CN116497269A

CN116497269A - Preparation method and system of high-magnetic-induction oriented silicon steel ultrathin strip

Info

Publication number: CN116497269A
Application number: CN202310296757.9A
Authority: CN
Inventors: 张凤泉
Original assignee: Individual
Current assignee: Individual
Priority date: 2023-03-22
Filing date: 2023-03-22
Publication date: 2023-07-28

Abstract

The invention provides a preparation method and a system of a high-magnetic-induction oriented silicon steel ultrathin strip, wherein the method comprises the following steps: melting molten steel with required componentsWhen the alloy molten steel reaches a certain temperature, stirring uniformly, and then spraying the alloy molten steel onto a crystallization roller rotating at a high speed in a plane stream state sequentially through a tundish, a nozzle bag and a nozzle, so that the alloy molten steel is instantaneously solidified, and a plane stream steel belt is formed; then entering a nitrogen protection area for cooling, and automatically coiling the cooled silicon steel thin strip coil into a silicon steel thin strip coil through a coiling machine; finally, the aluminum alloy is subjected to reducing rolling by a cold rolling mill, heating crystallization treatment by a continuous annealing furnace and Al coating ₂ O ₃ And (5) carrying out secondary crystallization on the isolation layer and the high-temperature bell-type furnace to finally obtain the finished product of the high-magnetic induction oriented silicon steel ultrathin strip. The invention can realize the rapid solidification of molten steel and has the advantages of simple equipment, convenient operation, large preparation amount, compact material, low cost and the like.

Description

Preparation method and system of high-magnetic-induction oriented silicon steel ultrathin strip

Technical Field

The invention relates to the field of electrical steel, in particular to a method and a system for preparing a high-magnetic-induction oriented silicon steel ultrathin strip based on a plane flow injection technology.

Background

The extremely thin oriented silicon steel is a soft magnetic material in the important field, is also one of important materials in the fields of electronic industry, electric power industry and the like, is mainly represented by thinner steel strips compared with other magnetic performance materials, is applicable to products with higher frequency and higher magnetic induction requirements, and is beneficial to miniaturization of the products. Under the condition of meeting product design, the extremely thin oriented silicon steel can enable the iron core to be manufactured smaller, and has the characteristics of four high and three small, namely: high technical threshold, high gold content, high quality precision, high added value, small yield, small market and small consumption. The main frequency of the high magnetic induction oriented silicon steel ultrathin strip product is 400-3000 Hz, and the thickness is 0.10mm (0.08 mm), 0.05mm and 0.03mm according to the new national standard, and the width is below 350mm, so that the high magnetic induction oriented silicon steel ultrathin strip product is widely applied to high-end industries such as reactors, precise electronics, computer components, intelligent hardware, electric energy power components, intelligent automobile connectors, electrical manufacturing, ship fittings, instruments, pulse navigation, medical electronics, aerospace, high-speed rail cars, communication components, precise machining, welding cutting, laser machining, electronic materials, medical appliances, military manufacturing, surface chemical treatment machining, electrical appliance precise components, precise machinery and the like.

At present, the existing technological process for producing the high magnetic induction oriented silicon steel ultrathin strip at home and abroad is shown in figure 3. Firstly, a non-bottom layer oriented silicon steel semi-finished product is adopted as a raw material, and the non-bottom layer oriented silicon steel semi-finished product is mainly formed by processing oriented silicon steel (HiB steel) through the following process: adding Al into MgO through one-time rolling and continuous decarburization annealing nitriding ₂ O ₃ (aluminum oxide and calcium aluminate) are used as isolating agents, coated on the surface of the steel strip, and subjected to high-temperature annealing. The purpose of the high temperature annealing is: 1) And (5) performing secondary recrystallization. At the time of high-temperature annealing, the primary recrystallized structureThe oriented grains in the steel strip are abnormal and grow up, so that the steel strip becomes a secondary recrystallization structure with single orientation, and the material obtains a final finished product with low iron loss and high magnetic induction. 2) Purifying the steel. The steel contains necessary inclusions of sulfides, nitrides and the like, but if the inclusions remain in the silicon steel product, the inclusions distort the crystal lattice and become resistance to the magnetization process, which is detrimental to the magnetic properties. 3) By adding Al2O3 release agent into MgO, a vitreous film-magnesium silicate bottom layer is not formed. Then, the non-bottom oriented silicon steel semi-finished product serving as a raw material is subjected to shearing, weak acid cleaning, drying and rolling, the steel strip is rolled to 0.10mm, 0.08mm or 0.05mm and 0.03mm, and then surface cleaning, continuous annealing, surface coating, drying treatment, inspection, packaging and warehousing are carried out. The production method mainly adopts the whole flow of high magnetic induction oriented silicon steel to produce a non-bottom oriented silicon steel coil which is used as a raw material of the extremely-thin oriented silicon steel, and then carries out deep processing such as cold rolling, annealing and the like. The process flow is long, the production efficiency is low, the production cost is high, and the yield is low.

