A method for preparing tellurium-containing non-oriented silicon steel ultra-thin strip by using plane flow casting method

Abstract

The application relates to a method for preparing tellurium-containing non-oriented silicon steel ultra-thin strips by using a plane flow casting method, and belongs to the technical field of material preparation. The method solves the problems of low spinning forming rate, poor macroscopic size and surface quality of the strips and low magnetic performance of the non-oriented silicon steel ultra-thin strips prepared by using the plane flow casting method in the prior art. The method comprises the following steps: S1, adopting vacuum induction melting and pouring a mother alloy ingot, wherein the raw materials are pig iron, silicon and tellurium with a purity greater than 99.99%; S2, plane flow casting: placing the mother alloy ingot and a purifying agent into a quartz tube of a nozzle of a plane flow casting machine, heating to melting, spinning and spraying onto a rotating cooling copper roller to perform directional solidification, and finally stripping the silicon steel ultra-thin strips; S3, performing cold rolling treatment on the silicon steel ultra-thin strips with tension; and S4, performing annealing treatment on the rolled silicon steel ultra-thin strips. The method improves the material yield and the magnetic performance of the non-oriented silicon steel ultra-thin strips prepared by using the plane flow casting method.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of material preparation, and particularly relates to a method for preparing a tellurium-containing non-oriented silicon steel ultra-thin strip by using a plane flow casting method. BACKGROUND

[0002] As an important soft magnetic material, non-oriented silicon steel is a core material for preparing engine and motor cores, and is widely used in power electronic devices such as large, medium and small generators and small motors. The most important performance index affecting its efficiency is magnetic performance. The thickness reduction 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 mainly two ways for preparing non-oriented silicon steel ultra-thin strips. One is to use a traditional rolling method. Although the non-oriented silicon steel ultra-thin strip with a thickness of less than 0.1 mm can be produced by using the traditional rolling method, the method has obvious disadvantages. The whole preparation process is complex and has many procedures, which directly leads to a long production cycle. In addition, a large amount of energy is consumed in the production process, and the cost is also increased, which makes the method face many obstacles in large-scale popularization and application. The other way is to use a double-roller thin strip continuous casting technology. The technology can realize the sub-rapid solidification of molten steel, and then directly form a relatively thick initial casting strip. The initial casting strip is further thinned by using a rolling process, and the non-oriented silicon steel ultra-thin strip with a thickness of 0.1 mm can also be prepared. Unfortunately, there are still some problems to be solved in the technology at present, such as poor quality of the produced thin strip and poor product yield, which limit the further development and application of the technology.

[0004] The non-oriented silicon steel ultra-thin strip is prepared by using the plane flow casting method. The process flow is short, the energy consumption is low, the rapid solidification of liquid metal can be realized in a short time, the obtained strip has uniform and fine structure, and contains columnar crystal structure which is beneficial to magnetic performance. However, the melting point of the silicon steel melt is high, the fluidity is poor, and the surface tension is large, so the application range of the plane flow casting technology is small. The forming ability, macroscopic size and surface quality of the produced strip are not ideal, and the magnetic performance is poor. SUMMARY

[0005] In view of the above analysis, the embodiments of the present application aim to provide a method for preparing a tellurium-containing non-oriented silicon steel ultra-thin strip by using a plane flow casting method, so as to solve at least one of the problems of low spinning forming rate, poor macroscopic size and surface quality of the strip, and poor magnetic performance of the non-oriented silicon steel ultra-thin strip prepared by using the existing plane flow casting method.

[0006] In one aspect, the embodiments of the present application disclose a method for preparing a tellurium-containing non-oriented silicon steel ultra-thin strip by using a plane flow casting method, which comprises the following steps:

[0007] S1, adopting vacuum induction melting and pouring mother alloy ingot, raw materials are pig iron, silicon and tellurium with purity greater than 99.99%;

[0008] S2, planar flow casting: putting the mother alloy ingot prepared in S1 and purifying agent into a quartz tube with nozzle of planar flow casting machine and heating to melt, then spraying to rotating cooling copper roller to perform directional solidification, and finally stripping out silicon steel ultra-thin strip;

[0009] S3, performing cold rolling treatment with tension to the silicon steel ultra-thin strip prepared in S2;

[0010] S4, performing annealing treatment to the rolled silicon steel ultra-thin strip.

