness. Therefore, the phosphorus content should be controlled within 0.030%.

[0042] Aluminum (Als): Similar to silicon, aluminum increases resistivity, shrinks the austenite phase region, and promotes grain growth. When its content reaches a certain level, it can form coarse AlN, improving texture, reducing iron loss, and decreasing anisotropy. A certain aluminum content will coarsen the steel and promote carbon graphitization. Therefore, the aluminum content is controlled between 0.25% and 0.55%. As an example, the mass percentage of Als in the non-oriented silicon steel of this application can be 0.25wt%, 0.28wt%, 0.3wt%, 0.32wt%, 0.35wt%, 0.38wt%, 0.4wt%, 0.42wt%, 0.45wt%, 0.48wt%, 0.5wt%, 0.52wt%, 0.55wt%, or any range of the above values.

[0043] Titanium (Ti): Titanium is a harmful element. When the titanium content exceeds a certain level, the precipitated Ti(CN) nails the grain boundaries, hindering grain growth, resulting in significantly refined grains, increased iron loss, and decreased magnetic induction. Therefore, the titanium content should be controlled within 0.0020%.

[0044] Nitrogen (N): Nitrogen is a harmful element that easily forms fine AlN particles, inhibiting grain growth. An important purpose of heating, hot rolling, and annealing processes is to prevent the precipitation of fine AlN or to coarsen existing AlN in the steel. Therefore, the nitrogen content is controlled within 0.0030%.

[0045] Tin (Sn): Small amounts of tin congregating at the boundary can hinder... <111> The formation of texture improves the magnetic properties of the material, prevents the formation of small grains on the surface during lamination annealing, significantly reduces iron loss, and has a tin content of 0.030%~0.050%. As an example, the mass percentage content of Sn in the non-oriented silicon steel of this application can be 0.03wt%, 0.032wt%, 0.035wt%, 0.038wt%, 0.04wt%, 0.042wt%, 0.045wt%, 0.048wt%, 0.05wt%, or any range of the above values.

[0046] In some embodiments, the mass percentage of carbon in the molten steel during step S100 is 0.03wt% to 0.05wt%. For example, the mass percentage of carbon can be 0.03wt%, 0.032wt%, 0.035wt%, 0.038wt%, 0.04wt%, 0.042wt%, 0.045wt%, 0.048wt%, 0.05wt%, or any range of the above values. This content range avoids the problem of excessive carbon content leading to carbide precipitation during subsequent processing, which in turn causes increased iron loss and deterioration of magnetic properties. It also provides suitable fluidity and formability for the molten steel, ensuring the quality of subsequent billet forming. At the same time, this carbon content can be precisely matched with the subsequent RH vacuum treatment, facilitating the precise adjustment of the carbon content to the required range for the finished product and improving the stability of process control.

[0047] In some embodiments, the mass percentage of oxygen in the molten steel during step S100 is 0.06wt% to 0.08wt%. For example, the mass percentage of oxygen can be 0.6wt%, 0.62wt%, 0.65wt%, 0.68wt%, 0.7wt%, 0.72wt%, 0.75wt%, 0.78wt%, 0.8wt%, or any range of the above values. An appropriate amount of oxygen can promote the nucleation and uniform distribution of fine oxide inclusions (such as Al2O3, SiO2, etc.) in the molten steel. These fine inclusions can act as inhibitors of subsequent grain growth, optimizing the magnetic domain structure of the finished silicon steel to reduce iron loss, while avoiding an increase in large-size oxide inclusions due to excessive oxygen content, thus preventing any impact on the magnetic properties and processing toughness of the silicon steel.

[0048] In some embodiments, the temperature of the molten steel is 1635℃ to 1675℃. For example, the temperature of the molten steel can be 1635℃, 1640℃, 1645℃, 1650℃, 1655℃, 1660℃, 1665℃, 1670℃, 1675℃, or any combination of the above values. This temperature range ensures that the molten steel has excellent fluidity, which on the one hand facilitates the circulation and stirring of the molten steel during RH vacuum treatment, improves degassing and impurity removal efficiency, and ensures the cleanliness of the molten steel; on the other hand, it avoids excessively high temperatures that lead to coarse steel crystal grains and increased energy consumption, while preventing excessively low temperatures that cause the billet to solidify too quickly during continuous casting, easily resulting in cracks or blockage of the crystallizer, thus ensuring the continuous and efficient operation of the continuous casting process.