The casting process uses casting roller as crystallizer, alloy liquid contacts with casting roller, and the obtained oriented silicon steel has solidification structure and texture obviously different from that of traditional continuous casting blank, and the characteristic of the subfast solidification can fully inhibit the coarsening process of the second phase particles, thus fundamentally solving the defect of high temperature heating of the oriented silicon steel blank and providing favorable conditions for fine, uniform and dispersed distribution of inhibitors required for preparing oriented silicon steel. However, in the production of the oriented high silicon steel, the requirements on control of solidification structure, precipitation of inhibitor, cold working plasticity and the like are higher, and the problems are difficult to overcome, so that the oriented high silicon steel in the prior art still has the defects of low purity, poor stability, low magnetic induction intensity and high iron loss.

The Chinese patent CN114561597A discloses a low-iron-loss high-magnetic induction oriented silicon steel ribbon and a preparation method thereof, wherein the oriented silicon steel ribbon comprises the following chemical components in percentage by mass: c:0.003-0.008; si:3.0 to 4.0; al:0.5 to 1.0; mn:0.06 to 0.12; cu:0.2 to 0.4; n:0.01-0.02; s: 0.004-0.02; nb:0.001 to 0.01; the balance of Fe and unavoidable impurities; the preparation process comprises the following steps: smelting, strip casting, normalizing, cold rolling, recrystallization annealing and high-temperature annealing are adopted, and the method is characterized in that the high-intensity magnetic field annealing is adopted to control the precipitation of inhibitors and the nucleation and growth of Goss texture in the preparation process, thereby realizing the precise control of the texture. However, this method makes it difficult to achieve a finer size and a uniform distribution of the inhibitor for recrystallization annealing of the ribbon under a strong magnetic field, and the strong magnetic field requires more complicated equipment.

The industrial continuous production method of the oriented silicon steel ultrathin strip disclosed in China patent CN113617839A comprises the steps of asynchronous rolling, degreasing, heat treatment, rapid cooling, insulating layer coating, drying and sintering, and tape collecting; wherein, the asynchronous ratio used in the asynchronous rolling is 1:1.05 to 1:1.24; in the heat treatment process, the first step is preheating, the preheating temperature is 500-700 ℃, and the preheating time is 4-120 seconds; the second step is phase change heat treatment, the temperature of the phase change heat treatment is 820-920 ℃, and the phase change heat treatment time is 100-600 seconds; in the rapid cooling process, the steel strip is cooled to below 350 ℃ within 30 seconds. The method is only used for carrying out post-hot rolling working procedure treatment, and the nucleation and growth of the Goss texture cannot be effectively controlled.

Therefore, a preparation method of the high-magnetic-induction oriented silicon steel ultrathin strip capable of effectively shortening the process flow and improving the production efficiency is needed.

Disclosure of Invention

In view of the problems of long process flow, low production efficiency, high production cost, low yield, accurate control of tissue texture and precipitated phases in the preparation process and the like in the prior art, the invention aims to provide a preparation method and a system for a high-magnetic-induction oriented silicon steel ultrathin strip based on a planar flow injection technology.

According to one aspect of the invention, there is provided a method for preparing an extremely thin strip of high magnetic induction oriented silicon steel, comprising:

step S1: putting raw materials containing preset chemical components into a smelting furnace to be smelted into molten steel; wherein the raw materials comprise the following elements in percentage by mass: c is less than or equal to 0.0030 percent, si:2.5 to 6.5 percent, mn:0.15 to 0.25 percent, P is less than or equal to 0.015 percent, S:0.02% -0.05%, als:0.03 to 0.08 percent, cu:0.05 to 0.15 percent, N:0.006 to 0.015 percent, ti is less than or equal to 0.0030 percent, sn is less than or equal to 0.012 percent or Bi is less than or equal to 0.030 percent; the bias factor pj= (3×sn/50+bi/83) ×10000 composed of Sn and Bi satisfies the relationship: pj is more than or equal to 3.5 and less than or equal to 9.5, and the balance is iron and unavoidable impurities;

step S2: placing the molten steel into a tundish to control the temperature and superheat degree of the molten steel;

step S3: preheating a nozzle package, lifting a flow control plug rod of the tundish after the preheating reaches the preheating temperature of the nozzle package, injecting molten steel in the tundish into the nozzle package, and opening a nozzle when the liquid level of the nozzle package reaches a preset height, so that the molten steel is sprayed onto a crystallization roller rotating at a high speed in a plane stream state to be solidified and formed into a plane stream steel belt; wherein argon protection is adopted in the process of plane flow injection of the molten steel;

step S4: enabling the plane flow injection steel strip to enter a nitrogen protection area for cooling, and automatically coiling the plane flow injection steel strip through a coiling machine after cooling to obtain a silicon steel strip coil;

step S5: carrying out reducing rolling on the silicon steel thin strip coil on a cold rolling mill to obtain a cold-rolled silicon steel thin strip coil;

step S6: introducing the cold-rolled silicon steel thin strip into a continuous annealing furnace, heating to a first preset temperature to finish primary recrystallization, and then coating Al after the steel strip is cooled to a second preset temperature ₂ O ₃ The isolation layer liquid is cooled to normal temperature after being dried;

step S7: will be coated with Al ₂ O ₃ The silicon steel thin strip coil of the isolation layer is placed into a high-temperature bell-type furnace, heated to a third preset temperature under the protection of full hydrogen, kept warm, slowly cooled and discharged from the furnace, and secondary recrystallization and steel purification are completed;

step S8: and (3) carrying out surface cleaning on the silicon steel thin strip after the furnace is discharged, coating an insulating coating, drying and sintering, finishing, checking, packaging and warehousing to obtain a finished product of the high-magnetic-induction oriented silicon steel ultrathin strip.

