High-S-content non-oriented silicon steel ultra-thin strip based on plane flow casting technology and preparation method

Abstract

The invention discloses a high-S-content non-oriented silicon steel ultra-thin strip based on a plane flow casting technology. The high-S-content non-oriented silicon steel ultra-thin strip comprises the following components in percentage by weight: 0.005-0.2% of S, 2.5-4.5% of Si and the balance of silicon. The preparation method comprises the steps of smelting; pouring into an ingot; cutting the steel ingot; performing high-frequency heating; spray-casting and melt-spinning to the thickness of the product; flattening is conducted; annealing treatment; cooling to room temperature along with the furnace for later use; through ultra-fast solidification, the adverse effect of a traditional harmful element S on the magnetic / mechanical properties of the non-oriented silicon steel thin strip is relieved, the S removal cost in the silicon steel smelting process is remarkably reduced, and on the premise that it is guaranteed that B50 of the non-oriented silicon steel thin strip is larger than or equal to 1.61 T and Pt1.0 / 400 is smaller than or equal to 12.88 W / kg, the production technological process is shortened by not lower than 25%, the cost is reduced by at least 35%, and the production efficiency is improved. And the method is easy to operate, low in pollution, high in efficiency and good in finished product quality.

Description

Technical Field

[0001] The invention relates to an ultra-thin non-oriented silicon steel strip and a preparation method thereof, and in particular to an ultra-thin non-oriented silicon steel strip with a high S content based on a plane flow casting technology and a preparation method thereof. Background Art

[0002] Silicon steel is the main material for the cores of various electrical components such as generators, transformers, and motors, and is one of the most important magnetic materials. Reducing the thickness of silicon steel can reduce eddy current losses. At the same time, the small volume and mass of thin strips meet the development requirements of low energy consumption, lightweight, and high efficiency of new magnetic materials. However, silicon will increase the brittleness of the alloy, and silicon steel with a high silicon content will make it difficult to roll. Therefore, the production process of traditional thin-gauge non-oriented silicon steel is extremely complicated and has high energy consumption costs, which does not conform to the green and low-carbon development trend of the steel industry. Planar flow casting technology can process and shape extremely thin silicon steel strips with extremely high cooling speeds and simple process flows, meeting the requirements for low cost and high performance of non-oriented silicon steel strips.

[0003] In the existing silicon steel production technology, S is usually present in steel materials as a harmful element. S is prone to intergranular segregation in steel to form low-melting-point FeS, which causes hot brittleness and deteriorates the hot processing ability of silicon steel. In addition, at low temperatures, the solubility of S in ferrite is extremely small, and the precipitated S atoms will form precipitate particles such as FeS and MnS with Fe and Mn atoms, which have an adverse effect on the magnetic properties. Therefore, the control of S in the silicon steel strip produced by traditional processes is extremely strict, which will undoubtedly increase the smelting cost of silicon steel. Planar flow casting technology has the characteristics of ultra-fast cooling, which can effectively reduce S intergranular segregation and precipitation, thereby reducing the adverse effects of S on the magnetic properties of non-oriented silicon steel. Therefore, the use of planar flow casting technology is conducive to the production of non-oriented silicon steel strips with high S content, which is crucial to reducing the smelting cost of silicon steel.

[0004] After searching:

[0005] The document with Chinese patent publication number CN118028686A discloses "A method for preparing cerium-containing Fe-6.5wt.%Si high silicon steel strip by single-roller strip spinning method". This method uses single-roller strip spinning technology to prepare high silicon steel strip with a Ce content of 0.006% to 0.08%. The grains are refined by adding rare earth elements to the silicon steel strip, achieving the effect of microalloying. This production method improves the performance of the strip by adding rare earth elements, but it is mainly studied for high silicon steel strips, and the cost of rare earth elements is high, and the addition method is complicated, resulting in increased energy consumption and greater pollution.

[0006] The document with Chinese patent publication number CN118291852A discloses "A method for preparing non-oriented silicon steel ultra-thin strip by plane flow casting". This method uses plane flow casting technology to control the chemical composition of the alloy and utilizes the influence of different elements on the alloy to prepare non-oriented silicon steel ultra-thin strip that is easy to form and has good spreadability. However, it has strict requirements on the content of elements such as P, S, B, and Mn in the steel, which increases the complexity of the process, increases the cost, reduces resource utilization, and increases the difficulty of operation.