[0049] In some embodiments, the temperature of the billet after heat treatment in step S400 is 1100℃~1140℃. For example, the temperature of the billet after heat treatment can be 1100℃, 1110℃, 1120℃, 1130℃, 1140℃, or any range of the above values.

[0050] In some embodiments, the heating treatment time in step S400 is 150 min to 350 min. For example, the heating treatment time can be 150 min, 200 min, 250 min, 300 min, 350 min, or any range of the above values.

[0051] In some embodiments, the temperature of the heated steel billet in step S400 is 1080°C to 1120°C. For example, the temperature of the heated steel billet can be 1080°C, 1090°C, 1100°C, 1110°C, 1120°C, or any range of the above values.

[0052] In some embodiments, the final rolling temperature in step S500 is 860°C to 900°C. For example, the final rolling temperature can be 860°C, 870°C, 880°C, 890°C, 900°C, or any range of the above values.

[0053] In some embodiments, the winding temperature in step S600 is 660°C to 700°C. For example, the winding temperature can be 660°C, 670°C, 680°C, 690°C, 700°C, or any range of the above values. A higher winding temperature combined with a lower heating temperature can ensure that the precipitates in the steel after winding are fully exuded and further grown.

[0054] In some embodiments, the temperature of the hot-rolled plate after cooling in step S600 is ≥300°C.

[0055] In some embodiments, the relative reduction rate of the cold rolling process in step S700 is 80% to 85%. For example, the relative reduction rate can be 80%, 81%, 82%, 83%, 84%, 85%, or any range of the above values. The main purpose of pickling is to remove the iron oxide scale from the surface of the steel sheet while rolling a thicker hot-rolled sheet into a thinner cold-rolled sheet. A larger reduction rate is beneficial for reducing iron loss in the finished product.

[0056] In some embodiments, the annealing temperature in step S800 is 970°C to 980°C. For example, the annealing temperature can be 970°C, 972°C, 974°C, 976°C, 978°C, 980°C, or any range of the above values.

[0057] In some embodiments, the holding time for the annealing process in step S800 is 1.5 min to 2 min. For example, the holding time can be 1.5 min, 1.6 min, 1.7 min, 1.8 min, 1.9 min, 2 min, or any range of the above values.

[0058] In some embodiments, the annealing speed in step S800 is 130 m / min to 150 m / min. For example, the annealing speed can be 130 m / min, 135 m / min, 140 m / min, 145 m / min, 150 m / min, or any range of the above values.

[0059] In the above embodiments, controlling the annealing temperature, the holding time of the annealing treatment, and the speed of the annealing treatment can eliminate the strain generated by the cold rolling process and promote grain growth through recrystallization of the cold-rolled sheet, so as to fully recrystallize the steel sheet and ensure its magnetism, hardness, and magnetic aging.

[0060] In some embodiments, the coating treatment employs a semi-organic coating. For example, the semi-organic coating may be TM4-A, TM5-A, GF-M4, or GF-WG1003.

[0061] In some embodiments, step S100 may include: S110, molten iron pretreatment: molten iron for non-oriented silicon steel is obtained by desulfurization treatment using the KR mechanical stirring method. The mass percentage of sulfur in the molten iron is ≤0.0010wt%, and the temperature of the molten iron leaving the station is ≥1300℃.

[0062] S120, converter steelmaking: molten iron in S110 is smelted to obtain non-oriented silicon steel. The mass percentage of carbon element in the molten steel is 0.030wt%~0.050wt%, the mass percentage of oxygen element is 0.060wt%~0.080wt%, and the temperature of the molten steel is 1635℃~1675℃.

[0063] In some embodiments, step S200 includes: degassing the molten non-oriented silicon steel from step S100 in an RH furnace under vacuum, adjusting its temperature and composition; lifting the ladle containing the molten steel at the RH processing station by a hydraulic lifting device, immersing it in the two immersion pipes at the bottom of the vacuum tank to form a sealed container inside the vacuum tank; turning on the vacuum pump and rapidly evacuating it to a vacuum level below 133 Pa; determining the decarburization mode (natural decarburization or forced decarburization) and oxygen blowing amount based on the [C], [O] and final temperature conditions in the molten steel for decarburization and heating; adding ferrosilicon or aluminum blocks for deoxidation and alloying after the carbon content in the molten steel reaches the required level; adding other alloys such as metallic manganese, aluminum blocks, or ferrosilicon after a vacuum cycle of ≥4 min; and finally, circulating the molten steel under a vacuum level for 8 min to 12 min before exiting the furnace.

