Non-oriented electrical steel and preparation method thereof

Abstract

The invention provides non-oriented electrical steel and a preparation method thereof. The non-oriented electrical steel comprises the following components in percentage by mass: less than or equal to 0.0025% of C, 0.85%-1.00% of Si, 0.25%-0.35% of Mn, less than or equal to 0.030% of P, less than or equal to 0.005% of S, 0.25%-0.40% of Als, less than or equal to 0.0030% of N, less than or equal to 0.0020% of Ti, 0.001%-0.013% of Ca, 0.020%-0.040% of Sb, less than or equal to 0.010% of C, S, N and Ti, and the balance of Fe and inevitable trace elements. By reasonably controlling the content of each chemical component in the non-oriented electrical steel, the non-oriented electrical steel with low alloy cost, high efficiency and high quality can be produced.

Description

Technical Field

[0001] The present application relates to the field of electrical steel, and in particular to a non-oriented electrical steel and a preparation method thereof. Background Art

[0002] As an important core material in rotating machinery, non-oriented electrical steel has a significant impact on the working efficiency of rotating machinery. The development direction of non-oriented electrical steel products is low iron loss, high magnetic induction and high efficiency. The development of the motor industry has increasingly stringent requirements for electrical steel products. The existing electrical steel market is highly competitive, and products with good cost performance are also a competitive advantage in the market. On the premise of seizing market opportunities, enterprises must not only produce products that satisfy customers but also ensure high-efficiency production, which is the only way to improve economic benefits. In order to further improve production efficiency while ensuring product quality, improving economic benefits by improving technology on the basis of existing products is also the development direction of electrical steel.

[0003] The magnetic properties of non-oriented electrical steel are mainly evaluated by iron loss and magnetic flux density. Iron loss refers to the energy loss that occurs at a specific magnetic flux density and frequency, and magnetic flux density refers to the degree of magnetization obtained under a specific magnetic field. The lower the iron loss and the higher the magnetic flux density, the more efficient the rotating machinery can be manufactured under the same conditions. Therefore, it is extremely important to manufacture non-oriented electrical steel with low iron loss and magnetic flux density.

[0004] The non-oriented electrical steel alloy produced by the existing technology has the disadvantages of high cost and low efficiency. Summary of the invention

[0005] The present application provides a non-oriented electrical steel and a preparation method thereof, aiming to reduce the problems of high iron loss and high production cost of the non-oriented electrical steel.

[0006] In a first aspect, an embodiment of the present application provides a non-oriented electrical steel, comprising the following components in percentage by mass: C≤0.0025%, Si: 0.85%~1.00%, Mn: 0.25%~0.35%, P≤0.030%, S≤0.005%, Als: 0.25%~0.40%, N≤0.0030%, Ti≤0.0020%, Ca: 0.001%~0.013%, Sb: 0.020%~0.040%, wherein C+S+N+Ti≤0.010%, and the rest are Fe and unavoidable trace elements.

[0007] According to an embodiment of the first aspect of the present application, the non-oriented electrical steel has a two-phase region of ferrite and austenite.

[0008] According to the embodiment of the first aspect of the present application, the magnetic induction intensity of the non-oriented electrical steel is greater than 1.71T, and the iron loss value is less than 3.82W / kg.

[0009] In a second aspect, an embodiment of the present application provides a method for preparing a non-oriented electrical steel, comprising: continuous casting to obtain a cast ingot, the cast ingot comprising the following components in mass percentage: C≤0.0025%, Si: 0.85%~1.00%, Mn: 0.25%~0.35%, P≤0.030%, S≤0.005%, Als: 0.25%~0.40%, N≤0.0030%, Ti≤0.0020%, Ca: 0.001%~0.013%, Sb: 0.020%~0.040%, wherein C+S+N+Ti≤0.010%, and the rest are Fe and unavoidable trace elements; hot rolling, pickling, cold rolling and annealing the cast ingot to obtain the non-oriented electrical steel.

[0010] According to an embodiment of the second aspect of the present application, electromagnetic stirring is not performed during the continuous casting process, and the continuous casting speed is 1.6-1.7 m / min.

[0011] According to the embodiment of the second aspect of the present application, the process parameters of hot rolling include: the inlet temperature of the ingot is controlled at 200-800°C, the heating temperature is 1120-1160°C, the total time in the furnace is controlled at 200-400min, the outlet temperature is controlled at 1080-1120°C, the final rolling temperature is controlled at 850-890°C, and the coiling temperature is 700-740°C.

[0012] According to the embodiment of the second aspect of the present application, after the hot rolling process is completed, the temperature of the steel coil is ≥300°C when it is sent to the cold rolling raw material warehouse and is cooled naturally.

[0013] According to an embodiment of the second aspect of the present application, the relative reduction rate of the cold rolling process is 80% to 85%.

[0014] According to the embodiment of the second aspect of the present application, the process parameters of the annealing treatment include: annealing temperature of 920-930°C, holding time of 1.5-2min, and speed of 130-150m / min.