[0007] The document with Chinese patent publication number CN201811174624X discloses "A method for producing high-frequency thin-strip silicon steel". This method uses smelting-heating-pickling-cold rolling-annealing to prepare silicon steel thin strips with excellent performance under high frequency. However, this method still needs to be refined and decarburized to control the content of harmful elements. The requirements for superheat during the continuous casting process are precise. After the ingot reaches a specific temperature, it is hot rolled into the furnace to achieve the final optimization of product performance. At the same time, the S element needs to be within a lower range. It can be seen that the traditional processing methods have extremely stringent requirements for the control of the S element content, which makes the processing technology of silicon steel thin strips complicated, the cost increases, and the pollution increases. Planar flow casting technology has the characteristics of short process, high efficiency, low energy consumption, and green environmental protection, which meets the current green and low-carbon development requirements of the steel industry. Its ultra-rapid solidification characteristics are beneficial to eliminating the adverse effects of S on the magnetic / mechanical properties of silicon steel strips and reducing the S removal cost of the silicon steel smelting process. However, there are no reports on the research cases of preparing ultra-thin non-oriented silicon steel strips with high S content under the planar flow casting process. Therefore, it is necessary to study the preparation of ultra-thin non-oriented silicon steel strips with high S content based on the planar flow casting method. Summary of the invention

[0008] The present invention aims to overcome the shortcomings of the prior art and provide a method for reducing the adverse effects of the traditional harmful element S on the magnetic / mechanical properties of non-oriented silicon steel strips through ultra-fast solidification technology, significantly reducing the cost of removing S in the silicon steel smelting process, and ensuring the B quality of the non-oriented silicon steel strips. 50 ≥1.61T, Pt 1.0 / 400 Under the premise of ≤12.88W / kg, the production process time is shortened by no less than 25%, the cost is reduced by at least 35%, and the method for preparing ultra-thin strip of high S content non-oriented silicon steel based on plane flow casting technology has the characteristics of easy operation, low pollution, high efficiency and good finished product quality.

[0009] Measures to achieve the above objectives:

[0010] The invention discloses an ultra-thin strip of non-oriented silicon steel with high S content based on plane flow casting technology, wherein the components and weight percentages thereof are 0.005-0.2% S, 2.5-4.5% Si, and the rest are iron and other small amount of inevitable impurities.

[0011] Preferably, the weight percentage content of S is in the range of 0.01 to 0.16%.

[0012] Preferably, the weight percentage content of Si is in the range of 2.7 to 4.5%.

[0013] A method for preparing an ultra-thin strip of non-oriented silicon steel with a high S content based on a planar flow casting technology, comprising the following steps:

[0014] 1) Smelting: pure iron containing 99.99% iron, pure silicon containing 99.99% silicon, and pyrite containing 20-25% sulfur are added into a smelting furnace for smelting at a temperature of 1500-1650° C. until the set composition is reached;

[0015] 2) Casting into ingots. During the casting process, argon gas is used for protection throughout the process. The argon gas flow rate range is: 0.01~0.1

[0016] L / min;

[0017] 3) Cutting steel ingots: Cutting the smelted steel ingots into blocks suitable for high-frequency heating devices;

[0018] 4) Perform high-frequency heating: Heat the cut steel block to 1500-1650°C by induction heating to melt the steel block, and use argon gas protection throughout the process;

[0019] 5) Spray casting to product thickness, the argon pressure range is: 15 ~ 50kPa to spray the molten steel through the nozzle to form a strip, and cool to room temperature at a roller speed of 10 ~ 40m / s; control the thickness of the spray casting strip not more than 100μm;

[0020] 6) Leveling: the leveling reduction rate range is: 1-5%;

[0021] 7) Perform annealing treatment, first evacuate the annealing furnace, and control the vacuum degree not to exceed 10Pa; then perform annealing under argon protective atmosphere, the annealing temperature range is: 850~1000℃, and the annealing time range is: 20~60min;

[0022] 8) Cool to room temperature in the furnace and set aside.

[0023] Preferably, the length of the nozzle is 3-9 mm, and the width is set according to the requirements of the non-oriented silicon steel ultra-thin strip.