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

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

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

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

[0015] Preferably, the annealing atmosphere is controlled to be a mixed gas of hydrogen and nitrogen, wherein the H2 content is ≥50%, and the cooling time under the protective atmosphere is ≥8min.

[0016] On the other hand, the embodiment of the present application also discloses a tellurium-containing non-oriented silicon steel ultra-thin strip 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 0.05-0.065mm and a width of 15-50mm.

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

[0019] 1. The application adopts a plane flow casting method to prepare an ultra-thin strip of non-oriented silicon steel, and by optimizing alloy composition and melting the master alloy together with a purifying agent, the fluidity and purity of the master alloy melt meet the requirements of the plane flow casting method, the strip yield is improved, and the strip yield is greater than or equal to 90%.

[0020] 2. By optimizing alloy elements, adding purifying agents and adjusting plane flow casting and strip casting process parameters (roller speed, nozzle pressure, etc.), the molten steel is quickly cooled to form a strip by adhering to the roller, and an ultra-thin large-size non-oriented silicon steel ultra-thin strip product is prepared, with a thickness of 0.05-0.065mm and a width of 15-50mm.

[0021] 3. By optimizing the process parameters of the plane flow casting technology, the initial plane flow casting strip can have excellent microstructure, pattern and surface quality, and a high yield can be achieved; on this basis, after subsequent small reduction rolling and annealing, the grain growth is promoted, and the microstructure of the strip is further optimized, thereby improving the magnetic properties of the non-oriented silicon steel ultra-thin strip, and the prepared non-oriented silicon steel ultra-thin strip has a B 50 ≥1.66T, and a core loss P 1.0 / 1000Hz ≤32W / kg.

[0022] 4. By precisely controlling the total reduction rate and roller tension during cold rolling, the surface quality and pattern of the silicon steel ultra-thin strip are further optimized, and the deformation degree and dislocation distribution of the grains are adjusted, thereby providing driving force for subsequent annealing grain growth, promoting grain growth, improving microstructure and optimizing texture; on this basis, through subsequent annealing treatment, the growth ability of each oriented grain is improved, especially the growth advantage of {001} favorable orientation grains is more obvious, the microstructure uniformity is significantly optimized, and the magnetic properties are improved.

[0023] 5. By controlling the annealing temperature and time, annealing in a high-temperature hydrogen atmosphere can adjust the optimal grain size and texture, thereby further improving the magnetic properties; annealing in an atmosphere with a hydrogen content of more than 50% can not only prevent the non-oriented silicon steel ultra-thin strip from being oxidized, but also improve its grain growth ability, thereby optimizing the texture uniformity and improving the consistency and stability of the magnetic properties.

[0024] 6. The application designs a purifying agent suitable for non-oriented silicon steel master alloy, which meets the strict control of impurity elements and the requirement of melt fluidity for plane flow casting method; by melting the purifying agent together with the master alloy during plane flow casting, compared with adding the purifying agent during the master alloy smelting process, the effect of optimizing the fluidity of the molten steel and purifying impurities is better, which can significantly improve the strip yield while preparing wider strips (width range 15-50mm).

[0025] The technical solutions in the present application can be combined with each other to realize more preferred combination solutions. Other features and advantages of the present application will be described in the following description, and some advantages will become apparent from the description or can be learned by practice of the present application. The objects and other advantages of the present application can be realized and obtained by the content particularly pointed out in the description and the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0026] The accompanying drawings are included to provide a further understanding of the present application, and are incorporated in and constitute a part of this application, illustrate embodiments of the present application, and together with the description serve to explain the principles of the present application, and should not be considered limiting of the present application in scope, as the present application can admit to other equally effective embodiments.