Step S1, in the process of putting raw materials containing preset chemical components into a smelting furnace to be smelted into molten steel, controlling the temperature of the molten steel in the smelting furnace to be 1570-1670 ℃; the temperature of the molten steel in the tundish in the step S2 is controlled to 1550-1650 ℃.

In the alternative scheme, in the step S2, the temperature of the molten steel in the tundish is controlled to be 1530-1620 ℃, and the superheat degree of the molten steel is controlled to be 25-55 ℃.

In the optional scheme, in step S3, the preheating temperature ty=1200-45×si of the nozzle package is determined according to si%, and the preheating temperature of the nozzle package is controlled to be 900-1100 ℃.

The method comprises the following steps of controlling the fluctuation range of the liquid level in a nozzle package and the linear speed at the roller surface of a crystallization roller in the process of opening the nozzle to spray the molten steel onto the crystallization roller rotating at high speed in a plane flow state to solidify and form a plane flow steel belt; wherein,,

the linear speed Vx=300+ (55-delta t)/delta m of the surface of the crystallization roller is m/min, wherein delta t is the degree of superheat, and the unit is the degree of temperature; δm is the target thickness of the cast strip, and the unit is mm; the fluctuation range of the liquid level in the nozzle bag is controlled to be +/-2 mm, and the linear speed at the roller surface of the crystallization roller is controlled to be 300-1200 m/min.

Wherein, the optional scheme is that argon is adopted for protection in the process of plane flow injection of the molten steel, and the flow rate ya=12+ [ delta ] t/2 of the argon is controlled according to the melting temperature Tg of the molten steel, wherein the unit is L/min;

and (3) enabling the steel strip with the plane flow stream to enter a nitrogen protection area for cooling to below 200 ℃, and automatically coiling by a coiling machine to obtain a silicon steel strip coil with the thickness of 0.08-0.18 mm.

Wherein, in the alternative scheme, in the process of reducing rolling the silicon steel thin strip coil on a cold rolling mill,

the roller diameter ratio lambda=400×δs/tau of the reducing rolling, wherein s is the actual thickness of the casting strip, the unit is mm, and tau is the target rolling reduction rate of the cold rolling; the roller diameter ratio is controlled to be 0.8-1.8; the reduction rate of the reducing rolling is controlled between 35% and 60%;

the thickness of the silicon steel thin strip coil obtained after cold rolling is 0.05-0.10 mm.

Wherein, the first preset temperature is 750 ℃ to 950 ℃, after the cold rolled silicon steel thin strip is introduced into a continuous annealing furnace to be heated to the first preset temperature, the heat preservation time is 25 to 60 seconds, the silicon steel thin strip is cooled to normal temperature, and the furnace atmosphere N of the continuous annealing furnace is realized ₂ 、H ₂ Mixing dry gas, H ₂ /N ₂ Coating Al on the silicon steel thin strip coil in an environment with the volume ratio of 20-80% ₂ O ₃ And (5) separating the layer liquid, drying and cooling to normal temperature.

Wherein, the optional scheme is that the third temperature is 1050-1200 ℃, the heat preservation time is 2.5-25 h, and the furnace is taken out after slow cooling to below 200 ℃.

Wherein, alternatively, according to another aspect of the invention, there is provided a high magnetic induction oriented silicon steel ultrathin strip preparation system comprising a smelting furnace, a tundish, a crystallization roller, a coiling machine, a cold rolling mill, a continuous annealing furnace and a high temperature bell-type furnace, wherein,

the smelting furnace is used for smelting raw materials containing preset chemical components into molten steel; wherein the raw materials comprise the following elements in percentage by mass: c is less than or equal to 0.0030 percent, si:2.5 to 6.5 percent, mn:0.15 to 0.25 percent, P is less than or equal to 0.015 percent, S:0.02% -0.05%, als:0.03 to 0.08 percent, cu:0.05 to 0.15 percent, N:0.006 to 0.015 percent, ti is less than or equal to 0.0030 percent, sn is less than or equal to 0.012 percent or Bi is less than or equal to 0.030 percent; the bias factor pj= (3×sn/50+bi/83) ×10000 composed of Sn and Bi satisfies the relationship: pj is more than or equal to 3.5 and less than or equal to 9.5, and the balance is iron and unavoidable impurities;

the tundish is used for accommodating the molten steel for preparing a plane stream so as to control the temperature and superheat degree of the molten steel; the method comprises the steps that a nozzle package is arranged at the lower part of a tundish, the nozzle package is preheated before plane stream injection, after the preheating reaches the preheating temperature of the nozzle package, a flow control plug rod of the tundish is lifted, molten steel in the tundish is injected into the nozzle package, and when the liquid level of the nozzle package reaches a preset height, a nozzle is opened, so that the molten steel is sprayed onto a crystallization roller rotating at a high speed in a plane stream injection state to be solidified and formed into a plane stream injection steel belt; wherein argon protection is adopted in the process of plane flow injection of the molten steel;