[0064] In some embodiments, the superheat of the continuous casting process in step S300 is 15°C to 30°C. For example, the superheat can be 15°C, 18°C, 20°C, 22°C, 25°C, 28°C, 30°C, or any range of the above values.

[0065] In some embodiments, the casting speed of the billet in step S300 is 1.0 m / min to 1.2 m / min. For example, the casting speed can be 1.0 m / min, 1.02 m / min, 1.05 m / min, 1.08 m / min, 1.1 m / min, 1.12 m / min, 1.15 m / min, 1.18 m / min, 1.2 m / min, or any range of the above values.

[0066] Non-oriented silicon steel This application provides a non-oriented silicon steel, which is prepared by the above-described preparation method.

[0067] In some embodiments, the metallographic structure of non-oriented silicon steel has a two-phase region of ferrite and austenite.

[0068] In some embodiments, the iron loss of non-oriented silicon steel is ≤3.3W / Kg, and preferably, the iron loss of non-oriented silicon steel is ≤3.2W / Kg.

[0069] In some embodiments, the magnetic induction of non-oriented silicon steel is ≥1.7T.

[0070] In some embodiments, the non-oriented silicon steel of this application may be 50W470 electrical steel.

[0071] Silicon steel products This application provides a silicon steel product, prepared using the aforementioned non-oriented silicon steel. The silicon steel product can be a stator / rotor core. The stator / rotor core can be used in compressors, transformers, industrial circulating water pumps, and cooling tower fans. It can also be used in small and medium-sized motors such as machine tool spindle motors, conveyor motors, and mixer motors.

[0072] Example The following embodiments describe the disclosure of this application in more detail. These embodiments are for illustrative purposes only, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosure of this application. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on mass, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing. The instruments used in the embodiments are also commercially available. The magnetic properties of the non-oriented silicon steel were detected in a magnetic property detector.

[0073] Example 1-1 A 50W470 non-oriented silicon steel comprises, by mass percentage, the following components: C: 0.0020 wt%; Si: 1.91 wt%; Mn: 0.73 wt%; P: 0.012 wt%; S: 0.0028 wt%; Al: 0.40 wt%; N: 0.0022 wt%; Ti: 0.0014 wt%; Sn: 0.042 wt%; the remainder being iron and unavoidable trace elements. It is prepared by the following method: In step S100, the molten steel in the converter is smelted to obtain non-oriented silicon steel. The mass percentage of C element in the molten steel is 0.042%, the mass percentage of O element is 0.070%, the temperature of the molten steel is 1672℃, and 300kg of modifier and 600kg of lime are added when tapping the steel.

[0074] Step S200: The molten steel of the above-mentioned non-oriented silicon steel is subjected to RH vacuum treatment to obtain RH vacuum treated molten steel. The molten steel inlet temperature is 1620℃, the oxygen content at inlet is 0.055% by mass, the oxygen content at the decarburization endpoint is 0.035% by mass, the time interval between adding aluminum and silicon is 4 minutes, the net circulation time of the molten steel after alloying is 8 minutes, and the molten steel treatment cycle is 30 minutes.

[0075] Step S300: The RH vacuum-treated molten steel is continuously cast to obtain a billet. The tundish temperature is 1545℃, the superheat is 28℃, the casting speed is 1.2 m / min, and the equiaxed crystal ratio of the billet is 60%. A special protective slag for electrical steel is used.

[0076] Step S400: The above-mentioned billet is heated to obtain a heated steel billet, wherein the billet entering the furnace is 460℃, the billet heating temperature is 1135℃, the total time in the furnace is 350min, and the exit temperature is controlled at 1120℃.

[0077] In step S500, the heated steel billet is subjected to hot rolling to obtain a hot-rolled plate. The final rolling temperature is 870℃.

[0078] Step S600 involves coiling and cooling the hot-rolled sheet to obtain a cooled hot-rolled sheet. The coiling temperature is 680°C.