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

[0028] The preferred embodiments of the present application will be described in detail below with reference to the drawings, wherein the drawings constitute a part of this application, and are used to explain the principles of the embodiments of the present application, and are not considered limiting the scope of the present application, as the present application can admit to other equally effective embodiments.

[0029] In one aspect, one specific embodiment of the present application 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:

[0030] S1, using vacuum induction melting to pour the master alloy ingot, the raw materials are pig iron, silicon and tellurium with a purity of more than 99.99%;

[0031] S2, planar flow casting: placing the master alloy ingot prepared in S1 and the purifying agent into the quartz tube of the planar flow casting machine with a nozzle and heating to melt, then spraying to the rotating cooling copper roller for directional rapid solidification, and finally stripping out the silicon steel ultra-thin strip;

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

[0033] S4, performing annealing treatment on the rolled silicon steel ultra-thin strip.

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

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

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

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

[0038] It should be noted that the weight of the purifying agent added in S2 is 0.5wt%-0.8wt% of the total weight of the master alloy. Too little purifying agent does not have the effect of purifying impurities and improving fluidity, and too much purifying agent does not significantly improve the purification effect and increases the cost. Compared with adding the purifying agent during the melting process of the master alloy, adding the purifying agent during the planar flow casting process can optimize the fluidity of the steel liquid and improve the impurity purification effect, which can significantly improve the strip forming rate while preparing wider strips.

[0039] The mechanism and effect of the components of the purifying agent and the added elements of the master alloy will be described below.

[0040] Silicon: The addition of silicon can greatly increase the resistivity, reduce the eddy current loss, and effectively reduce the iron loss; at the same time, the increase of silicon is beneficial to reduce the magnetostriction, thereby reducing the noise of the iron core during operation; the increase of silicon content can also reduce the melting point of the melt, to a certain extent, improve the formability during the preparation of ultra-thin strips of non-oriented silicon steel by planar flow casting. However, excessive silicon can reduce the saturation magnetic induction value and affect the processing plasticity. Therefore, the silicon content is controlled to be 2.5wt%-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 the steel liquid. This makes the steel liquid better fill the mold or form a uniform thin strip during the solidification process, which is beneficial to produce silicon steel products with thinner thickness and more accurate size, and can also reduce defects such as pores and inclusions caused by poor fluidity of the steel liquid. Therefore, the tellurium content is controlled to be 0.05wt%-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, is a good desulfurizer, and can combine with aluminum oxide in the molten steel to form a low-melting-point substance, thereby floating up during the cooling process of the melt to achieve the ability to purify the melt; however, excessive addition of calcium oxide will cause the melt to become viscous and the fluidity to deteriorate, so it is controlled at 25wt%-40wt%, such as 25wt%, 30wt%, 35wt%, 40wt%.

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

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

[0045] Titanium dioxide: Titanium dioxide can have good deoxidizing effect, purify the steel liquid, and promote the nucleation of grains. Titanium dioxide (TiO2) as a heterogeneous phase can provide additional nucleation sites for grains during crystallization. Because there are some active sites on the surface of TiO2, these sites can interact with solute atoms, like a "small pit", solute atoms are easy to gather in these "small pits" and begin to form crystal nuclei. Therefore, the content of titanium dioxide is controlled at 5wt%-10wt%, such as 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%.

[0046] Preferably, during the spraying of the strip in S2, the nozzle width is controlled at 15-50mm, the gap size of the nozzle is 0.045-0.065mm, the distance between the nozzle and the copper roller is 0.1-0.2mm, the pressure of the nozzle when spraying is 0.01-0.03MPa, and the rotating speed of the copper roller is 20-30m / s.

