High-grade non-oriented silicon steel annealing process control method

Abstract

The application discloses a continuous annealing process control method for high-grade non-oriented silicon steel, which comprises the following steps: (1) grading heating, grading annealing process under the action of a protective atmosphere, including a temperature rising preheating process, a radiation heating annealing process and a soaking annealing process; (2) sectional cooling; and (3) dew point temperature control, wherein the dew point of the atmosphere in the annealing process is controlled to be between-30 and-15 DEG C. The application aims to provide an annealing process control method for high-grade non-oriented silicon steel, and high magnetic induction, low iron loss and good surface quality are obtained.

Description

Technical Field

[0001] This invention relates to a method for controlling the annealing process of high-grade non-oriented silicon steel. Background Technology

[0002] To meet the growing demand for high-efficiency motor steel, steel for new energy vehicle drive motors, and the need to reduce generator and motor losses, high-grade non-oriented silicon steel is widely used, with its thickness gradually decreasing as application frequency increases. High-grade non-oriented silicon steel has high Si and Al content, and the annealing process directly affects its magnetic properties, surface quality, and coating performance. Continuous annealing process control methods can determine the annealing heating zone temperature, cooling zone cooling rate, and atmosphere dew point, providing guidance for industrial annealing production and enabling the production of high-performance, high-grade non-oriented silicon steel.

[0003] Currently, application number 201410010968.2 discloses an annealing method for high-grade electrical steel, focusing on a method of using an aluminum plate-made asbestos insulation board lined with a square cylindrical inner shell to insulate hot-rolled coils, replacing the normalizing process. This invention elaborates on the fabrication of the protective cover, the composition of the insulating material, and the implementation of the insulation process, providing guidance for non-normalizing annealing.

[0004] Application No. 202111652927.X discloses a method for producing high-grade non-oriented silicon steel 50BW350 using a bell-type intermediate annealing process, detailing steps such as chemical composition design, hot rolling, cold rolling, and annealing. This invention focuses on adjusting the chemical composition, secondary cold rolling, and bell-type intermediate annealing to improve the magnetic properties and surface quality of 50BW350.

[0005] Application No. 201110415947.5 discloses a method for producing high-grade non-oriented silicon steel, describing the entire production process from smelting, continuous casting, hot rolling, coiling, normalizing, secondary cold rolling, annealing and cooling, coating, to finishing. This invention details the effects of lower process heat treatment temperatures, lower normalizing temperatures, intermediate annealing temperatures, and lower finished product annealing temperatures on the properties of the finished product. It is comprehensive and provides a detailed description of the production process for high-grade non-oriented silicon steel. Summary of the Invention

[0006] The purpose of this invention is to provide a method for controlling the annealing process of high-grade non-oriented silicon steel to obtain high magnetic induction, low iron loss, and good surface quality.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] This invention discloses a method for controlling the annealing process of high-grade non-oriented silicon steel, comprising:

[0009] (1) Staged heating

[0010] The graded annealing process under a protective atmosphere includes a preheating process, a radiation heating annealing process, and a soaking annealing process, among which:

[0011] The aforementioned preheating process conditions are: 500-750℃, and the steel strip residence time is 10-20s;

[0012] The radiation heating annealing process conditions are as follows: Heating section 1: 800-1000℃, steel strip dwell time 20-60s; Heating section 2: 1000-1050℃, steel strip dwell time 30-40s.

[0013] The homogenization annealing process conditions are as follows: the heat treatment temperature is controlled between 950-1050℃, and the strip dwell time is 1-10min.

[0014] (2) Segmented cooling

[0015] Under a reducing atmosphere, the strip steel is slowly cooled from the initial annealing cooling temperature to 800-900℃ in the tube cooling section at a cooling rate of 9-10℃ / s at the maximum process speed of the unit; then, the strip steel is cooled from 800-900℃ to 450-550℃ in the controlled cooling section at a cooling rate of 13-17℃ / s at the maximum process speed of the unit; finally, the strip steel is cooled from 450-550℃ to 100-150℃ in the rapid cooling section at a cooling rate of 22-26℃ / s at the maximum process speed of the unit.

[0016] (3) Dew point temperature control

[0017] During the annealing process, the atmosphere dew point is controlled at -30 to -15℃.

[0018] Furthermore, in (2), the tube cooling section uses heat-resistant alloy radiant tubes spliced ​​together in a horizontally staggered arrangement for indirect cooling. The indirect cooling is achieved by using a fan to draw in the heat and remove it, thus slowly reducing the furnace temperature.