[0024] Preferably, the melting temperature ranges from 1510 to 1620°C.

[0025] Preferably, the argon pressure used during the spray casting is 21-43 kPa.

[0026] Preferably, the vacuum degree of the annealing furnace is in the range of 4-8 Pa.

[0027] Preferably, the annealing temperature ranges from 860 to 970° C., and the annealing time ranges from 20 to 55 minutes.

[0028] Functions and mechanisms of each component and main process in the present invention

[0029] S: In the traditional non-oriented silicon steel manufacturing process, S cannot form atoms dissolved in the crystal lattice due to its extremely low solubility at low temperatures. Therefore, it often combines with Mn and Fe to form fine precipitate phases, which have an adverse effect on the magnetic properties. However, at the extremely high cooling rate of this process, the precipitation and segregation of S will be inhibited, and the addition of S element can significantly improve the formability of the thin strip, optimize the surface quality, and further improve the stacking factor during winding and enhance the saturation magnetic induction intensity.

[0030] Si: Si can effectively increase the resistivity of ferrite, which is beneficial to reducing iron loss. The addition of Si element usually does not have a significant negative impact on the processing of electrical steel. However, the increase in Si content will significantly reduce the plasticity of the steel plate and increase the difficulty of cold processing. Under the plane flow casting process, the increase in brittleness caused by the increase in Si content can be effectively suppressed, thereby ensuring excellent processing performance while increasing the resistivity.

[0031] The reason why the present invention controls the melting temperature range to be 1500-1650° C. is that within this temperature range, the experimental materials can be completely melted, the components can be evenly mixed, and the content of each component of the sample can be accurately controlled.

[0032] The reason why the present invention controls the argon flow rate range to be: 0.01~0.1L / min is that excessive gas flow rate will have a certain impact on the belt-spinning process and will also increase costs. Therefore, the gas flow rate is controlled while ensuring the argon atmosphere filling to reduce the impact on the belt-spinning forming and save costs.

[0033] The reason why the induction heating temperature range is controlled to be 1500-1650°C and argon protection is used throughout the process is that the steel ingot can be fully melted within this temperature range and the superheat will not be too high. The argon filling is because the high-temperature strip forming process in the atmosphere will cause the thin strip to oxidize and deteriorate the surface quality of the strip.

[0034] The reason why the present invention controls the argon pressure range to be: 15-50kPa, so that the molten steel liquid is sprayed out through the nozzle to form a casting strip, and is cooled to room temperature at a roller speed of 10-40m / s, and the thickness of the spray-cast casting strip is controlled not to exceed 100μm; this is because within this pressure range, the molten metal can be evenly spray-cast onto the surface of the copper roller, and the thickness of the casting strip within the roller speed range is uniform and less than 100μm, which effectively reduces eddy current loss.

[0035] The reason why the flattening reduction rate is controlled within the range of 1-5% in the present invention is that a small reduction rate can flatten the warping of the cast belt, reduce surface fluctuations, and has no effect on the structure of the cast belt.

[0036] The reason why the vacuum degree is controlled not to exceed 10Pa, the annealing temperature range is: 850-1000°C, and the annealing time range is: 20-60min is because the air tightness of the instrument can be better in a low negative pressure state. By annealing within this temperature and time range, the internal stress of the casting strip can be completely eliminated, and it will not be affected by the deterioration of magnetic properties caused by long-term high-temperature annealing.

[0037] Compared with the prior art, the present invention reduces the adverse effects of the traditional harmful element S on the magnetic / mechanical properties of non-oriented silicon steel strips through ultra-fast solidification, significantly reduces the cost of S removal during the silicon steel smelting process, and ensures the B 50 ≥1.61T, Pt 1.0 / 400 Under the premise of ≤12.88W / kg, the production process can be shortened by no less than 25%, the cost can be reduced by at least 35%, and it has the advantages of easy operation, low pollution, high efficiency and good finished product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The ultra-thin strip of non-oriented silicon steel with high S content prepared in the embodiment of the present invention;

[0039] Figure 2 The longitudinal section metallographic structure of the ultra-thin strip of non-oriented silicon steel with high S content of the present invention;

[0040] Figure 3 The surface metallographic structure of the ultra-thin strip of non-oriented silicon steel with high S content of the present invention;