[0047] Specifically, the nozzle width, i.e. the total width of the nozzle in the transverse direction, determines the transverse coverage of the melt jet, thereby affecting the width of the thin strip; a larger nozzle gap can increase the flow of molten metal, but too large a gap can lead to uneven distribution of the metal liquid, affecting the thickness uniformity of the thin strip; a smaller gap size can improve the cooling speed, ensuring rapid solidification of the metal liquid, and form a high-quality thin strip; a smaller distance between the nozzle and the copper roller can ensure the formation of a stable pool of metal liquid between the nozzle and the copper roller, improving the cooling effect, and an excessively large distance can lead to unstable flow of the metal liquid, forming an uneven thin strip; appropriate nozzle jet pressure can ensure uniform jetting of the metal liquid onto the copper roller, forming a high-quality thin strip, and excessively high pressure can cause the metal liquid to splash, forming an uneven thin strip; the rotation speed of the copper roller affects the cooling speed of the metal liquid and the thickness of the thin strip, and excessively high rotation speed can cause the metal liquid to not adhere to the roller and not form a strip, and excessively low rotation speed can result in slow cooling speed, which is not conducive to rapid solidification of the spun strip.

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

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

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

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

[0052] In one possible design, the cold rolling reduction rate is 8%, and the subsequent annealing is performed at a temperature of 1150℃ for 1 h, the growth ability of each oriented grain is improved, and the {001} favorable orientation grain growth advantage is obvious during the grain growth process, and the microstructure uniformity is also obviously optimized. Appropriate tension during cold rolling can ensure uniform deformation of the strip during rolling, thereby obtaining more uniform texture, thereby improving the consistency of magnetic properties.

[0053] By tension rolling, the surface quality and profile of the silicon steel ultra-thin strip are further optimized, the deformation degree of the crystal grains is increased, more dislocations are introduced, and driving force is provided for subsequent annealing grain growth, so that the grain growth is promoted, the structure is improved, and the texture is optimized.

[0054] Further, in S4, the annealing holding temperature is controlled to be 900-1200 DEG C, and the annealing time is controlled to be 1-3 hours.

[0055] In the process of small reduction rolling and annealing, the grains grow unevenly, the average grain size is increased from 6 microns to 200-500 microns, and the proportion of favorable {001} oriented grains is increased, thereby realizing the optimization of magnetic properties.

[0056] Preferably, the annealing atmosphere is controlled to be a mixed gas of hydrogen and nitrogen, wherein the H2 volume fraction is greater than or equal to 50%, and the cooling time under the protective atmosphere is greater than or equal to 8 minutes.

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

[0058] By optimizing the alloy composition, melting the master alloy together with the purifying agent, the fluidity and purity of the master alloy melt of the present application meet the requirements of the plane flow casting method, the strip production yield is improved, and the production cost is reduced by more than 15% compared with the process without Te element and purifying agent.

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

[0060] Specifically, as 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 alloying elements and purifying agents and the regulation of the planar flow casting and strip casting process parameters (roller speed, nozzle pressure, etc.) make the molten steel adhere to the roller and cool quickly into a strip, thereby preparing the non-oriented silicon steel ultra-thin strip product with large size and ultra-thin thickness.

[0061] To sum up, the present application adopts the planar flow casting method to prepare the non-oriented silicon steel ultra-thin strip, optimizes the alloy composition, melts the master alloy together with the purifying agent, so that the fluidity and purity of the master alloy melt meet the requirements of the planar flow casting method, improves the strip forming rate, and then cooperates with subsequent small reduction rolling and annealing to promote grain growth and improve the microstructure of the strip, thereby improving the magnetic properties of the non-oriented silicon steel ultra-thin strip, and the prepared non-oriented silicon steel ultra-thin strip has the following properties: B 50 ≥1.66T, iron loss P 1.0 / 1000Hz ≤32W / kg, forming rate ≥90%.

[0062] The method for preparing the tellurium-containing non-oriented silicon steel ultra-thin strip by the planar flow casting method will be described below in combination with specific examples.