the coiling machine is used for automatically coiling the plane flow injection steel strip after the plane flow injection steel strip enters a nitrogen protection zone for cooling, so as to obtain a silicon steel strip coil;

the cold rolling mill is used for reducing and rolling the silicon steel thin strip coil to obtain a cold-rolled silicon steel thin strip coil;

the continuous annealing furnace is used for heating the cold-rolled silicon steel thin strip coil to a first preset temperature to complete primary recrystallization, and then coating Al after the steel strip is cooled to a second preset temperature ₂ O ₃ The isolation layer liquid is cooled to normal temperature after being dried;

the high temperature bell-type furnace is used for coating Al ₂ O ₃ Heating the silicon steel thin strip coil of the isolation layer to a third preset temperature under the protection of full hydrogen, preserving heat, slowly cooling, discharging, and finishing secondary recrystallization and steel purification;

and (3) carrying out surface cleaning on the silicon steel thin strip after the furnace is discharged, coating an insulating coating, drying and sintering, finishing, checking, packaging and warehousing to obtain a finished product of the high-magnetic-induction oriented silicon steel ultrathin strip.

According to the preparation method and the system for the high-magnetic-induction oriented silicon steel ultrathin strip, required components of molten steel are melted to a certain temperature and uniformly stirred, the molten steel is uniformly poured onto a crystallization roller through a tundish (bottom pouring furnace), a nozzle bag and a nozzle, cooling water is introduced into the crystallization roller, and the molten alloy is instantly solidified through high-speed rotation of the crystallization roller, so that the ultrathin plane flow pouring steel strip is formed. Compared with the prior art, the invention has the following technical advantages:

(1) The ultra-fast solidification plane stream injection process and the ultra-fast cooling process are adopted to obtain the silicon steel ultra-thin strip, so that the process flow is shortened, and the energy conservation and the carbon reduction are facilitated; the ultra-fast solidification plane flow injection process solves the forming problem of the silicon steel thin strip, and the ultra-fast cooling process realizes the uniformity, fineness and dispersion of the precipitated phase in the silicon steel thin strip, thereby achieving the purpose of inhibiting the growth of primary recrystallized grains.

(2) The raw materials are designed by adopting ultra-low carbon components, so that a decarburization process of a post process is omitted;

(3) The whole process of the plane stream injection technology adopts protective atmosphere, so that the oxidation of the steel belt is avoided, and the subsequent working procedure does not need acid washing;

(4) The reducing rolling by a cold rolling mill effectively reduces the rolling force to improve the plate shape, and the sharp {111} <112> texture is easy to form in the rolling direction, and the high magnetic induction finished product is obtained after the high temperature heat treatment.

According to the technical advantages, the method is an ultra-short plane flow injection process, can realize rapid solidification of molten steel, and has the advantages of simple equipment, convenience in operation, large preparation amount, compact material, low cost and the like.

To the accomplishment of the foregoing and related ends, one or more aspects of the invention comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative aspects of the invention. These aspects are indicative, however, of but a few of the various ways in which the principles of the invention may be employed. Furthermore, the invention is intended to include all such aspects and their equivalents.

Drawings

Other objects and results of the present invention will become more apparent and readily appreciated by reference to the following description and claims in conjunction with the accompanying drawings and a more complete understanding of the invention. In the drawings:

FIG. 1 is a flow chart of a method for producing a very thin strip of high magnetic induction oriented silicon steel according to an embodiment of the present invention;

FIG. 2 is a process flow diagram of preparing a high magnetic induction oriented silicon steel ultrathin strip by planar streamer according to an embodiment of the invention; and

FIG. 3 is a flow chart of a conventional process for producing a high magnetic induction oriented silicon steel strip.

The same reference numerals will be used throughout the drawings to refer to similar or corresponding features or functions.

Detailed Description

In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more embodiments, so as to provide a thorough understanding of the technical problems, aspects, and advantages of the present invention. It will be apparent, however, that the embodiments may be practiced without these specific details, and that the specific embodiments described herein are merely illustrative of the invention and are not intended to be limiting of the invention. In other instances, well-known structures and devices are shown in block diagram form in order to facilitate describing one or more embodiments.

The invention provides a scheme for preparing the high-magnetic induction oriented silicon steel ultrathin strip based on a planar flow injection process, which aims to solve the problems of long process flow, low production efficiency, high production cost, low yield, accurate control of texture and precipitated phases in the preparation process and the like in the existing process technology of the high-magnetic induction oriented silicon steel ultrathin strip.