[0015] According to an embodiment of the second aspect of the present application, before the step of continuous casting to obtain a cast billet, the method further includes:

[0016] Hot metal pretreatment: Using KR mechanical stirring desulfurization technology, the outlet [S] is controlled at ≤0.0010%, and the outlet temperature is controlled at ≥1300℃;

[0017] Converter steelmaking: the tapping end point [C] is controlled at 0.035% to 0.055%, the tapping end point [O] is controlled at 0.060-0.080%, and the converter end point temperature is controlled at 1645-1685℃;

[0018] RH vacuum treatment: The primary molten steel from the converter is vacuum degassed, and the temperature and composition are adjusted in the RH furnace. The ladle containing the molten steel is lifted by the hydraulic lifting device at the RH treatment station and the two immersion tubes at the bottom of the vacuum tank are immersed to form a closed container inside the vacuum tank. The vacuum pump is turned on and the vacuum is quickly evacuated to a maximum vacuum degree below 133Pa. According to the [C], [O] and terminal temperature in the primary molten steel from the converter, the decarburization mode (natural decarburization or forced decarburization) and the amount of oxygen blowing are determined for decarburization and temperature increase. When the carbon content in the molten steel reaches the requirement, ferrosilicon or aluminum blocks are added for deoxidation and alloying. After the maximum vacuum cycle is ≥4min, ferrophosphorus, metallic manganese, aluminum blocks or other alloys such as ferrosilicon are added. After all alloys are added, the net cycle is 8-12min at the maximum vacuum degree before breaking through the air and exiting the station.

[0019] Compared with the prior art, this application has at least the following beneficial effects:

[0020] The present application can produce non-oriented electrical steel with low alloy cost, high efficiency and high quality by reasonably controlling the content of each chemical component in the non-oriented electrical steel. Among them, ultra-low content of C, S, N, Ti and other element components are designed to ensure the purity of the steel, and suitable beneficial elements Si, Als, Mn and P content are designed so that the non-oriented electrical steel has a two-phase region of ferrite and austenite to ensure that there are no corrugated defects on the surface under high drawing speed conditions in the production process. Considering that this type of steel requires lower iron loss and higher magnetic induction intensity, an appropriate amount of segregation element Sb is added to improve the magnetic properties of the finished product. The present application is aimed at 50W600 electrical steel produced by the prior art, and adopts a component system with low Si, low Als, low alloy cost and a two-phase region to cooperate with the production process to obtain electrical steel with better magnetic properties and good surface quality. DETAILED DESCRIPTION

[0021] In order to make the application purpose, technical solution and beneficial technical effect of the present application clearer, the present application is further described in detail in conjunction with the embodiments below. It should be understood that the embodiments described in this specification are only for explaining the present application, not for limiting the present application.

[0022] For simplicity, only some numerical ranges are explicitly disclosed herein. However, any lower limit can be combined with any upper limit to form an unambiguous range; and any lower limit can be combined with other lower limits to form an unambiguous range, and any upper limit can be combined with any other upper limit to form an unambiguous range. In addition, although not explicitly stated, each point or single value between the range endpoints is included in the range. Thus, each point or single value can be combined with any other point or single value as its own lower limit or upper limit or with other lower limits or upper limits to form an unambiguous range.

[0023] In the description of this article, it should be noted that, unless otherwise specified, “above” and “below” are inclusive of the number itself, and the “multiple” in “one or more” means more than two.

[0024] The above disclosure of this application is not intended to describe every disclosed embodiment or every implementation in this application. The following description more specifically illustrates exemplary embodiments. In many places throughout this application, guidance is provided through a series of examples, which can be combined in various forms.

[0025] Non-oriented electrical steel is a silicon-iron soft magnetic alloy with very low carbon content, and is a type of steel with low iron loss and high magnetic induction. The inventors have noticed that the existing process for producing non-oriented electrical steel has the disadvantages of high cost and low efficiency.

[0026] Based on this, the inventors conducted extensive research to produce a low-cost, high-efficiency, and high-quality non-oriented electrical steel.

[0027] Non-oriented electrical steel

[0028] In a first aspect, an embodiment of the present application provides a non-oriented electrical steel, comprising the following components in percentage by mass: C≤0.0025%, Si: 0.85%-1.00%, Mn: 0.25%-0.35%, P≤0.030%, S≤0.005%, Als: 0.25%-0.40%, N≤0.0030%, Ti≤0.0020%, Ca: 0.001%-0.013%, Sb: 0.020%-0.040%, wherein C+S+N+Ti≤0.010%, and the rest are Fe and unavoidable trace elements.

[0029] In the technical solution of the present application, by reasonably controlling the content of each chemical component in the non-oriented electrical steel, the steel has a lower iron loss at a lower cost, thereby improving the magnetic properties of the non-oriented electrical steel.

[0030] The chemical composition and content of the technical solution of this application are described in detail below.

[0031] C: Carbon is a harmful element. When the amount of carbon increases, the iron loss P 15 The value increases, so the carbon content in the finished product is required to be as low as possible. In this application, the carbon content is controlled within the range below 0.0025%.

[0032] According to the implementation manner of the present application, the content of element C is 0.0015%, 0.0017%, 0.0019%, 0.0021%, 0.0023%, and 0.0025%. Of course, the content of element C may also be any combination range of the above values.