[0041] Figure 4 It is a sample for testing magnetic properties of an ultra-thin strip of non-oriented silicon steel with a high S content according to the present invention. DETAILED DESCRIPTION

[0042] The present invention is described in detail below:

[0043] Example 1

[0044] A high-S content non-oriented silicon steel ultra-thin strip based on plane flow casting technology, the components and weight percentages of which are: S: 0.006%, Si: 2.5%, and the rest are iron and other small amounts of unavoidable impurities;

[0045] Preparation method:

[0046] 1) Smelting: pure iron containing 99.99% iron, pure silicon containing 99.99% silicon, and pyrite containing 21% sulfur are added into a smelting furnace for smelting at a smelting temperature of 1515° C. until the set composition is reached;

[0047] 2) Casting into ingots. During the casting process, argon gas is used for protection throughout the process, and the argon gas flow rate is controlled to 0.019

[0048] L / min;

[0049] 3) Cutting steel ingot: The weight of the steel block after cutting is 5g;

[0050] 4) Perform high-frequency heating: Place the cut steel block into a quartz test tube, and use an induction coil to heat the cut steel block to 1550°C to melt the steel block, with argon protection throughout the process;

[0051] 5) Spray casting and strip throwing until the product thickness is 85 μm, using argon pressure at 25 kPa to spray molten steel through the nozzle for strip throwing, and cooling to room temperature at a roller speed of 12 m / s; the thickness of the spray casting strip is about 85 μm;

[0052] 6) Leveling: the leveling reduction rate is 2.3%;

[0053] 7) Perform annealing treatment, first evacuate the annealing furnace to a vacuum degree of 4 Pa; then perform annealing under an argon protective atmosphere at an annealing temperature of 855°C and an annealing time of 20 min;

[0054] 8) Cool to room temperature in the furnace and set aside.

[0055] After testing and statistics, the magnetic properties of the thin strip produced are: B 50 =1.62T,Pt 1.0 / 400 =11.94W / kg, the production process time is shortened by 30% compared with the existing technology, and the cost is reduced by 40%.

[0056] Example 2

[0057] A high-S content non-oriented silicon steel ultra-thin strip based on plane flow casting technology, the components and weight percentages of which are: S: 0.009%, Si: 2.8%, and the rest are iron and other small amounts of unavoidable impurities;

[0058] Preparation method:

[0059] 1) Smelting: pure iron containing 99.99% iron, pure silicon containing 99.99% silicon, and pyrite containing 21% sulfur are added into a smelting furnace for smelting at a smelting temperature of 1540° C. until the set composition is reached;

[0060] 2) Casting into ingots, during this casting process, argon gas is used for protection throughout the process, and the argon gas flow rate is controlled to 0.024

[0061] L / min;

[0062] 3) Cutting steel ingot: The weight of the steel block after cutting is 6g;

[0063] 4) Perform high-frequency heating: Place the cut steel block into a quartz test tube, and use an induction coil to heat the cut steel block to 1570°C to melt the steel block, with argon protection throughout the process;

[0064] 5) Spray casting and strip throwing until the product thickness is 80 μm, using argon pressure of 30 kPa to spray molten steel through the nozzle for strip throwing, and cooling to room temperature at a roller speed of 15 m / s; the thickness of the spray casting strip is about 80 μm;

[0065] 6) Leveling: the leveling reduction rate is 2.8%;

[0066] 7) Perform annealing treatment, first evacuate the annealing furnace to a vacuum degree of 5 Pa; then perform annealing under an argon protective atmosphere, the annealing temperature is 880°C, and the annealing time is 30 min;

[0067] 8) Cool to room temperature in the furnace and set aside.

[0068] After testing and statistics, the magnetic properties of the thin strip produced are: B 50 =1.63T,Pt 1.0 / 400 =12.43W / kg, the production process time is shortened by 32% compared with the existing technology, and the cost is reduced by 43%.