According to the invention, the plane flow injection steel strip is solidified and formed under the protection of argon, and is cooled under the protection of nitrogen, so that a silicon steel thin strip with fine grains, uniform structure, uniform precipitation of inhibitors such as MnS, alN and the like and dispersion is obtained; the silicon steel strip is rolled in a reducing way by a cold rolling mill, larger stress and strain gradient are generated in the silicon steel strip, so that the distortion in the cold rolled strip steel can be increased, the number of recrystallized grains taking the energy storage as a recrystallization driving force can be greatly increased during high-temperature annealing, more eta textures are provided, and the grains in the {110} <001> orientation are increased; in addition, due to the genetic effect of the texture, the perfect Gaussian texture is formed, and therefore the magnetic performance of the silicon steel ultrathin strip finished product is improved.

Specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

Fig. 1 and 2 respectively show a flow of a method for preparing a high magnetic induction oriented silicon steel ultrathin strip and a process flow of preparing the high magnetic induction oriented silicon steel ultrathin strip by planar flow casting according to an embodiment of the invention.

As shown in fig. 1 and fig. 2 together, the preparation method of the high magnetic induction oriented silicon steel ultrathin strip mainly comprises the following eight steps:

step S1: putting raw materials containing preset chemical components into a smelting furnace to be smelted into molten steel; wherein the raw materials comprise the following elements in percentage by mass: c is less than or equal to 0.0030 percent, si:2.5 to 6.5 percent, mn:0.15 to 0.25 percent, P is less than or equal to 0.015 percent, S:0.02% -0.05%, als:0.03 to 0.08 percent, cu:0.05 to 0.15 percent, N:0.006 to 0.015 percent, ti is less than or equal to 0.0030 percent, sn is less than or equal to 0.012 percent or Bi is less than or equal to 0.030 percent; the bias factor pj= (3×sn/50+bi/83) ×10000 composed of Sn and Bi satisfies the relationship: pj is more than or equal to 3.5 and less than or equal to 9.5, and the balance is iron and unavoidable impurities.

Wherein, in the process of putting raw materials containing preset chemical components into a smelting furnace to be smelted into molten steel, the temperature of the molten steel is controlled to be 1570-1670 ℃ in a specific embodiment of the invention.

Step S2: the molten steel is placed (e.g., poured) into a tundish (also known as a bottom pouring spout) to control the temperature and superheat of the molten steel.

The tundish has heating and heat preservation functions, and can conveniently control the superheat degree of molten steel. In one embodiment of the present invention, the temperature of the molten steel in the tundish is controlled within 1550-1650 ℃, a more preferred control temperature is 1530-1620 ℃, and the superheat degree of the molten steel is controlled within 25-55 ℃ by the tundish.

Step S3: preheating a nozzle package, lifting a flow control plug rod of the tundish after the preheating reaches the preheating temperature of the nozzle package, injecting molten steel in the tundish into the nozzle package, and opening a nozzle when the liquid level of the nozzle package reaches a preset height (for example, 240mm plus or minus 2 mm), so that the molten steel is sprayed onto a crystallization roller rotating at a high speed in a plane stream state to be solidified and formed into a plane stream steel belt; wherein argon protection is adopted in the process of plane flow injection of the molten steel.

In order to keep the temperature of the molten steel of the plane stream uniform in the plane retention process and improve the solidification effect, the natural gas is required to be ignited to preheat the nozzle bag before the injection is started, and the injection can be started only when the certain temperature is reached.

Specifically, as an example, the nozzle packet preheating temperature ty=1200-45×si, in degrees celsius, may be determined from Si%. In one embodiment of the present invention, the preheating temperature of the nozzle pack is controlled to 900-1100 ℃.

And in the process of opening the nozzle to spray the molten steel onto the crystallization roller rotating at a high speed in a plane stream state to solidify and form the plane stream steel strip, controlling the fluctuation range of the liquid level in the nozzle package and the linear speed at the roller surface of the crystallization roller. Specifically, by way of example, in one embodiment of the invention, the linear velocity at the face of the crystallization roll vx=300+ (55- Δt)/δm×4 in m/min, where Δt is the degree of superheat in degrees celsius; δm is the target thickness of the cast strip, and the unit is mm; the fluctuation range of the liquid level in the nozzle bag is controlled to be +/-2 mm, and the linear speed at the roller surface of the crystallization roller is controlled to be 300-1200 m/min.

Step S4: and enabling the plane flow injection steel strip to enter a nitrogen protection area for cooling, and automatically coiling the plane flow injection steel strip through a coiling machine after cooling to obtain a silicon steel strip coil.

In the process of the plane stream, namely from the initial position of the plane stream to the forming position of the steel strip, argon is adopted for protection. Specifically, the flow rate ya=12+Deltat/2 of argon can be controlled according to the molten steel smelting temperature Tg, and the unit is L/min; the steel strip with plane flow injection enters a nitrogen protection area to be cooled to be below 200 ℃, and is automatically coiled by a coiling machine, so that the silicon steel strip coil with the thickness of 0.08-0.18 mm can be obtained.

Step S5: and carrying out reducing rolling on the silicon steel thin strip coil on a cold rolling mill to obtain a cold rolled silicon steel thin strip coil.