[0063] Example 1

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

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

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

[0067] S1, melting the raw materials of pure iron, silicon and tellurium with a purity greater than 99.99% in a vacuum induction furnace to obtain a master alloy;

[0068] S2, preparing the non-oriented silicon steel ultra-thin strip by the planar flow casting method, putting the master alloy and purifying agent into the quartz tube of the nozzle and heating to melting, wherein the composition of the purifying agent is calcium oxide: 35wt%, graphite powder: 45wt%, silicon carbide: 15wt%, and titanium dioxide: 5wt%, the weight of the purifying agent is 0.5wt% of the total weight of the master alloy; and the nozzle width is controlled to be 50 mm, the gap size is 0.045 mm, the distance between the nozzle and the copper roller is 0.1 mm, the pressure of the nozzle when spraying is 0.02 MPa, and the copper roller rotating speed is 25 m / s;

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

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

[0071] After detection and statistics, the surface of the silicon steel ultra-thin strip is smooth, the magnetic properties of the non-oriented silicon steel ultra-thin strip containing trace tellurium are: B 50 =1.668T, P 1.0 / 1000Hz =30.81W / kg, the strip winding yield is 90.85%, and the high performance requirement standard of the soft magnetic product is completely met. As shown in Table 3.

[0072] Embodiment 2

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

[0074] The mother alloy raw material composition and the weight percentage are as follows: 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 the non-oriented silicon steel ultra-thin strip containing tellurium by using a plane flow casting method is as shown in Table 2, and the steps are as follows:

[0076] S1, melting the raw materials of pig iron, silicon and tellurium with a purity greater than 99.99% in a vacuum induction furnace to obtain a mother alloy;

[0077] S2, preparing the non-oriented silicon steel ultra-thin strip by using a plane flow casting method, putting the mother alloy and a purifying agent into a quartz tube of a strip nozzle and heating to melting, wherein the composition of the purifying agent is as follows: calcium oxide: 25wt%, graphite powder: 50wt%, silicon carbide: 20wt%, and titanium dioxide: 5wt%, the weight of the purifying agent is 0.6wt% of the total weight of the mother 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 of the nozzle spraying is 0.02MPa, and the copper roller rotating speed is 30m / s;

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

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

[0080] After detection and statistics, the surface of the silicon steel ultra-thin strip is smooth, the magnetic properties of the non-oriented silicon steel ultra-thin strip containing trace tellurium are: B 50 =1.672T, P 1.0 / 1000Hz= 30.88 W / kg, the strip yield is 91.5%, which fully meets the high performance requirement standard of soft magnetic products. As shown in Table 3.

[0081] Example 3

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

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

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

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

[0086] S2, using a plane flow casting method to prepare the ultra-thin strip of non-oriented silicon steel, the mother alloy and a purifying agent are put into a quartz tube of a strip nozzle and heated to melt, wherein the composition of the purifying agent is calcium oxide: 25wt%, graphite powder: 50wt%, silicon carbide: 15wt%, and titanium dioxide: 10wt%, the weight of the purifying agent is 0.5wt% of the total weight of the mother alloy; and 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 of the nozzle when spraying is 0.01MPa, and the copper roller rotating speed is 20m / s;

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

[0088] S4, the ultra-thin strip of non-oriented silicon steel is subjected to annealing treatment, wherein the annealing holding temperature is 1000℃, the annealing time is controlled to be 2h, the annealing atmosphere is 70% hydrogen+30% nitrogen, and the cooling time is 10min.

[0089] After detection and statistics, the surface of the silicon steel ultra-thin strip is smooth, the magnetic properties of the non-oriented silicon steel ultra-thin strip containing trace tellurium are as follows: B 50 = 1.672T, P 1.0 / 1000Hz = 29.85 W / kg, the strip yield is 92.2%, which fully meets the high performance requirement standard of soft magnetic products. As shown in Table 3.