[0033] Si: Silicon has a decisive influence on the organization, texture and magnetic properties of non-oriented electrical steel. As the silicon content increases, the resistivity increases, the austenite phase area shrinks, the eddy current loss decreases, the grains coarsen, the hysteresis loss decreases, the iron loss value decreases and the magnetic induction value also decreases; silicon can reduce the harm of impurity elements in steel, graphitize carbon, and reduce the harmful effects of carbon on magnetic properties; silicon has an affinity with oxygen, plays a deoxidizing role, and forms silicon nitride with nitrogen, reducing the solubility of nitrogen in steel. Taking all the influencing factors into consideration, this application controls the silicon content to 0.85%-1.00%.

[0034] According to the implementation manner of the present application, the Si element content is 0.85%, 0.86%, 0.87%, 0.88%, 0.89%, 0.90%, 0.91%, 0.92%, 0.93%, 0.94% or 0.95%. Of course, the Si element content can also be any combination range of the above values.

[0035] Mn: Mn and S will form MnS inclusions to prevent the hot brittleness caused by the formation of low-melting-point FeS along the grain boundaries and improve the thermoplasticity of the material. At the same time, manganese expands the austenite phase region and promotes the growth of MnS inclusions, which is beneficial to the subsequent grain growth. The manganese content is designed to be 0.25-0.35%.

[0036] According to the embodiments of the present application, the content of Mn element is 0.20%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29% or 0.30%. Of course, the content of Mn element can also be any combination range of the above values.

[0037] S: Sulfur is a harmful element. The formation of fine MnS inclusions will hinder grain growth and increase iron loss. The main effect of S is that the harmful effect of sulfur on magnetic properties in electrical steel is related to the presence of fine particles of manganese sulfide in the matrix and free sulfur on the grain boundaries. The influence of Mn and S is mainly because the supersaturated Mn and S in the steel will disperse and precipitate in the form of MnS particles, causing an increase in iron loss. Therefore, the sulfur content is controlled within the range of 0 to 0.005% in this application.

[0038] P: Phosphorus can significantly increase hardness and improve punching performance. The present application controls the phosphorus content within the range of 0.030.

[0039] According to the implementation manner of the present application, the content of P element is 0.020%, 0.021%, 0.022%, 0.023%, 0.024%, 0.025%, 0.026%, 0.027%, 0.028%, 0.029% or 0.030%. Of course, the content of P element can also be any combination range of the above values.

[0040] Al: Aluminum has similar effects to silicon, which can increase resistivity, reduce austenite phase area and promote grain growth. When its content reaches a certain amount, it can form coarse AlN, improve texture, reduce iron loss and reduce anisotropy. When the aluminum content reaches a certain amount, it will coarsen the steel and promote carbon graphitization. In this application, the aluminum content is controlled within the range of 0.25%-0.40%.

[0041] According to the implementation manner of the present application, the Al content is 0.25%, 0.30%, 0.35% or 0.40%. Of course, the Al content may also be any combination range of the above values.

[0042] Ti: Titanium is a harmful element. When the titanium content exceeds a certain amount, the precipitated Ti(CN) will pin the grain boundary, hinder the growth of grains, significantly refine the grains, increase the iron loss, and reduce the magnetic induction. The present application controls the titanium content within the range of 0.0020%.

[0043] N: Nitrogen is a harmful element that easily forms fine AlN particles to inhibit grain growth. An important purpose of the heating, hot rolling and annealing process is to prevent the precipitation of fine AlN or to coarsen the existing AlN in the steel. In this application, the nitrogen content is controlled within the range of 0.0030%.

[0044] Sb: A small amount of antimony gathers at the boundary and can hinder the magnetic induction <111> The formation of texture improves the magnetic induction strength of the material, and the antimony content is 0.020-0.040%.

[0045] According to an embodiment of the present application, the Sb element content is 0.20%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, 0.30%, 0.31%, 0.32%, 0.33%, 0.34%, 0.35%, 0.36%, 0.37%, 0.38%, 0.39% or 0.40%. Of course, the Sb element content can also be any combination range of the above numerical values.

[0046] Impurity elements C, S, N, and Ti are most harmful to iron loss, which cause serious lattice distortion and large internal stress. The finished product requires that such elements should be as low as possible. They have a very bad effect on grain growth and texture components, especially fine dispersed precipitates such as MnS, AlN, Ti (CN), etc., which obviously hinder the grain growth during annealing. The total content of C+S+N+Ti is controlled within the range of 0.010% in this application.

[0047] The present application can produce non-oriented electrical steel with low alloy cost, high efficiency and high quality by reasonably controlling the content of each chemical component in the non-oriented electrical steel. Among them, ultra-low content of C, S, N, Ti and other element components are designed to ensure the purity of steel, and suitable beneficial elements Si, Als, Mn and P content are designed so that the non-oriented electrical steel has a two-phase region of ferrite and austenite to ensure that there are no corrugated defects on the surface under high drawing speed conditions in the production process. At the same time, the content of Si and Mn is low, which can reduce the amount of alloy elements added in the alloying treatment step, which is not only conducive to reducing costs, but also conducive to reducing the introduction of impurity elements. Considering that this type of steel requires lower iron loss and higher magnetic induction intensity, an appropriate amount of segregation element Sb is added to improve the magnetic properties of the finished product. The present application is aimed at 50W600 electrical steel produced by the prior art, and adopts a component system with low Si, low Als, low alloy cost and two-phase region to cooperate with the production process, so as to obtain electrical steel with better magnetic properties and good surface quality.