In the process of reducing rolling the silicon steel thin strip coil on a cold rolling mill, the roller diameter ratio lambda=400×δs/tau of reducing rolling, wherein s is the actual thickness of the cast strip, the unit is mm, and tau is the cold rolling target rolling reduction; the roller diameter ratio is controlled to be 0.8-1.8; the reduction rate of the reducing rolling is controlled between 35% and 60%. The thickness of the silicon steel thin strip coil obtained after cold rolling is 0.05-0.10 mm, and the thickness of the silicon steel thin strip coil is further reduced.

Step S6: introducing the cold-rolled silicon steel thin strip into a continuous annealing furnace, heating to a first preset temperature to finish primary recrystallization, and then coating Al after the steel strip is cooled to a second preset temperature ₂ O ₃ And (3) drying the isolation layer liquid and cooling to normal temperature.

Wherein the first preset temperature is 750-950 ℃, after the cold rolled silicon steel thin strip is introduced into a continuous annealing furnace and heated to the first preset temperature, the heat preservation time is 25-60 s, the silicon steel thin strip is cooled to normal temperature, and the silicon steel thin strip is subjected to the heat preservation in the furnace atmosphere N of the continuous annealing furnace ₂ 、H ₂ Mixing dry gas, H ₂ /N ₂ Coating Al on the silicon steel thin strip coil in an environment with the volume ratio of 20-80% ₂ O ₃ And (5) separating the layer liquid, drying and cooling to normal temperature.

Step S7: will be coated with Al ₂ O ₃ The silicon steel thin strip coil of the isolation layer is placed into a high-temperature bell-type furnace, heated to a third preset temperature under the protection of full hydrogen, kept warm, slowly cooled and discharged, and secondary recrystallization and steel purification are completed. Specifically, as an example, the third temperature is 1050-1200 ℃, the heat preservation time is 2.5-25 h, and the furnace can be discharged after slow cooling to below 200 ℃.

And finally, detecting the magnetic property of the finished product of the oriented silicon steel ultrathin strip.

The working principle of the invention is as follows:

the invention relates to a plane flow injection process of an ultra-short flow, namely, required component molten steel is melted to a certain temperature and stirred uniformly, and then evenly flows onto a crystallization roller sequentially through a tundish (bottom injection furnace), a nozzle bag and a nozzle, cooling water is introduced into the crystallization roller, and alloy molten steel is instantly solidified through high-speed rotation of the crystallization roller to form a silicon steel ultrathin strip, so that the silicon steel ultrathin strip formed by the plane flow injection process is also called a plane flow injection steel strip.

The plane flow injection steel strip is solidified and formed under the protection of argon, and is cooled under the protection of nitrogen, so that a silicon steel thin strip with fine grains, uniform tissues, uniform precipitation of inhibitors such as MnS, alN and the like and dispersion is obtained; the silicon steel strip is rolled in a reducing way by a cold rolling mill, larger stress and strain gradient are generated in the silicon steel strip, so that the distortion in the cold rolled strip steel can be increased, the number of recrystallized grains taking the energy storage as a recrystallization driving force can be greatly increased during high-temperature annealing, more eta textures are provided, and the grains in the {110} <001> orientation are increased; in addition, due to the genetic effect of the texture, the formation of a perfect Gaussian texture is facilitated, and the magnetic performance is improved.

In addition, the surface energy plays an important role in grain growth due to the high surface and volume ratio of the silicon steel thin strip. The grain surface energies of the different orientations are different, which is related to the atomic dense face. Grains with low surface energy can grow preferentially. (110) The surface energy of the face grains is lowest, next to the (100) face, the highest is the (111) face. The thinner the plate band, the greater the effect of the surface energy, the greater the driving force for the growth of recrystallized grains, which is readily carried out. When the non-oriented silicon steel thin strip is produced, due to the fact that the capability of adsorbing impurity atoms on the free surfaces of crystal grains of different crystal faces is different, by controlling the atmosphere during annealing, a small amount of strong polar gas hydrogen sulfide is added into a pure hydrogen atmosphere to be adsorbed to crystal grains of different directions as impurities. Adsorbed hydrogen sulfide gas may cause a decrease in the surface energy of the crystal grains. And among the crystal faces, the (100) face is most easy to adsorb, so that the surface energy of the (100) face crystal grains is the lowest, the oriented crystal grains are preferentially larger than the (110) face, and the development of Goss texture which is beneficial to the performance of the oriented silicon steel is inhibited.

Compared with common oriented silicon steel, the oriented high silicon steel has the problems of insufficient precipitation of the conventional inherent inhibitors (MnS, mnSe, alN and the like), limited addition of grain boundary segregation elements (Sn, sb and the like) and the like, so that the matching difficulty of the texture-inhibitor in the high-temperature annealing process is increased. Therefore, selecting proper inhibitors and matching reasonable tissue and texture control processes is a key to developing a rapid annealing mode for preparing oriented high silicon steel technology. In the preparation process of the oriented high silicon steel, the inhibitor is dispersed and separated out in the hot rolling stage, and is dissolved back and coarsened in the subsequent deformation and annealing processes. In the primary recrystallization process, the inhibitor regulates and controls the growth behavior of crystal grains and refines tissues. In the final annealing stage, the inhibitor blocks the growth of matrix grains, induces abnormal growth of certain oriented grains, and finally completes secondary recrystallization.

