Method for preparing tellurium-containing non-oriented silicon steel ultrathin strip by utilizing plane flow casting method

Abstract

The invention relates to a method for preparing a tellurium-containing non-oriented silicon steel ultrathin strip by using a plane flow casting method, belongs to the technical field of material preparation, and solves the problems of low melt-spinning forming rate, poor macroscopic size and surface quality of the strip and low magnetic property of the non-oriented silicon steel ultrathin strip prepared by using the plane flow casting method in the prior art. A method for preparing a tellurium-containing non-oriented silicon steel ultrathin strip through a plane flow casting method comprises the following steps that S1, a mother alloy ingot is cast through vacuum induction melting, and raw materials are pig iron with the purity larger than 99.99%, silicon and tellurium; s2, plane flow casting: putting the mother alloy ingot and a purifying agent into a quartz tube with a nozzle of a plane flow casting machine, heating until the mother alloy ingot and the purifying agent are melted, carrying out melt-spinning and spraying the mother alloy ingot and the purifying agent onto a rotating cooling copper roller for directional solidification, and finally stripping a silicon steel ultrathin strip; s3, cold rolling treatment with tension is conducted on the silicon steel ultra-thin strip; and S4, the rolled silicon steel ultrathin strip is subjected to annealing treatment. And the yield and the magnetic performance of the non-oriented silicon steel ultrathin strip prepared by the plane flow casting method are improved.

Description

Technical Field

[0001] The invention relates to the technical field of material preparation, and in particular to a method for preparing a tellurium-containing non-oriented silicon steel ultra-thin strip by using a plane flow casting method. Background Art

[0002] As an important soft magnetic material, non-oriented silicon steel is the core material for the preparation of engine and motor cores. It is widely used in power electronic equipment such as large, medium and small generators and small motors. The most important performance indicator affecting its efficiency is magnetic properties. Reducing the thickness of silicon steel sheets can significantly reduce the high-frequency iron loss, thereby meeting the requirements of industrial development for high-frequency and low-loss core products.

[0003] There are two main ways to prepare non-oriented silicon steel ultra-thin strips: First, through the traditional rolling method, although it is possible to produce non-oriented silicon steel ultra-thin strips with a thickness of less than 0.1 mm, its disadvantages are also quite significant. The entire preparation process is cumbersome and complicated, with many steps, which directly leads to the extension of the production cycle. In addition, during the production process, the energy consumption is astonishingly large, and the cost also increases accordingly, making this method face many obstacles in large-scale promotion and application. Second, the use of double-roller thin strip continuous casting technology can enable the steel liquid to achieve sub-rapid solidification, and then directly form it into a thicker initial cast strip, and then further thin it with the help of the rolling process, which can also achieve the goal of preparing non-oriented silicon steel ultra-thin strips with a thickness of 0.1 mm. Unfortunately, there are still some problems that need to be overcome at this stage of this technology, such as the poor quality of the thin strips produced and poor performance in terms of yield, which have restricted its further development and application.

[0004] The plane flow casting method is used to prepare non-oriented silicon steel ultra-thin strips. The process is short and the energy consumption is low. It can achieve rapid solidification of liquid metal in a short time to obtain uniform and fine strips with columnar crystal structure that is beneficial to magnetism. However, the high melting point, poor fluidity and high surface tension of silicon steel melt make its application range in plane flow casting technology very small. The strip forming ability, macroscopic size and surface quality produced are not ideal, and the magnetic properties are not good. Summary of the invention

[0005] In view of the above analysis, an embodiment of the present invention aims to provide a method for preparing tellurium-containing non-oriented silicon steel ultra-thin strip by planar flow casting, so as to solve at least one of the problems of low strip forming rate, poor macroscopic size and surface quality of the strip, and low magnetic properties in the existing planar flow casting method for preparing non-oriented silicon steel ultra-thin strip.

[0006] On the one hand, an embodiment of the present invention discloses a method for preparing a tellurium-containing non-oriented silicon steel ultra-thin strip by using a planar flow casting method, comprising the following steps:

[0007] S1. The master alloy ingot is cast by vacuum induction melting, and the raw materials are pig iron, silicon and tellurium with a purity greater than 99.99%;

[0008] S2, plane flow casting: the master alloy ingot prepared in S1 and the purifier are placed in a quartz tube with a nozzle of a plane flow casting machine and heated until melted, and then the strip is ejected onto a rotating cooling copper roller for directional solidification, and finally the silicon steel ultra-thin strip is peeled off;

[0009] S3, performing a tension-based cold rolling process on the ultra-thin silicon steel strip prepared in S2;

[0010] S4. Annealing the rolled ultra-thin silicon steel strip.

[0011] Preferably, the chemical composition of the master alloy ingot in S1 is, in terms of mass percentage, tellurium: 0.05wt% to 0.1wt%; silicon: 2.5wt% to 3.5wt%; the rest is iron and a small amount of other inevitable impurities.

[0012] Specifically, during the belt ejection in S2, the nozzle width is controlled to be 15-50 mm, the nozzle gap size is 0.045-0.065 mm, the distance between the nozzle and the copper roller is 0.1-0.2 mm, the pressure during nozzle ejection is 0.01-0.03 MPa, and the copper roller rotation speed is 20-30 m / s.

[0013] Furthermore, in S3, the total reduction rate of the cold rolling process is controlled to be 2% to 20%, the front tension of the rolling roll is 40 to 60N, and the rear tension is 30 to 50N.

[0014] Exemplarily, in S4, the annealing temperature is controlled to be 900° C. to 1200° C., and the annealing time is controlled to be 1 h to 3 h.

[0015] Preferably, the annealing atmosphere is controlled to be a mixed gas of hydrogen and nitrogen, wherein H 2 Content ≥50%, and the cooling time is controlled under protective atmosphere for ≥8min.