[0048] In some embodiments, the non-oriented electrical steel has a two-phase region of ferrite and austenite.

[0049] The content of austenite is higher than that of ferrite, and the content of austenite can reach more than 50%. The high content of austenite is conducive to efficient continuous casting production, and it is not easy to form deformed tissue and corrugated stripe defects on the surface under high pulling speed.

[0050] Method for preparing non-oriented electrical steel

[0051] In a second aspect, an embodiment of the present application provides a method for preparing the above-mentioned non-oriented electrical steel, comprising the following steps:

[0052] Continuously casting to obtain a cast billet, the cast billet comprising the following components in percentage by mass: C≤0.0025%, Si: 0.85%-1.00%, Mn: 0.25%-0.35%, P≤0.030%, S≤0.005%, Als: 0.25%-0.40%, N≤0.0030%, Ti≤0.0020%, Ca: 0.001%-0.013%, Sb: 0.020%-0.040%, wherein C+S+N+Ti≤0.010%, and the rest are Fe and inevitable trace elements; hot rolling, pickling, cold rolling and annealing are performed on the cast billet to obtain non-oriented electrical steel.

[0053] According to the implementation mode of the present application, the present application can produce non-oriented electrical steel with low alloy cost, high efficiency and high quality by reasonably controlling the content of each chemical component in the non-oriented electrical steel. Among them, ultra-low content of C, S, N, Ti and other element components are designed to ensure the purity of steel, and suitable beneficial elements Si, Als, Mn and P content are designed so that the non-oriented electrical steel has a ferrite and austenite two-phase region to ensure that there are no corrugated defects on the surface under high drawing speed conditions in the production process. At the same time, the Si and Mn contents are low, which can reduce the amount of alloy elements added in the alloying treatment step, which is not only conducive to reducing costs but also conducive to reducing the introduction of impurity elements. Considering that this type of steel requires lower iron loss and higher magnetic induction intensity, an appropriate amount of segregation element Sb is added to improve the magnetic properties of the finished product. This application is aimed at 50W600 electrical steel produced by the prior art, and adopts a component system with low Si, low Als, low alloy cost and two-phase region to cooperate with the production process, so as to obtain electrical steel with good magnetic properties and good surface quality.

[0054] In some embodiments, the proportion of columnar crystals in the ingot is 80% to 95%.

[0055] In the embodiment of the present application, the content of elements is adjusted to make the proportion of columnar crystals higher. A higher proportion of columnar crystals is beneficial to enhancing the {100} plane texture, which is beneficial to improving the magnetic induction and reducing the iron loss.

[0056] In some embodiments, electromagnetic stirring is not performed during the continuous casting process, and the continuous casting speed is 1.6-1.7 m / min.

[0057] In the embodiment of the present application, the element composition and its content are controlled so that the austenite content is high, electromagnetic stirring is not required, good surface quality is maintained, and a higher drawing speed can be achieved.

[0058] In some embodiments, the superheat of the continuous casting tundish is controlled at 15°C to 35°C, a high-silicon thermal insulation covering agent is used for the tundish, and electrical steel protective slag is used.

[0059] According to the embodiment of the present application, the superheat degree of the continuous casting ladle used in continuous casting is 15°C to 35°C, and continuous casting can be carried out in combination with the continuous casting speed of the present application to ensure the strength and iron loss of non-oriented electrical steel. The continuous casting ladle can use alkaline covering agents and electrical steel protective slag to protect the molten steel therein.

[0060] In some embodiments, the process parameters of hot rolling include: the furnace entry temperature of the ingot is controlled at 200-800°C, the heating temperature is 1120-1160°C, the total furnace time is controlled at 200-400min, the furnace exit temperature is controlled at 1080-1120°C, the final rolling temperature is controlled at 850-890°C, and the coiling temperature is 700-740°C.

[0061] According to the implementation method of the present application, during the hot rolling of the slab, the slab with qualified quality is sent to the heating furnace for heating by stacking slow cooling or direct hot rolling mode, and the heating and heat preservation time is sufficient. The higher the heating temperature, the better the hot rolling plasticity, but the product magnetism is reduced; the lower the heating temperature, the poorer the plasticity, but the higher the magnetism. Therefore, under the condition that the rolling mill capacity allows, the heating temperature should be as low as possible to prevent the second phase precipitates such as MnS and AlN in the steel from solid solution. After solid solution, the solubility decreases with the decrease of the steel plate temperature during the hot rolling process, and the fine dispersed precipitation hinders the growth of grains during annealing, and the {111} component increases, and the magnetism deteriorates.

[0062] The main purpose of hot rolling is to make the precipitates in the slab fully precipitate and grow, so a low heating temperature is used and a higher coiling temperature is used to ensure that the precipitates grow further after coiling.