[0019] Furthermore, in (2), the controlled cooling and rapid cooling sections use 10 and 8 cooling fans respectively to spray and cool the strip above and below, so that the strip is cooled evenly.

[0020] Furthermore, in step (2), the protective atmosphere for the annealing process is a single-component hydrogen or nitrogen gas, or a mixture of hydrogen and nitrogen gas.

[0021] Furthermore, the mass concentration of hydrogen in the mixed gas is between 0% and 25%.

[0022] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0023] The beneficial effect of this invention is that by using graded heating, segmented cooling, and controlled dew point temperature, it is possible to obtain high-grade non-oriented silicon steel with high magnetic induction intensity, low iron loss, and good surface quality. Attached Figure Description

[0024] The present invention will be further described below with reference to the accompanying drawings.

[0025] Figure 1 The annealed metallographic structure is shown in Example 3. Detailed Implementation

[0026] To better explain the present invention, the main contents of the present invention are further illustrated below with reference to specific embodiments.

[0027] Tables 1 and 2 show the process parameters for Examples 1-3 and Comparative Examples 1-3 in the continuous annealing heating and cooling sections, respectively.

[0028] Table 1. Process parameters of the continuous annealing heating section in various embodiments and comparative examples of the present invention.

[0029]

[0030] Table 2. Continuous annealing cooling section and dew point process parameters for each embodiment and comparative example of the present invention.

[0031]

[0032] The product performance obtained by the processes of Examples 1-3 and Comparative Examples 1-3 are shown in Table 3.

[0033] Table 3 Performance results of the products prepared in each embodiment and comparative example of the present invention

[0034]

[0035]

[0036] As shown in Table 3, the embodiments of the present invention, while ensuring that the main process parameters are all within the specified range, can obtain high-grade non-oriented silicon steel products with good magnetic properties, surface quality, and coating. Among them, the magnetic induction B... 50 The iron loss P is 1.70-1.73T. 1.5 / 50 The concentration is 3.45-3.55 W / kg, P 1.0 / 400 With a strength of 18.45-21.52 W / kg, the surface quality and coating quality were improved while ensuring good magnetic properties.

[0037] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for controlling the annealing process of high-grade non-oriented silicon steel, characterized in that: include: (1) Staged heating The graded annealing process under a protective atmosphere includes a preheating process, a radiation heating annealing process, and a soaking annealing process, wherein: The preheating process conditions are: 500-750℃, and the steel strip residence time is 10-20 s; The radiation heating annealing process conditions are as follows: Heating section 1: 800-1000℃, steel strip dwell time 20-60 s; Heating section 2: 1000-1050℃, steel strip dwell time 30-40 s. The homogenization annealing process conditions are as follows: the heat treatment temperature is controlled between 950-1050℃, and the strip dwell time is 1-10min. (2) Segmented cooling Under a reducing atmosphere, the strip steel is slowly cooled from the annealing cooling start temperature to 800-900℃ in the tube cooling section at a cooling rate of 9-10℃ / s at the maximum process speed of the unit; then, the strip steel is cooled from 800-900℃ to 450-500℃ in the controlled cooling section at a cooling rate of 13-17℃ / s at the maximum process speed of the unit; finally, the strip steel is cooled from 450-500℃ to 100-150℃ in the rapid cooling section at a cooling rate of 22-26℃ / s at the maximum process speed of the unit. (3) Dew point temperature control During the annealing process, the atmosphere dew point is controlled at -30 to -15°C; High-grade non-oriented silicon steel magnetic induction B 50 The iron loss is 1.70-1.73 T, and the iron loss is P. 1.5 / 50 The concentration is 3.45-3.55 W / kg, P 1.0 / 400 It ranges from 18.45 to 21.52 W / kg.

2. The method for controlling the annealing process of high-grade non-oriented silicon steel according to claim 1, characterized in that: In (2), the tube cooling section uses heat-resistant alloy radiant tubes spliced ​​together in a horizontally staggered arrangement to achieve indirect cooling. The indirect cooling is achieved by using a fan to draw in the heat and remove it, so as to slowly reduce the furnace temperature.

3. The method for controlling the annealing process of high-grade non-oriented silicon steel according to claim 1, characterized in that: In (2), 10 and 8 cooling fans are used in the controlled cooling and rapid cooling sections to spray and cool the strip above and below, respectively, so that the strip is cooled evenly.

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