[0016] On the other hand, the embodiment of the present invention further discloses a tellurium-containing non-oriented silicon steel ultra-thin strip, which is prepared by the planar flow casting method. 50 ≥1.66T, iron loss P 1.0 / 1000Hz ≤32W / kg.

[0017] Specifically, the non-oriented silicon steel ultra-thin strip has a thickness of 0.05 to 0.065 mm and a width of 15 to 50 mm.

[0018] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0019] 1. The present invention adopts a plane flow casting method to prepare non-oriented silicon steel ultra-thin strips. By optimizing the alloy composition and melting the master alloy together with the purifier, the fluidity and purity of the master alloy melt of the present invention meet the requirements of the plane flow casting method, thereby improving the yield rate of the strip casting, and the yield rate is ≥90%.

[0020] 2. The present invention optimizes alloy elements, adds purifiers, and regulates plane flow casting strip process parameters (roller speed, nozzle pressure, etc.) to make the molten steel closer to the roller and cool quickly into a strip, thereby preparing ultra-thin large-size non-oriented silicon steel ultra-thin strip products with a thickness of 0.05-0.065mm and a width of 15-50mm.

[0021] 3. The present invention optimizes the process parameters of the plane flow casting technology, so that the initial plane flow casting strip can have excellent organizational structure, version and surface quality, and achieve a high yield rate; on this basis, through the subsequent small reduction rate rolling and annealing, the grain growth is promoted, and the strip organizational structure is further optimized, thereby improving the magnetic properties of the non-oriented silicon steel ultra-thin strip. The prepared non-oriented silicon steel ultra-thin strip B 50 ≥1.66T, iron loss P 1.0 / 1000Hz ≤32W / kg.

[0022] 4. The present invention further optimizes the surface quality and pattern of the silicon steel ultra-thin strip by precisely controlling the total reduction rate, roll tension and other parameters during the cold rolling process, while regulating the deformation degree and dislocation distribution of the grains, thereby providing a driving force for the subsequent annealing grain growth, promoting grain growth, improving the organizational structure, and optimizing the texture; on this basis, through subsequent annealing treatment, the growth ability of each oriented grain is improved, especially the growth advantage of the {001} favorable oriented grains is more obvious, the organizational uniformity is also significantly optimized, and the magnetic properties are improved.

[0023] 5. The present invention controls the annealing temperature and time and performs annealing in a high-temperature hydrogen atmosphere, which can adjust the optimal grain size and texture, thereby further improving the magnetic properties; annealing is performed in an atmosphere with a hydrogen content exceeding 50%, so that the ultra-thin strip of non-oriented silicon steel is not oxidized and its grain growth ability can be improved, thereby optimizing the texture uniformity and improving the consistency and stability of the magnetic properties.

[0024] 6. The present invention designs a purifier suitable for non-oriented silicon steel master alloy, which meets the requirements of the plane flow casting method for strict control of impurity elements and melt fluidity; by adding the purifier during the plane flow casting process and melting it together with the master alloy, compared with adding the purifier during the master alloy smelting process, the fluidity of the molten steel is optimized and the impurity purification effect is better, and it can significantly improve the yield rate of the strip while preparing a wider strip (width range 15 to 50 mm).

[0025] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0027] Figure 1 The invention discloses a tellurium-containing non-oriented silicon steel ultra-thin strip prepared by the process of the invention. DETAILED DESCRIPTION

[0028] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0029] On the one hand, a specific embodiment of the present invention discloses a method for preparing a tellurium-containing non-oriented silicon steel ultra-thin strip by plane flow casting, comprising the following steps:

[0030] S1. The master alloy ingot is cast by vacuum induction melting, and the raw materials are pig iron, silicon and tellurium with a purity greater than 99.99%;

[0031] S2, plane flow casting: the master alloy ingot and the purifier prepared in S1 are placed in a quartz tube with a nozzle of a plane flow casting machine and heated until melted, and then the strip is ejected onto a rotating cooling copper roller for directional rapid solidification, and finally the silicon steel ultra-thin strip is peeled off;

[0032] S3, performing a tension-based cold rolling process on the ultra-thin silicon steel strip prepared in S2;

[0033] S4. Annealing the rolled ultra-thin silicon steel strip.

[0034] It should be noted that before the master alloy ingot in S2 is placed in the quartz tube, the master alloy is cut into small pieces of 1 to 2 kg by wire cutting to facilitate placement in the quartz tube.

[0035] Specifically, the chemical composition of the master alloy ingot in S1 is, in terms of mass percentage, tellurium: 0.05wt% to 0.1wt%; silicon: 2.5wt% to 3.5wt%; the rest is iron and a small amount of other inevitable impurities.

[0036] Furthermore, the components of the purifier in S2 include, by mass percentage: calcium oxide: 25wt% to 40wt%; graphite powder: 35wt% to 50wt%; silicon carbide: 15wt% to 25wt%; titanium dioxide: 5wt% to 10wt%.

[0037] Specifically, each component of the purifier is added in the form of powder, and its particle size distribution range is 10 μm to 70 μm. The purifier powder in this particle size range can provide a larger specific surface area, thereby increasing the contact area with the melt, improving the reaction rate between the purifier and impurities (such as oxygen, sulfur, etc.) in the melt, effectively reducing the impurity content in the melt, and ensuring that the purifier is dispersed more evenly in the melt, avoiding inconsistent local purification effects caused by particles that are too large or too small, thereby improving the purity and composition uniformity of the master alloy.