[0079] In step S700, the cooled hot-rolled plate is subjected to pickling and cold rolling to obtain a cold-rolled sheet, wherein the hot-rolled coil exit temperature is 353°C and the relative reduction rate of the cold rolling process is 82%.

[0080] In step S800, the above-mentioned cold-rolled sheet is subjected to annealing and coating treatment to obtain non-oriented silicon steel. The annealing temperature is 980℃, the annealing holding time is 2 min, and the annealing speed is 130 m / min.

[0081] Examples 1-2 to Examples 1-8 The difference between Examples 1-2 to 1-8 and Example 1-1 lies in the different control parameters during the steel preparation process, as detailed in Table 1.

[0082] Table 1. Preparation parameters for Examples 1-1 to 1-8 The non-oriented silicon steel obtained in Examples 1-1 to 1-8 was processed into 0.5mm×500mm×500mm samples. The samples were placed in a magnetic property detector, and the transverse and longitudinal magnetic properties were measured respectively. The average value was taken as the test value. The results are shown in Table 2.

[0083] Table 2 Performance Tables of Examples 1-1 to 1-8 Example 2-1 A 50W470 non-oriented silicon steel comprises, by mass percentage: C: 0.0024wt%; Si: 1.86wt%; Mn: 0.70wt%; P: 0.009wt%; S: 0.0025wt%; Al: 0.38wt%; N: 0.0019wt%; Ti: 0.0013wt%; Sn: 0.036wt%; the remainder being iron and unavoidable trace elements. It is prepared by the following method: In step S100, the molten steel in the converter is smelted to obtain non-oriented silicon steel. The mass percentage of C element in the molten steel is 0.034%, the mass percentage of O element is 0.060%, the temperature of the molten steel is 1666℃, and 300kg of modifier and 800kg of lime are added when tapping the steel.

[0084] Step S200: The molten steel of the above-mentioned non-oriented silicon steel is subjected to RH vacuum treatment to obtain RH vacuum treated molten steel. The molten steel inlet temperature is 1630℃, the mass percentage of oxygen element at the inlet is 0.042%, the mass percentage of oxygen element at the decarburization endpoint is 0.030%, the time interval between adding aluminum and silicon is 4 min, the net circulation time of the molten steel after alloying is 9 min, and the molten steel treatment cycle is 30 min.

[0085] Step S300: The RH vacuum-treated molten steel is continuously cast to obtain a billet. The tundish temperature is 1540℃, the superheat is 23℃, the casting speed is 1.2 m / min, and the equiaxed crystal ratio of the billet is 58%. A special protective slag for electrical steel is used.

[0086] Step S400: The above-mentioned billet is heated to obtain a heated steel billet, wherein the billet entering the furnace is 545℃, the billet heating temperature is 1125℃, the total time in the furnace is 225min, and the exit temperature is controlled at 1110℃.

[0087] In step S500, the heated steel billet is subjected to hot rolling to obtain a hot-rolled plate. The final rolling temperature is 870℃.

[0088] Step S600 involves coiling and cooling the hot-rolled sheet to obtain a cooled hot-rolled sheet. The coiling temperature is 680°C.

[0089] Step S700: The cooled hot-rolled plate is subjected to pickling and cold rolling to obtain a cold-rolled sheet, wherein the hot-rolled coil exit temperature is 353°C and the relative reduction rate of the cold rolling process is 84%.

[0090] In step S800, the above-mentioned cold-rolled sheet is subjected to annealing and coating treatment to obtain non-oriented silicon steel. The annealing temperature is 980℃, the annealing holding time is 2 min, and the annealing speed is 130 m / min.

[0091] Examples 2-2 to 2-10 The difference between Examples 2-2 to 2-10 and Example 2-1 lies in the different control parameters during the steel preparation process, as detailed in Table 3.

[0092] Table 3. Preparation parameters for Examples 2-1 to 2-10 The non-oriented silicon steel obtained in Examples 2-1 to 2-10 was processed into 0.5mm×500mm×500mm samples. The samples were placed in a magnetic property detector, and the transverse and longitudinal magnetic properties were measured respectively. The average value was taken as the test value. The results are shown in Table 4.