The following conditions need to be met by selecting a suitable inhibitor:

(1) Before the secondary recrystallization starts, the inhibitor is used as second phase particles and is uniformly distributed on the grain boundaries of the recrystallized grains;

(2) In the secondary recrystallization process, the inhibitor is cured along with the rise of temperature, and the capability of pinning grain boundaries is reduced;

(3) The inhibitor can be decomposed at high temperature and under special atmosphere, so that the influence on the magnetic properties of the alloy is reduced.

Wherein, the failure behavior of the inhibitor in the hot rolling precipitation and secondary recrystallization annealing process is a key factor for determining the secondary recrystallization behavior and quality. Therefore, the chemical composition of the present invention adopts a combination of the conventional intrinsic inhibitor (MnS, alN, cu S) and the grain boundary segregation elements (Sn, bi), thereby further enhancing the effect of the precipitated phase.

Table 1 below shows the chemical compositions and the list of the polymerization factors of each of the examples and the comparative examples

TABLE 1

As shown in table 1 above, it is possible to obtain:

1) The bias factor pj= (3×sn/50+bi/83) ×10000;

2) Comparative example 1 the comparative example of example 1 was obtained as s=0.065% higher than S of example 1; comparative example 2 was the comparative example of example 6 because n=0.0023% was lower than n=0.0129% of example 6; comparative example 3 was a comparative example of example 8 because of no Sn and no Bi; comparative example 4 the comparative example of example 10 was obtained because ti=0.0048% > 0.0030%.

Table 2 below is a list of process parameters carried out in each of the examples and comparative examples

Table 2 (I)

In table 2 (one) above, the degree of superheat Δt=tg-Td of the molten steel at the bottom pouring, in units of °c; nozzle preheating temperature ty=1200-45×si, in units of °c; the crystallization roll linear velocity vx=300+ (55- Δt)/δm×4 in m/min; argon flow ya=12+. DELTA.t/2 in L/min.

Table 2 (II)

In the above table (two), the cold rolling target reduction τ= (δm—δl)/δm; the roll diameter ratio λ=400×δs/τ of the reducing rolling.

The invention adopts reducing rolling, the texture components are basically similar to synchronous rolling, but the difference is made in the intensity and symmetry of the texture distribution, and the reducing rolling is helpful for improving the cold rolling texture, so that the gamma texture of the slow roller side is reinforced. Alpha texture is inhibited and the increase is not linearly incremental with increasing asynchronous speed ratio. The formation and distribution of the cold rolled texture of the metal is thus closely linked to the stress state of the deformation zone.

Under the condition of reducing rolling, a rubbing-rolling area is formed in the deformation area due to the opposite directions of the friction force of the upper roller and the lower roller on steel. This shearing causes some shear strain. Since the shear strain acts in opposite directions in adjacent passes of the metal deformation, the effect of the shear strain on the strip after a reciprocal reversible rolling process may be substantially counteracted. Namely, under the condition of reducing rolling, the external force acting on the deformation zone is still mainly based on rolling pressure, and the texture still has good macroscopic statistics, so the rotation mode of crystal grains and the cold rolling texture composition have a plurality of similarities with synchronous rolling. However, under the condition of reducing rolling, the cold rolling texture component is asymmetric in the thickness direction due to the existence of a rubbing rolling area. Under the synchronous rolling condition, the surface layer and the middle layer of the thin strip have alpha textures with certain strength and quantity, and the components are stable in the subsequent high-temperature annealing process, so that the development of the three-time recrystallized Gaussian texture is not facilitated. However, the strength of these components is relatively low (the subsurface layers are substantially equal) under reducing rolling conditions and there is no concentration in the (001) <110> orientation, indicating that shear strain can effectively suppress the formation of the detrimental texture components. Meanwhile, the shear strain relatively increases the strength and the quantity of the {111} <112> textures of the surface layer and the middle layer, and the shear deformation of the surface layer of the cold-rolled sheet is more obvious because the pass reduction rate is higher than that of synchronous rolling, so that the enhancement of the texture components is beneficial to the occurrence of three times of recrystallization. The speed ratio is increased and the eta texture is increased. As the asynchronous speed ratio increases, the number of Goss nuclei increases.

Table 3 below is a list of the detected magnetic properties of each of the examples and comparative examples.

TABLE 3 Table 3

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As is clear from table 3 above, comparative example 1 was the comparative example of example 2 because s=0.065% was higher than s=0.046% of example 2, and the magnetic properties b800=1.94 t, p1.0/400=6.40W/Kg of example 2 were significantly better than the magnetic properties b800=1.84 t, p1.0/400=7.22W/Kg of comparative example 1; comparative example 2 the magnetic properties b800=1.84 t, p1.0/400=6.12W/Kg of example 6 are significantly better than those b800=1.78 t, p1.0/400=7.60W/Kg of comparative example 2, since n=0.0023% is lower than n=0.0129% of example 6 to be the comparative example of example 6; comparative example 3 was a comparative example of example 8 (Sn: 0.0091%, bi: 0.015%) in that the magnetic properties b800=1.78 t, p1.0/400=6.50W/Kg of example 8 were significantly better than those of comparative example 3, b800=1.66 t, p1.0/400=6.84W/Kg; comparative example 4 the magnetic properties b800=1.74 t, p1.0/400=5.60W/Kg of example 10 are significantly better than those b800=1.56 t, p1.0/400=7.81W/Kg of comparative example 4 because ti=0.0048% >0.0030% is the comparative example of example 10. Compared with the comparative example, the high magnetic induction oriented high silicon steel ultrathin strip obtained by the embodiment of the invention has excellent magnetic performance.