[0038] It should be noted that the weight of the purifier added to S2 is 0.5wt% to 0.8wt% of the total weight of the master alloy. Too little purifier addition will not purify impurities and improve their fluidity, while too much purifier addition will not significantly improve the purification effect and increase costs. By adding the purifier and melting it together with the master alloy during the plane casting process, compared with adding the purifier during the master alloy smelting process, the fluidity of the molten steel is optimized and the impurity purification effect is better, and the yield rate of the strip can be significantly improved while preparing a wider strip.

[0039] The following describes the mechanism and function of the elements added to each master alloy and the purifier composition of the present invention:

[0040] Silicon: The addition of silicon can significantly increase the resistivity, reduce eddy current loss, and effectively reduce iron loss; at the same time, the increase of silicon is conducive to reducing magnetostriction, thereby reducing the noise when the core is working; the increase of silicon content can also reduce the melting point of the melt, and to a certain extent improve the formability of non-oriented silicon steel ultra-thin strips prepared by the plane flow casting method. However, excessive silicon will reduce the saturation magnetic induction intensity value and affect the processing plasticity. Therefore, the silicon content is controlled to be 2.5wt% to 3.5wt%, such as 2.5wt%, 2.6wt%, 2.7wt%, 2.8wt%, 2.9wt%, 3.0wt%, 3.2wt%, and 3.5wt%.

[0041] Tellurium: The addition of tellurium can effectively improve the fluidity of molten steel. This allows the molten steel to better fill the mold or form a uniform thin strip during the solidification process, which is conducive to the production of silicon steel products with thinner thickness and more precise dimensions. It can also reduce defects caused by poor fluidity of molten steel, such as pores and inclusions. Therefore, the tellurium content is controlled to be 0.05wt% to 0.1wt%, such as 0.05wt%, 0.06wt%, 0.07wt%, 0.08wt%, 0.09wt%, and 0.1wt%.

[0042] Calcium oxide: Calcium oxide can ensure the control of the basicity of the non-oriented silicon steel master alloy melt and is a good desulfurizer. At the same time, calcium oxide can combine with aluminum oxide in the molten steel to form a low-melting-point substance, which will float up during the cooling process of the melt and achieve the ability to purify the melt; but excessive addition of calcium oxide will cause the melt to become viscous and the fluidity to deteriorate, so it is controlled at 25wt% to 40wt%, such as 25wt%, 30wt%, 35wt%, and 40wt%.

[0043] Graphite powder: Graphite powder has good lubrication effect, can be used as a solid lubricant to improve the fluidity of molten steel, and can also reduce the impurity elements in molten steel, so the graphite powder is controlled at 35wt% to 50wt%, such as 35wt%, 40wt%, 45wt%, 50wt%.

[0044] Silicon carbide: It promotes the floating of inclusions in the molten steel, promotes the floating of inclusions in the steel to the slag interface, modifies the inclusions in the molten steel, and reduces the oxidizability in the molten steel. On the one hand, the silicon carbide particles themselves can adsorb some tiny inclusions in the molten steel. Since the surface of silicon carbide has a certain activity, it can attract and fix these inclusions. For example, for some tiny non-metallic inclusions, silicon carbide can adsorb them on its surface like a "carrier"; on the other hand, in the molten steel, silicon carbide has a strong reducibility. When there are some oxidizing inclusions, such as oxide inclusions (such as aluminum oxide, manganese dioxide, etc.), silicon carbide can react chemically with them to form complex inclusions containing silicon, aluminum and other elements. The melting point of these new inclusions will be reduced, and they will float to the upper layer when the molten steel solidifies. Therefore, it is controlled at 25wt% to 35wt%, such as 25wt%, 28wt%, 30wt%, 32wt%, and 35wt%.

[0045] Titanium dioxide: Titanium dioxide can play a good deoxidation effect, purify the molten steel and promote the nucleation of grains. 2 ) as a heterogeneous phase can provide additional nucleation sites for grains during the crystallization process, because TiO 2 There are some active sites on the surface, which can interact with solute atoms, just like "small pits". Solute atoms tend to gather in these "small pits" and begin to form crystal nuclei. Therefore, the titanium dioxide content is controlled at 5wt% to 10wt%, such as 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, and 10wt%.

[0046] Preferably, during the belt ejection in S2, the nozzle width is controlled to be 15-50 mm, the nozzle gap size is 0.045-0.065 mm, the distance between the nozzle and the copper roller is 0.1-0.2 mm, the nozzle pressure during ejection is 0.01-0.03 MPa, and the copper roller rotation speed is 20-30 m / s.

[0047] Specifically, the nozzle width, that is, the total lateral width of the nozzle, determines the lateral coverage of the melt injection, thereby affecting the width of the thin strip; a larger nozzle gap can increase the flow rate of molten metal, but a too large gap will lead to uneven distribution of the molten metal, affecting the thickness uniformity of the thin strip. A smaller gap size can increase the cooling rate, ensure that the molten metal solidifies quickly, and form a high-quality thin strip; a smaller distance between the nozzle and the copper roller can ensure that the molten metal forms a stable molten pool between the nozzle and the copper roller, thereby improving the cooling effect. A too large distance may cause the molten metal to flow unstably and form an uneven thin strip; appropriate nozzle injection pressure can ensure that the molten metal is evenly sprayed onto the copper roller to form a high-quality thin strip. Excessive pressure causes the molten metal to splash and form an uneven thin strip; the copper roller rotation speed affects the cooling rate of the molten metal and the thickness of the thin strip. If the rotation speed is too high, the molten metal will not stick to the roller and will not form a strip. If the rotation speed is too low, the cooling rate will be slow, which is not conducive to rapid solidification of the strip.

[0048] Through good process coordination, the surface quality and yield rate of the prepared non-oriented silicon steel ultra-thin strip are improved, and the yield rate of the strip is ≥90%.