[0093] Table 4 Performance Tables of Examples 2-1 to 2-10 Example 3-1 A 50W470 non-oriented silicon steel comprises, by mass percentage: C: 0.0016wt%; Si: 1.96wt%; Mn: 0.73wt%; P: 0.007wt%; S: 0.0019wt%; Als: 0.42wt%; N: 0.0010wt%; Ti: 0.0012wt%; Sn: 0.034wt%; the remainder being iron and unavoidable trace elements. It is prepared by the following method: In step S100, the molten steel in the converter is smelted to obtain non-oriented silicon steel. The mass percentage of C element in the molten steel is 0.032%, the mass percentage of O element is 0.065%, the temperature of the molten steel is 1655℃, and 300kg of modifier and 800kg of lime are added when tapping the steel.

[0094] Step S200: The molten steel of the above-mentioned non-oriented silicon steel is subjected to RH vacuum treatment to obtain RH vacuum treated molten steel. The molten steel inlet temperature is 1620℃, the oxygen content at inlet is 0.05% by mass, the oxygen content at the decarburization endpoint is 0.035% by mass, the time interval between adding aluminum and silicon is 4 minutes, the net circulation time of the molten steel after alloying is 10 minutes, and the molten steel treatment cycle is 30 minutes.

[0095] Step S300: The RH vacuum-treated molten steel is continuously cast to obtain a billet. The tundish temperature is 1547℃, the superheat is 30℃, the casting speed is 1.2 m / min, and the equiaxed crystal ratio of the billet is 60%. Electrical steel-specific protective slag is used.

[0096] Step S400: The above-mentioned billet is heated to obtain a heated steel billet, wherein the billet entering the furnace is 485℃, the billet heating temperature is 1135℃, the total time in the furnace is 280min, and the exit temperature is controlled at 1095℃.

[0097] Step S500: The heated steel billet is subjected to hot rolling to obtain a hot-rolled plate. The final rolling temperature is 885℃.

[0098] Step S600 involves coiling and cooling the hot-rolled sheet to obtain a cooled hot-rolled sheet. The coiling temperature is 685°C.

[0099] Step S700: The cooled hot-rolled plate is pickled and cold-rolled to obtain a cold-rolled sheet, wherein the hot-rolled coil exit temperature is 353°C and the relative reduction rate of the cold rolling process is 85%.

[0100] In step S800, the above-mentioned cold-rolled sheet is subjected to annealing and coating treatment to obtain non-oriented silicon steel. The annealing temperature is 980℃, the annealing holding time is 2 min, and the annealing speed is 130 m / min.

[0101] Examples 3-2 to 3-9 The difference between Examples 3-2 to 3-9 and Example 3-1 lies in the different control parameters during the steel preparation process, as detailed in Table 5.

[0102] Table 5. Preparation parameters for Examples 3-1 to 3-9 The non-oriented silicon steel obtained in Examples 3-1 to 3-9 was processed into 0.5mm×500mm×500mm samples. The samples were placed in a magnetic property detector, and the transverse and longitudinal magnetic properties were measured respectively. The average value was taken as the test value. The results are shown in Table 6.

[0103] Table 6 Performance Tables of Examples 3-1 to 3-9 Comparative Example 1-1 A non-oriented silicon steel comprises, by mass percentage: C: 0.0025 wt%; Si: 2.05 wt%; Mn: 0.22 wt%; P: 0.013 wt%; S: 0.0025 wt%; Als: 0.30 wt%; N: 0.0024 wt%; Ti: 0.0020 wt%; the remainder being iron and unavoidable trace elements. It is prepared by the following method: Step A100: The molten steel in the converter is smelted to obtain non-oriented silicon steel. The mass percentage of C element in the molten steel is 0.033%, the mass percentage of O element is 0.055%, the temperature of the molten steel is 1662℃, and 200kg of modifier and 600kg of lime are added when tapping the steel.

[0104] Step A200 involves subjecting the molten non-oriented silicon steel to RH vacuum treatment to obtain RH vacuum-treated molten steel. The molten steel's inlet temperature is 1623℃, the oxygen content at inlet is 0.04% by mass, the oxygen content at the decarburization endpoint is 0.026% by mass, the time interval between aluminum and silicon additions is 3 minutes, the net circulation time of the molten steel after alloying is 6 minutes, and the molten steel treatment cycle is 30 minutes.