[0063] In some embodiments, after the hot rolling process is completed, the temperature of the steel coil is ≥300° C. when it is sent to the cold rolling raw material warehouse and is cooled naturally.

[0064] According to the implementation of the present application, during the slow cooling of the hot-rolled sheet, a large amount of second phase precipitates such as AlN and MnS are precipitated in the hot-rolled sheet after high-temperature coiling. In order to promote the growth of the precipitates after annealing, the steel coil is required to be slowly cooled after the hot-rolled coil is off the line for a period of not less than 48 hours. For example, the slow cooling time is 48 hours, 49 hours, 50 hours, 52 hours, 55 hours or 60 hours.

[0065] In some embodiments, the relative reduction ratio of the cold rolling process is 80% to 85%.

[0066] According to the implementation of the present application, the main purpose of pickling cold rolling is to remove the iron oxide scale on the surface of the steel plate while rolling the thicker hot-rolled plate into a thinner cold-rolled plate. The setting of the reduction rate is mainly determined by the rolling mill capacity. For this type of steel, a larger reduction rate is conducive to reducing the iron loss of the finished product. Setting the reduction rate to 75% to 85% increases the uniformity of the particles, which is conducive to reducing the iron loss of the finished product.

[0067] In some embodiments, the process parameters of the annealing treatment include: annealing temperature of 920-930° C., holding time of 1.5-2 min, and speed of 130-150 m / min.

[0068] According to the implementation method of the present application, the main purpose of annealing is to eliminate the strain generated by the cold rolling process and promote grain growth through recrystallization of the cold rolled strip, so that the steel plate is fully recrystallized to ensure that the magnetic properties meet the required conditions. Compared with the single annealing process, continuous annealing of the steel material not only has no effect on the structural strength of the obtained non-oriented electrical steel, but also can further reduce the iron loss and improve the magnetic induction intensity of the non-oriented electrical steel.

[0069] According to the implementation mode of the present application, if the annealing temperature of the non-oriented electrical steel is too high and the annealing time is too long, the magnetic induction intensity of the non-oriented electrical steel will not meet the requirements, while if the annealing temperature is too low and the annealing time is too short, the iron loss of the non-oriented electrical steel will be too high. Therefore, setting the annealing temperature to 920℃~930℃ and the holding time to 1.5min~2min can further reduce the iron loss of the non-oriented electrical steel and improve its magnetic induction intensity.

[0070] In some embodiments, before the step of continuous casting to obtain a casting billet, the method further comprises:

[0071] Hot metal pretreatment: Using KR mechanical stirring desulfurization technology, the outlet [S] is controlled at ≤0.0010%, and the outlet temperature is controlled at ≥1300℃;

[0072] Converter steelmaking: the tapping end point [C] is controlled at 0.035% to 0.055%, the tapping end point [O] is controlled at 0.060-0.080%, and the converter end point temperature is controlled at 1645-1685℃;

[0073] RH vacuum treatment: The primary molten steel from the converter is vacuum degassed, and the temperature and composition are adjusted in the RH furnace. The ladle containing the molten steel is lifted by the hydraulic lifting device at the RH treatment station and the two immersion tubes at the bottom of the vacuum tank are immersed to form a closed container inside the vacuum tank. The vacuum pump is turned on and the vacuum is quickly evacuated to a maximum vacuum degree below 133Pa. According to the [C], [O] and terminal temperature in the primary molten steel from the converter, the decarburization mode (natural decarburization or forced decarburization) and the amount of oxygen blowing are determined for decarburization and temperature increase. When the carbon content in the molten steel reaches the requirement, ferrosilicon or aluminum blocks are added for deoxidation and alloying. After the maximum vacuum cycle is ≥4min, ferrophosphorus, metallic manganese, aluminum blocks or other alloys such as ferrosilicon are added. After all alloys are added, the net cycle is 8-12min at the maximum vacuum degree before breaking through the air and exiting the station.

[0074] In some embodiments, the method further comprises applying a coating to the non-oriented electrical steel, wherein the coating is a semi-organic coating.

[0075] Example

[0076] The following examples more specifically describe the disclosure of the present application, which are intended for illustrative purposes only, as it will be apparent to those skilled in the art that various modifications and variations are possible within the scope of the disclosure of the present application. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are by weight, and all reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further processing, and the instruments used in the examples are commercially available.

[0077] Example 1

[0078] Non-oriented electrical steel includes the following components in percentage by mass:

[0079] C: 0.0020Wt%; Si: 0.90Wt%; Mn: 0.30Wt%; P: 0.025Wt%; S: 0.0040Wt%; Als: 0.30Wt%; N: 0.0015%; Ti: 0.0015%; Sb: 0.025%, C+S+N+Ti: 0.009%; the rest are iron and inevitable trace elements.

[0080] The preparation method of non-oriented electrical steel is as follows:

[0081] Converter steelmaking: end point C is 0.040%; temperature is 1665°C, end point [O] content is 0.070%, and 100kg aluminum block and 600kg lime are added during steelmaking.

[0082] RH molten steel refining treatment: molten steel inlet temperature is 1620℃, inlet [O] content is 0.058%, decarburization end point [O] is 0.035%, aluminum silicon addition time interval is 4min, net circulation time of molten steel after alloying is 10min, and molten steel treatment cycle is 30min.