[0049] It should be noted that in the process of preparing ultra-thin silicon steel strip by planar flow casting, the control of smaller nozzle gap size and the setting of other strip throwing parameters can only be achieved when the fluidity and impurity purification degree of the molten steel reach a high level; if the fluidity and purification degree of the molten steel are insufficient, the optimization of the above parameters will be difficult to achieve.

[0050] Preferably, the nozzle width is controlled to be 15mm, 20mm, 25mm, 30mm, 40mm, and 50mm, the nozzle gap size is 0.045mm, 0.05mm, 0.055mm, and 0.065mm, the distance between the nozzle and the copper roller is 0.1mm, 0.12mm, 0.14mm, 0.15mm, and 0.2mm, the pressure during nozzle spraying is 0.01MPa, 0.02MPa, and 0.03MPa, and the copper roller rotation speed is 20m / s, 25m / s, and 30m / s.

[0051] Furthermore, in S3, the total reduction rate of the cold rolling process is controlled to be 2% to 20%, the front tension of the rolling roll is 40 to 60N, and the rear tension is 30 to 50N.

[0052] In a possible design, the cold rolling reduction rate is 8%, combined with subsequent annealing at a temperature of 1150°C for 1 hour. The grain growth capacity of each orientation is improved, and in the grain growth process, the {001} favorable orientation grain growth has an obvious advantage, and the uniformity of the organization is also significantly optimized. Appropriate tension during cold rolling can ensure uniform deformation of the strip during rolling, thereby obtaining a more uniform texture and improving the consistency of magnetic properties.

[0053] By rolling with tension, the surface quality and pattern of ultra-thin silicon steel strips can be further optimized, while the deformation degree of grains can be increased and more dislocations can be introduced, thereby providing driving force for subsequent annealing grain growth, promoting grain growth, improving organizational structure, and optimizing texture. Preferably, the total reduction rate of the cold rolling process is 5%, 8%, 10%, 15%, 20%; the front tension of the rolling roller is 40N, 45N, 50N, 55N, 60N; the rear tension of the rolling roller is 30N, 35N, 40N, 45N, 50N.

[0054] Furthermore, in S4, the annealing temperature is controlled to be 900°C to 1200°C, and the annealing time is controlled to be 1h to 3h. Through high temperature annealing, the internal stress of the non-oriented silicon steel ultra-thin strip is eliminated, the organizational texture is optimized, and the magnetic properties are further improved.

[0055] During the small reduction rate rolling + annealing process, the grains grow unevenly, the average grain size increases from 6μm to 200-500μm, and the proportion of favorable {001} oriented grains increases, thereby optimizing the magnetic properties.

[0056] Preferably, the annealing atmosphere is controlled to be a mixed gas of hydrogen and nitrogen, wherein H 2 The volume fraction is ≥50%, and the cooling time is controlled to be ≥8min under the protective atmosphere. The hydrogen atmosphere can protect the non-oriented silicon steel ultra-thin strip from oxidation and improve its grain growth capacity. If the hydrogen content is too low, the surface is easily oxidized during the annealing process, and the surface quality is reduced.

[0057] On the other hand, a specific embodiment of the present invention further discloses a tellurium-containing non-oriented silicon steel ultra-thin strip, which is prepared by the plane flow casting method. 50 ≥1.66T, iron loss P 1.0 / 1000Hz ≤32W / kg, yield rate ≥90%.

[0058] By optimizing the alloy composition and melting the master alloy together with the purifier, the fluidity and purity of the master alloy melt of the present invention meet the requirements of the plane flow casting method, thereby improving the yield rate of strip casting. Compared with the process without adding Te element and purifier, the production cost can be reduced by more than 15% due to the increase in the yield rate.

[0059] By controlling the process parameters of the plane flow casting technology, the initial plane flow casting strip has a better initial structure, texture, pattern and surface quality; at the same time, through subsequent rolling and annealing treatment, its structure is further optimized and its magnetic properties are improved.

[0060] Specifically, Figure 1As shown, the non-oriented silicon steel ultra-thin strip has a thickness of 0.05-0.065 mm and a width of 15-50 mm. The addition of alloy elements and purifiers and the regulation of plane flow casting strip process parameters (roller speed, nozzle pressure, etc.) make the molten steel more closely attached to the roller and quickly cooled into a strip, thereby preparing an ultra-thin large-size non-oriented silicon steel ultra-thin strip product.

[0061] In summary, the present invention adopts the plane flow casting method to prepare the non-oriented silicon steel ultra-thin strip. By optimizing the alloy composition and melting the master alloy with the purifier, the fluidity and purity of the master alloy melt of the present invention meet the requirements of the plane flow casting method, and the strip throwing yield rate is improved. Then, through the cooperation of subsequent small reduction rate rolling and annealing, the grain growth is promoted, the strip microstructure and texture are improved, and the magnetic properties of the non-oriented silicon steel ultra-thin strip are improved. The prepared non-oriented silicon steel ultra-thin strip B 50 ≥1.66T, iron loss P 1.0 / 1000Hz ≤32W / kg, yield rate ≥90%.

[0062] The method for preparing tellurium-containing non-oriented silicon steel ultra-thin strip by plane flow casting of the present invention is described below with reference to specific embodiments.

[0063] Example 1

[0064] This embodiment provides a tellurium-containing non-oriented silicon steel ultra-thin strip and a preparation method thereof.

[0065] The composition and weight percentage of the master alloy raw materials are: tellurium: 0.05wt%, silicon: 3.0wt%, and the rest is iron and a small amount of other inevitable impurities, as shown in Table 1.