[0105] Step A300 involves continuous casting of the RH vacuum-treated molten steel to obtain a billet. The tundish temperature is 1546℃, the superheat is 28℃, the casting speed is 1.1 m / min, and the equiaxed crystal ratio of the billet is 45%. A special protective slag for electrical steel is used.

[0106] Step A400: The above-mentioned billet is heated to obtain a heated steel billet, wherein the billet entering the furnace is 172°C, the billet heating temperature is 1120°C, the total time in the furnace is 180 min, and the exit temperature is controlled at 1100°C.

[0107] Step A500 involves hot rolling the heated steel billet to obtain a hot-rolled plate. The final rolling temperature is 885℃.

[0108] Step A600 involves coiling the hot-rolled sheet to obtain a hot-rolled steel coil. The coiling temperature is 585℃.

[0109] Step A700 involves normalizing the hot-rolled steel coil to obtain a normalized hot-rolled steel coil. The normalizing annealing temperature is 950℃, the normalizing annealing time is 2.5 min, and the normalizing annealing speed is 50 m / min. The main purpose of normalizing the hot-rolled steel coil is to make the microstructure of the hot-rolled plate more uniform, increase the recrystallized grains, and prevent corrugated defects. Simultaneously, it coarsens the grains and precipitates, strengthens the (100) and (110) components, weakens the (111) component, and significantly improves the magnetic properties.

[0110] Step A800 involves pickling and cold rolling the normalized hot-rolled steel coil to obtain a cold-rolled sheet, wherein the relative reduction rate of the cold rolling process is 75%.

[0111] Step A900 involves annealing and coating the cold-rolled sheet to obtain non-oriented silicon steel. The annealing temperature is 960℃, the annealing holding time is 1.5 min, and the annealing speed is 135 m / min.

[0112] Comparative Examples 1-2 to 1-7 The difference between Comparative Examples 1-2 to 1-7 and Comparative Example 1-1 lies in the different control parameters during the steel preparation process, as detailed in Table 7.

[0113] Table 7 Preparation parameters of Comparative Examples 1-1 to 1-7 The non-oriented silicon steel obtained from Comparative Examples 1-1 to 1-7 was processed into 0.5mm×500mm×500mm samples. The samples were placed in a magnetic property tester, and the transverse and longitudinal magnetic properties were measured respectively. The average value was taken as the test value. The results are shown in Table 8.

[0114] Table 8 Performance Tables of Comparative Examples 1-1 to 1-7 Comparative Example 2-1 A non-oriented silicon steel comprises, by mass percentage: C: 0.0020 wt%; Si: 2.15 wt%; Mn: 0.23 wt%; P: 0.010 wt%; S: 0.0036 wt%; Al: 0.35 wt%; N: 0.0017 wt%; Ti: 0.0020 wt%; the remainder being iron and unavoidable trace elements. It is prepared by the following method: Step A100: The molten steel in the converter is smelted to obtain non-oriented silicon steel. The mass percentage of carbon element in the molten steel is 0.04%, the mass percentage of oxygen element is 0.06%, the temperature of the molten steel is 1655℃, and 200kg of modifier and 600kg of lime are added when tapping the steel.

[0115] Step A200 involves subjecting the molten non-oriented silicon steel to RH vacuum treatment to obtain RH vacuum-treated molten steel. The molten steel's inlet temperature is 1615℃, the oxygen content at inlet is 0.053% by mass, the oxygen content at the decarburization endpoint is 0.03% by mass, the time interval between aluminum and silicon additions is 3 minutes, the net circulation time of the molten steel after alloying is 6 minutes, and the molten steel treatment cycle is 29 minutes.

[0116] Step A300 involves continuous casting of the RH vacuum-treated molten steel to obtain a billet. The tundish temperature is 1540℃, the superheat is 22℃, the casting speed is 1.2 m / min, and the equiaxed grain ratio of the billet is 44%. A special protective slag for electrical steel is used.

[0117] Step A400: The above-mentioned billet is heated to obtain a heated steel billet, wherein the billet entering the furnace is 135℃, the billet heating temperature is 1125℃, the total time in the furnace is 175min, and the exit temperature is controlled at 1105℃.

[0118] Step A500 involves hot rolling the heated steel billet to obtain a hot-rolled plate. The final rolling temperature is 860℃.