[0083] Slab continuous casting: Tundish temperature is 1555℃, superheat is 28℃, casting speed is 1.6m / min, and the proportion of columnar crystals in the slab is 89%. Special protective slag for electrical steel is used.

[0084] Conventional hot rolling:

[0085] Table 1 Parameters of hot rolling in Example 1

[0086]

[0087] Pickling and cold rolling: The cooled steel coils with coil numbers of Examples 1-1 to 1-9 were subjected to cold rolling, and the reduction ratio was 82%.

[0088] Continuous furnace annealing coating: The annealing temperature of Examples 1-1 to 1-9 is 925° C., the holding time is 2 min, and the annealing speed is 135 m / min.

[0089] Example 2

[0090] Non-oriented electrical steel, comprising the following components in percentage by mass:

[0091] C: 0.0022Wt%; Si: 0.88Wt%; Mn: 0.28Wt%; P: 0.026Wt%; S: 0.0045Wt%; Als: 0.27Wt%; N: 0.0017%; Ti: 0.0015%; Sb: 0.029%, C+S+N+Ti: 0.0099%; the rest are iron and inevitable trace elements.

[0092] The preparation method of non-oriented electrical steel is as follows:

[0093] Converter steelmaking: end point C is 0.050%; temperature is 1680°C, end point [O] content is 0.061%, and 100kg aluminum block and 600kg lime are added during steelmaking.

[0094] RH molten steel refining treatment: molten steel inlet temperature is 1615℃, inlet [O] content is 0.050%, decarburization end point [O] is 0.026%, aluminum silicon addition time interval is 4min, net steel circulation time after alloying is 9min, and steel treatment cycle is 30min.

[0095] Slab continuous casting: Tundish temperature is 1550℃, superheat is 23℃, casting speed is 1.65m / min, the proportion of columnar crystals in the slab is 90%. Special protective slag for electrical steel is used.

[0096] Conventional hot rolling:

[0097] Table 2 Parameters of hot rolling of Example 2

[0098]

[0099] Pickling and cold rolling: The cooled steel coils with coil numbers of Examples 2-1 to 2-8 were subjected to cold rolling, and the reduction ratio was 80%.

[0100] Continuous furnace annealing coating: The annealing temperature of Examples 2-1 to 2-8 is 921° C.; the holding time is 1.5 min; and the annealing speed is 140 m / min.

[0101] Example 3

[0102] Non-oriented electrical steel, including the following components in percentage by mass:

[0103] C: 0.0015Wt%; Si: 0.95Wt%; Mn: 0.33Wt%; P: 0.020Wt%; S: 0.0035Wt%; Als: 0.35Wt%; N: 0.0016%; Ti: 0.0016%; Sb: 0.035%, C+S+N+Ti: 0.0082%; the rest are iron and inevitable trace elements.

[0104] The preparation method of non-oriented electrical steel is as follows:

[0105] Converter steelmaking: end point C is 0.035%; temperature is 1658°C, end point [O] content is 0.065%, and 100kg aluminum block and 600kg lime are added during steelmaking.

[0106] RH molten steel refining treatment: molten steel inlet temperature is 1615℃, inlet [O] content is 0.050%, decarburization end point [O] is 0.026%, aluminum silicon addition time interval is 4min, net steel circulation time after alloying is 8min, and molten steel treatment cycle is 28min.

[0107] Slab continuous casting: Tundish temperature is 1549℃, superheat is 22℃, casting speed is 1.7m / min, and the proportion of columnar crystals in the slab is 92%. Special protective slag for electrical steel is used.

[0108] Conventional hot rolling:

[0109] Table 3 Parameters of hot rolling of Example 3

[0110]

[0111] Pickling and cold rolling: The cooled steel coils with coil numbers of Examples 3-1 to 3-9 were subjected to cold rolling, and the reduction ratio was 84%.

[0112] Continuous furnace annealing coating: The annealing temperature of Examples 3-1 to 3-9 is all 928°C; the holding time is all 2 minutes, and the annealing speed is all 145 m / min.

[0113] Comparative Example 1

[0114] Non-oriented electrical steel, including the following components in percentage by mass:

[0115] C: 0.0035Wt%; Si: 1.35Wt%; Mn: 0.35Wt%; P: 0.030Wt%; S: 0.0055Wt%; Als: 0.30Wt%; N: 0.0018%; Ti: 0.0025%; the rest are iron and inevitable trace elements.

[0116] The preparation method of non-oriented electrical steel is as follows:

[0117] Converter steelmaking: end point C is 0.041%; temperature is 1675°C, end point [O] content is 0.058%, and 200kg modifier and 600kg lime are added during steelmaking.

[0118] RH molten steel refining treatment: molten steel inlet temperature is 1623℃, inlet [O] content is 0.042%, decarburization end point [O] is 0.028%, aluminum silicon addition time interval is 3min, net circulation time of molten steel after alloying is 6min, and molten steel treatment cycle is 30min.