[0066] The method for preparing tellurium-containing non-oriented silicon steel ultra-thin strip by plane flow casting is shown in Table 2, and the steps are as follows:

[0067] S1. Using pig iron, silicon and tellurium raw materials with a purity greater than 99.99% to melt in a vacuum induction furnace to obtain a master alloy;

[0068] S2. A non-oriented silicon steel ultra-thin strip is prepared by a planar flow casting method. The master alloy and a purifier are placed in a quartz tube with a nozzle and heated until melted. The purifier comprises 35wt% calcium oxide, 45wt% graphite powder, 15wt% silicon carbide, and 5wt% titanium dioxide. The weight of the purifier is 0.5wt% of the total weight of the master alloy. The nozzle width is controlled to be 50mm, the gap size is 0.045mm, the distance between the nozzle and the copper roller is 0.1mm, the pressure during nozzle spraying is 0.02MPa, and the rotation speed of the copper roller is 25m / s.

[0069] S3, rolling the non-oriented silicon steel ultra-thin strip, wherein the total reduction rate is 5%, the front tension of the roller is 55N, and the rear tension is 45N;

[0070] S4. The non-oriented silicon steel ultra-thin strip is annealed, wherein the annealing holding temperature is 900° C., the annealing time is controlled to be 1 hour, the annealing atmosphere is 50% hydrogen + 50% nitrogen, and the cooling time is 10 minutes.

[0071] After testing and statistics, the surface of the silicon steel ultra-thin strip is smooth, and the magnetic properties of the non-oriented silicon steel ultra-thin strip containing trace amounts of tellurium are: B 50 =1.668T,P 1.0 / 1000Hz =30.81W / kg, the yield rate of the strip is 90.85%, which fully meets the high performance requirements of soft magnetic products.

[0072] Example 2

[0073] This embodiment provides a tellurium-containing non-oriented silicon steel ultra-thin strip and a preparation method thereof.

[0074] The composition and weight percentage of the master alloy raw materials are: tellurium: 0.06wt%, silicon: 2.5wt%, and the rest is iron and a small amount of other inevitable impurities, as shown in Table 1.

[0075] The method for preparing tellurium-containing non-oriented silicon steel ultra-thin strip by plane flow casting is shown in Table 2, and the steps are as follows:

[0076] S1. Using pig iron, silicon and tellurium raw materials with a purity greater than 99.99% to melt in a vacuum induction furnace to obtain a master alloy;

[0077] S2. A non-oriented silicon steel ultra-thin strip is prepared by a planar flow casting method. A master alloy and a purifier are placed in a quartz tube with a nozzle and heated until melted. The purifier comprises 25wt% calcium oxide, 50wt% graphite powder, 20wt% silicon carbide, and 5wt% titanium dioxide. The weight of the purifier is 0.6wt% of the total weight of the master alloy. The nozzle width is controlled to be 40mm, the gap size is 0.050mm, the distance between the nozzle and the copper roller is 0.12mm, the pressure during nozzle spraying is 0.02MPa, and the rotation speed of the copper roller is 30m / s.

[0078] S3, rolling the non-oriented silicon steel ultra-thin strip, wherein the total reduction rate is 10%, the front tension of the roller is 60N, and the rear tension is 50N;

[0079] S4. The non-oriented silicon steel ultra-thin strip is annealed, wherein the annealing holding temperature is 950° C., the annealing time is controlled to be 2 h, the annealing atmosphere is 50% hydrogen + 50% nitrogen, and the cooling time is 8 min.

[0080] After testing and statistics, the surface of the silicon steel ultra-thin strip is smooth, and the magnetic properties of the non-oriented silicon steel ultra-thin strip containing trace amounts of tellurium are: B 50 =1.672T,P 1.0 / 1000Hz=30.88W / kg, the yield rate of the strip is 91.5%, which fully meets the high performance requirements of soft magnetic products.

[0081] Example 3

[0082] This embodiment provides a tellurium-containing non-oriented silicon steel ultra-thin strip and a preparation method thereof.

[0083] The composition and weight percentage of the master alloy raw materials are: tellurium: 0.10wt%, silicon: 3.0wt%, and the rest is iron and a small amount of other inevitable impurities, as shown in Table 1.

[0084] The method for preparing tellurium-containing non-oriented silicon steel ultra-thin strip by plane flow casting is shown in Table 2, and the steps are as follows:

[0085] S1. Using pig iron, silicon and tellurium raw materials with a purity greater than 99.99% to melt in a vacuum induction furnace to obtain a master alloy;

[0086] S2. A non-oriented silicon steel ultra-thin strip is prepared by a planar flow casting method. A master alloy and a purifier are placed in a quartz tube with a nozzle and heated until melted. The purifier comprises 25wt% calcium oxide, 50wt% graphite powder, 15wt% silicon carbide, and 10wt% titanium dioxide. The weight of the purifier is 0.5wt% of the total weight of the master alloy. The nozzle width is controlled to be 35mm, the gap size is 0.05mm, the distance between the nozzle and the copper roller is 0.14mm, the pressure during nozzle spraying is 0.01MPa, and the rotation speed of the copper roller is 20m / s.

[0087] S3, rolling the non-oriented silicon steel ultra-thin strip, wherein the total reduction rate is 15%, the front tension of the roller is 40N, and the rear tension is 30N;

[0088] S4. The non-oriented silicon steel ultra-thin strip is annealed, wherein the annealing holding temperature is 1000° C., the annealing time is controlled to be 2 hours, the annealing atmosphere is 70% hydrogen + 30% nitrogen, and the cooling time is 10 minutes.

[0089] After testing and statistics, the surface of the silicon steel ultra-thin strip is smooth, and the magnetic properties of the non-oriented silicon steel ultra-thin strip containing trace amounts of tellurium are: B 50 =1.672T,P 1.0 / 1000Hz =29.85W / kg, the yield rate of the strip is 92.2%, which fully meets the high performance requirements of soft magnetic products.