[0119] Step A600 involves coiling the hot-rolled sheet to obtain a hot-rolled steel coil. The coiling temperature is 580℃.

[0120] Step A700: The hot-rolled steel coil is subjected to normalizing annealing to obtain a normalized hot-rolled steel coil. The normalizing annealing temperature is 950℃, the normalizing annealing time is 2 min, and the normalizing annealing speed is 45 m / min.

[0121] Step A800 involves pickling and cold rolling the normalized hot-rolled steel coil to obtain a cold-rolled sheet, wherein the relative reduction rate of the cold rolling process is 73%.

[0122] Step A900 involves annealing and coating the cold-rolled sheet to obtain non-oriented silicon steel. The annealing temperature is 965℃, the annealing holding time is 1.5 min, and the annealing speed is 140 m / min.

[0123] Comparative Examples 2-2 to 2-8 The difference between Comparative Examples 2-2 to 2-8 and Comparative Example 2-1 lies in the different control parameters during the steel preparation process, as detailed in Table 9.

[0124] Table 9 Preparation parameters of Comparative Examples 2-1 to 2-8 The non-oriented silicon steel obtained from Comparative Examples 2-1 to 2-8 was processed into 0.5mm×500mm×500mm samples. The samples were placed in a magnetic property tester, and the transverse and longitudinal magnetic properties were measured respectively. The average value was taken as the test value. The results are shown in Table 10.

[0125] Table 10 Performance Tables of Comparative Examples 2-1 to 2-8 Comparative Example 3-1 A non-oriented silicon steel comprises, by mass percentage: C: 0.0019 wt%; Si: 2.10 wt%; Mn: 0.20 wt%; P: 0.025 wt%; S: 0.0028 wt%; Al: 0.22 wt%; N: 0.0022 wt%; Ti: 0.0018 wt%; the remainder being iron and unavoidable trace elements. It is prepared by the following method: Step A100: The molten steel in the converter is smelted to obtain non-oriented silicon steel. The mass percentage of C element in the molten steel is 0.03%, the mass percentage of O element is 0.07%, the temperature of the molten steel is 1648℃, and 200kg of modifier and 600kg of lime are added when tapping the steel.

[0126] Step A200 involves subjecting the molten non-oriented silicon steel to RH vacuum treatment to obtain RH vacuum-treated molten steel. The molten steel's inlet temperature is 1622℃, the oxygen content at inlet is 0.053% by mass, the oxygen content at the decarburization endpoint is 0.035% by mass, the time interval between aluminum and silicon additions is 3 minutes, the net circulation time of the alloyed molten steel is 6 minutes, and the molten steel treatment cycle is 28 minutes.

[0127] Step A300 involves continuous casting of the RH vacuum-treated molten steel to obtain a billet. The tundish temperature is 1538℃, the superheat is 20℃, the casting speed is 1.2 m / min, and the equiaxed crystal ratio of the billet is 50%. A special protective slag for electrical steel is used.

[0128] Step A400: The above-mentioned billet is heated to obtain a heated steel billet, wherein the billet entering the furnace is 155℃, the billet heating temperature is 1120℃, the total time in the furnace is 170min, and the exit temperature is controlled at 1110℃.

[0129] Step A500 involves hot rolling the heated steel billet to obtain a hot-rolled plate. The final rolling temperature is 870℃.

[0130] Step A600 involves coiling the hot-rolled sheet to obtain a hot-rolled steel coil. The coiling temperature is 575℃.

[0131] Step A700: The hot-rolled steel coil is subjected to normalizing annealing to obtain a normalized hot-rolled steel coil. The normalizing annealing temperature is 960℃, the normalizing annealing time is 2 min, and the normalizing annealing speed is 55 m / min.

[0132] Step A800 involves pickling and cold rolling the normalized hot-rolled steel coil to obtain a cold-rolled sheet, wherein the relative reduction rate of the cold rolling process is 70%.

[0133] Step A900 involves annealing and coating the cold-rolled sheet to obtain non-oriented silicon steel. The annealing temperature is 965℃, the annealing holding time is 1.5 min, and the annealing speed is 145 m / min.

[0134] Comparative Examples 3-2 to 3-7 The difference between Comparative Examples 3-2 to 3-7 and Comparative Example 3-1 lies in the different control parameters during the steel preparation process, as detailed in Table 11.