[0090] Example 4

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

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

[0093] A method for preparing a tellurium-containing non-oriented silicon steel ultra-thin strip by using a plane flow casting method 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, using a plane flow casting method to prepare a non-oriented silicon steel ultra-thin strip, putting the master alloy and a purifying agent into a quartz tube with a strip nozzle and heating to melting, wherein the composition of the purifying agent is calcium oxide: 35wt%, graphite powder: 45wt%, silicon carbide: 15wt%, and titanium dioxide: 5wt%, the weight of the purifying agent is 0.8wt% of the total weight of the master alloy; and 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 of the nozzle when spraying is 0.03MPa, and the copper roller rotating speed is 25m / s;

[0096] S3, performing rolling treatment on 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, performing annealing treatment on the non-oriented silicon steel ultra-thin strip, wherein the annealing holding temperature is 1100℃, the annealing time is controlled to be 1h, the annealing atmosphere is 90% hydrogen+10% nitrogen, and the cooling time is 8min.

[0098] After detection and statistics, the surface of the silicon steel ultra-thin strip is smooth, the magnetic properties of the non-oriented silicon steel ultra-thin strip containing trace tellurium are as follows: B 50 =1.684T, P 1.0 / 1000Hz =31.88W / kg, and the strip forming rate is 93.4%, which fully meets the high performance requirement standard of soft magnetic products. As shown in Table 3.

[0099] Example 5

[0100] The 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 material are as follows: tellurium: 0.05wt%, silicon: 3.5wt%, and the rest is iron and a small amount of other unavoidable impurities. As shown in Table 1.

[0102] A method for preparing a tellurium-containing non-oriented silicon steel ultra-thin strip by using a plane flow casting method 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, preparing the ultra-thin strip of non-oriented silicon steel by using the plane flow casting method, putting the master alloy and the purifying agent into the quartz tube of the strip nozzle and heating to melt, wherein the composition of the purifying agent is calcium oxide: 40wt%, graphite powder: 35wt%, silicon carbide: 20wt%, and titanium dioxide: 5wt%, the weight of the purifying agent is 0.7wt% of the total weight of the master alloy; and controlling the nozzle width to be 50mm, the gap size to be 0.065mm, the distance between the nozzle and the copper roller to be 0.2mm, the pressure of the nozzle spraying to be 0.3MPa, and the rotating speed of the copper roller to be 30m / s;

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

[0106] S4, performing the annealing treatment on the ultra-thin strip of non-oriented silicon steel, wherein the annealing holding temperature is 1150℃, the annealing time is controlled to be 1h, the annealing atmosphere is 100% hydrogen, and the cooling time is 10min.

[0107] After detection and statistics, the surface of the ultra-thin strip of silicon steel is smooth, the magnetic properties of the ultra-thin strip of non-oriented silicon steel containing trace tellurium are: B 50 = 1.701T, P 1.0 / 1000Hz = 31.85W / kg, the strip forming rate is 92.8%, and it completely meets the high performance requirement standard of soft magnetic products. As shown in Table 3.

[0108] Example 6

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

[0110] The raw material composition and the weight percentage of the master alloy are as follows: 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 the ultra-thin strip of non-oriented silicon steel containing tellurium by using the plane flow casting method is shown in Table 2, and the steps are as follows:

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

[0113] S2, the planar flow casting method is used to prepare the ultra-thin strip of non-oriented silicon steel, the master alloy and the purifying agent are put into the quartz tube of the strip nozzle and heated to melt, the purifying agent is composed of 35wt% calcium oxide, 45wt% graphite powder, 15wt% silicon carbide and 5wt% titanium dioxide, the weight of the purifying agent is 0.8wt% of the total weight of the master alloy; and the nozzle width is controlled to be 45mm, the gap size is 0.065mm, the distance between the nozzle and the copper roller is 0.15mm, the pressure of the nozzle when spraying is 0.025MPa, and the rotating speed of the copper roller is 25m / s.