[0090] Example 4

[0091] This embodiment provides a tellurium-containing non-oriented silicon steel ultra-thin strip and a preparation method thereof.

[0092] The composition and weight percentage of the master alloy raw materials are: tellurium: 0.05wt%, silicon: 3.0wt%, and the rest is iron and a small amount of other inevitable impurities, as shown in Table 1.

[0093] The method for preparing tellurium-containing non-oriented silicon steel ultra-thin strip by plane flow casting is shown in Table 2, and the steps are as follows:

[0094] S1. Using pig iron, silicon and tellurium raw materials with a purity greater than 99.99% to melt in a vacuum induction furnace to obtain a master alloy;

[0095] S2. A non-oriented silicon steel ultra-thin strip is prepared by a planar flow casting method. A master alloy and a purifier are placed in a quartz tube with a nozzle and heated until melted. The purifier comprises 35wt% calcium oxide, 45wt% graphite powder, 15wt% silicon carbide, and 5wt% titanium dioxide. The weight of the purifier is 0.8wt% of the total weight of the master alloy. The nozzle width is controlled to be 25mm, the gap size is 0.050mm, the distance between the nozzle and the copper roller is 0.2mm, the pressure during nozzle spraying is 0.03MPa, and the rotation speed of the copper roller is 25m / s.

[0096] S3, rolling the non-oriented silicon steel ultra-thin strip, wherein the total reduction rate is 10%, the front tension of the roller is 55N, and the rear tension is 50N;

[0097] S4. The non-oriented silicon steel ultra-thin strip is annealed, wherein the annealing holding temperature is 1100° C., the annealing time is controlled to be 1 hour, the annealing atmosphere is 90% hydrogen + 10% nitrogen, and the cooling time is 8 minutes.

[0098] After testing and statistics, the surface of the silicon steel ultra-thin strip is smooth, and the magnetic properties of the non-oriented silicon steel ultra-thin strip containing trace amounts of tellurium are: B 50 =1.684T,P 1.0 / 1000Hz =31.88W / kg, the yield rate of the strip is 93.4%, which fully meets the high performance requirements of soft magnetic products.

[0099] Example 5

[0100] This embodiment provides a tellurium-containing non-oriented silicon steel ultra-thin strip and a preparation method thereof.

[0101] The composition and weight percentage of the master alloy raw materials are: tellurium: 0.05wt%, silicon: 3.5wt%, and the rest is iron and a small amount of other inevitable impurities, as shown in Table 1.

[0102] The method for preparing tellurium-containing non-oriented silicon steel ultra-thin strip by plane flow casting is shown in Table 2, and the steps are as follows:

[0103] S1. Using pig iron, silicon and tellurium raw materials with a purity greater than 99.99% to melt in a vacuum induction furnace to obtain a master alloy;

[0104] S2. A non-oriented silicon steel ultra-thin strip is prepared by a planar flow casting method. A master alloy and a purifier are placed in a quartz tube with a nozzle and heated until melted. The purifier comprises 40wt% calcium oxide, 35wt% graphite powder, 20wt% silicon carbide, and 5wt% titanium dioxide. The weight of the purifier is 0.7wt% of the total weight of the master alloy. The nozzle width is controlled to be 50mm, the gap size is 0.065mm, the distance between the nozzle and the copper roller is 0.2mm, the pressure during nozzle spraying is 0.3MPa, and the rotation speed of the copper roller is 30m / s.

[0105] S3, rolling the non-oriented silicon steel ultra-thin strip, wherein the total reduction rate is 8%, the front tension of the roller is 40N, and the rear tension is 30N;

[0106] S4. The non-oriented silicon steel ultra-thin strip is annealed, wherein the annealing holding temperature is 1150° C., the annealing time is controlled to be 1 hour, the annealing atmosphere is 100% hydrogen, and the cooling time is 10 minutes.

[0107] After testing and statistics, the surface of the silicon steel ultra-thin strip is smooth, and the magnetic properties of the non-oriented silicon steel ultra-thin strip containing trace amounts of tellurium are: B 50 =1.701T,P 1.0 / 1000Hz =31.85W / kg, the yield rate of the strip is 92.8%, which fully meets the high performance requirements of soft magnetic products.

[0108] Example 6

[0109] This embodiment provides a tellurium-containing non-oriented silicon steel ultra-thin strip and a preparation method thereof.

[0110] The composition and weight percentage of the master alloy raw materials are: tellurium: 0.05wt%, silicon: 3.0wt%, and the rest is iron and a small amount of other inevitable impurities, as shown in Table 1.

[0111] The method for preparing tellurium-containing non-oriented silicon steel ultra-thin strip by plane flow casting is shown in Table 2, and the steps are as follows:

[0112] S1. Using pig iron, silicon and tellurium raw materials with a purity greater than 99.99% to melt in a vacuum induction furnace to obtain a master alloy;

[0113] S2. Prepare non-oriented silicon steel ultra-thin strip by planar flow casting method, put the master alloy and purifier into a quartz tube with a nozzle and heat them until they are melted, wherein the components of the purifier are calcium oxide: 35wt%, graphite powder: 45wt%, silicon carbide: 15wt%, titanium dioxide: 5wt%, and the weight of the added purifier is 0.8wt% of the total weight of the master alloy; and control the nozzle width to 45mm, the gap size to 0.065mm, the distance between the nozzle and the copper roller to 0.15mm, the pressure during nozzle spraying to 0.025MPa, and the rotation speed of the copper roller to 25m / s.

[0114] S3, rolling the non-oriented silicon steel ultra-thin strip, wherein the total reduction rate is 20%, the front tension of the roller is 60N, and the rear tension is 50N;

[0115] S4. The non-oriented silicon steel ultra-thin strip is annealed, wherein the annealing holding temperature is 1150° C., the annealing time is controlled to be 3 hours, the annealing atmosphere is 100% hydrogen, and the cooling time is 10 minutes.