The method for preparing the high magnetic induction oriented silicon steel ultrathin strip according to the invention is described above with reference to fig. 1 and 2, and the invention also provides a high magnetic induction oriented silicon steel ultrathin strip preparation system applying the method for preparing the high magnetic induction oriented silicon steel ultrathin strip, which mainly comprises a smelting furnace, a tundish, a nozzle pack, a nozzle, a crystallization roller, a coiling machine, a cold rolling mill, a continuous annealing furnace, a high-temperature bell type furnace and other equipment.

For a more specific implementation manner of the above-mentioned high magnetic induction oriented silicon steel ultrathin strip preparation system, reference may be made to the foregoing description of the embodiment of the high magnetic induction oriented silicon steel ultrathin strip preparation method, which is not described in detail herein.

The method and system for manufacturing the high magnetic induction oriented silicon steel ultra-thin strip according to the present invention are described above by way of example with reference to the accompanying drawings. However, it should be understood by those skilled in the art that various modifications can be made to the above-mentioned method and system for producing a high magnetic induction oriented silicon steel strip according to the present invention without departing from the present invention. Accordingly, the scope of the invention should be determined from the following claims.

Claims

1. The preparation method of the high magnetic induction oriented silicon steel ultrathin strip is characterized by comprising the following steps of:

2. The method for preparing the high magnetic induction oriented silicon steel ultrathin strip according to claim 1, wherein the method comprises the steps of,

in the process of putting raw materials containing preset chemical components into a smelting furnace to be smelted into molten steel, controlling the temperature of the molten steel in the smelting furnace to be 1570-1670 ℃;

the temperature of the molten steel in the tundish in the step S2 is controlled to 1550-1650 ℃.

3. The method for producing a very thin strip of high magnetic induction oriented silicon steel as claimed in claim 2, wherein the temperature of the molten steel in the tundish is controlled to 1530-1620 ℃ and the superheat degree of the molten steel is controlled to 25-55 ℃ in step S2.

4. The method for producing a very thin strip of high magnetic induction oriented silicon steel as claimed in claim 1, wherein in step S3, the preheating temperature Ty of the nozzle package is determined to be about 1200 to 45 x Si% in terms of Si% and the preheating temperature of the nozzle package is controlled to be 900 to 1100 ℃.

5. The method for producing an extremely thin strip of high magnetic induction oriented silicon steel as claimed in claim 1, characterized in that in the process of opening a nozzle to spray the molten steel in a plane stream state onto a crystallization roller rotating at a high speed to solidify and form a plane stream steel strip, the fluctuation range of the liquid level in the nozzle package and the linear velocity at the roller surface of the crystallization roller are controlled; wherein,,

6. The method for producing a very thin strip of high magnetic induction oriented silicon steel as claimed in claim 5, characterized in that,

argon protection is adopted in the process of plane flow injection of the molten steel, and the flow rate ya=12+ [ delta ] t/2 of the argon is controlled according to the melting temperature Tg of the molten steel, wherein the unit is L/min;

7. The method for producing a high magnetic induction oriented silicon steel strip according to claim 5, wherein, in the process of reducing rolling the silicon steel strip coil on a cold rolling mill,

8. The method for producing a very thin strip of high magnetic induction oriented silicon steel as claimed in claim 5, characterized in that,

the first preset temperature is 750-950 ℃, after the cold rolled silicon steel thin strip is introduced into a continuous annealing furnace and heated to the first preset temperature, the heat preservation time is 25-60 s, the silicon steel thin strip is cooled to normal temperature, and the furnace atmosphere N of the continuous annealing furnace is obtained ₂ 、H ₂ Mixing dry gas, H ₂ /N ₂ Coating Al on the silicon steel thin strip coil in an environment with the volume ratio of 20-80% ₂ O ₃ And (5) separating the layer liquid, drying and cooling to normal temperature.

9. The method for producing a very thin strip of high magnetic induction oriented silicon steel as claimed in claim 5, wherein the third temperature is 1050-1200 ℃, the holding time is 2.5-25 h, and the strip is gradually cooled to below 200 ℃ and discharged from the furnace.

10. A preparation system of a high magnetic induction oriented silicon steel ultrathin strip is characterized by comprising a smelting furnace, a tundish, a crystallization roller, a coiling machine, a cold rolling mill, a continuous annealing furnace and a high-temperature bell-type furnace, wherein,

the high temperature bell-type furnace is used for coating Al ₂ O ₃ Heating the silicon steel thin strip coil of the isolation layer to a third preset temperature under the protection of full hydrogen, preserving heat, slowly cooling, discharging, and finishingSecondary recrystallization and steel purification are carried out;