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

[0115] S4, the ultra-thin strip of non-oriented silicon steel is subjected to annealing treatment, wherein the annealing holding temperature is 1150℃, the annealing time is controlled to be 3h, the annealing atmosphere is 100% hydrogen, and the cooling time is 10min.

[0116] After detection and statistics, the surface of the silicon steel ultra-thin strip is smooth, the magnetic properties of the non-oriented silicon steel ultra-thin strip containing trace tellurium are as follows: B 50 =1.663T, P 1.0 / 1000Hz =28.08W / kg, and the strip forming yield is 91.8%, which fully meets the high performance requirement standard of soft magnetic products. As shown in Table 3.

[0117] Comparative Example 1

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

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

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

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

[0122] Comparative Example 2

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

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

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

[0126] The magnetic properties and the yield of the ultra-thin strip of the non-oriented silicon steel containing trace amount of tellurium are shown in Table 3.

[0127] Comparative Examples 3-6

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

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

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

[0131] The magnetic properties and the yield of the ultra-thin strip of the non-oriented silicon steel containing trace amount of tellurium are shown in Table 3.

[0132] Comparative Example 7

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

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

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

[0136] The magnetic properties and the yield of the ultra-thin strip of the non-oriented silicon steel containing trace amount of tellurium are shown in Table 3.

[0137] Comparative Examples 8-9

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

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

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

[0141] The magnetic properties and the yield of the ultra-thin strip of the non-oriented silicon steel containing trace amount of tellurium are shown in Table 3.

[0142] Comparative Example 10

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

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

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

[0146] Through detection and statistics, the magnetic properties and strip spinning yield of the tellurium-containing non-oriented silicon steel ultra-thin strip are shown in Table 3.

[0147] Comparative Example 11

[0148] The present 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 material are shown in Table 1.

[0150] The method for preparing the tellurium-containing non-oriented silicon steel ultra-thin strip by using the plane flow casting method is basically the same as that in Embodiment 1, except that the content of H2 in the annealing atmosphere is different, and the specific parameters are shown in Table 2.

[0151] Through detection and statistics, the magnetic properties and strip spinning yield of the tellurium-containing non-oriented silicon steel ultra-thin strip are shown in Table 3.

[0152] Comparative Example 12

[0153] The present 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 material are shown in Table 1.

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

[0156] Through detection and statistics, the magnetic properties and strip spinning yield of the tellurium-containing non-oriented silicon steel ultra-thin strip are shown in Table 3.

[0157] Table 1 Composition of master alloy and purifying agent in examples and comparative examples

[0158]

[0159]

[0160] Table 2 Preparation process parameters of silicon steel ultra-thin strip in examples and comparative examples

[0161]

[0162]

[0163] Table 3 Magnetic properties and yield of oriented silicon steel ultra-thin strip of examples and comparative examples

[0164]

[0165] As shown in Table 1, Table 2 and Table 3, the alloy composition, purifying agent composition and selection of planar flow casting process parameters, cold rolling process parameters and annealing process parameters of examples 1-6 all meet the requirements of the present application, and the prepared oriented silicon steel ultra-thin strip has B 50 ≥1.66T, iron loss P 1.0 / 1000Hz ≤32W / kg, yield ≥90%.

[0166] Comparative example 1 has higher silicon content than example 1, which exceeds the requirements of the present application, and although the formability is improved, the excess silicon element reduces the saturation magnetic induction value; comparative example 2 does not contain tellurium element in the master alloy raw material, and the steel fluid flowability is poor, and the yield is significantly reduced.

[0167] Comparative examples 3-6 do not meet the requirements of the present application in terms of purifying agent composition or percentage content, which causes the steel fluid flowability and impurity purification effect to decrease to different degrees, and the strip casting yield is reduced; comparative example 7 does not meet the requirements of the present application in terms of the mass fraction of the weight of the added purifying agent in the total weight of the master alloy, and the amount of the added purifying agent is too small to purify impurities and improve the fluidity, and the strip casting yield is low.