[0116] After testing and statistics, the surface of the silicon steel ultra-thin strip is smooth, and the magnetic properties of the non-oriented silicon steel ultra-thin strip containing trace amounts of tellurium are: B 50 =1.663T,P 1.0 / 1000Hz =28.08W / kg, the yield rate of the strip is 91.8%, which fully meets the high performance requirements of soft magnetic products.

[0117] Comparative Example 1

[0118] This comparative example provides a tellurium-containing non-oriented silicon steel ultra-thin strip and a preparation method thereof.

[0119] The composition and weight percentage of the master alloy raw materials are shown in Table 1, wherein the silicon content does not meet the requirements of the present invention.

[0120] The method for preparing tellurium-containing non-oriented silicon steel ultra-thin strip by plane flow casting is the same as that in Example 1, and the specific parameters are shown in Table 2.

[0121] After testing and statistics, the magnetic properties and yield rate of ultra-thin non-oriented silicon steel strip containing trace amounts of tellurium are shown in Table 3.

[0122] Comparative Example 2

[0123] This comparative example provides a tellurium-containing non-oriented silicon steel ultra-thin strip and a preparation method thereof.

[0124] The composition and weight percentage of the master alloy raw materials are shown in Table 1, wherein the master alloy raw materials do not contain tellurium element.

[0125] The method for preparing tellurium-containing non-oriented silicon steel ultra-thin strip by plane flow casting is the same as that in Example 1, and the specific parameters are shown in Table 2

[0126] After testing and statistics, the magnetic properties and yield rate of ultra-thin non-oriented silicon steel strip containing trace amounts of tellurium are shown in Table 3.

[0127] Comparative Examples 3 to 6

[0128] This comparative example provides a tellurium-containing non-oriented silicon steel ultra-thin strip and a preparation method thereof.

[0129] The composition and weight percentage of the master alloy raw materials are shown in Table 1.

[0130] The method for preparing tellurium-containing non-oriented silicon steel ultra-thin strip by plane flow casting is basically the same as that in Example 1, except that the composition or content of the purifier is different from that in Example 1. The specific parameters are shown in Table 2.

[0131] After testing and statistics, the magnetic properties and yield rate of ultra-thin non-oriented silicon steel strip containing trace amounts of tellurium are shown in Table 3.

[0132] Comparative Example 7

[0133] This comparative example provides a tellurium-containing non-oriented silicon steel ultra-thin strip and a preparation method thereof.

[0134] The composition and weight percentage of the master alloy raw materials are shown in Table 1.

[0135] The method for preparing tellurium-containing non-oriented silicon steel ultra-thin strip by plane flow casting is basically the same as that in Example 1, except that the mass fraction of the weight of the added purifier to the total weight of the master alloy is different from that in Example 1. The specific parameters are shown in Table 2.

[0136] After testing and statistics, the magnetic properties and yield rate of ultra-thin non-oriented silicon steel strip containing trace amounts of tellurium are shown in Table 3.

[0137] Comparative Examples 8 to 9

[0138] This comparative example provides a tellurium-containing non-oriented silicon steel ultra-thin strip and a preparation method thereof.

[0139] The composition and weight percentage of the master alloy raw materials are shown in Table 1.

[0140] The method for preparing tellurium-containing non-oriented silicon steel ultra-thin strip by plane flow casting is basically the same as that in Example 1, except that the nozzle width or gap size of the plane flow casting machine is different from that in Example 1. The specific parameters are shown in Table 2.

[0141] After testing and statistics, the magnetic properties and yield rate of ultra-thin non-oriented silicon steel strip containing trace amounts of tellurium are shown in Table 3.

[0142] Comparative Example 10

[0143] This comparative example provides a tellurium-containing non-oriented silicon steel ultra-thin strip and a preparation method thereof.

[0144] The composition and weight percentage of the master alloy raw materials are shown in Table 1.

[0145] The method for preparing tellurium-containing non-oriented silicon steel ultra-thin strip by plane flow casting is basically the same as that in Example 1, except that in step S3, the cold rolling reduction is different from that in Example 1. The specific parameters are shown in Table 2

[0146] After testing and statistics, the magnetic properties and yield rate of ultra-thin non-oriented silicon steel strip containing trace amounts of tellurium are shown in Table 3.

[0147] Comparative Example 11

[0148] This comparative example provides a tellurium-containing non-oriented silicon steel ultra-thin strip and a preparation method thereof.

[0149] The composition and weight percentage of the master alloy raw materials are shown in Table 1.

[0150] The method for preparing tellurium-containing non-oriented silicon steel ultra-thin strip by plane flow casting is basically the same as that in Example 1, except that the annealing atmosphere H 2 The content is different, and the specific parameters are shown in Table 2

[0151] After testing and statistics, the magnetic properties and yield rate of ultra-thin non-oriented silicon steel strip containing trace amounts of tellurium are shown in Table 3.

[0152] Comparative Example 12

[0153] This comparative example provides a tellurium-containing non-oriented silicon steel ultra-thin strip and a preparation method thereof.

[0154] The composition and weight percentage of the master alloy raw materials are shown in Table 1.

[0155] The method for preparing tellurium-containing non-oriented silicon steel ultra-thin strip by plane flow casting is basically the same as that in Example 1, except that the annealing temperature is different. The specific parameters are shown in Table 2.

[0156] After testing and statistics, the magnetic properties and yield rate of ultra-thin non-oriented silicon steel strip containing trace amounts of tellurium are shown in Table 3.