[0135] Table 11 Preparation parameters of Comparative Examples 3-1 to 3-7 The non-oriented silicon steel obtained from Comparative Examples 3-1 to 3-7 was processed into 0.5mm×500mm×500mm samples. The samples were placed in a magnetic property tester, and the transverse and longitudinal magnetic properties were measured respectively. The average value was taken as the test value. The results are shown in Table 12.

[0136] Table 12 Performance Tables of Comparative Examples 3-1 to 3-7 The above description is merely a specific implementation of this application. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the protection scope of this application.

Claims

1. A method for preparing non-oriented silicon steel, characterized in that, include: Provides molten steel for non-oriented silicon steel; The molten non-oriented silicon steel is subjected to RH vacuum treatment to obtain RH vacuum treated molten steel; The RH vacuum-treated molten steel is continuously cast to obtain a billet, wherein the billet comprises the following components by mass percentage: C: ≤0.0025wt%, Si: 1.7wt%~2wt%, Mn: 0.7wt%~1wt%, P: ≤0.03wt%, S: ≤0.0035wt%, Als: 0.25wt%~0.55wt%, N: ≤0.003wt%, Ti: ≤0.002wt%, Sn: 0.030wt%~0.05wt%, with the remainder being Fe and unavoidable trace elements. The equiaxed crystal ratio of the billet is 50%~70%. The cast billet is heated to obtain a heated steel billet; The heated steel billet is subjected to hot rolling to obtain a hot-rolled plate; The hot-rolled plate is subjected to coiling and cooling processes to obtain a cooled hot-rolled plate; The cooled hot-rolled plate is subjected to pickling and cold rolling processes to obtain a cold-rolled sheet. The cold-rolled sheet is subjected to annealing and coating treatment to obtain the non-oriented silicon steel.

2. The preparation method according to claim 1, characterized in that, In the step of providing molten steel for non-oriented silicon steel, the molten steel for non-oriented silicon steel satisfies at least one of the following: (1) The carbon content in the molten steel is 0.03wt%~0.05wt% by mass; (2) The oxygen content in the molten steel is 0.06wt%~0.08wt% by mass; (3) The temperature of the molten steel is 1635℃~1675℃.

3. The preparation method according to claim 1, characterized in that, In the step of heating the billet to obtain a heated steel billet, the temperature of the billet after heating is 1100℃~1140℃. And / or, the heat treatment time is 150 min to 350 min; And / or, the temperature of the heated steel billet is 1080℃~1120℃.

4. The preparation method according to claim 1, characterized in that, In the step of hot rolling the heated steel billet to obtain a hot-rolled plate, the final rolling temperature is 860℃~900℃.

5. The preparation method according to claim 1, characterized in that, In the step of performing coiling and cooling treatment on the hot-rolled plate to obtain a cooled hot-rolled plate, the temperature of the coiling treatment is 660℃~700℃. And / or, the temperature of the cooled hot-rolled plate is ≥300°C.

6. The preparation method according to claim 1, characterized in that, In the step of pickling and cold rolling the cooled hot-rolled plate to obtain a cold-rolled sheet, the relative reduction rate of the cold rolling process is 80% to 85%.

7. The preparation method according to claim 1, characterized in that, The step of annealing and coating the cold-rolled sheet to obtain the non-oriented silicon steel satisfies at least one of the following: (1) The annealing temperature of the annealing treatment is 970℃~980℃; (2) The holding time for the annealing treatment is 1.5 min to 2 min; (3) The annealing speed is 130m / min~150m / min; (4) The coating treatment adopts a semi-organic coating.

8. A non-oriented silicon steel, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 7.

9. The non-oriented silicon steel according to claim 8, characterized in that, The non-oriented silicon steel satisfies at least one of the following: (1) The metallographic structure of the non-oriented silicon steel has two phase regions: ferrite and austenite; (2) The iron loss of the non-oriented silicon steel is ≤3.3W / Kg, preferably, the iron loss of the non-oriented silicon steel is ≤3.2W / Kg; (3) The magnetic induction of the non-oriented silicon steel is ≥1.7T.

10. A silicon steel product, characterized in that, It is prepared by the non-oriented silicon steel according to any one of claims 8 to 9.

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