[0119] Slab continuous casting: Tundish temperature is 1555℃, superheat is 22℃, and casting speed is 1.2m / min. Electromagnetic stirring is used, and electromagnetic stirring parameters are: current 400A, frequency 3.0Hz, and the proportion of columnar crystals in the cast billet is 45%. Special protective slag for electrical steel is used.

[0120] Conventional hot rolling:

[0121] Table 4 Parameters of hot rolling of comparative example 1

[0122]

[0123] Pickling and cold rolling: The cooled steel coils with coil numbers of comparative examples 1-1 to 1-10 were subjected to cold rolling, and the reduction ratio was 78%.

[0124] Continuous furnace annealing coating: The annealing temperature of comparative examples 1-1 to 1-10 is 875° C., the holding time is 1.5 min, and the annealing speed is 135 m / min.

[0125] Comparative Example 2

[0126] Non-oriented electrical steel, including the following components in percentage by mass:

[0127] C: 0.0029Wt%; Si: 1.26Wt%; Mn: 0.20Wt%; P: 0.026Wt%; S: 0.0051Wt%; Als: 0.27Wt%; N: 0.0020%; Ti: 0.0024%; the rest are iron and inevitable trace elements.

[0128] The preparation method of non-oriented electrical steel is as follows:

[0129] Converter steelmaking: end point C is 0.05%; temperature is 1685°C, end point [O] content is 0.075%, and 100kg modifier and 300kg lime are added during steelmaking.

[0130] RH molten steel refining treatment: molten steel inlet temperature is 1618℃, inlet [O] content is 0.054%, decarburization end point [O] is 0.031%, aluminum silicon addition time interval is 3min, net steel circulation time after alloying is 7min, and molten steel treatment cycle is 31min.

[0131] Slab continuous casting: Tundish temperature is 1551℃, superheat is 28℃, and casting speed is 1.1m / min. Electromagnetic stirring is used, and electromagnetic stirring parameters are: current 400A, frequency 3.0Hz, and the proportion of columnar crystals in the slab is 48%. Special protective slag for electrical steel is used.

[0132] Conventional hot rolling:

[0133] Table 5 Parameters of hot rolling of comparative example 2

[0134]

[0135] Pickling and cold rolling: The cooled steel coils with coil numbers of comparative examples 2-1 to 2-9 were subjected to cold rolling, and the reduction ratio was 78%.

[0136] Continuous furnace annealing coating: The annealing temperature of comparative examples 2-1 to 2-9 is 885°C; the holding time is 2 minutes, and the annealing speed is 140 m / min.

[0137] Comparative Example 3

[0138] Non-oriented electrical steel, including the following components in percentage by mass:

[0139] C: 0.0034Wt%; Si: 1.22Wt%; Mn: 0.29Wt%; P: 0.024Wt%; S: 0.0046Wt%; Als: 0.26Wt%; N: 0.0021%; Ti: 0.0026%; the rest are iron and inevitable trace elements.

[0140] The preparation method of non-oriented electrical steel is as follows:

[0141] Converter steelmaking: end point C is 0.029%; temperature is 1646°C, end point [O] content is 0.076%, and 200kg modifier and 600kg lime are added during steelmaking.

[0142] RH molten steel refining treatment: molten steel inlet temperature is 1619℃, inlet [O] content is 0.054%, decarburization end point [O] is 0.030%, aluminum silicon addition time interval is 3min, net circulation time of molten steel after alloying is 6min, and molten steel treatment cycle is 28min.

[0143] Slab continuous casting: Tundish temperature is 1547℃, superheat is 24℃, and casting speed is 1.2m / min. Electromagnetic stirring is used, and electromagnetic stirring parameters are: current 400A, frequency 3.0Hz, and the proportion of columnar crystals in the cast billet is 50%. Special protective slag for electrical steel is used.

[0144] Conventional hot rolling:

[0145] Table 6 Parameters of hot rolling of comparative example 3

[0146]

[0147] Pickling and cold rolling: The cooled steel coils with coil numbers of Comparative Examples 3-1 to 3-8 were subjected to cold rolling, and the reduction rate was 70%.

[0148] Continuous furnace annealing coating: annealing temperature is 895℃; holding time is 1.5min, annealing speed is 145m / min.

[0149] The magnetic properties of the non-oriented electrical steels manufactured in Examples 1 to 3 and Comparative Examples 1 to 3 were tested. The test results are shown in Table 7. The tests are as follows:

[0150] Magnetic properties test method:

[0151] Magnetic property test: The annealed coated electrical steel sample is processed into a 0.5mm×500mm×500mm sample, and the transverse and longitudinal magnetic properties of the sample are measured using the Epstein square ring, and the average value is taken as the test value. At this time, the iron loss is the average iron loss when the magnetic flux density of 1.5T is excited at a frequency of 50Hz, and the magnetic induction intensity refers to the average magnetic induction intensity induced in a magnetic field of 5000A / m.