[0157] Table 1 Composition of master alloy and purifier in Examples and Comparative Examples

[0158]

[0159]

[0160] Table 2 Process parameters for preparing ultra-thin silicon steel strips in the examples and comparative examples

[0161]

[0162]

[0163] Table 3 Magnetic properties and yield rate of non-oriented silicon steel ultra-thin strips in the embodiments and comparative examples

[0164]

[0165] It can be seen from Table 1, Table 2 and Table 3 that the alloy composition, purifier composition and composition of Examples 1 to 6, as well as the selection of plane flow casting process parameters, cold rolling process parameters and annealing process parameters all meet the requirements of the present invention, and the prepared non-oriented silicon steel ultra-thin strip B 50 ≥1.66T, iron loss P 1.0 / 1000Hz ≤32W / kg, yield rate ≥90%.

[0166] Compared with Example 1, the silicon content in the alloy composition of Comparative Example 1 is higher than the requirement of the present invention. Although the formability is improved, the excess silicon element reduces the saturation magnetic induction intensity value; compared with Example 1, the mother alloy raw material of Comparative Example 2 does not contain tellurium element, the fluidity of the molten steel is poor, and the yield rate is significantly reduced.

[0167] Compared with Example 1, the composition or percentage of the purifier in Comparative Examples 3 to 6 does not meet the requirements of the present invention, resulting in a decrease in the fluidity of the molten steel and the purification effect of impurities to varying degrees, and a lower strip-spinning yield rate; compared with Example 1, the mass fraction of the weight of the added purifier in Comparative Example 7 does not meet the requirements of the present invention, and the amount of purifier added is too little to purify the impurities and improve their fluidity, resulting in a low strip-spinning yield rate.

[0168] Compared with Example 1, in Comparative Example 8, the total width of the nozzle of the planar flow casting machine is too large, which reduces the strip casting yield rate; compared with Example 1, in Comparative Example 9, the nozzle gap size of the planar flow casting machine is too small, resulting in the inability to obtain a relatively complete and continuous strip in the planar flow casting process.

[0169] Compared with Example 1, the cold rolling reduction in Comparative Example 10 is too large, the balance between iron loss and magnetic induction intensity is broken, and the magnetic properties are reduced.

[0170] Comparative Example 11 Compared with Example 1, the annealing atmosphere H 2 When the content is lower than 50%, the iron loss increases significantly; compared with Example 1, the annealing temperature of Comparative Example 12 is lower, resulting in increased iron loss and reduced magnetic induction intensity.

[0171] In summary, the present invention adopts the plane flow casting method to prepare the non-oriented silicon steel ultra-thin strip. By optimizing the alloy composition and melting the master alloy with the purifier, the fluidity and purity of the master alloy melt of the present invention meet the requirements of the plane flow casting method, and the strip throwing yield rate is improved. Then, through the cooperation of subsequent small reduction rate rolling and annealing, the grain growth is promoted, the strip microstructure and texture are improved, and the magnetic properties of the non-oriented silicon steel ultra-thin strip are improved. The prepared non-oriented silicon steel ultra-thin strip B 50 ≥1.66T, iron loss P1.0 / 1000Hz ≤32W / kg, yield rate ≥90%.

[0172] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for preparing tellurium-containing non-oriented silicon steel ultra-thin strip by plane flow casting, characterized in that: The steps include: S1. The master alloy ingot is cast by vacuum induction melting, and the raw materials are pig iron, silicon and tellurium with a purity greater than 99.99%; S2, plane flow casting: the master alloy ingot prepared in S1 and the purifier are placed in a quartz tube with a nozzle of a plane flow casting machine and heated until melted, and then the strip is ejected onto a rotating cooling copper roller for directional solidification, and finally the silicon steel ultra-thin strip is peeled off; S3, performing a tension-based cold rolling process on the ultra-thin silicon steel strip prepared in S2; S4. Annealing the rolled ultra-thin silicon steel strip.

2. The method according to claim 1, characterized in that The chemical composition of the master alloy ingot in S1 is, in terms of mass percentage, tellurium: 0.05wt% to 0.1wt%; silicon: 2.5wt% to 3.5wt%; the rest is iron and a small amount of other inevitable impurities.

3. The method according to claim 1, characterized in that During the belt ejection in S2, the nozzle width is controlled to be 15-50 mm, the nozzle gap size is 0.045-0.065 mm, and the distance between the nozzle and the copper roller is 0.1-0.2 mm.

4. The method according to claim 3, characterized in that: During the belt ejection in S2, the nozzle ejection pressure is 0.01-0.03 MPa, and the copper roller rotation speed is 20-30 m / s.

5. The method according to claim 1, characterized in that In S3, the cold rolling process is controlled, and the total reduction rate is controlled at 2% to 20%.

6. The method according to claim 5, characterized in that In S3, the cold rolling process is controlled, the front tension of the rolling roller is 40-60N, and the rear tension is 30-50N.

7. The method according to claim 1, characterized in that In S4, the annealing holding temperature is controlled to be 900° C. to 1200° C., and the annealing time is controlled to be 1 h to 3 h.

8. The method according to claim 7, characterized in that The annealing atmosphere is controlled to be a mixed gas of hydrogen and nitrogen, wherein the H2 content is ≥50%, and the cooling time is controlled to be ≥8min under the protective atmosphere.

9. A tellurium-containing non-oriented silicon steel ultra-thin strip, characterized in that: The non-oriented silicon steel ultra-thin strip B is prepared by the planar flow casting method according to any one of claims 1 to 8. 50 ≥1.66T, iron loss P 1.0 / 1000Hz ≤32W / kg.

10. The tellurium-containing non-oriented silicon steel ultra-thin strip according to claim 9, characterized in that: The tellurium-containing non-oriented silicon steel ultra-thin strip has a thickness of 0.05 to 0.065 mm and a width of 15 to 50 mm.

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