[0069] Example 3

[0070] A high-S content non-oriented silicon steel ultra-thin strip based on plane flow casting technology, the composition and weight percentage of which are 0.012% S, 3.0% Si, and the rest are iron and other small amounts of unavoidable impurities;

[0071] Preparation method:

[0072] 1) Smelting: pure iron containing 99.99% iron, pure silicon containing 99.99% silicon, and pyrite containing 21% sulfur are added into a smelting furnace for smelting at a smelting temperature of 1570° C. until the set composition is reached;

[0073] 2) Casting into ingots, during this casting process, argon gas is used for protection throughout the process, and the argon gas flow rate is controlled to 0.035

[0074] L / min;

[0075] 3) Cutting steel ingot: The weight of the steel block after cutting is 7g;

[0076] 4) Perform high-frequency heating: Place the cut steel block into a quartz test tube, and use an induction coil to heat the cut steel block to 1590°C to melt the steel block, and use argon protection throughout the process;

[0077] 5) Spray casting and strip throwing to product thickness of 90 μm: argon pressure of 35 kPa is used to spray molten steel through the nozzle for strip throwing, and the strip is cooled to room temperature at a roller speed of 17 m / s; the thickness of the spray casting strip is about 90 μm;

[0078] 6) Leveling: the leveling reduction rate is 3.1%;

[0079] 7) Annealing treatment: first, evacuate the annealing furnace to a vacuum degree of 6 Pa; then, anneal under an argon protective atmosphere at an annealing temperature of 910°C and an annealing time of 40 min;

[0080] 8) Cool to room temperature in the furnace and set aside.

[0081] After testing and statistics, the magnetic properties of the thin strip produced are: B 50 =1.61T,Pt 1.0 / 400 =12.37W / kg, the production process time is shortened by 33% compared with the existing technology, and the cost is reduced by 45%.

[0082] Example 4

[0083] A high-S content non-oriented silicon steel ultra-thin strip based on plane flow casting technology, the composition and weight percentage of which are 0.014% S, 3.3% Si, and the rest are iron and other small amounts of unavoidable impurities;

[0084] Preparation method:

[0085] 1) Smelting: pure iron containing 99.99% iron, pure silicon containing 99.99% silicon, and pyrite containing 21% sulfur are added into a smelting furnace for smelting at a smelting temperature of 1590° C. until the set composition is reached;

[0086] 2) Casting into ingots: During the casting process, argon gas is used for protection throughout the process, and the argon gas flow rate is controlled to 0.048

[0087] L / min;

[0088] 3) Cutting steel ingot: The weight of the steel block after cutting is 5g;

[0089] 4) Perform high-frequency heating: Place the cut steel block into a quartz test tube, use an induction coil to heat the cut steel block to 1575°C to melt the steel block, and use argon protection throughout the process;

[0090] 5) Spray casting and strip spinning until the product thickness is about 85 μm: the molten steel liquid is sprayed out through the nozzle under an argon pressure of 28 kPa for strip spinning, and cooled to room temperature at a roller speed of 20 m / s; the thickness of the spray casting strip is about 70 μm;

[0091] 6) Leveling: the leveling reduction rate is 1.8%;

[0092] 7) Perform annealing treatment, first evacuate the annealing furnace to a vacuum degree of 8 Pa; then perform annealing under an argon protective atmosphere, the annealing temperature is 930° C., and the annealing time is 40 min;

[0093] 8) Cool to room temperature in the furnace and set aside.

[0094] After testing and statistics, the magnetic properties of the thin strip produced are: B 50 =1.62T,Pt 1.0 / 400 =12.56W / kg, the production process time is shortened by 35% compared with the existing technology, and the cost is reduced by 47%.

[0095] Example 5

[0096] A high-S content non-oriented silicon steel ultra-thin strip based on plane flow casting technology, the composition and weight percentage of which are 0.016% S, 3.5% Si, and the rest are iron and other small amounts of unavoidable impurities;

[0097] Preparation method:

[0098] 1) Smelting: pure iron containing 99.99% iron, pure silicon containing 99.99% silicon, and pyrite containing 21% sulfur are added into a smelting furnace for smelting at a smelting temperature of 1620° C. until the set composition is reached;

[0099] 2) Casting into ingots. During the casting process, argon gas is used for protection throughout the process, and the argon gas flow rate is controlled to be 0.062

[0100] L / min;

[0101] 3) Cutting steel ingot: The weight of the steel block after cutting is 6g;

[0102] 4) Perform high-frequency heating: Place the cut steel block into a quartz test tube, and use an induction coil to heat the cut steel block to 1600°C to melt the steel block, and use argon gas protection throughout the process;