[0152] Table 7 Test results of Examples 1 to 3 and Comparative Examples 1 to 3

[0153]

[0154]

[0155] As can be seen from Table 1, compared with Comparative Examples 1 to 3, the embodiments of the present application follow the following principles when designing the composition: ultra-low C, S, N, Ti, pure steel, suitable beneficial elements Si, Als, Mn and P make it have a ferrite and austenite two-phase region to ensure that there is no corrugation defect on the surface at a high pulling speed, considering that this type of steel requires lower iron loss and higher magnetic induction intensity, an appropriate amount of segregation element Sb is added to improve the magnetic properties of the finished product; a low heating temperature is used during hot rolling, and a high coiling temperature is used to ensure that the precipitates grow further after coiling; a larger reduction rate is adopted during cold rolling to reduce the iron loss of the finished product; during annealing, the strain generated by the cold rolling process is eliminated by recrystallization and the grain growth is promoted, so that the steel plate is fully recrystallized to ensure that the magnetism, hardness and magnetic aging meet the required conditions. Finally, the non-oriented electrical steel of Examples 1-3 of the present application has excellent processing performance and magnetic properties, the magnetic induction intensity is greater than 1.71T, and the iron loss value is less than 3.82W / kg.

[0156] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present application, and these modifications or replacements should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A non-oriented electrical steel, characterized in that: It includes the following components in mass percentage: C≤0.0025%, Si: 0.85%~1.00%, Mn: 0.25%~0.35%, P≤0.030%, S≤0.005%, Als: 0.25%~0.40%, N≤0.0030%, Ti≤0.0020%, Ca: 0.001%~0.013%, Sb: 0.020%~0.040%, wherein C+S+N+Ti≤0.010%, and the rest are Fe and inevitable trace elements.

2. The non-oriented electrical steel material according to claim 1, characterized in that: The non-oriented electrical steel has a two-phase region of ferrite and austenite.

3. The non-oriented electrical steel according to claim 1 or 2, characterized in that: The magnetic induction intensity of the non-oriented electrical steel is greater than 1.71T, and the iron loss value is less than 3.82W / kg.

4. A method for preparing non-oriented electrical steel, characterized in that: include: Continuously casting to obtain a casting billet, the casting billet comprising the following components in percentage by mass: C≤0.0025%, Si: 0.85%-1.00%, Mn: 0.25%-0.35%, P≤0.030%, S≤0.005%, Als: 0.25%-0.40%, N≤0.0030%, Ti≤0.0020%, Ca: 0.001%-0.013%, Sb: 0.020%-0.040%, wherein C+S+N+Ti≤0.010%, and the rest being Fe and inevitable trace elements; The ingot is subjected to hot continuous rolling, pickling, cold continuous rolling and annealing treatment to obtain non-oriented electrical steel.

5. The method for preparing non-oriented electrical steel according to claim 4, characterized in that: No electromagnetic stirring is performed during the continuous casting process, and the continuous casting speed is 1.6-1.7 m / min.

6. The method for preparing non-oriented electrical steel according to claim 4, characterized in that: The process parameters of the hot rolling include: the furnace entry temperature of the ingot is controlled at 200-800°C, the heating temperature is 1120-1160°C, the total furnace time is controlled at 200-400min, the furnace exit temperature is controlled at 1080-1120°C, the final rolling temperature is controlled at 850-890°C, and the coiling temperature is 700-740°C.

7. The method for preparing non-oriented electrical steel according to claim 6, characterized in that: After the hot rolling treatment is completed, the temperature of the steel coil is ≥300° C. when it is sent to the cold rolling raw material warehouse and is cooled naturally.

8. The method for preparing non-oriented electrical steel according to claim 4, characterized in that: The relative reduction rate of the cold rolling process is 80% to 85%.

9. The method for preparing non-oriented electrical steel according to claim 4, characterized in that: The process parameters of the annealing treatment include: annealing temperature of 920-930° C., holding time of 1.5-2 min, and speed of 130-150 m / min.

10. The method for preparing non-oriented electrical steel according to claim 4, characterized in that: Before the step of continuous casting to obtain a cast billet, the method further comprises: Hot metal pretreatment: Using KR mechanical stirring desulfurization technology, the outlet [S] is controlled at ≤0.0010%, and the outlet temperature is controlled at ≥1300℃; Converter steelmaking: the tapping end point [C] is controlled at 0.035% to 0.055%, the tapping end point [O] is controlled at 0.060-0.080%, and the converter end point temperature is controlled at 1645-1685℃; RH vacuum treatment: The primary molten steel from the converter is vacuum degassed, and the temperature and composition are adjusted in the RH furnace. The ladle containing the molten steel is lifted by the hydraulic lifting device at the RH treatment station and the two immersion tubes at the bottom of the vacuum tank are immersed to form a closed container inside the vacuum tank. The vacuum pump is turned on and the vacuum is quickly evacuated to a maximum vacuum degree below 133Pa. According to the [C], [O] and terminal temperature in the primary molten steel from the converter, the decarburization mode (natural decarburization or forced decarburization) and the amount of oxygen blowing are determined for decarburization and temperature increase. When the carbon content in the molten steel reaches the requirement, ferrosilicon or aluminum blocks are added for deoxidation and alloying. After the maximum vacuum cycle is ≥4min, ferrophosphorus, metallic manganese, aluminum blocks or other alloys such as ferrosilicon are added. After all alloys are added, the net cycle is 8-12min at the maximum vacuum degree before breaking through the air and exiting the station.

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