[0168] Comparative example 8 has too large nozzle total width of the planar flow casting machine, which reduces the strip casting yield; comparative example 9 has too small nozzle gap size of the planar flow casting machine, which causes the planar flow casting process to fail to obtain a relatively complete and continuous strip.

[0169] Comparative example 10 has too large cold rolling reduction, which breaks the balance between the iron loss and the magnetic induction, and the magnetic properties decrease.

[0170] Comparative example 11 has lower H2 content in the annealing atmosphere than 50%, which significantly increases the iron loss; comparative example 12 has lower annealing temperature, which causes the iron loss to increase and the magnetic induction to decrease.

[0171] In summary, the present application uses planar flow casting method to prepare oriented silicon steel ultra-thin strip, optimizes the alloy composition, melts the master alloy and purifying agent together, so that the fluidity and purity of the master alloy melt of the present application meet the requirements of the planar flow casting method, improve the strip casting yield, and then cooperate with subsequent small reduction rolling and annealing to promote grain growth and improve the microstructure of the strip, thereby improving the magnetic properties of the oriented silicon steel ultra-thin strip, and the prepared oriented silicon steel ultra-thin strip has B 50 ≥1.66T, iron loss P 1.0 / 1000Hz≤ 32 W / kg, yield ≥ 90%.

[0172] The above description is merely that of the preferred embodiments of the application, but the protection scope of the application is not limited thereto, and any changes or substitutions easily conceived by those skilled in the art within the technical scope disclosed by the application should be covered within the protection scope of the application.

Claims

1. A method for producing a Te-containing non-oriented silicon steel ultra-thin strip by a planar flow casting method, characterized by, It comprises the following steps: S1, using vacuum induction melting and pouring mother alloy ingot, raw materials are pure iron, silicon and tellurium with purity greater than 99.99%; the chemical composition of the mother alloy ingot is as follows: tellurium: 0.05wt%-0.1wt%; silicon: 2.5wt%-3.5wt%; the rest is iron and a small amount of other inevitable impurities; S2, plane flow casting: the mother alloy ingot prepared in S1 and a purifying agent are put into a quartz tube with a nozzle of a plane flow casting machine and heated to melt, then spun out to a rotating cooling copper roller for directional solidification, and finally peeled off to obtain a silicon steel ultra-thin strip; the composition of the purifying agent comprises the following components in mass percentage: calcium oxide: 25wt%-40wt%; graphite powder: 35wt%-50wt%; silicon carbide: 15wt%-25wt%; titanium dioxide: 5wt%-10wt%; S3, the silicon steel ultra-thin strip prepared in S2 is subjected to cold rolling treatment with tension; S4, the silicon steel ultra-thin strip after rolling is subjected to annealing treatment.

2. The method of claim 1, wherein, The chemical composition of the mother alloy ingot in S1 is as follows: tellurium: 0.06wt%-0.09wt%; silicon: 2.5wt%-3.5wt%; the rest is iron and a small amount of other inevitable impurities.

3. The method of claim 1, wherein, During the spinning out in S2, the nozzle width is controlled to be 15-50mm, the nozzle gap size is 0.045-0.065mm, and the distance between the nozzle and the copper roller is 0.1-0.2mm.

4. The method of claim 3, wherein, During the spinning out in S2, the pressure of the nozzle when spraying is 0.01-0.03MPa, and the copper roller rotating speed is 20-30m / s.

5. The method of claim 1, wherein, In S3, the cold rolling process is controlled, and the total reduction rate is controlled to be 2%-20%.

6. The method of claim 5, wherein, In S3, the cold rolling process is controlled, and the front tension of the rolling roller is 40-60N, and the back tension is 30-50N.

7. The method of claim 1, wherein, In S4, the annealing holding temperature is controlled to be 900°C-1200°C, and the annealing time is controlled to be 1h-3h.

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

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

10. The Te-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 0.05-0.065mm and a width of 15-50mm.

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