[0103] 5) Spray casting and strip throwing until the product thickness is about 65 μm, the molten steel liquid is sprayed out through the nozzle under the argon pressure of 35 kPa for strip throwing, and cooled to room temperature at a roller speed of 25 m / s; the thickness of the spray casting strip is about 65 μm;

[0104] 6) Leveling: the leveling reduction rate is 1.3%;

[0105] 7) Annealing treatment: first, evacuate the annealing furnace to a vacuum degree of 10 Pa; then, annealing is performed under an argon protective atmosphere at an annealing temperature of 950° C. and an annealing time of 50 min;

[0106] 8) Cool to room temperature in the furnace and set aside.

[0107] After testing and statistics, the magnetic properties of the thin strip produced are: B 50 =1.64T,Pt 1.0 / 400 =11.58W / kg, the production process time is shortened by 38% compared with the existing technology, and the cost is reduced by 47%.

[0108] This specific implementation is only the best example and is not a restrictive implementation of the technical solution of the present invention.

Claims

1. A high S content non-oriented silicon steel ultra-thin strip based on plane flow casting technology, the components and weight percentage content of which are: S: 0.005~0.2%, Si: 2.5~4.5%, the rest are iron and other small amounts of inevitable impurities.

2. The ultra-thin strip of non-oriented silicon steel with high S content based on the plane flow casting technology as claimed in claim 1, characterized in that: The weight percentage content of S is in the range of 0.01% to 0.16%.

3. The ultra-thin strip of non-oriented silicon steel with high S content based on the plane flow casting technology as claimed in claim 1, characterized in that: The weight percentage content of Si ranges from 2.7% to 4.5%.

4. The method for preparing an ultra-thin strip of non-oriented silicon steel with a high S content based on a planar flow casting technology according to claim 1, comprising the following steps: 1) Smelting: pure iron containing 99.99% iron, pure silicon containing 99.99% silicon, and pyrite containing 20% ​​to 25% sulfur are added into a smelting furnace for smelting at a temperature of 1500 to 1650° C. until the set composition is reached; 2) Casting into ingots. During the casting process, argon gas is used for protection throughout the process, and the argon gas flow rate is controlled within the range of: 0.01~0.1L / min; 3) Cutting steel ingots: Cutting the smelted steel ingots into blocks suitable for high-frequency heating devices; 4) Perform high-frequency heating: Heat the cut steel block to 1500-1650°C by induction heating to melt the steel block, and use argon gas protection throughout the process; 5) Spray casting and stripping to product thickness, the argon pressure range is: 15-50kPa to spray the molten steel through the nozzle for stripping, and cool to room temperature at a roller speed of 10-40m / s; the thickness of the spray casting strip is controlled not to exceed 100μm; 6) Leveling: the leveling reduction rate range is: 1-5%; 7) Perform annealing treatment, first evacuate the annealing furnace, and control the vacuum degree not to exceed 10Pa; then perform annealing under argon protective atmosphere, the annealing temperature range is: 850~1000℃, and the annealing time range is: 20~60min; 8) Cool to room temperature in the furnace and set aside.

5. The method for preparing an ultra-thin strip of non-oriented silicon steel with a high S content based on a plane flow casting technology according to claim 4, characterized in that: The length of the nozzle ranges from 3 to 9 mm, and the width is set according to the needs of the required non-oriented silicon steel ultra-thin strip.

6. The method for preparing an ultra-thin strip of non-oriented silicon steel with a high S content based on a plane flow casting technology according to claim 4, characterized in that: The melting temperature range is: 1510~1620℃.

7. The method for preparing an ultra-thin strip of non-oriented silicon steel with a high S content based on a plane flow casting technology according to claim 4, characterized in that: The argon pressure range during spray casting is: 21~43kPa.

8. The method for preparing an ultra-thin strip of non-oriented silicon steel with a high S content based on a plane flow casting technology according to claim 4, characterized in that: The vacuum range of the annealing furnace is: 4~8Pa.

9. The method for preparing an ultra-thin strip of non-oriented silicon steel with a high S content based on a plane flow casting technology according to claim 4, characterized in that: The annealing temperature range is: 860~970℃, and the annealing time range is: 20~55min.

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